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skia2/docs/SkImageInfo_Reference.bmh
Cary Clark a4f581a475 fix global method indentation 
Check to see if a method is inside a struct or class
before increasing its indentation. Also, add missing
description.

Docs-Preview: https://skia.org/?cl=118381
Bug: skia:6898
Change-Id: I9402442a89dafc96d87bf69f157dcfa40cdf6e2b
Reviewed-on: https://skia-review.googlesource.com/118381
Commit-Queue: Cary Clark <caryclark@skia.org>
Reviewed-by: Cary Clark <caryclark@skia.org>
2018-04-03 20:02:25 +00:00

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#Topic Image_Info
#Alias Image_Info_Reference
Image_Info specifies the dimensions and encoding of the pixels in a Bitmap.
The dimensions are integral width and height. The encoding is how pixel
bits describe Color_Alpha, transparency; Color components red, blue,
and green; and Color_Space, the range and linearity of colors.
Image_Info describes an uncompressed raster pixels. In contrast, Image
additionally describes compressed pixels like PNG, and Surface describes
destinations on the GPU. Image and Surface may be specified by Image_Info,
but Image and Surface may not contain Image_Info.
#Subtopic Overview
#Subtopic Subtopic
#Populate
##
##
#Subtopic Constant
#Populate
##
# ------------------------------------------------------------------------------
#Subtopic Alpha_Type
#Line # encoding for pixel transparency ##
#Alias Alpha_Type
#Alias Alpha_Types
#PhraseDef list_of_alpha_types
kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType,
kUnpremul_SkAlphaType
##
#Enum SkAlphaType
#Line # encoding for pixel transparency ##
#Code
enum SkAlphaType {
kUnknown_SkAlphaType,
kOpaque_SkAlphaType,
kPremul_SkAlphaType,
kUnpremul_SkAlphaType,
kLastEnum_SkAlphaType = kUnpremul_SkAlphaType,
};
##
Describes how to interpret the alpha component of a pixel. A pixel may
be opaque, or Color_Alpha, describing multiple levels of transparency.
In simple blending, Color_Alpha weights the draw color and the destination
color to create a new color. If alpha describes a weight from zero to one:
#Formula
new color = draw color * alpha + destination color * (1 - alpha)
##
In practice alpha is encoded in two or more bits, where 1.0 equals all bits set.
Color_RGB may have Color_Alpha included in each component value; the stored
value is the original Color_RGB multiplied by Color_Alpha. Premultiplied color
components improve performance.
#Const kUnknown_SkAlphaType 0
Alpha_Type is uninitialized.
##
#Const kOpaque_SkAlphaType 1
Pixels are opaque. The Color_Type must have no explicit alpha
component, or all alpha components must be set to their maximum value.
##
#Const kPremul_SkAlphaType 2
Pixels have alpha premultiplied into color components.
Surface pixels must be premultiplied.
##
#Const kUnpremul_SkAlphaType 3
Pixel color component values are independent of alpha value.
Images generated from encoded data like PNG do not premultiply pixel color
components. kUnpremul_SkAlphaType is supported for Image pixels, but not for
Surface pixels.
##
#NoExample
##
#SeeAlso SkColorType SkColorSpace
#Enum SkAlphaType ##
#Subtopic Opaque
Use Opaque as a hint to optimize drawing when alpha component
of all pixel is set to its maximum value of 1.0; all alpha component bits are set.
If Image_Info is set to Opaque but all alpha values are not 1.0, results are
undefined.
#Example
#Height 64
#Description
SkPreMultiplyARGB parameter a is set to 255, its maximum value, and is interpreted
as Color_Alpha of 1.0. kOpaque_SkAlphaType may be set to improve performance.
If SkPreMultiplyARGB parameter a is set to a value smaller than 255,
kPremul_SkAlphaType must be used instead to avoid undefined results.
The four displayed values are the original component values, though not necessarily
in the same order.
##
SkPMColor color = SkPreMultiplyARGB(255, 50, 100, 150);
SkString s;
s.printf("%u %u %u %u", SkColorGetA(color), SkColorGetR(color),
SkColorGetG(color), SkColorGetB(color));
SkPaint paint;
paint.setAntiAlias(true);
canvas->drawString(s, 10, 62, paint);
canvas->scale(50, 50);
SkBitmap bitmap;
SkImageInfo imageInfo = SkImageInfo::Make(1, 1, kN32_SkColorType, kOpaque_SkAlphaType);
if (bitmap.installPixels(imageInfo, (void*) &color, imageInfo.minRowBytes())) {
canvas->drawBitmap(bitmap, 0, 0);
}
##
#Subtopic Opaque ##
#Subtopic Premul
Use Premul when stored color components are the original color multiplied by the
alpha component. The alpha component range of 0.0 to 1.0 is achieved by dividing
the integer bit value by the maximum bit value.
#Formula
stored color = original color * alpha / max alpha
##
The color component must be equal to or smaller than the alpha component,
or the results are undefined.
#Example
#Description
SkPreMultiplyARGB parameter a is set to 150, less than its maximum value, and is
interpreted as Color_Alpha of about 0.6. kPremul_SkAlphaType must be set, since
SkPreMultiplyARGB parameter a is set to a value smaller than 255,
to avoid undefined results.
The four displayed values reflect that the alpha component has been multiplied
by the original color.
##
#Height 64
SkPMColor color = SkPreMultiplyARGB(150, 50, 100, 150);
SkString s;
s.printf("%u %u %u %u", SkColorGetA(color), SkColorGetR(color),
SkColorGetG(color), SkColorGetB(color));
SkPaint paint;
paint.setAntiAlias(true);
canvas->drawString(s, 10, 62, paint);
canvas->scale(50, 50);
SkBitmap bitmap;
SkImageInfo imageInfo = SkImageInfo::Make(1, 1, kN32_SkColorType, kPremul_SkAlphaType);
if (bitmap.installPixels(imageInfo, (void*) &color, imageInfo.minRowBytes())) {
canvas->drawBitmap(bitmap, 0, 0);
}
##
#Subtopic Premul ##
#Subtopic Unpremul
Use Unpremul if stored color components are not divided by the alpha component.
Some drawing destinations may not support Unpremul.
#Bug 7079
#Example
#Height 64
#Description
SkColorSetARGB parameter a is set to 150, less than its maximum value, and is
interpreted as Color_Alpha of about 0.6. color is not premultiplied;
color components may have values greater than color alpha.
The four displayed values are the original component values, though not necessarily
in the same order.
##
SkColor color = SkColorSetARGB(150, 50, 100, 255);
SkString s;
s.printf("%u %u %u %u", SkColorGetA(color), SkColorGetR(color),
SkColorGetG(color), SkColorGetB(color));
SkPaint paint;
paint.setAntiAlias(true);
canvas->drawString(s, 10, 62, paint);
canvas->scale(50, 50);
SkBitmap bitmap;
SkImageInfo imageInfo = SkImageInfo::Make(1, 1, kN32_SkColorType, kUnpremul_SkAlphaType);
if (bitmap.installPixels(imageInfo, (void*) &color, imageInfo.minRowBytes())) {
canvas->drawBitmap(bitmap, 0, 0);
}
##
#Subtopic Unpremul ##
#Method static inline bool SkAlphaTypeIsOpaque(SkAlphaType at)
#In Property
#Line # returns if Alpha_Type equals kOpaque_SkAlphaType ##
Returns true if Alpha_Type equals kOpaque_SkAlphaType. kOpaque_SkAlphaType is a
hint that the Color_Type is opaque, or that all Color_Alpha values are set to
their 1.0 equivalent. If Alpha_Type is kOpaque_SkAlphaType, and Color_Type is not
opaque, then the result of drawing any pixel with a Color_Alpha value less than
1.0 is undefined.
#Param at one of: #list_of_alpha_types#
##
#Return true if at equals kOpaque_SkAlphaType ##
#NoExample
##
##
#Subtopic Alpha_Type ##
# ------------------------------------------------------------------------------
#Subtopic Color_Type
#Line # encoding for pixel color ##
#Alias Color_Type
#Alias Color_Types
#PhraseDef list_of_color_types
kUnknown_SkColorType, kAlpha_8_SkColorType, kRGB_565_SkColorType,
kARGB_4444_SkColorType, kRGBA_8888_SkColorType, kRGB_888x_SkColorType,
kBGRA_8888_SkColorType, kRGBA_1010102_SkColorType, kRGB_101010x_SkColorType,
kGray_8_SkColorType, kRGBA_F16_SkColorType
##
#Subtopic Native
#Alias Native_Color_Type
#Substitute native SkColorType
##
#Enum SkColorType
#Line # encoding for pixel color ##
#Code
enum SkColorType {
kUnknown_SkColorType,
kAlpha_8_SkColorType,
kRGB_565_SkColorType,
kARGB_4444_SkColorType,
kRGBA_8888_SkColorType,
kRGB_888x_SkColorType,
kBGRA_8888_SkColorType,
kRGBA_1010102_SkColorType,
kRGB_101010x_SkColorType,
kGray_8_SkColorType,
kRGBA_F16_SkColorType,
kLastEnum_SkColorType = kRGBA_F16_SkColorType,
###$
#if SK_PMCOLOR_BYTE_ORDER(B,G,R,A)
kN32_SkColorType = kBGRA_8888_SkColorType,
#elif SK_PMCOLOR_BYTE_ORDER(R,G,B,A)
kN32_SkColorType = kRGBA_8888_SkColorType,
#else
#error "SK_*32_SHIFT values must correspond to BGRA or RGBA byte order"
#endif
$$$#
};
#Code ##
Describes how pixel bits encode color. A pixel may be an alpha mask, a
gray level, Color_RGB, or Color_ARGB.
kN32_SkColorType selects the native 32-bit Color_ARGB format. On Little_Endian
processors, pixels containing 8-bit Color_ARGB components pack into 32-bit
kBGRA_8888_SkColorType. On Big_Endian processors, pixels pack into 32-bit
kRGBA_8888_SkColorType.
#Const kUnknown_SkColorType 0
Color_Type is uninitialized; encoding format and size is unknown.
##
#Const kAlpha_8_SkColorType 1
Encodes Color_Alpha as Alpha_8 pixel in an 8-bit byte.
##
#Const kRGB_565_SkColorType 2
Encodes Color_RGB as BGR_565 pixel in a 16-bit word.
##
#Const kARGB_4444_SkColorType 3
Encodes Color_ARGB as ABGR_4444 pixel in a 16-bit word.
##
#Const kRGBA_8888_SkColorType 4
Encodes Color_ARGB as RGBA_8888 pixel in a 32-bit word.
##
#Const kRGB_888x_SkColorType 5
Encodes Color_RGB as RGB_888x pixel in a 32-bit word.
##
#Const kBGRA_8888_SkColorType 6
Encodes Color_ARGB as BGRA_8888 pixel in a 32-bit word.
##
#Const kRGBA_1010102_SkColorType 7
Encodes Color_ARGB as RGBA_1010102 pixel in a 32-bit word.
##
#Const kRGB_101010x_SkColorType 8
Encodes Color_RGB as RGB_101010x pixel in a 32-bit word.
##
#Const kGray_8_SkColorType 9
Encodes Color_Gray as Gray_8 in an 8-bit byte.
