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skia2/docs/SkPixmap_Reference.bmh
Cary Clark d0530ba8f4 wip pixmap docs 
wip pixmap docs

Docs-Preview: https://skia.org/?cl=42522
Bug: skia: 6898
Change-Id: I85947bc36ea057ed008b87d7bef2efa82d7c89ad
Reviewed-on: https://skia-review.googlesource.com/42522
Reviewed-by: Cary Clark <caryclark@skia.org>
Commit-Queue: Cary Clark <caryclark@skia.org>
2017-09-14 16:05:21 +00:00

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#Topic Pixmap
#Class SkPixmap
Pixmap provides a utility to pair SkImageInfo with pixels and row bytes.
Pixmap is a low level class which provides convenience functions to access
raster destinations. Canvas can not draw Pixmap, nor does Pixmap provide
a direct drawing destination.
Use Bitmap to draw pixels referenced by Pixmap; use Surface to draw into
pixels referenced by Pixmap.
Pixmap does not try to manage the lifetime of the pixel memory. Use PixelRef
to manage pixel memory; PixelRef is safe across threads.
#Topic Overview
#Subtopic Subtopics
#Table
#Legend
# topics # description ##
#Legend ##
# Image_Info_Access # Returns all or part of Image_Info. ##
# Initialization # Sets fields for use. ##
# Reader # Examine pixel value. ##
# Writer # Copy to pixel values. ##
# Readable_Address # Returns read only pixels. ##
# Writable_Address # Returns writable pixels. ##
#Table ##
#Subtopic ##
#Subtopic Constructors
#Table
#Legend
# # description ##
#Legend ##
# SkPixmap() # Constructs with default values. ##
# SkPixmap(const SkImageInfo& info, const void* addr, size_t rowBytes) # Constructs from Image_Info, pixels. ##
#Table ##
#Subtopic ##
#Subtopic Member_Functions
#Table
#Legend
# function # description ##
#Legend ##
# addr() # Returns readable pixel address as void pointer. ##
# addr16 # Returns readable pixel address as 16-bit pointer. ##
# addr32 # Returns readable pixel address as 32-bit pointer. ##
# addr64 # Returns readable pixel address as 64-bit pointer. ##
# addr8 # Returns readable pixel address as 8-bit pointer. ##
# addrF16 # Returns readable pixel component address as 16-bit pointer. ##
# alphaType # Returns Image_Info Alpha_Type. ##
# bounds() # Returns width and height as Rectangle. ##
# colorSpace # Returns Image_Info Color_Space. ##
# colorType # Returns Image_Info Color_Type. ##
# computeIsOpaque # Returns true if all pixels are opaque. ##
# erase() # Writes Color to pixels. ##
# extractSubset # Sets pointer to portion of original. ##
# getColor # Returns one pixel as Unpremultiplied Color. ##
# getSafeSize # Returns minimum size required for pixels in 32 bits. ##
# getSafeSize64 # Returns minimum size required for pixels in 64 bits. ##
# getSize64 # Returns conservative size required for pixels. ##
# height() # Returns pixel row count. ##
# info() # Returns Image_Info. ##
# isOpaque # Returns true if Image_Info describes opaque pixels. ##
# readPixels # Copies and converts pixels. ##
# reset() # Reuses existing Pixmap with replacement values. ##
# rowBytes # Returns interval between rows in bytes. ##
# rowBytesAsPixels # Returns interval between rows in pixels. ##
# scalePixels # Scales and converts pixels. ##
# setColorSpace # Sets Image_Info Color_Space. ##
# shiftPerPixel # Returns bit shift from pixels to bytes. ##
# width() # Returns pixel column count. ##
# writable_addr # Returns writable pixel address as void pointer. ##
# writable_addr16 # Returns writable pixel address as 16-bit pointer. ##
# writable_addr32 # Returns writable pixel address as 32-bit pointer. ##
# writable_addr64 # Returns writable pixel address as 64-bit pointer. ##
# writable_addr8 # Returns writable pixel address as 8-bit pointer. ##
# writable_addrF16 # Returns writable pixel component address as 16-bit pointer. ##
#Table ##
#Subtopic ##
#Topic Overview ##
#Subtopic Initialization
# ------------------------------------------------------------------------------
#Method SkPixmap()
Creates an empty Pixmap without pixels, with kUnknown_SkColorType, with
kUnknown_SkAlphaType, and with a width and height of zero. Use
reset() to associate pixels, SkColorType, SkAlphaType, width, and height
after Pixmap has been created.
