SkImageInfo Reference
===
# Image Info
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.
## Overview
## Constant
SkImageInfo related constants are defined by enum, enum class, #define, const, and constexpr.
| Topic |
Description |
|---|
| SkAlphaType |
encoding for pixel transparency |
| SkColorType |
encoding for pixel color |
| SkYUVColorSpace |
color range of YUV pixels |
| kARGB_4444_SkColorType |
pixel with 4 bits for alpha, red, green, blue; in 16-bit word |
| kAlpha_8_SkColorType |
pixel with Alpha in 8-bit byte |
| kBGRA_8888_SkColorType |
pixel with 8 bits for blue, green, red, alpha; in 32-bit word |
| kGray_8_SkColorType |
pixel with Grayscale level in 8-bit byte |
| kJPEG_SkYUVColorSpace |
describes full range |
| kLastEnum_SkAlphaType |
last valid value |
| kLastEnum_SkColorType |
last valid value |
| kLastEnum_SkYUVColorSpace |
last valid value |
| kN32_SkColorType |
native ARGB 32-bit encoding |
| kOpaque_SkAlphaType |
pixel is opaque |
| kPremul_SkAlphaType |
pixel components are Premultiplied by Alpha |
| kRGBA_1010102_SkColorType |
10 bits for red, green, blue; 2 bits for alpha; in 32-bit word |
| kRGBA_8888_SkColorType |
pixel with 8 bits for red, green, blue, alpha; in 32-bit word |
| kRGBA_F16_SkColorType |
pixel with half floats for red, green, blue, alpha; in 64-bit word |
| kRGBA_F32_SkColorType |
pixel using C float for red, green, blue, alpha; in 128-bit word |
| kRGB_101010x_SkColorType |
pixel with 10 bits each for red, green, blue; in 32-bit word |
| kRGB_565_SkColorType |
pixel with 5 bits red, 6 bits green, 5 bits blue, in 16-bit word |
| kRGB_888x_SkColorType |
pixel with 8 bits each for red, green, blue; in 32-bit word |
| kRec601_SkYUVColorSpace |
describes SDTV range |
| kRec709_SkYUVColorSpace |
describes HDTV range |
| kUnknown_SkAlphaType |
uninitialized |
| kUnknown_SkColorType |
uninitialized |
| kUnpremul_SkAlphaType |
pixel components are independent of Alpha |
## Alpha Type
## Enum SkAlphaType
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:
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.
RGB may have Color Alpha included in each component value; the stored
value is the original RGB multiplied by Color Alpha. Premultiplied color
components improve performance.
### Constants
### See Also
SkColorType SkColorSpace
## Alpha Type Opaque
Use kOpaque_SkAlphaType 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 kOpaque_SkAlphaType but all alpha values are not 1.0,
results are undefined.
### Example
## Alpha Type Premul
Use kPremul_SkAlphaType 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.
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
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.
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.
static inline bool SkAlphaTypeIsOpaque(SkAlphaType at)
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.
### Parameters
### Return Value
true if at equals kOpaque_SkAlphaType
---
## Color Type
## Enum SkColorType
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,
kRGBA_F32_SkColorType,
kLastEnum_SkColorType = kRGBA_F32_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
#endif
};
Describes how pixel bits encode color. A pixel may be an alpha mask, a
Grayscale, RGB, or ARGB.
kN32_SkColorType selects the native 32-bit ARGB format. On Little Endian
processors, pixels containing 8-bit ARGB components pack into 32-bit
kBGRA_8888_SkColorType. On Big Endian processors, pixels pack into 32-bit
kRGBA_8888_SkColorType.
### Constants
| Const |
Value |
Details |
Description |
|---|
kUnknown_SkColorType |
0 |
|
Color Type is set to kUnknown_SkColorType by default. If set,
encoding format and size is unknown.
|
kAlpha_8_SkColorType |
1 |
Color Type Alpha 8 |
Stores 8-bit byte pixel encoding that represents transparency. Value of zero
is completely transparent; a value of 255 is completely opaque.
|
kRGB_565_SkColorType |
2 |
Color Type RGB 565 |
Stores 16-bit word pixel encoding that contains five bits of blue,
six bits of green, and five bits of red.
|
kARGB_4444_SkColorType |
3 |
Color Type ARGB 4444 |
Stores 16-bit word pixel encoding that contains four bits of alpha,
four bits of blue, four bits of green, and four bits of red.