##
#Const kRGBA_F16_SkColorType 10
Encodes Color_ARGB as RGBA_F16 in a 64-bit word.
##
#ToDo can be 4 or 6; how to document? ##
#Const kN32_SkColorType 4
Encodes Color_ARGB as either RGBA_8888 or BGRA_8888, whichever
is native to the platform.
##
#NoExample
##
#SeeAlso SkAlphaType SkColorSpace
#Enum SkColorType ##
#Subtopic Alpha_8
Alpha_8 is an 8-bit byte pixel encoding that represents transparency. A value of zero is
completely transparent; a value of 255 is completely opaque. Bitmap with Alpha_8
pixels does not visibly draw, because its pixels have no color information.
The paired SkAlphaType is ignored.
#Example
#Description
Alpha_8 pixels can modify another draw. orangePaint fills the bounds of bitmap,
with its transparency set to alpha8 pixel value.
##
#Height 64
canvas->scale(16, 16);
SkBitmap bitmap;
SkImageInfo imageInfo = SkImageInfo::Make(2, 2, kAlpha_8_SkColorType, kOpaque_SkAlphaType);
bitmap.allocPixels(imageInfo);
SkCanvas offscreen(bitmap);
offscreen.clear(SK_ColorGREEN);
SkPaint orangePaint;
orangePaint.setARGB(0xFF, 0xFF, 0xA5, 0x00);
canvas->drawBitmap(bitmap, 0, 0, &orangePaint);
uint8_t alpha8[] = { 0xFF, 0xBB, 0x77, 0x33 };
SkPixmap alphaPixmap(imageInfo, &alpha8, imageInfo.minRowBytes());
if (bitmap.writePixels(alphaPixmap, 0, 0)) {
canvas->drawBitmap(bitmap, 2, 2, &orangePaint);
}
##
##
#Subtopic BGR_565
BGR_565 is a 16-bit word pixel encoding that contains five bits of blue,
six bits of green, and five bits of red. BGR_565 is fully opaque as if its
Color_Alpha was set to one, and should always be paired with kOpaque_SkAlphaType.
#Illustration
#Example
#Height 96
canvas->scale(16, 16);
SkBitmap bitmap;
SkImageInfo imageInfo = SkImageInfo::Make(2, 2, kRGB_565_SkColorType, kOpaque_SkAlphaType);
bitmap.allocPixels(imageInfo);
SkCanvas offscreen(bitmap);
offscreen.clear(SK_ColorGREEN);
canvas->drawBitmap(bitmap, 0, 0);
auto pack565 = [](unsigned r, unsigned g, unsigned b) -> uint16_t {
return (b << 0) | (g << 5) | (r << 11);
};
uint16_t red565[] = { pack565(0x1F, 0x00, 0x00), pack565(0x17, 0x00, 0x00),
pack565(0x0F, 0x00, 0x00), pack565(0x07, 0x00, 0x00) };
uint16_t blue565[] = { pack565(0x00, 0x00, 0x1F), pack565(0x00, 0x00, 0x17),
pack565(0x00, 0x00, 0x0F), pack565(0x00, 0x00, 0x07) };
SkPixmap redPixmap(imageInfo, &red565, imageInfo.minRowBytes());
if (bitmap.writePixels(redPixmap, 0, 0)) {
canvas->drawBitmap(bitmap, 2, 2);
}
SkPixmap bluePixmap(imageInfo, &blue565, imageInfo.minRowBytes());
if (bitmap.writePixels(bluePixmap, 0, 0)) {
canvas->drawBitmap(bitmap, 4, 4);
}
##
##
#Subtopic ABGR_4444
ABGR_4444 is a 16-bit word pixel encoding that contains four bits of alpha,
four bits of blue, four bits of green, and four bits of red.
#Illustration
If paired with kPremul_SkAlphaType: blue, green, and red components are
premultiplied by the alpha value. If blue, green, or red is greater than alpha,
the drawn result is undefined.
If paired with kUnpremul_SkAlphaType: alpha, blue, green, and red components
may have any value. There may be a performance penalty with unpremultipled
pixels.
If paired with kOpaque_SkAlphaType: all alpha component values are at the maximum;
blue, green, and red components are fully opaque. If any alpha component is
less than 15, the drawn result is undefined.
#Bug 7648
#Example
#Height 96
canvas->scale(16, 16);
SkBitmap bitmap;
SkImageInfo imageInfo = SkImageInfo::Make(2, 2, kARGB_4444_SkColorType, kPremul_SkAlphaType);
bitmap.allocPixels(imageInfo);
SkCanvas offscreen(bitmap);
offscreen.clear(SK_ColorGREEN);
canvas->drawBitmap(bitmap, 0, 0);
auto pack4444 = [](unsigned a, unsigned r, unsigned g, unsigned b) -> uint16_t {
return (a << 0) | (b << 4) | (g << 8) | (r << 12);
};
uint16_t red4444[] = { pack4444(0xF, 0xF, 0x0, 0x0), pack4444(0xF, 0xb, 0x0, 0x0),
pack4444(0xF, 0x7, 0x0, 0x0), pack4444(0xF, 0x3, 0x0, 0x0) };
uint16_t blue4444[] = { pack4444(0xF, 0x0, 0x0, 0xF), pack4444(0xF, 0x0, 0x0, 0xb),
pack4444(0xF, 0x0, 0x0, 0x7), pack4444(0xF, 0x0, 0x0, 0x3) };
SkPixmap redPixmap(imageInfo, &red4444, imageInfo.minRowBytes());
if (bitmap.writePixels(redPixmap, 0, 0)) {
canvas->drawBitmap(bitmap, 2, 2);
}
SkPixmap bluePixmap(imageInfo, &blue4444, imageInfo.minRowBytes());
if (bitmap.writePixels(bluePixmap, 0, 0)) {
canvas->drawBitmap(bitmap, 4, 4);
}
##
##
#Subtopic RGBA_8888
RGBA_8888 is a 32-bit word pixel encoding that contains eight bits of red,
eight bits of green, eight bits of blue, and eight bits of alpha.
#Illustration
If paired with kPremul_SkAlphaType: red, green, and blue components are
premultiplied by the alpha value. If red, green, or blue is greater than alpha,
the drawn result is undefined.
If paired with kUnpremul_SkAlphaType: alpha, red, green, and blue components
may have any value. There may be a performance penalty with unpremultipled
pixels.
If paired with kOpaque_SkAlphaType: all alpha component values are at the maximum;
red, green, and blue components are fully opaque. If any alpha component is
less than 255, the drawn result is undefined.
On Big_Endian platforms, RGBA_8888 is the native Color_Type, and will have
the best performance. Use kN32_SkColorType to choose the best Color_Type for
the platform at compile time.
#Example
#Height 96
canvas->scale(16, 16);
SkBitmap bitmap;
SkImageInfo imageInfo = SkImageInfo::Make(2, 2, kRGBA_8888_SkColorType, kPremul_SkAlphaType);
bitmap.allocPixels(imageInfo);
SkCanvas offscreen(bitmap);
offscreen.clear(SK_ColorGREEN);
canvas->drawBitmap(bitmap, 0, 0);
auto pack8888 = [](unsigned a, unsigned r, unsigned g, unsigned b) -> uint32_t {
return (r << 0) | (g << 8) | (b << 16) | (a << 24);
};
uint32_t red8888[] = { pack8888(0xFF, 0xFF, 0x0, 0x0), pack8888(0xFF, 0xbb, 0x0, 0x0),
pack8888(0xFF, 0x77, 0x0, 0x0), pack8888(0xFF, 0x33, 0x0, 0x0) };
uint32_t blue8888[] = { pack8888(0xFF, 0x0, 0x0, 0x0FF), pack8888(0xFF, 0x0, 0x0, 0x0bb),
pack8888(0xFF, 0x0, 0x0, 0x077), pack8888(0xFF, 0x0, 0x0, 0x033) };
SkPixmap redPixmap(imageInfo, &red8888, imageInfo.minRowBytes());
if (bitmap.writePixels(redPixmap, 0, 0)) {
canvas->drawBitmap(bitmap, 2, 2);
}
SkPixmap bluePixmap(imageInfo, &blue8888, imageInfo.minRowBytes());
if (bitmap.writePixels(bluePixmap, 0, 0)) {
canvas->drawBitmap(bitmap, 4, 4);
}
##
##
#Subtopic RGB_888x
RGB_888x is a 32-bit word pixel encoding that contains eight bits of red,
eight bits of green, eight bits of blue, and eight unused bits. RGB_888x is fully
opaque as if its Color_Alpha was set to one, and should always be paired with
kOpaque_SkAlphaType.
#Illustration
#Example
#Bug 7645
#Height 96
#Platform cpu
canvas->scale(16, 16);
SkBitmap bitmap;
SkImageInfo imageInfo = SkImageInfo::Make(2, 2, kRGB_888x_SkColorType, kOpaque_SkAlphaType);
bitmap.allocPixels(imageInfo);
SkCanvas offscreen(bitmap);
offscreen.clear(SK_ColorGREEN);
canvas->drawBitmap(bitmap, 0, 0);
auto pack888 = [](unsigned r, unsigned g, unsigned b) -> uint32_t {
return (r << 0) | (g << 8) | (b << 16);
};
uint32_t red888[] = { pack888(0xFF, 0x00, 0x00), pack888(0xbb, 0x00, 0x00),
pack888(0x77, 0x00, 0x00), pack888(0x33, 0x00, 0x00) };
uint32_t blue888[] = { pack888(0x00, 0x00, 0xFF), pack888(0x00, 0x00, 0xbb),
pack888(0x00, 0x00, 0x77), pack888(0x00, 0x00, 0x33) };
if (bitmap.installPixels(imageInfo, (void*) red888, imageInfo.minRowBytes())) {
canvas->drawBitmap(bitmap, 2, 2);
}
if (bitmap.installPixels(imageInfo, (void*) blue888, imageInfo.minRowBytes())) {
canvas->drawBitmap(bitmap, 4, 4);
}
##
##
#Subtopic BGRA_8888
BGRA_8888 is a 32-bit word pixel encoding that contains eight bits of blue,
eight bits of green, eight bits of red, and eight bits of alpha.
#Illustration
If paired with kPremul_SkAlphaType: blue, green, and red components are
premultiplied by the alpha value. If blue, green, or red is greater than alpha,
the drawn result is undefined.
If paired with kUnpremul_SkAlphaType: blue, green, red, and alpha components
may have any value. There may be a performance penalty with unpremultipled
pixels.
If paired with kOpaque_SkAlphaType: all alpha component values are at the maximum;
blue, green, and red components are fully opaque. If any alpha component is
less than 255, the drawn result is undefined.
On Little_Endian platforms, BGRA_8888 is the native Color_Type, and will have
the best performance. Use kN32_SkColorType to choose the best Color_Type for
the platform at compile time.
#Example
#Height 96
canvas->scale(16, 16);
SkBitmap bitmap;
SkImageInfo imageInfo = SkImageInfo::Make(2, 2, kBGRA_8888_SkColorType, kPremul_SkAlphaType);
bitmap.allocPixels(imageInfo);
SkCanvas offscreen(bitmap);
offscreen.clear(SK_ColorGREEN);
canvas->drawBitmap(bitmap, 0, 0);
auto pack8888 = [](unsigned a, unsigned r, unsigned g, unsigned b) -> uint32_t {
return (b << 0) | (g << 8) | (r << 16) | (a << 24);
};
uint32_t red8888[] = { pack8888(0xFF, 0xFF, 0x0, 0x0), pack8888(0xFF, 0xbb, 0x0, 0x0),
pack8888(0xFF, 0x99, 0x0, 0x0), pack8888(0xFF, 0x55, 0x0, 0x0) };
uint32_t blue8888[] = { pack8888(0xFF, 0x0, 0x0, 0x0FF), pack8888(0xFF, 0x0, 0x0, 0x0bb),
pack8888(0xFF, 0x0, 0x0, 0x099), pack8888(0xFF, 0x0, 0x0, 0x055) };
SkPixmap redPixmap(imageInfo, &red8888, imageInfo.minRowBytes());
if (bitmap.writePixels(redPixmap, 0, 0)) {
canvas->drawBitmap(bitmap, 2, 2);
}
SkPixmap bluePixmap(imageInfo, &blue8888, imageInfo.minRowBytes());
if (bitmap.writePixels(bluePixmap, 0, 0)) {
canvas->drawBitmap(bitmap, 4, 4);
}
##
##
#Subtopic RGBA_1010102
RGBA_1010102 is a 32-bit word pixel encoding that contains ten bits of red,
ten bits of green, ten bits of blue, and two bits of alpha. Possible alpha
values are zero: fully transparent; one: 33% opaque; two: 67% opaque;
three: fully opaque.
#Illustration
If paired with kPremul_SkAlphaType: red, green, and blue components are
premultiplied by the alpha value. If red, green, or blue is greater than the
alpha replicated to ten bits, the drawn result is undefined.
If paired with kUnpremul_SkAlphaType: alpha, red, green, and blue components
may have any value. There may be a performance penalty with unpremultipled
pixels.
If paired with kOpaque_SkAlphaType: all alpha component values are at the maximum;
red, green, and blue components are fully opaque. If any alpha component is
less than 3, the drawn result is undefined.
#Example
#Bug 7645
#Height 96
#Platform cpu
canvas->scale(16, 16);
SkBitmap bitmap;
SkImageInfo imageInfo = SkImageInfo::Make(2, 2, kRGBA_1010102_SkColorType, kOpaque_SkAlphaType);
bitmap.allocPixels(imageInfo);
SkCanvas offscreen(bitmap);
offscreen.clear(SK_ColorGREEN);
canvas->drawBitmap(bitmap, 0, 0);
auto pack1010102 = [](unsigned r, unsigned g, unsigned b, unsigned a) -> uint32_t {
return (r << 0) | (g << 10) | (b << 20) | (a << 30);
};
uint32_t redBits[] = { pack1010102(0x3FF, 0x000, 0x000, 0x3),
pack1010102(0x2ff, 0x000, 0x000, 0x3),
pack1010102(0x1ff, 0x000, 0x000, 0x3),
pack1010102(0x0ff, 0x000, 0x000, 0x3) };
uint32_t blueBits[] = { pack1010102(0x000, 0x000, 0x3FF, 0x3),
pack1010102(0x000, 0x000, 0x2ff, 0x3),
pack1010102(0x000, 0x000, 0x1ff, 0x3),
pack1010102(0x000, 0x000, 0x0ff, 0x3) };
if (bitmap.installPixels(imageInfo, (void*) redBits, imageInfo.minRowBytes())) {
canvas->drawBitmap(bitmap, 2, 2);
}
SkPixmap bluePixmap(imageInfo, &blueBits, imageInfo.minRowBytes());
if (bitmap.installPixels(imageInfo, (void*) blueBits, imageInfo.minRowBytes())) {
canvas->drawBitmap(bitmap, 4, 4);
}
##
##
#Subtopic RGB_101010x
RGB_101010x is a 32-bit word pixel encoding that contains ten bits of red,
ten bits of green, ten bits of blue, and two unused bits. RGB_101010x is fully
opaque as if its Color_Alpha was set to one, and should always be paired with
kOpaque_SkAlphaType.
#Illustration
#Example
#Bug 7645
#Height 96
#Platform cpu
canvas->scale(16, 16);
SkBitmap bitmap;
SkImageInfo imageInfo = SkImageInfo::Make(2, 2, kRGB_101010x_SkColorType, kOpaque_SkAlphaType);
bitmap.allocPixels(imageInfo);
SkCanvas offscreen(bitmap);
offscreen.clear(SK_ColorGREEN);
canvas->drawBitmap(bitmap, 0, 0);
auto pack101010x = [](unsigned r, unsigned g, unsigned b) -> uint32_t {
return (r << 0) | (g << 10) | (b << 20);
};
uint32_t redBits[] = { pack101010x(0x3FF, 0x000, 0x000), pack101010x(0x2ff, 0x000, 0x000),
pack101010x(0x1ff, 0x000, 0x000), pack101010x(0x0ff, 0x000, 0x000) };
uint32_t blueBits[] = { pack101010x(0x000, 0x000, 0x3FF), pack101010x(0x000, 0x000, 0x2ff),
pack101010x(0x000, 0x000, 0x1ff), pack101010x(0x000, 0x000, 0x0ff) };
if (bitmap.installPixels(imageInfo, (void*) redBits, imageInfo.minRowBytes())) {
canvas->drawBitmap(bitmap, 2, 2);
}
SkPixmap bluePixmap(imageInfo, &blueBits, imageInfo.minRowBytes());
if (bitmap.installPixels(imageInfo, (void*) blueBits, imageInfo.minRowBytes())) {
canvas->drawBitmap(bitmap, 4, 4);
}
##
##
#Subtopic Gray_8
Gray_8 is an 8-bit byte pixel encoding that represents equal values for red,
blue, and green, reprsenting colors from black to white. Gray_8 is fully
opaque as if its Color_Alpha was set to one, and should always be paired with
kOpaque_SkAlphaType.
#Example
#Height 64
canvas->scale(16, 16);
SkBitmap bitmap;
SkImageInfo imageInfo = SkImageInfo::Make(2, 2, kGray_8_SkColorType, kOpaque_SkAlphaType);
bitmap.allocPixels(imageInfo);
SkCanvas offscreen(bitmap);
offscreen.clear(SK_ColorGREEN);
canvas->drawBitmap(bitmap, 0, 0);
uint8_t gray8[] = { 0xFF, 0xBB, 0x77, 0x33 };
SkPixmap grayPixmap(imageInfo, &gray8, imageInfo.minRowBytes());
if (bitmap.writePixels(grayPixmap, 0, 0)) {
canvas->drawBitmap(bitmap, 2, 2);
}
##
##
#Subtopic RGBA_F16
RGBA_F16 is a 64-bit word pixel encoding that contains sixteen bits of blue,
sixteen bits of green, sixteen bits of red, and sixteen bits of alpha.
Each component encodes a floating point value using
#A Half floats # https://www.khronos.org/opengl/wiki/Small_Float_Formats ##
. Meaningful colors are represented by the range 0.0 to 1.0, although smaller
and larger values may be useful when used in combination with Transfer_Mode.
#Illustration
If paired with kPremul_SkAlphaType: blue, green, and red components are
premultiplied by the alpha value. If blue, green, or red is greater than alpha,
the drawn result is undefined.
If paired with kUnpremul_SkAlphaType: blue, green, red, and alpha components
may have any value. There may be a performance penalty with unpremultipled
pixels.
If paired with kOpaque_SkAlphaType: all alpha component values are at the maximum;
blue, green, and red components are fully opaque. If any alpha component is
less than 255, the drawn result is undefined.
#ToDo
FloatToHalf should be replaced with SkFloatToHalf if/when that's made public
##
#Example
#Height 96
#Function
union FloatUIntUnion {
uint32_t fUInt;
float fFloat;
};
uint16_t FloatToHalf(float f) {
static const FloatUIntUnion magic = { 15 << 23 };
static const uint32_t round_mask = ~0xfffu;
FloatUIntUnion floatUnion;
floatUnion.fFloat = f;
uint32_t sign = floatUnion.fUInt & 0x80000000u;
floatUnion.fUInt ^= sign;
floatUnion.fUInt &= round_mask;
floatUnion.fFloat *= magic.fFloat;
floatUnion.fUInt -= round_mask;
return (floatUnion.fUInt >> 13) | (sign >> 16);
}
##
void draw(SkCanvas* canvas) {
canvas->scale(16, 16);
SkBitmap bitmap;
SkImageInfo imageInfo = SkImageInfo::Make(2, 2, kRGBA_F16_SkColorType, kPremul_SkAlphaType);
bitmap.allocPixels(imageInfo);
SkCanvas offscreen(bitmap);
offscreen.clear(SK_ColorGREEN);
canvas->drawBitmap(bitmap, 0, 0);
auto H = [](float c) -> uint16_t {
return FloatToHalf(c);
};
// R G B A
uint16_t red_f16[][4] = { { H(1.0f), H(0.0f), H(0.0f), H(1.0f) },
{ H(.75f), H(0.0f), H(0.0f), H(1.0f) },
{ H(.50f), H(0.0f), H(0.0f), H(1.0f) },
{ H(.25f), H(0.0f), H(0.0f), H(1.0f) } };
uint16_t blue_f16[][4] = { { H(0.0f), H(0.0f), H(1.0f), H(1.0f) },
{ H(0.0f), H(0.0f), H(.75f), H(1.0f) },
{ H(0.0f), H(0.0f), H(.50f), H(1.0f) },
{ H(0.0f), H(0.0f), H(.25f), H(1.0f) } };
SkPixmap redPixmap(imageInfo, red_f16, imageInfo.minRowBytes());
if (bitmap.writePixels(redPixmap, 0, 0)) {
canvas->drawBitmap(bitmap, 2, 2);
}
SkPixmap bluePixmap(imageInfo, blue_f16, imageInfo.minRowBytes());
if (bitmap.writePixels(bluePixmap, 0, 0)) {
canvas->drawBitmap(bitmap, 4, 4);
}
}
##
##
#Subtopic Color_Type ##
# ------------------------------------------------------------------------------
#Method int SkColorTypeBytesPerPixel(SkColorType ct)
#In Property
#Line # returns Color_Type byte size ##
Returns the number of bytes required to store a pixel, including unused padding.
Returns zero if ct is kUnknown_SkColorType or invalid.
#Param ct one of: #list_of_color_types#
##
#Return bytes per pixel ##
#Example
#Height 192
const char* colors[] = { "Unknown", "Alpha_8", "RGB_565", "ARGB_4444", "RGBA_8888", "RGB_888x",
"BGRA_8888", "RGBA_1010102", "RGB_101010x", "Gray_8", "RGBA_F16" };
SkPaint paint;
paint.setTypeface(SkTypeface::MakeFromName("monospace", SkFontStyle()));
paint.setAntiAlias(true);
paint.setTextSize(10);
int y = 15;
canvas->drawString(" colorType bytes", 10, y, paint);
for (SkColorType colorType : { #list_of_color_types#
} ) {
int result = SkColorTypeBytesPerPixel(colorType);
SkString string;
string.printf("%13s %4d", colors[(int) colorType], result);
canvas->drawString(string, 10, y += 14, paint);
}
##
#SeeAlso SkImageInfo::bytesPerPixel
##
# ------------------------------------------------------------------------------
#Method bool SkColorTypeIsAlwaysOpaque(SkColorType ct)
#In Property
#Line # returns if Color_Type includes Color_Alpha ##
Returns true if Color_Type always decodes Color_Alpha to 1.0, making the pixel
fully opaque. If true, Color_Type does not reserve bits to encode Color_Alpha.