|
kRGBA_8888_SkColorType |
4 |
Color Type RGBA 8888 |
Stores 32-bit word pixel encoding that contains eight bits of red,
eight bits of green, eight bits of blue, and eight bits of alpha.
|
kRGB_888x_SkColorType |
5 |
Color Type RGB 888 |
Stores 32-bit word pixel encoding that contains eight bits of red,
eight bits of green, eight bits of blue, and eight unused bits.
|
kBGRA_8888_SkColorType |
6 |
Color Type BGRA 8888 |
Stores 32-bit word pixel encoding that contains eight bits of blue,
eight bits of green, eight bits of red, and eight bits of alpha.
|
kRGBA_1010102_SkColorType |
7 |
Color Type RGBA 1010102 |
Stores 32-bit word pixel encoding that contains ten bits of red,
ten bits of green, ten bits of blue, and two bits of alpha.
|
kRGB_101010x_SkColorType |
8 |
Color Type RGB 101010 |
Stores 32-bit word pixel encoding that contains ten bits of red,
ten bits of green, ten bits of blue, and two unused bits.
|
kGray_8_SkColorType |
9 |
Color Type Gray 8 |
Stores 8-bit byte pixel encoding that equivalent to equal values for red,
blue, and green, representing colors from black to white.
|
kRGBA_F16_SkColorType |
10 |
Color Type RGBA F16 |
Stores 64-bit word pixel encoding that contains 16 bits of blue,
16 bits of green, 16 bits of red, and 16 bits of alpha. Each component
is encoded as a half float.
|
kRGBA_F32_SkColorType |
11 |
Color Type RGBA F32 |
Stores 128-bit word pixel encoding that contains 32 bits of blue,
32 bits of green, 32 bits of red, and 32 bits of alpha. Each component
is encoded as a single precision float.
|
kLastEnum_SkColorType |
11 |
|
Used by tests to iterate through all valid values.
|
kN32_SkColorType |
4 or 6 |
|
Encodes ARGB as either kRGBA_8888_SkColorType or
kBGRA_8888_SkColorType, whichever is native to the platform.
|
### See Also
SkAlphaType SkColorSpace
## Color Type Alpha 8
Alpha pixels encode transparency without color information. Value of zero is
completely transparent; a value of 255 is completely opaque. Bitmap
pixels do not visibly draw, because its pixels have no color information.
When SkColorType is set to kAlpha_8_SkColorType, the paired SkAlphaType is
ignored.
### Example
Alpha pixels can modify another draw. orangePaint fills the bounds of bitmap,
with its transparency set to alpha8 pixel value.
### See Also
ARGB 4444 RGBA 8888
## Color Type ARGB 4444
kARGB_4444_SkColorType encodes ARGB to fit in 16-bit word. Each
component: alpha, blue, green, and red; use four bits, describing 16 levels.
Note that kARGB_4444_SkColorType is misnamed; the acronym does not
describe the actual component order.
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.
### Example
### See Also
RGBA 8888
## Color Type RGBA 8888
kRGBA_8888_SkColorType encodes ARGB into a 32-bit word. Each component:
red, green, blue, alpha; use eight bits, describing 256 levels.
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, kRGBA_8888_SkColorType 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
### See Also
RGB 888 BGRA 8888
## Color Type RGB 888
kRGB_888x_SkColorType encodes RGB into a 32-bit word. Each component:
red, green, blue; use eight bits, describing 256 levels. Eight bits are
unused. Pixels described by kRGB_888x_SkColorType are fully opaque as if
their Color Alpha was set to one, and should always be paired with
kOpaque_SkAlphaType.
### Example
### See Also
RGBA 8888 BGRA 8888
## Color Type BGRA 8888
kBGRA_8888_SkColorType encodes ARGB into a 32-bit word. Each component:
blue, green, red, and alpha; use eight bits, describing 256 levels.
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 Unpremultiplied
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, kBGRA_8888_SkColorType 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
### See Also
RGBA 8888
## Color Type RGBA 1010102
kRGBA_1010102_SkColorType encodes ARGB into a 32-bit word. Each
Color component: red, green, and blue; use ten bits, describing 1024 levels.
Two bits contain alpha, describing four levels. Possible alpha
values are zero: fully transparent; one: 33% opaque; two: 67% opaque;
three: fully opaque.
At present, Color in Paint does not provide enough precision to
draw all colors possible to a kRGBA_1010102_SkColorType Surface.