#Param ct one of: #list_of_color_types#
##
#Return true if Color_Alpha is always set to 1.0 ##
#Example
#Height 192
const char* colors[] = { "Unknown", "Alpha_8", "RGB_565", "ARGB_4444", "RGBA_8888", "RGB_888x",
"BGRA_8888", "RGBA_1010102", "RGB_101010x", "Gray_8", "RGBA_F16" };
SkPaint paint;
paint.setTypeface(SkTypeface::MakeFromName("monospace", SkFontStyle()));
paint.setAntiAlias(true);
paint.setTextSize(10);
int y = 15;
canvas->drawString(" colorType bytes", 10, y, paint);
for (SkColorType colorType : { #list_of_color_types#
} ) {
bool result = SkColorTypeIsAlwaysOpaque(colorType);
SkString string;
string.printf("%13s %6s", colors[(int) colorType], result ? "true" : "false");
canvas->drawString(string, 10, y += 14, paint);
}
##
#SeeAlso SkColorTypeValidateAlphaType
##
# ------------------------------------------------------------------------------
#Method bool SkColorTypeValidateAlphaType(SkColorType colorType, SkAlphaType alphaType,
SkAlphaType* canonical = nullptr)
#In Property
#Line # returns if Alpha_Type is valid ##
Returns true if canonical can be set to a valid Alpha_Type for colorType. If
there is more than one valid canonical Alpha_Type, set to alphaType, if valid.
If true is returned and canonical is not nullptr, store valid Alpha_Type.
Returns false only if alphaType is kUnknown_SkAlphaType, color type is not
kUnknown_SkColorType, and Color_Type is not always opaque. If false is returned,
canonical is ignored.
For kUnknown_SkColorType: set canonical to kUnknown_SkAlphaType and return true.
For kAlpha_8_SkColorType: set canonical to kPremul_SkAlphaType or
kOpaque_SkAlphaType and return true if alphaType is not kUnknown_SkAlphaType.
For kRGB_565_SkColorType, kRGB_888x_SkColorType, kRGB_101010x_SkColorType, and
kGray_8_SkColorType: set canonical to kOpaque_SkAlphaType and return true.
For kARGB_4444_SkColorType, kRGBA_8888_SkColorType, kBGRA_8888_SkColorType,
kRGBA_1010102_SkColorType, and kRGBA_F16_SkColorType: set canonical to alphaType
and return true if alphaType is not kUnknown_SkAlphaType.
#Param colorType one of: #list_of_color_types#
##
#Param alphaType one of: #list_of_alpha_types#
##
#Param canonical storage for Alpha_Type ##
#Return true if valid Alpha_Type can be associated with colorType ##
#Example
#Height 640
const char* colors[] = { "Unknown", "Alpha_8", "RGB_565", "ARGB_4444", "RGBA_8888", "RGB_888x",
"BGRA_8888", "RGBA_1010102", "RGB_101010x", "Gray_8", "RGBA_F16" };
const char* alphas[] = {"Unknown ", "Opaque ", "Premul ", "Unpremul"};
SkAlphaType alphaTypes[] = { #list_of_alpha_types#
};
SkPaint paint;
paint.setTypeface(SkTypeface::MakeFromName("monospace", SkFontStyle()));
paint.setAntiAlias(true);
paint.setTextSize(10);
int y = 15;
canvas->drawString(" colorType alphaType canonical", 10, y, paint);
for (SkColorType colorType : { #list_of_color_types#
} ) {
for (SkAlphaType alphaType : alphaTypes) {
SkAlphaType canonicalAlphaType = kUnknown_SkAlphaType;
bool result = SkColorTypeValidateAlphaType(colorType, alphaType, &canonicalAlphaType);
SkString string;
string.printf("%13s %10s %10s", colors[(int) colorType], alphas[(int) alphaType],
result ? alphas[(int) canonicalAlphaType] : "------ ");
canvas->drawString(string, 10, y += 14, paint);
}
}
##
#SeeAlso SkColorTypeIsAlwaysOpaque
##
# ------------------------------------------------------------------------------
#Subtopic YUV_ColorSpace
#Alias YUV_ColorSpace
#Enum SkYUVColorSpace
#Line # color range of YUV pixels ##
#Code
enum SkYUVColorSpace {
kJPEG_SkYUVColorSpace,
kRec601_SkYUVColorSpace,
kRec709_SkYUVColorSpace,
kLastEnum_SkYUVColorSpace = kRec709_SkYUVColorSpace,
};
##
Describes color range of YUV pixels. The color mapping from YUV to RGB varies
depending on the source. YUV pixels may be generated by JPEG images, standard
video streams, or high definition video streams. Each has its own mapping from
YUV and RGB.
JPEG YUV values encode the full range of 0 to 255 for all three components.
Video YUV values range from 16 to 235 for all three components. Details of
encoding and conversion to RGB are described in
#A YCbCr color space # https://en.wikipedia.org/wiki/YCbCr ##
.
#Const kJPEG_SkYUVColorSpace 0
Describes standard JPEG color space;
#A CCIR 601 # https://en.wikipedia.org/wiki/Rec._601 ##
with full range of 0 to 255 for components.
##
#Const kRec601_SkYUVColorSpace 1
Describes standard used by SDTV;
#A CCIR 601 # https://en.wikipedia.org/wiki/Rec._601 ##
with studio range of 16 to 235 range for components.
##
#Const kRec709_SkYUVColorSpace 2
Describes standard used by HDTV;
#A Rec. 709 # http://en.wikipedia.org/wiki/Rec._709 ##
with studio range of 16 to 235 range for components.
##
#NoExample
##
#SeeAlso SkImage::MakeFromYUVTexturesCopy SkImage::MakeFromNV12TexturesCopy
#Enum SkYUVColorSpace ##
#Subtopic YUV_ColorSpace ##
# ------------------------------------------------------------------------------
#Struct SkImageInfo
Describes pixel dimensions and encoding. Bitmap, Image, PixMap, and Surface
can be created from Image_Info. Image_Info can be retrieved from Bitmap and
Pixmap, but not from Image and Surface. For example, Image and Surface
implementations may defer pixel depth, so may not completely specify Image_Info.
Image_Info contains dimensions, the pixel integral width and height. It encodes
how pixel bits describe Color_Alpha, transparency; Color components red, blue,
and green; and Color_Space, the range and linearity of colors.
#Subtopic Member_Function
#Populate
##
#Subtopic Related_Function
#Populate
##
# ------------------------------------------------------------------------------
#Subtopic Constructor
#Populate
##
#Method SkImageInfo()
#In Constructor
#Line # creates with zero dimensions, kUnknown_SkColorType, kUnknown_SkAlphaType ##
Creates an empty Image_Info with kUnknown_SkColorType, kUnknown_SkAlphaType,
a width and height of zero, and no Color_Space.
#Return empty Image_Info ##
#Example
#Height 32
#Description
An empty Image_Info may be passed to SkCanvas::accessTopLayerPixels as storage
for the Canvas actual Image_Info.
##
SkImageInfo imageInfo;
size_t rowBytes;
SkIPoint origin;
(void) canvas->accessTopLayerPixels(&imageInfo, &rowBytes, &origin);
const char* alphaType[] = { "Unknown", "Opaque", "Premul", "Unpremul" };
SkString string;
string.printf("k%s_SkAlphaType", alphaType[(int) imageInfo.alphaType()]);
SkPaint paint;
canvas->drawString(string, 20, 20, paint);
##
#SeeAlso Make MakeN32 MakeS32 MakeA8
#Method ##
# ------------------------------------------------------------------------------
#Method static SkImageInfo Make(int width, int height, SkColorType ct, SkAlphaType at,
sk_sp<SkColorSpace> cs = nullptr)
#In Constructor
#Line # creates Image_Info from dimensions, Color_Type, Alpha_Type, Color_Space ##
Creates Image_Info from integral dimensions width and height, Color_Type ct,
Alpha_Type at, and optionally Color_Space cs.
If Color_Space cs is nullptr and Image_Info is part of drawing source: Color_Space
defaults to sRGB, mapping into Surface Color_Space.
Parameters are not validated to see if their values are legal, or that the
combination is supported.
#Param width pixel column count; must be zero or greater ##
#Param height pixel row count; must be zero or greater ##
#Param ct one of: #list_of_color_types#
##
#Param at one of: #list_of_alpha_types#
##
#Param cs range of colors; may be nullptr ##
#Return created Image_Info ##
#Example
#Height 48
uint8_t storage[][5] = {{ 0xCA, 0xDA, 0xCA, 0xC9, 0xA3 },
{ 0xAC, 0xA8, 0x89, 0xA7, 0x87 },
{ 0x9B, 0xB5, 0xE5, 0x95, 0x46 },
{ 0x90, 0x81, 0xC5, 0x71, 0x33 },
{ 0x75, 0x55, 0x44, 0x40, 0x30 }};
SkImageInfo imageInfo = SkImageInfo::Make(5, 5, kGray_8_SkColorType, kOpaque_SkAlphaType);
SkPixmap pixmap(imageInfo, storage[0], sizeof(storage) / 5);
SkBitmap bitmap;
bitmap.installPixels(pixmap);
canvas->scale(8, 8);
canvas->drawBitmap(bitmap, 0, 0);
##
#SeeAlso MakeN32 MakeN32Premul MakeS32 MakeA8
#Method ##
# ------------------------------------------------------------------------------
#Method static SkImageInfo MakeN32(int width, int height, SkAlphaType at,
sk_sp<SkColorSpace> cs = nullptr)
#In Constructor
#Line # creates Image_Info with Native_Color_Type ##
Creates Image_Info from integral dimensions width and height, kN32_SkColorType,
Alpha_Type at, and optionally Color_Space cs. kN32_SkColorType will equal either
kBGRA_8888_SkColorType or kRGBA_8888_SkColorType, whichever is optimal.
If Color_Space cs is nullptr and Image_Info is part of drawing source: Color_Space
defaults to sRGB, mapping into Surface Color_Space.
Parameters are not validated to see if their values are legal, or that the
combination is supported.
#Param width pixel column count; must be zero or greater ##
#Param height pixel row count; must be zero or greater ##
#Param at one of: #list_of_alpha_types#
##
#Param cs range of colors; may be nullptr ##
#Return created Image_Info ##
#Example
#Height 128
SkBitmap bitmap;
bitmap.allocPixels(SkImageInfo::MakeN32(16, 16, kPremul_SkAlphaType));
SkCanvas offscreen(bitmap);
offscreen.clear(SK_ColorWHITE);
SkPaint paint;
offscreen.drawString("g", 0, 10, paint);
canvas->scale(8, 8);
canvas->drawBitmap(bitmap, 0, 0);
##
#SeeAlso Make MakeN32Premul MakeS32 MakeA8
#Method ##
# ------------------------------------------------------------------------------
#Method static SkImageInfo MakeS32(int width, int height, SkAlphaType at)
#In Constructor
#Line # creates Image_Info with Native_Color_Type, sRGB Color_Space ##
Creates Image_Info from integral dimensions width and height, kN32_SkColorType,
Alpha_Type at, with sRGB Color_Space.
Parameters are not validated to see if their values are legal, or that the
combination is supported.
#Param width pixel column count; must be zero or greater ##
#Param height pixel row count; must be zero or greater ##
#Param at one of: #list_of_alpha_types#
##
#Return created Image_Info ##
#Example
#Set sRGB
#Height 128
#Description
Top gradient is drawn to offscreen without Color_Space. It is darker than middle
gradient, drawn to offscreen with sRGB Color_Space. Bottom gradient shares bits
with middle, but does not specify the Color_Space in noColorSpaceBitmap. A source
without Color_Space is treated as sRGB; the bottom gradient is identical to the
middle gradient.
##
const int width = 256;
const int height = 32;
SkImageInfo info = SkImageInfo::MakeN32Premul(width, height);
SkColor gradColors[] = { 0xFFAA0055, 0xFF11CC88 };
SkPoint gradPoints[] = { { 0, 0 }, { width, 0 } };
SkPaint gradPaint;
gradPaint.setShader(SkGradientShader::MakeLinear(gradPoints, gradColors, nullptr,
SK_ARRAY_COUNT(gradColors), SkShader::kClamp_TileMode));
SkBitmap bitmap;
bitmap.allocPixels(SkImageInfo::MakeN32(width, height, kPremul_SkAlphaType));
SkCanvas offscreen(bitmap);
offscreen.drawRect(SkRect::MakeWH(width, height), gradPaint);
canvas->drawBitmap(bitmap, 0, 0);
bitmap.allocPixels(SkImageInfo::MakeS32(width, height, kPremul_SkAlphaType));
SkCanvas sRGBOffscreen(bitmap);
sRGBOffscreen.drawRect(SkRect::MakeWH(width, height), gradPaint);
canvas->drawBitmap(bitmap, 0, 48);
SkBitmap noColorSpaceBitmap;
noColorSpaceBitmap.setInfo(SkImageInfo::MakeN32(width, height, kPremul_SkAlphaType));
noColorSpaceBitmap.setPixels(bitmap.getAddr(0, 0));
canvas->drawBitmap(noColorSpaceBitmap, 0, 96);
##
#SeeAlso Make MakeN32 MakeN32Premul MakeA8
#Method ##
# ------------------------------------------------------------------------------
#Method static SkImageInfo MakeN32Premul(int width, int height, sk_sp<SkColorSpace> cs = nullptr)
#In Constructor
#Line # creates Image_Info with Native_Color_Type, kPremul_SkAlphaType ##
Creates Image_Info from integral dimensions width and height, kN32_SkColorType,
kPremul_SkAlphaType, with optional Color_Space.
If Color_Space cs is nullptr and Image_Info is part of drawing source: Color_Space
defaults to sRGB, mapping into Surface Color_Space.
Parameters are not validated to see if their values are legal, or that the
combination is supported.
#Param width pixel column count; must be zero or greater ##
#Param height pixel row count; must be zero or greater ##
#Param cs range of colors; may be nullptr ##
#Return created Image_Info ##
#Example
#Height 128
SkBitmap bitmap;
bitmap.allocPixels(SkImageInfo::MakeN32Premul(18, 18));
SkCanvas offscreen(bitmap);
offscreen.clear(SK_ColorWHITE);
SkPaint paint;
paint.setAntiAlias(true);
paint.setTextSize(15);
offscreen.drawString("\xF0\x9F\x98\xB8", 1, 15, paint);
canvas->scale(6, 6);
canvas->drawBitmap(bitmap, 0, 0);
##
#SeeAlso MakeN32 MakeS32 MakeA8 Make
#Method ##
# ------------------------------------------------------------------------------
#Method static SkImageInfo MakeN32Premul(const SkISize& size)
#In Constructor
Creates Image_Info from integral dimensions width and height, kN32_SkColorType,
kPremul_SkAlphaType, with Color_Space set to nullptr.
If Image_Info is part of drawing source: Color_Space defaults to sRGB, mapping
into Surface Color_Space.
Parameters are not validated to see if their values are legal, or that the
combination is supported.
#Param size width and height, each must be zero or greater ##
#Return created Image_Info ##
#Example
#Height 128
SkBitmap bitmap;
bitmap.allocPixels(SkImageInfo::MakeN32Premul({18, 18}));
SkCanvas offscreen(bitmap);
offscreen.clear(SK_ColorWHITE);
SkPaint paint;
paint.setAntiAlias(true);
paint.setTextSize(15);
offscreen.drawString("\xF0\x9F\x98\xB9", 1, 15, paint);
canvas->scale(6, 6);
canvas->drawBitmap(bitmap, 0, 0);
##
#SeeAlso MakeN32 MakeS32 MakeA8 Make
#Method ##
# ------------------------------------------------------------------------------
#Method static SkImageInfo MakeA8(int width, int height)
#In Constructor
#Line # creates Image_Info with kAlpha_8_SkColorType, kPremul_SkAlphaType ##
Creates Image_Info from integral dimensions width and height, kAlpha_8_SkColorType,
kPremul_SkAlphaType, with Color_Space set to nullptr.
#Param width pixel column count; must be zero or greater ##
#Param height pixel row count; must be zero or greater ##
#Return created Image_Info ##
#Example
#Height 64
uint8_t pixels[][8] = { { 0x00, 0x00, 0x3f, 0x00, 0x00, 0x00, 0x00, 0x00},
{ 0x00, 0x7f, 0xff, 0x3f, 0x3f, 0x7f, 0x3f, 0x00},
{ 0x3f, 0xff, 0x7f, 0x00, 0x7f, 0xff, 0x7f, 0x00},
{ 0x00, 0x3f, 0x00, 0x00, 0x3f, 0x7f, 0x3f, 0x00},
{ 0x3f, 0x7f, 0x7f, 0x3f, 0x00, 0x00, 0x00, 0x00},
{ 0x7f, 0xff, 0xff, 0x7f, 0x00, 0x3f, 0x7f, 0x3f},
{ 0x7f, 0xff, 0xff, 0x7f, 0x00, 0x7f, 0xff, 0x7f},
{ 0x3f, 0x7f, 0x7f, 0x3f, 0x00, 0x3f, 0x7f, 0x3f} };
SkBitmap bitmap;
bitmap.installPixels(SkImageInfo::MakeA8(8, 8),
(void*) pixels, sizeof(pixels[0]));
SkPaint paint;
canvas->scale(4, 4);
for (auto color : { SK_ColorRED, SK_ColorBLUE, 0xFF007F00} ) {
paint.setColor(color);
canvas->drawBitmap(bitmap, 0, 0, &paint);
canvas->translate(12, 0);
}
##
#SeeAlso MakeN32 MakeS32 Make
#Method ##
# ------------------------------------------------------------------------------
#Method static SkImageInfo MakeUnknown(int width, int height)
#In Constructor
#Line # creates Image_Info with kUnknown_SkColorType, kUnknown_SkAlphaType ##
Creates Image_Info from integral dimensions width and height, kUnknown_SkColorType,
kUnknown_SkAlphaType, with Color_Space set to nullptr.
Returned Image_Info as part of source does not draw, and as part of destination
can not be drawn to.
#Param width pixel column count; must be zero or greater ##
#Param height pixel row count; must be zero or greater ##
#Return created Image_Info ##
#Example
#Height 32
#Width 384
SkImageInfo info; // default constructor
SkString string;
string.printf("SkImageInfo() %c= SkImageInfo::MakeUnknown(0, 0)",
info == SkImageInfo::MakeUnknown(0, 0) ? '=' : '!');
SkPaint paint;
canvas->drawString(string, 0, 12, paint);
##
#SeeAlso SkImageInfo() MakeN32 MakeS32 Make
#Method ##
# ------------------------------------------------------------------------------
#Method static SkImageInfo MakeUnknown()
#In Constructor
Creates Image_Info from integral dimensions width and height set to zero,
kUnknown_SkColorType, kUnknown_SkAlphaType, with Color_Space set to nullptr.
Returned Image_Info as part of source does not draw, and as part of destination
can not be drawn to.
#Return created Image_Info ##
#Example
#Height 32
#Width 384
SkImageInfo info; // default constructor
SkString string;
string.printf("SkImageInfo() %c= SkImageInfo::MakeUnknown()",
info == SkImageInfo::MakeUnknown() ? '=' : '!');
SkPaint paint;
canvas->drawString(string, 0, 12, paint);
##
#SeeAlso SkImageInfo() MakeN32 MakeS32 Make
#Method ##
# ------------------------------------------------------------------------------
#Subtopic Property
#Populate
#Line # metrics and attributes ##
##
#Method int width() const
#In Property
#Line # returns pixel column count ##
Returns pixel count in each row.
#Return pixel width ##
#Example
#Image 4
#Height 96
canvas->translate(10, 10);
canvas->drawBitmap(source, 0, 0);
SkImageInfo imageInfo = source.info();
canvas->translate(0, imageInfo.height());
SkPaint paint;
paint.setTextAlign(SkPaint::kCenter_Align);
canvas->drawLine(0, 10, imageInfo.width(), 10, paint);
canvas->drawString("width", imageInfo.width() / 2, 25, paint);
##
#SeeAlso height SkBitmap::width SkPixelRef::width SkImage::width SkSurface::width
#Method ##
# ------------------------------------------------------------------------------
#Method int height() const
#In Property
#Line # returns pixel row count ##
Returns pixel row count.
#Return pixel height ##
#Example
#Image 4
#Height 96
canvas->translate(10, 20);
canvas->drawBitmap(source, 0, 0);
SkImageInfo imageInfo = source.info();
SkPaint paint;
paint.setTextAlign(SkPaint::kCenter_Align);
paint.setVerticalText(true);
canvas->drawLine(imageInfo.width() + 10, 0, imageInfo.width() + 10, imageInfo.height(), paint);
canvas->drawString("height", imageInfo.width() + 25, imageInfo.height() / 2, paint);
##
#SeeAlso width SkBitmap::height SkPixelRef::height SkImage::height SkSurface::height
#Method ##
# ------------------------------------------------------------------------------
#Method SkColorType colorType() const
#In Property
#Line # returns Color_Type ##
Returns Color_Type, one of: #list_of_color_types#.
#Return Color_Type ##
#Example
const char* colors[] = {"Unknown", "Alpha_8", "RGB_565", "ARGB_4444", "RGBA_8888", "RGB_888x",
"BGRA_8888", "RGBA_1010102", "RGB_101010x", "Gray_8", "RGBA_F16"};
SkImageInfo info = SkImageInfo::MakeA8(16, 32);
SkDebugf("color type: k" "%s" "_SkColorType\n", colors[info.colorType()]);
#StdOut
color type: kAlpha_8_SkColorType
##
##
#SeeAlso alphaType SkPixmap::colorType SkBitmap::colorType
#Method ##
# ------------------------------------------------------------------------------
#Method SkAlphaType alphaType() const
#In Property
#Line # Returns Alpha_Type ##
Returns Alpha_Type, one of: #list_of_alpha_types#.