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 Unpremultiplied
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 three, the drawn result is undefined.
### Example
### See Also
RGB 101010 RGBA 8888
## Color Type RGB 101010
kRGB_101010x_SkColorType encodes RGB into a 32-bit word. Each
Color component: red, green, and blue; use ten bits, describing 1024 levels.
Two bits are unused. Pixels described by kRGB_101010x_SkColorType are fully
opaque as if its Color Alpha was set to one, and should always be paired
with kOpaque_SkAlphaType.
At present, Color in Paint does not provide enough precision to
draw all colors possible to a kRGB_101010x_SkColorType Surface.
### Example
### See Also
RGBA 1010102
## Color Type Gray 8
kGray_8_SkColorType encodes Grayscale level in eight bits that is equivalent
to equal values for red, blue, and green, representing colors from black to
white. Pixels described by kGray_8_SkColorType are fully
opaque as if its Color Alpha was set to one, and should always be paired with
kOpaque_SkAlphaType.
### Example
### See Also
Alpha 8
## Color Type RGBA F16
kRGBA_F16_SkColorType encodes ARGB into a 64-bit word. Each component:
blue, green, red, and alpha; use 16 bits, describing a floating point value,
from -65500 to 65000 with 3.31 decimal digits of precision.
At present, Color in Paint does not provide enough precision or range to
draw all colors possible to a kRGBA_F16_SkColorType Surface.
Each component encodes a floating point value using Half floats .
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.
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 Unpremultiplied
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 one, the drawn result is undefined.
### Example
### See Also
SkColor4f
## Color Type RGBA F32
kRGBA_F32_SkColorType encodes ARGB into a 128-bit word. Each component:
blue, green, red, and alpha; use 32 bits, describing a floating point value,
from -3.402823e+38 to 3.402823e+38 with 7.225 decimal digits of precision.
At present, Color in Paint does not provide enough precision or range to
draw all colors possible to a kRGBA_F32_SkColorType Surface.
Each component encodes a floating point value using single-precision floats .
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.
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 Unpremultiplied
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 one, the drawn result is undefined.
### See Also
SkColor4f
## SkColorTypeBytesPerPixel
int SkColorTypeBytesPerPixel(SkColorType ct)
Returns the number of bytes required to store a pixel, including unused padding.
Returns zero if ct is kUnknown_SkColorType or invalid.
### Parameters
ct |
one of: 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 |
### Return Value
bytes per pixel
### Example
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
### See Also
SkImageInfo::bytesPerPixel
---
## SkColorTypeIsAlwaysOpaque
bool SkColorTypeIsAlwaysOpaque(SkColorType ct)
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.
### Parameters
ct |
one of: 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 |
### Return Value
true if Color Alpha is always set to 1.0
### Example
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
### See Also
SkColorTypeValidateAlphaType
---
## SkColorTypeValidateAlphaType
bool SkColorTypeValidateAlphaType(SkColorType colorType, SkAlphaType alphaType,
SkAlphaType* canonical = nullptr)
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.
### Parameters
colorType |
one of: 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 |
alphaType |
one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType,
kUnpremul_SkAlphaType |
canonical |
storage for Alpha Type |
### Return Value
true if valid Alpha Type can be associated with colorType
### Example
kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType,
kUnpremul_SkAlphaType 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
### See Also
SkColorTypeIsAlwaysOpaque
---
## YUV ColorSpace
## Enum SkYUVColorSpace
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 YCbCr color space .
### Constants
### See Also
SkImage::MakeFromYUVTexturesCopy SkImage::MakeFromNV12TexturesCopy
# Struct SkImageInfo
## Constant
SkImageInfo related constants are defined by enum, enum class, #define, const, and constexpr.
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.
## Member Function
SkImageInfo member functions read and modify the structure properties.
## Related Function
SkImageInfo global, struct, and class related member functions share a topic.