#Return Alpha_Type ##
#Example
const char* alphas[] = {"Unknown", "Opaque", "Premul", "Unpremul"};
SkImageInfo info = SkImageInfo::MakeA8(16, 32);
SkDebugf("alpha type: k" "%s" "_SkAlphaType\n", alphas[info.alphaType()]);
#StdOut
alpha type: kPremul_SkAlphaType
##
##
#SeeAlso colorType SkPixmap::alphaType SkBitmap::alphaType
#Method ##
# ------------------------------------------------------------------------------
#Method SkColorSpace* colorSpace() const
#In Property
#Line # returns Color_Space ##
Returns Color_Space, the range of colors. The reference count of
Color_Space is unchanged. The returned Color_Space is immutable.
#Return Color_Space, or nullptr ##
#Example
#Description
SkColorSpace::MakeSRGBLinear creates Color_Space with linear gamma
and an sRGB gamut. This Color_Space gamma is not close to sRGB gamma.
##
SkImageInfo info = SkImageInfo::MakeN32(16, 32, kPremul_SkAlphaType,
SkColorSpace::MakeSRGBLinear());
SkColorSpace* colorSpace = info.colorSpace();
SkDebugf("gammaCloseToSRGB: %s gammaIsLinear: %s isSRGB: %s\n",
colorSpace->gammaCloseToSRGB() ? "true" : "false",
colorSpace->gammaIsLinear() ? "true" : "false",
colorSpace->isSRGB() ? "true" : "false");
#StdOut
gammaCloseToSRGB: false gammaIsLinear: true isSRGB: false
##
##
#SeeAlso Color_Space SkPixmap::colorSpace SkBitmap::colorSpace
#Method ##
# ------------------------------------------------------------------------------
#Method sk_sp<SkColorSpace> refColorSpace() const
#In Property
#Line # returns Color_Space ##
Returns smart pointer to Color_Space, the range of colors. The smart pointer
tracks the number of objects sharing this Color_Space reference so the memory
is released when the owners destruct.
The returned Color_Space is immutable.
#Return Color_Space wrapped in a smart pointer ##
#Example
SkImageInfo info1 = SkImageInfo::MakeN32(16, 32, kPremul_SkAlphaType,
SkColorSpace::MakeSRGBLinear());
SkImageInfo info2 = SkImageInfo::MakeN32(16, 32, kPremul_SkAlphaType,
info1.refColorSpace());
SkColorSpace* colorSpace = info2.colorSpace();
SkDebugf("gammaCloseToSRGB: %s gammaIsLinear: %s isSRGB: %s\n",
colorSpace->gammaCloseToSRGB() ? "true" : "false",
colorSpace->gammaIsLinear() ? "true" : "false",
colorSpace->isSRGB() ? "true" : "false");
##
#SeeAlso Color_Space SkBitmap::refColorSpace
#Method ##
# ------------------------------------------------------------------------------
#Method bool isEmpty() const
#In Property
#Line # returns if dimensions contain pixels ##
Returns if Image_Info describes an empty area of pixels by checking if either
width or height is zero or smaller.
#Return true if either dimension is zero or smaller ##
#Example
for (int width : { 0, 2 } ) {
for (int height : { 0, 2 } ) {
SkImageInfo imageInfo= SkImageInfo::MakeA8(width, height);
SkDebugf("width: %d height: %d empty: %s\n", width, height,
imageInfo.isEmpty() ? "true" : "false");
}
}
#StdOut
width: 0 height: 0 empty: true
width: 0 height: 2 empty: true
width: 2 height: 0 empty: true
width: 2 height: 2 empty: false
##
##
#SeeAlso dimensions bounds SkBitmap::empty SkPixmap::bounds
#Method ##
# ------------------------------------------------------------------------------
#Method bool isOpaque() const
#In Property
#Line # returns if Alpha_Type is kOpaque_SkAlphaType ##
Returns true if Alpha_Type is set to hint that all pixels are opaque; their
Color_Alpha value is implicitly or explicitly 1.0. If true, and all pixels are
not opaque, Skia may draw incorrectly.
Does not check if Color_Type allows Alpha, or if any pixel value has
transparency.
#Return true if Alpha_Type is kOpaque_SkAlphaType ##
#Example
const int height = 2;
const int width = 2;
SkBitmap bitmap;
SkImageInfo imageInfo = SkImageInfo::Make(width, height, kN32_SkColorType, kPremul_SkAlphaType);
bitmap.setInfo(imageInfo);
for (int index = 0; index < 2; ++index) {
bitmap.allocPixels();
bitmap.eraseColor(0x00000000);
SkDebugf("isOpaque: %s\n", imageInfo.isOpaque() ? "true" : "false");
bitmap.eraseColor(0xFFFFFFFF);
SkDebugf("isOpaque: %s\n", imageInfo.isOpaque() ? "true" : "false");
imageInfo = imageInfo.makeAlphaType(kOpaque_SkAlphaType);
bitmap.setInfo(imageInfo);
}
#StdOut
isOpaque: false
isOpaque: false
isOpaque: true
isOpaque: true
##
##
#SeeAlso Color_Alpha SkColorTypeValidateAlphaType SkBitmap::isOpaque SkImage::isOpaque SkPixmap::isOpaque
#Method ##
# ------------------------------------------------------------------------------
#Method SkISize dimensions() const
#In Property
#Line # returns width() and height() ##
Returns ISize { width(), height() }.
#Return integral size of width() and height() ##
#Example
const int height = 2;
const int width = 2;
SkImageInfo imageInfo = SkImageInfo::Make(width, height, kN32_SkColorType, kPremul_SkAlphaType);
SkISize dimensions = imageInfo.dimensions();
SkIRect bounds = imageInfo.bounds();
SkIRect dimensionsAsBounds = SkIRect::MakeSize(dimensions);
SkDebugf("dimensionsAsBounds %c= bounds\n", dimensionsAsBounds == bounds ? '=' : '!');
#StdOut
dimensionsAsBounds == bounds
##
##
#SeeAlso width height bounds SkBitmap::dimensions
#Method ##
# ------------------------------------------------------------------------------
#Method SkIRect bounds() const
#In Property
#Line # returns width() and height() as Rectangle ##
Returns IRect { 0, 0, width(), height() }.
#Return integral rectangle from origin to width() and height() ##
#Example
#Height 64
#Image 4
canvas->scale(.5f, .5f);
SkImageInfo imageInfo = source.info();
SkIRect bounds = imageInfo.bounds();
for (int x : { 0, bounds.width() } ) {
for (int y : { 0, bounds.height() } ) {
canvas->drawBitmap(source, x, y);
}
}
##
#SeeAlso width height dimensions
#Method ##
# ------------------------------------------------------------------------------
#Method bool gammaCloseToSRGB() const
#In Property
#Line # Returns if Color_Space gamma is approximately the same as sRGB ##
Returns true if associated Color_Space is not nullptr, and Color_Space gamma
is approximately the same as sRGB.
This includes the
###$
$A sRGB transfer function $ https://en.wikipedia.org/wiki/SRGB#The_sRGB_transfer_function_(%22gamma%22) $$
$$$#
as well as a gamma curve described by a 2.2 exponent.
#Return true if Color_Space gamma is approximately the same as sRGB ##
#Example
#Height 144
const int width = 256;
const int height = 64;
auto drawLabel = [=](const char* what, bool closeToSRGB) -> void {
SkString string;
string.printf("%s gamma is %s" "close to sRGB", what, closeToSRGB ? "" : "not ");
SkPaint paint;
paint.setAntiAlias(true);
paint.setTextAlign(SkPaint::kCenter_Align);
canvas->drawString(string, width / 2, 56, paint);
};
SkColor gradColors[] = { 0xFFFF7F00, 0xFF00FF7F, 0xFF0000FF, 0xFF7F7FFF };
SkPoint gradPoints[] = { { 0, 0 }, { width, 0 }, { width * 2, 0 }, { width * 3, 0 } };
SkPaint gradPaint;
gradPaint.setShader(SkGradientShader::MakeLinear(gradPoints, gradColors, nullptr,
SK_ARRAY_COUNT(gradColors), SkShader::kClamp_TileMode));
canvas->drawRect(SkRect::MakeWH(width, height), gradPaint);
drawLabel("canvas", canvas->imageInfo().gammaCloseToSRGB());
SkBitmap bitmap;
SkImageInfo offscreenInfo = SkImageInfo::MakeS32(width, height, kPremul_SkAlphaType);
bitmap.allocPixels(offscreenInfo);
SkCanvas sRGBOffscreen(bitmap);
sRGBOffscreen.drawRect(SkRect::MakeWH(width, height), gradPaint);
canvas->translate(0, 80);
canvas->drawBitmap(bitmap, 0, 0);
drawLabel("offscreen", offscreenInfo.gammaCloseToSRGB());
##
#SeeAlso SkColorSpace::gammaCloseToSRGB
#Method ##
# ------------------------------------------------------------------------------
#Method SkImageInfo makeWH(int newWidth, int newHeight) const
#In Constructor
#Line # creates Image_Info with changed dimensions ##
Creates Image_Info with the same Color_Type, Color_Space, and Alpha_Type,
with dimensions set to width and height.
#Param newWidth pixel column count; must be zero or greater ##
#Param newHeight pixel row count; must be zero or greater ##
#Return created Image_Info ##
#Example
#Height 144
#Image 3
SkImageInfo canvasImageInfo = canvas->imageInfo();
SkRect canvasBounds = SkRect::Make(canvasImageInfo.bounds());
canvas->drawBitmapRect(source, source.bounds(), canvasBounds, nullptr);
SkImageInfo insetImageInfo =
canvasImageInfo.makeWH(canvasBounds.width() / 2, canvasBounds.height() / 2);
SkBitmap inset;
inset.allocPixels(insetImageInfo);
SkCanvas offscreen(inset);
offscreen.drawBitmapRect(source, source.bounds(), SkRect::Make(inset.bounds()), nullptr);
canvas->drawBitmap(inset, canvasBounds.width() / 4, canvasBounds.height() / 4);
##
#SeeAlso Make makeAlphaType makeColorSpace makeColorType
#Method ##
# ------------------------------------------------------------------------------
#Method SkImageInfo makeAlphaType(SkAlphaType newAlphaType) const
#In Constructor
#Line # creates Image_Info with changed Alpha_Type ##
Creates Image_Info with same Color_Type, Color_Space, width, and height,
with Alpha_Type set to newAlphaType.
Created Image_Info contains newAlphaType even if it is incompatible with
Color_Type, in which case Alpha_Type in Image_Info is ignored.
#Param newAlphaType one of: #list_of_alpha_types#
##
#Return created Image_Info ##
#Example
#Image 3
const int width = 256;
const int height = 128;
SkColor pixels[height][width];
for (int y = 0; y < height; ++y) {
for (int x = 0; x < width; ++x) {
int red = SkScalarRoundToInt(255 * SkScalarAbs(SkScalarSin((x * 4 + y) * 0.03f)));
int blue = SkScalarRoundToInt(255 * SkScalarAbs(SkScalarCos((x * 3 + y) * 0.04f)));
int green = SkScalarRoundToInt(255 * SkScalarAbs(SkScalarSin((x * 2 + y) * 0.05f)));
int alpha = SkScalarRoundToInt(255 * SkScalarAbs(SkScalarCos((x * 1 + y) * 0.006f)));
pixels[y][x] =
SkColorSetARGB(alpha, red * alpha / 255, green * alpha / 255, blue * alpha / 255);
}
}
SkBitmap bitmap;
SkImageInfo info = SkImageInfo::Make(width, height, kBGRA_8888_SkColorType, kPremul_SkAlphaType);
bitmap.installPixels(info, (void*) pixels, sizeof(SkColor) * width);
canvas->drawBitmap(source, 0, 0);
canvas->drawBitmap(bitmap, 0, 0);
SkImageInfo unpremulInfo = info.makeAlphaType(kUnpremul_SkAlphaType);
bitmap.installPixels(unpremulInfo, (void*) pixels, sizeof(SkColor) * width);
canvas->drawBitmap(bitmap, 0, 128);
##
#SeeAlso Make MakeA8 makeColorType makeColorSpace
#Method ##
# ------------------------------------------------------------------------------
#Method SkImageInfo makeColorType(SkColorType newColorType) const
#In Constructor
#Line # creates Image_Info with changed Color_Type ##
Creates Image_Info with same Alpha_Type, Color_Space, width, and height,
with Color_Type set to newColorType.
#Param newColorType one of: #list_of_color_types#
##
#Return created Image_Info ##
#Example
const int width = 256;
const int height = 128;
SkColor pixels[height][width];
for (int y = 0; y < height; ++y) {
for (int x = 0; x < width; ++x) {
int red = SkScalarRoundToInt(255 * SkScalarAbs(SkScalarSin((x * 4 + y) * 0.03f)));
int blue = SkScalarRoundToInt(255 * SkScalarAbs(SkScalarCos((x * 3 + y) * 0.04f)));
int green = SkScalarRoundToInt(255 * SkScalarAbs(SkScalarSin((x * 2 + y) * 0.05f)));
int alpha = SkScalarRoundToInt(255 * SkScalarAbs(SkScalarCos((x * 1 + y) * 0.006f)));
pixels[y][x] =
SkColorSetARGB(alpha, red * alpha / 255, green * alpha / 255, blue * alpha / 255);
}
}
SkBitmap bitmap;
SkImageInfo info = SkImageInfo::Make(width, height, kBGRA_8888_SkColorType, kPremul_SkAlphaType);
bitmap.installPixels(info, (void*) pixels, sizeof(SkColor) * width);
canvas->drawBitmap(source, 0, 0);
canvas->drawBitmap(bitmap, 0, 0);
SkImageInfo rgbaInfo = info.makeColorType(kRGBA_8888_SkColorType);
bitmap.installPixels(rgbaInfo, (void*) pixels, sizeof(SkColor) * width);
canvas->drawBitmap(bitmap, 0, 128);
##
#SeeAlso Make makeAlphaType makeColorSpace
#Method ##
# ------------------------------------------------------------------------------
#Method SkImageInfo makeColorSpace(sk_sp<SkColorSpace> cs) const
#In Constructor
#Line # creates Image_Info with changed Color_Space ##
Creates Image_Info with same Alpha_Type, Color_Type, width, and height,
with Color_Space set to cs.
#Param cs range of colors; may be nullptr ##
#Return created Image_Info ##
#Example
#Height 224
const int width = 256;
const int height = 64;
auto drawLabel = [=](const char* what, bool closeToSRGB) -> void {
SkString string;
string.printf("%s gamma is %s" "close to sRGB", what, closeToSRGB ? "" : "not ");
SkPaint paint;
paint.setAntiAlias(true);
paint.setTextAlign(SkPaint::kCenter_Align);
canvas->drawString(string, width / 2, 56, paint);
};
SkColor gradColors[] = { 0xFFFF7F00, 0xFF00FF7F, 0xFF0000FF, 0xFF7F7FFF };
SkPoint gradPoints[] = { { 0, 0 }, { width, 0 }, { width * 2, 0 }, { width * 3, 0 } };
SkPaint gradPaint;
gradPaint.setShader(SkGradientShader::MakeLinear(gradPoints, gradColors, nullptr,
SK_ARRAY_COUNT(gradColors), SkShader::kClamp_TileMode));
canvas->drawRect(SkRect::MakeWH(width, height), gradPaint);
drawLabel("canvas", canvas->imageInfo().gammaCloseToSRGB());
SkBitmap bitmap;
SkImageInfo offscreenInfo = SkImageInfo::MakeS32(width, height, kPremul_SkAlphaType);
bitmap.allocPixels(offscreenInfo);
SkCanvas sRGBOffscreen(bitmap);
sRGBOffscreen.drawRect(SkRect::MakeWH(width, height), gradPaint);
canvas->translate(0, 80);
canvas->drawBitmap(bitmap, 0, 0);
drawLabel("offscreen", offscreenInfo.gammaCloseToSRGB());
SkImageInfo linearGamma =
offscreenInfo.makeColorSpace(offscreenInfo.colorSpace()->makeLinearGamma());
bitmap.allocPixels(linearGamma);
SkCanvas lgOffscreen(bitmap);
lgOffscreen.drawRect(SkRect::MakeWH(width, height), gradPaint);
canvas->translate(0, 80);
canvas->drawBitmap(bitmap, 0, 0);
drawLabel("linear", linearGamma.gammaCloseToSRGB());
##
#SeeAlso Make MakeS32 makeAlphaType makeColorType
#Method ##
# ------------------------------------------------------------------------------
#Method int bytesPerPixel() const
#In Property
#Line # returns number of bytes in pixel based on Color_Type ##
Returns number of bytes per pixel required by Color_Type.
Returns zero if colorType( is kUnknown_SkColorType.
#Return bytes in pixel ##
#Example
const char* colors[] = {"Unknown", "Alpha_8", "RGB_565", "ARGB_4444", "RGBA_8888", "RGB_888x",
"BGRA_8888", "RGBA_1010102", "RGB_101010x", "Gray_8", "RGBA_F16"};
for (SkColorType colorType : { #list_of_color_types#
} ) {
SkImageInfo info = SkImageInfo::Make(1, 1, colorType, kOpaque_SkAlphaType);
SkDebugf("color: k" "%s" "_SkColorType" "%*s" "bytesPerPixel: %d\n",
colors[colorType], 13 - strlen(colors[colorType]), " ",
info.bytesPerPixel());
}
#StdOut
color: kUnknown_SkColorType bytesPerPixel: 0
color: kAlpha_8_SkColorType bytesPerPixel: 1
color: kRGB_565_SkColorType bytesPerPixel: 2
color: kARGB_4444_SkColorType bytesPerPixel: 2
color: kRGBA_8888_SkColorType bytesPerPixel: 4
color: kRGB_888x_SkColorType bytesPerPixel: 4
color: kBGRA_8888_SkColorType bytesPerPixel: 4
color: kRGBA_1010102_SkColorType bytesPerPixel: 4
color: kRGB_101010x_SkColorType bytesPerPixel: 4
color: kGray_8_SkColorType bytesPerPixel: 1
color: kRGBA_F16_SkColorType bytesPerPixel: 8
##
##
#SeeAlso width shiftPerPixel SkBitmap::bytesPerPixel
#Method ##
# ------------------------------------------------------------------------------
#Method int shiftPerPixel() const
#In Property
#Line # returns bit shift from pixels to bytes ##
Returns bit shift converting row bytes to row pixels.
Returns zero for kUnknown_SkColorType.
#Return one of: 0, 1, 2, 3; left shift to convert pixels to bytes ##
#Example
const char* colors[] = {"Unknown", "Alpha_8", "RGB_565", "ARGB_4444", "RGBA_8888", "RGB_888x",
"BGRA_8888", "RGBA_1010102", "RGB_101010x", "Gray_8", "RGBA_F16"};
for (SkColorType colorType : { #list_of_color_types#
} ) {
SkImageInfo info = SkImageInfo::Make(1, 1, colorType, kOpaque_SkAlphaType);
SkDebugf("color: k" "%s" "_SkColorType" "%*s" "shiftPerPixel: %d\n",
colors[colorType], 14 - strlen(colors[colorType]), " ",
info.shiftPerPixel());
}
#StdOut
color: kUnknown_SkColorType shiftPerPixel: 0
color: kAlpha_8_SkColorType shiftPerPixel: 0
color: kRGB_565_SkColorType shiftPerPixel: 1
color: kARGB_4444_SkColorType shiftPerPixel: 1
color: kRGBA_8888_SkColorType shiftPerPixel: 2
color: kRGB_888x_SkColorType shiftPerPixel: 2
color: kBGRA_8888_SkColorType shiftPerPixel: 2
color: kRGBA_1010102_SkColorType shiftPerPixel: 2
color: kRGB_101010x_SkColorType shiftPerPixel: 2
color: kGray_8_SkColorType shiftPerPixel: 0
color: kRGBA_F16_SkColorType shiftPerPixel: 3
##
##
#SeeAlso bytesPerPixel minRowBytes SkBitmap::shiftPerPixel SkPixmap::shiftPerPixel
#Method ##
# ------------------------------------------------------------------------------
#Method uint64_t minRowBytes64() const
#In Property
#Line # returns width() times bytesPerPixel in 64 bits ##
Returns minimum bytes per row, computed from pixel width() and Color_Type, which
specifies bytesPerPixel(). Bitmap maximum value for row bytes must be representable
as a positive value in a 32-bit signed integer.
#Return width() times bytesPerPixel as unsigned 64-bit integer ##
#Example
for (int shift = 24; shift < 32; ++shift) {
int width = 1 << shift;
SkImageInfo imageInfo =
SkImageInfo::Make(width, 1, kRGBA_F16_SkColorType, kPremul_SkAlphaType);
uint64_t minRowBytes = imageInfo.minRowBytes64();
bool widthTooLarge = (uint64_t) (int32_t) minRowBytes != minRowBytes;
SkDebugf("RGBA_F16 width %d (0x%08x) %s\n",
width, width, widthTooLarge ? "too large" : "OK");
}
#StdOut
RGBA_F16 width 16777216 (0x01000000) OK
RGBA_F16 width 33554432 (0x02000000) OK
RGBA_F16 width 67108864 (0x04000000) OK
RGBA_F16 width 134217728 (0x08000000) OK
RGBA_F16 width 268435456 (0x10000000) too large
RGBA_F16 width 536870912 (0x20000000) too large
RGBA_F16 width 1073741824 (0x40000000) too large
RGBA_F16 width -2147483648 (0x80000000) too large
##
##
#SeeAlso minRowBytes computeByteSize computeMinByteSize validRowBytes
#Method ##
# ------------------------------------------------------------------------------
#Method size_t minRowBytes() const
#In Property
#Line # returns width() times bytesPerPixel in 32 bits ##
Returns minimum bytes per row, computed from pixel width() and Color_Type, which
specifies bytesPerPixel(). Bitmap maximum value for row bytes must be representable
as a positive value in a 32-bit signed integer.