## Constructor
SkImageInfo can be constructed or initialized by these functions, including C++ class constructors.
| Topic |
Description |
|---|
| Make |
creates Image Info from dimensions, Color Type, Alpha Type, Color Space |
| MakeA8 |
creates Image Info with kAlpha_8_SkColorType, kPremul_SkAlphaType |
| MakeN32 |
creates Image Info with Native_Color_Type |
| MakeN32Premul |
creates Image Info with Native_Color_Type, kPremul_SkAlphaType |
|
MakeN32Premul(int width, int height, sk sp<SkColorSpace> cs = nullptr) |
|
MakeN32Premul(const SkISize& size) |
| MakeS32 |
creates Image Info with Native_Color_Type, sRGB Color Space |
| MakeUnknown |
creates Image Info with kUnknown_SkColorType, kUnknown_SkAlphaType |
|
MakeUnknown(int width, int height) |
|
MakeUnknown() |
| SkImageInfo() |
creates with zeroed dimensions, kUnknown_SkColorType, kUnknown_SkAlphaType |
| makeAlphaType |
creates Image Info with changed Alpha Type |
| makeColorSpace |
creates Image Info with changed Color Space |
| makeColorType |
creates Image Info with changed Color Type |
| makeWH |
creates Image Info with changed dimensions |
| reset |
sets zero dimensions, kUnknown_SkColorType, kUnknown_SkAlphaType |
## SkImageInfo
SkImageInfo()
Creates an empty Image Info with kUnknown_SkColorType, kUnknown_SkAlphaType,
a width and height of zero, and no Color Space.
### Return Value
empty Image Info
### Example
### See Also
Make MakeN32 MakeS32 MakeA8
---
## Make
static SkImageInfo Make(int width, int height, SkColorType ct, SkAlphaType at,
sk sp<SkColorSpace> cs = nullptr)
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.
### Parameters
width |
pixel column count; must be zero or greater |
height |
pixel row count; must be zero or greater |
ct |
one of: 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 |
at |
one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType,
kUnpremul_SkAlphaType |
cs |
range of colors; may be nullptr |
### Return Value
created Image Info
### Example
### See Also
MakeN32 MakeN32Premul[2] MakeS32 MakeA8
---
## MakeN32
static SkImageInfo MakeN32(int width, int height, SkAlphaType at, sk sp<SkColorSpace> cs = nullptr)
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.
### Parameters
### Return Value
created Image Info
### Example
### See Also
Make MakeN32Premul[2] MakeS32 MakeA8
---
## MakeS32
static SkImageInfo MakeS32(int width, int height, SkAlphaType at)
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.
### Parameters
### Return Value
created Image Info
### Example
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.
static SkImageInfo MakeN32Premul(int width, int height, sk sp<SkColorSpace> cs = nullptr)
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.
### Parameters
width |
pixel column count; must be zero or greater |
height |
pixel row count; must be zero or greater |
cs |
range of colors; may be nullptr |
### Return Value
created Image Info
### Example
### See Also
MakeN32 MakeS32 MakeA8 Make
---
static SkImageInfo MakeN32Premul(const SkISize& size)
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.
### Parameters
size |
width and height, each must be zero or greater |
### Return Value
created Image Info
### Example
### See Also
MakeN32 MakeS32 MakeA8 Make
---
## MakeA8
static SkImageInfo MakeA8(int width, int height)
Creates Image Info from integral dimensions width and height, kAlpha_8_SkColorType,
kPremul_SkAlphaType, with Color Space set to nullptr.
### Parameters
width |
pixel column count; must be zero or greater |
height |
pixel row count; must be zero or greater |
### Return Value
created Image Info
### Example
### See Also
MakeN32 MakeS32 Make
---
## MakeUnknown
static SkImageInfo MakeUnknown(int width, int height)
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.
### Parameters
width |
pixel column count; must be zero or greater |
height |
pixel row count; must be zero or greater |
### Return Value
created Image Info
### Example
### See Also
SkImageInfo() MakeN32 MakeS32 Make
---
static SkImageInfo MakeUnknown()
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 Value
created Image Info
### Example
### See Also
SkImageInfo() MakeN32 MakeS32 Make
---
## Property
## width
int width() const
Returns pixel count in each row.
### Return Value
pixel width
### Example
### See Also
height SkBitmap::width SkPixelRef::width SkImage::width SkSurface::width
---
## height
int height() const
Returns pixel row count.
### Return Value
pixel height
### Example
### See Also
width SkBitmap::height SkPixelRef::height SkImage::height SkSurface::height
---
## colorType
SkColorType colorType() const
Returns Color Type, one of: 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.
### Return Value
Color Type
### Example
#### Example Output
~~~~
color type: kAlpha_8_SkColorType
~~~~
### See Also
alphaType SkPixmap::colorType SkBitmap::colorType
---
## alphaType
SkAlphaType alphaType() const
Returns Alpha Type, one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType,
kUnpremul_SkAlphaType.
### Return Value
Alpha Type
### Example
#### Example Output
~~~~
alpha type: kPremul_SkAlphaType
~~~~
### See Also
colorType SkPixmap::alphaType SkBitmap::alphaType
---
## colorSpace
SkColorSpace* colorSpace() const
Returns Color Space, the range of colors. The reference count of
Color Space is unchanged. The returned Color Space is immutable.
### Return Value
Color Space, or nullptr
### Example
#### Example Output
~~~~
gammaCloseToSRGB: false gammaIsLinear: true isSRGB: false
~~~~
### See Also
Color Space SkPixmap::colorSpace SkBitmap::colorSpace
---
## refColorSpace
sk sp<SkColorSpace> refColorSpace() const
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 Value
Color Space wrapped in a smart pointer
### Example
### See Also
Color Space SkBitmap::refColorSpace
---
## isEmpty
bool isEmpty() const
Returns if Image Info describes an empty area of pixels by checking if either
width or height is zero or smaller.
### Return Value
true if either dimension is zero or smaller
### Example
#### Example Output
~~~~
width: 0 height: 0 empty: true
width: 0 height: 2 empty: true
width: 2 height: 0 empty: true
width: 2 height: 2 empty: false
~~~~
### See Also
dimensions bounds SkBitmap::empty SkPixmap::bounds
---
## isOpaque
bool isOpaque() const
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 Value
true if Alpha Type is kOpaque_SkAlphaType
### Example
#### Example Output
~~~~
isOpaque: false
isOpaque: false
isOpaque: true
isOpaque: true
~~~~
### See Also
Color Alpha SkColorTypeValidateAlphaType SkBitmap::isOpaque SkImage::isOpaque SkPixmap::isOpaque
---
## dimensions
SkISize dimensions() const
Returns ISize { width, height }.
### Return Value
integral size of width and height
### Example
#### Example Output
~~~~
dimensionsAsBounds == bounds
~~~~
### See Also
width height bounds SkBitmap::dimensions
---
## bounds
SkIRect bounds() const
Returns IRect { 0, 0, width, height }.
### Return Value
integral rectangle from origin to width and height
### Example
### See Also
width height dimensions
---
## gammaCloseToSRGB
bool gammaCloseToSRGB() const
Returns true if associated Color Space is not nullptr, and Color Space gamma
is approximately the same as sRGB.
This includes the sRGB transfer function as well as a gamma curve described by a 2.2 exponent.
### Return Value
true if Color Space gamma is approximately the same as sRGB
### Example
### See Also
SkColorSpace::gammaCloseToSRGB
---
## makeWH
SkImageInfo makeWH(int newWidth, int newHeight) const
Creates Image Info with the same Color Type, Color Space, and Alpha Type,
with dimensions set to width and height.
### Parameters
newWidth |
pixel column count; must be zero or greater |
newHeight |
pixel row count; must be zero or greater |
### Return Value
created Image Info
### Example
### See Also
Make makeAlphaType makeColorSpace makeColorType
---
## makeAlphaType
SkImageInfo makeAlphaType(SkAlphaType newAlphaType) const
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.
### Parameters
### Return Value
created Image Info
### Example
### See Also
Make MakeA8 makeColorType makeColorSpace
---
## makeColorType
SkImageInfo makeColorType(SkColorType newColorType) const
Creates Image Info with same Alpha Type, Color Space, width, and height,
with Color Type set to newColorType.
### Parameters
newColorType |
one of: 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 |
### Return Value
created Image Info
### Example
### See Also
Make makeAlphaType makeColorSpace
---
## makeColorSpace
SkImageInfo makeColorSpace(sk sp<SkColorSpace> cs) const
Creates Image Info with same Alpha Type, Color Type, width, and height,
with Color Space set to cs.
### Parameters
cs |
range of colors; may be nullptr |
### Return Value
created Image Info
### Example
### See Also
Make MakeS32 makeAlphaType makeColorType
---
## bytesPerPixel
int bytesPerPixel() const
Returns number of bytes per pixel required by Color Type.
Returns zero if colorType( is kUnknown_SkColorType.
### Return Value
bytes in pixel
### Example
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
#### Example Output
~~~~
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
~~~~
### See Also
width shiftPerPixel SkBitmap::bytesPerPixel
---
## shiftPerPixel
int shiftPerPixel() const
Returns bit shift converting row bytes to row pixels.