#Return width() times bytesPerPixel as signed 32-bit integer ##
#Example
for (int shift = 24; shift < 32; ++shift) {
int width = 1 << shift;
SkImageInfo imageInfo =
SkImageInfo::Make(width, 1, kRGBA_F16_SkColorType, kPremul_SkAlphaType);
size_t minRowBytes = imageInfo.minRowBytes();
bool widthTooLarge = !minRowBytes;
SkDebugf("RGBA_F16 width %d (0x%08x) %s\n",
width, width, widthTooLarge ? "too large" : "OK");
}
#StdOut
RGBA_F16 width 16777216 (0x01000000) OK
RGBA_F16 width 33554432 (0x02000000) OK
RGBA_F16 width 67108864 (0x04000000) OK
RGBA_F16 width 134217728 (0x08000000) OK
RGBA_F16 width 268435456 (0x10000000) too large
RGBA_F16 width 536870912 (0x20000000) too large
RGBA_F16 width 1073741824 (0x40000000) too large
RGBA_F16 width -2147483648 (0x80000000) too large
##
##
#SeeAlso minRowBytes64 computeByteSize computeMinByteSize validRowBytes
#Method ##
# ------------------------------------------------------------------------------
#Method size_t computeOffset(int x, int y, size_t rowBytes) const
#In Utility
#Line # returns byte offset within pixel array ##
Returns byte offset of pixel from pixel base address.
Asserts in debug build if x or y is outside of bounds. Does not assert if
rowBytes is smaller than minRowBytes, even though result may be incorrect.
#Param x column index, zero or greater, and less than width() ##
#Param y row index, zero or greater, and less than height() ##
#Param rowBytes size of pixel row or larger ##
#Return offset within pixel array ##
#Example
#Height 128
uint8_t pixels[][12] = { { 0x00, 0x00, 0x00, 0xFF, 0xFF, 0x00, 0x00, 0x00},
{ 0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00},
{ 0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0x00},
{ 0xFF, 0xFF, 0x00, 0xFF, 0xFF, 0x00, 0xFF, 0xFF},
{ 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
{ 0x00, 0x00, 0xFF, 0x00, 0x00, 0xFF, 0x00, 0x00},
{ 0x00, 0xFF, 0x00, 0x00, 0x00, 0x00, 0xFF, 0x00},
{ 0x00, 0x00, 0xFF, 0x00, 0x00, 0xFF, 0x00, 0x00} };
SkImageInfo imageInfo = SkImageInfo::MakeA8(8, 8);
SkBitmap bitmap;
bitmap.installPixels(imageInfo, (void*) pixels, sizeof(pixels[0]));
SkPaint paint;
paint.setColor(SK_ColorRED);
canvas->drawBitmapRect(bitmap, SkRect::MakeWH(8, 8), SkRect::MakeWH(32, 32), &paint);
size_t offset = imageInfo.computeOffset(2, 3, sizeof(pixels[0]));
pixels[0][offset] = 0x7F;
offset = imageInfo.computeOffset(5, 3, sizeof(pixels[0]));
pixels[0][offset] = 0x7F;
bitmap.installPixels(imageInfo, (void*) pixels, sizeof(pixels[0]));
canvas->drawBitmapRect(bitmap, SkRect::MakeWH(8, 8), SkRect::MakeWH(128, 128), &paint);
##
#SeeAlso height width minRowBytes computeByteSize
#Method ##
# ------------------------------------------------------------------------------
#Subtopic Operator
#Populate
##
#Method bool operator==(const SkImageInfo& other)_const
#Line # compares Image_Info for equality ##
Compares Image_Info with other, and returns true if width, height, Color_Type,
Alpha_Type, and Color_Space are equivalent.
#Param other Image_Info to compare ##
#Return true if Image_Info equals other ##
#Example
SkImageInfo info1 = SkImageInfo::Make(10, 20, kGray_8_SkColorType, kPremul_SkAlphaType);
SkImageInfo info2 = SkImageInfo::Make(20, 10, kAlpha_8_SkColorType, kUnpremul_SkAlphaType);
SkDebugf("info1 %c= info2\n", info1 == info2 ? '=' : '!');
info2 = info2.makeWH(10, 20);
SkDebugf("info1 %c= info2\n", info1 == info2 ? '=' : '!');
info2 = info2.makeColorType(kGray_8_SkColorType);
SkDebugf("info1 %c= info2\n", info1 == info2 ? '=' : '!');
info2 = info2.makeAlphaType(kPremul_SkAlphaType);
SkDebugf("info1 %c= info2\n", info1 == info2 ? '=' : '!');
#StdOut
info1 != info2
info1 != info2
info1 != info2
info1 == info2
##
##
#SeeAlso operator!=(const SkImageInfo& other)_const SkColorSpace::Equals
#Method ##
# ------------------------------------------------------------------------------
#Method bool operator!=(const SkImageInfo& other)_const
#Line # compares Image_Info for inequality ##
Compares Image_Info with other, and returns true if width, height, Color_Type,
Alpha_Type, and Color_Space are equivalent.
#Param other Image_Info to compare ##
#Return true if Image_Info is not equal to other ##
#Example
SkImageInfo info1 = SkImageInfo::Make(10, 20, kGray_8_SkColorType, kPremul_SkAlphaType);
SkImageInfo info2 = SkImageInfo::Make(20, 10, kAlpha_8_SkColorType, kUnpremul_SkAlphaType);
SkDebugf("info1 %c= info2\n", info1 != info2 ? '!' : '=');
info2 = info2.makeWH(10, 20);
SkDebugf("info1 %c= info2\n", info1 != info2 ? '!' : '=');
info2 = info2.makeColorType(kGray_8_SkColorType);
SkDebugf("info1 %c= info2\n", info1 != info2 ? '!' : '=');
info2 = info2.makeAlphaType(kPremul_SkAlphaType);
SkDebugf("info1 %c= info2\n", info1 != info2 ? '!' : '=');
#StdOut
info1 != info2
info1 != info2
info1 != info2
info1 == info2
##
##
#SeeAlso operator==(const SkImageInfo& other)_const SkColorSpace::Equals
#Method ##
# ------------------------------------------------------------------------------
#Method size_t computeByteSize(size_t rowBytes) const
#In Utility
#Line # memory required by pixel buffer with given row bytes ##
Returns storage required by pixel array, given Image_Info dimensions, Color_Type,
and rowBytes. rowBytes is assumed to be at least as large as minRowBytes().
Returns zero if height is zero.
Returns SK_MaxSizeT if answer exceeds the range of size_t.
#Param rowBytes size of pixel row or larger ##
#Return memory required by pixel buffer ##
#Example
#Height 130
SkImageInfo info = SkImageInfo::MakeN32Premul(2, 2);
const size_t size = info.computeByteSize(100000);
SkAutoTMalloc<SkPMColor> storage(size);
SkPMColor* pixels = storage.get();
SkBitmap bitmap;
bitmap.setInfo(info);
bitmap.setPixels(pixels);
bitmap.eraseColor(SK_ColorRED);
canvas->scale(50, 50);
canvas->rotate(8);
canvas->drawBitmap(bitmap, 2, 0);
##
#SeeAlso computeMinByteSize validRowBytes
#Method ##
# ------------------------------------------------------------------------------
#Method size_t computeMinByteSize() const
#In Utility
#Line # least memory required by pixel buffer ##
Returns storage required by pixel array, given Image_Info dimensions, and
Color_Type. Uses minRowBytes() to compute bytes for pixel row.
Returns zero if height is zero.
Returns SK_MaxSizeT if answer exceeds the range of size_t.
#Return least memory required by pixel buffer ##
#Example
#Height 130
SkImageInfo info = SkImageInfo::MakeN32Premul(2, 2);
const size_t size = info.computeMinByteSize();
SkAutoTMalloc<SkPMColor> storage(size);
SkPMColor* pixels = storage.get();
SkBitmap bitmap;
bitmap.setInfo(info);
bitmap.setPixels(pixels);
bitmap.eraseColor(SK_ColorRED);
canvas->scale(50, 50);
canvas->rotate(8);
canvas->drawBitmap(bitmap, 2, 0);
##
#SeeAlso computeByteSize validRowBytes
#Method ##
# ------------------------------------------------------------------------------
#Method static bool ByteSizeOverflowed(size_t byteSize)
#In Utility
#Line # checks result of computeByteSize and computeMinByteSize ##
Returns true if byteSize equals SK_MaxSizeT. computeByteSize and
computeMinByteSize return SK_MaxSizeT if size_t can not hold buffer size.
#Param byteSize result of computeByteSize or computeMinByteSize ##
#Return true if computeByteSize or computeMinByteSize result exceeds size_t ##
#Example
SkImageInfo info = SkImageInfo::MakeN32Premul(2, 1000000000);
for (size_t rowBytes = 100000000; rowBytes < 10000000000000LL; rowBytes *= 10) {
const size_t size = info.computeByteSize(rowBytes);
SkDebugf("rowBytes:%llu size:%llu overflowed:%s\n", rowBytes, size,
SkImageInfo::ByteSizeOverflowed(size) ? "true" : "false");
}
#StdOut
rowBytes:100000000 size:99999999900000008 overflowed:false
rowBytes:1000000000 size:999999999000000008 overflowed:false
rowBytes:10000000000 size:9999999990000000008 overflowed:false
rowBytes:100000000000 size:18446744073709551615 overflowed:true
rowBytes:1000000000000 size:18446744073709551615 overflowed:true
##
##
#SeeAlso computeByteSize computeMinByteSize validRowBytes
#Method ##
# ------------------------------------------------------------------------------
#Method bool validRowBytes(size_t rowBytes) const
#In Utility
#Line # checks if row bytes is large enough to contain pixel row ##
Returns true if rowBytes is smaller than width times pixel size.
#Param rowBytes size of pixel row or larger ##
#Return true if rowBytes is large enough to contain pixel row ##
#Example
SkImageInfo info = SkImageInfo::MakeN32Premul(16, 8);
for (size_t rowBytes = 60; rowBytes < 72; rowBytes += sizeof(SkPMColor)) {
SkDebugf("validRowBytes(%llu): %s\n", rowBytes, info.validRowBytes(rowBytes) ?
"true" : "false");
}
#StdOut
validRowBytes(60): false
validRowBytes(64): true
validRowBytes(68): true
##
##
#SeeAlso ByteSizeOverflowed computeByteSize computeMinByteSize
#Method ##
# ------------------------------------------------------------------------------
#Method void reset()
#In Constructor
#Line # sets zero dimensions, kUnknown_SkColorType, kUnknown_SkAlphaType ##
Creates an empty Image_Info with kUnknown_SkColorType, kUnknown_SkAlphaType,
a width and height of zero, and no Color_Space.
#Example
SkImageInfo info = SkImageInfo::MakeN32Premul(16, 8);
SkImageInfo copy = info;
SkDebugf("info %c= copy\n", info == copy ? '=' : '!');
copy.reset();
SkDebugf("info %c= reset copy\n", info == copy ? '=' : '!');
SkDebugf("SkImageInfo() %c= reset copy\n", SkImageInfo() == copy ? '=' : '!');
#StdOut
info == copy
info != reset copy
SkImageInfo() == reset copy
##
##
#SeeAlso SkImageInfo()
#Method ##
# ------------------------------------------------------------------------------
#Subtopic Utility
#Populate
#Line # rarely called management functions ##
##
#Method void validate() const
#In Utility
#Line # asserts if Image_Info is invalid (debug only) ##
Asserts if internal values are illegal or inconsistent. Only available if
SK_DEBUG is defined at compile time.
#NoExample
##
#SeeAlso validRowBytes SkBitmap::validate
#Method ##
#Struct SkImageInfo ##
#Topic Image_Info ##
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