Returns zero for kUnknown_SkColorType.
### Return Value
one of: 0, 1, 2, 3; left shift to convert pixels to bytes
### Example
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
#### Example Output
~~~~
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
~~~~
### See Also
bytesPerPixel minRowBytes SkBitmap::shiftPerPixel SkPixmap::shiftPerPixel
---
## minRowBytes64
uint64_t minRowBytes64() const
Returns minimum bytes per row, computed from pixel width and Color Type, which
specifies bytesPerPixel. Bitmap maximum value for row bytes must fit
in 31 bits.
### Return Value
width times bytesPerPixel as unsigned 64-bit integer
### Example
#### Example Output
~~~~
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
~~~~
### See Also
minRowBytes computeByteSize computeMinByteSize validRowBytes
---
## minRowBytes
size_t minRowBytes() const
Returns minimum bytes per row, computed from pixel width and Color Type, which
specifies bytesPerPixel. Bitmap maximum value for row bytes must fit
in 31 bits.
### Return Value
width times bytesPerPixel as signed 32-bit integer
### Example
#### Example Output
~~~~
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
~~~~
### See Also
minRowBytes64 computeByteSize computeMinByteSize validRowBytes
---
## computeOffset
size_t computeOffset(int x, int y, size_t rowBytes) const
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.
### Parameters
x |
column index, zero or greater, and less than width |
y |
row index, zero or greater, and less than height |
rowBytes |
size of pixel row or larger |
### Return Value
offset within pixel array
### Example
### See Also
height width minRowBytes computeByteSize
---
## Operator
SkImageInfo operators inline class member functions with arithmetic equivalents.
## operator==
bool operator==(const SkImageInfo& other) _const
Compares Image Info with other, and returns true if width, height, Color Type,
Alpha Type, and Color Space are equivalent.
### Parameters
### Return Value
true if Image Info equals other
### Example
#### Example Output
~~~~
info1 != info2
info1 != info2
info1 != info2
info1 == info2
~~~~
### See Also
operator!=(const SkImageInfo& other) const SkColorSpace::Equals
---
## operator!=
bool operator!=(const SkImageInfo& other) _const
Compares Image Info with other, and returns true if width, height, Color Type,
Alpha Type, and Color Space are not equivalent.
### Parameters
### Return Value
true if Image Info is not equal to other
### Example
#### Example Output
~~~~
info1 != info2
info1 != info2
info1 != info2
info1 == info2
~~~~
### See Also
operator==(const SkImageInfo& other) const SkColorSpace::Equals
---
## computeByteSize
size_t computeByteSize(size_t rowBytes) const
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 SIZE_MAX if answer exceeds the range of size_t.
### Parameters
### Return Value
memory required by pixel buffer
### Example
### See Also
computeMinByteSize validRowBytes
---
## computeMinByteSize
size_t computeMinByteSize() const
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 SIZE_MAX if answer exceeds the range of size_t.
### Return Value
least memory required by pixel buffer
### Example
### See Also
computeByteSize validRowBytes
---
## ByteSizeOverflowed
static bool ByteSizeOverflowed(size_t byteSize)
Returns true if byteSize equals SIZE_MAX. computeByteSize and
computeMinByteSize return SIZE_MAX if size_t can not hold buffer size.
### Parameters
### Return Value
true if computeByteSize or computeMinByteSize result exceeds size_t
### Example
#### Example Output
~~~~
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
~~~~
### See Also
computeByteSize computeMinByteSize validRowBytes
---
## validRowBytes
bool validRowBytes(size_t rowBytes) const
Returns true if rowBytes is smaller than width times pixel size.
### Parameters
### Return Value
true if rowBytes is large enough to contain pixel row
### Example
#### Example Output
~~~~
validRowBytes(60): false
validRowBytes(64): true
validRowBytes(68): true
~~~~
### See Also
ByteSizeOverflowed computeByteSize computeMinByteSize
---
## reset
void reset()
Creates an empty Image Info with kUnknown_SkColorType, kUnknown_SkAlphaType,
a width and height of zero, and no Color Space.
### Example
#### Example Output
~~~~
info == copy
info != reset copy
SkImageInfo() == reset copy
~~~~
### See Also
SkImageInfo()
---
## Utility
## validate
void validate() const
Asserts if internal values are illegal or inconsistent. Only available if
SK_DEBUG is defined at compile time.
### See Also
validRowBytes SkBitmap::validate
---