#Return empty Pixmap ##
#Example
void draw(SkCanvas* canvas) {
const char* alphas[] = {"Unknown", "Opaque", "Premul", "Unpremul"};
const char* colors[] = {"Unknown", "Alpha", "RGB_565", "ARGB_4444", "RGBA_8888", "BGRA_8888",
"Gray_8", "RGBA_F16"};
SkPixmap pixmap;
for (int i = 0; i < 2; ++i) {
SkDebugf("width: %2d height: %2d", pixmap.width(), pixmap.height());
SkDebugf(" color: k%s_SkColorType", colors[pixmap.colorType()]);
SkDebugf(" alpha: k%s_SkAlphaType\n", alphas[pixmap.alphaType()]);
pixmap.reset(SkImageInfo::Make(25, 35, kRGBA_8888_SkColorType, kOpaque_SkAlphaType),
nullptr, 0);
}
}
#StdOut
width: 0 height: 0 color: kUnknown_SkColorType alpha: kUnknown_SkAlphaType
width: 25 height: 35 color: kRGBA_8888_SkColorType alpha: kOpaque_SkAlphaType
##
##
#SeeAlso SkPixmap(const SkImageInfo& info, const void* addr, size_t rowBytes) reset() SkAlphaType SkColorType
##
# ------------------------------------------------------------------------------
#Method SkPixmap(const SkImageInfo& info, const void* addr, size_t rowBytes)
Creates Pixmap from info width, height, SkAlphaType, and SkColorType.
addr points to pixels, or nullptr. rowBytes should be
#Formula
info.width() * info.bytesPerPixel()
##
or larger.
No parameter checking is performed; it is up to the caller to ensure that
addr and rowBytes agree with info.
The memory lifetime pixels are managed by the caller. When Pixmap goes
out of scope, addr is unaffected.
Pixmap may be later modified by reset() to change its size, pixel type, or
storage.
#Param info width, height, SkAlphaType, SkColorType of Image_Info ##
#Param addr pointer to pixels allocated by caller; may be nullptr ##
#Param rowBytes size of one row of addr; width times pixel size, or larger ##
#Return initialized Pixmap ##
#Example
#Image 3
#Description
SkImage::MakeRasterCopy takes const SkPixmap& as an argument. The example
constructs a SkPixmap from the brace-delimited parameters.
##
SkDebugf("image alpha only = %s\n", image->isAlphaOnly() ? "true" : "false");
SkPMColor pmColors = 0;
sk_sp<SkImage> copy = SkImage::MakeRasterCopy({SkImageInfo::MakeA8(1, 1),
(uint8_t*)&pmColors,
1});
SkDebugf("copy alpha only = %s\n", copy->isAlphaOnly() ? "true" : "false");
#StdOut
image alpha only = false
copy alpha only = true
##
##
#SeeAlso SkPixmap() reset() SkAlphaType SkColorType
##
# ------------------------------------------------------------------------------
#Method void reset()
Sets width, height, row bytes to zero; pixel address to nullptr; SkColorType to
kUnknown_SkColorType; and SkAlphaType to kUnknown_SkAlphaType.
The prior pixels are unaffected; it is up to the caller to release pixels
memory if desired.
#Example
void draw(SkCanvas* canvas) {
const char* alphas[] = {"Unknown", "Opaque", "Premul", "Unpremul"};
const char* colors[] = {"Unknown", "Alpha", "RGB_565", "ARGB_4444", "RGBA_8888", "BGRA_8888",
"Gray_8", "RGBA_F16"};
SkPixmap pixmap(SkImageInfo::Make(25, 35, kRGBA_8888_SkColorType, kOpaque_SkAlphaType),
nullptr, 0);
for (int i = 0; i < 2; ++i) {
SkDebugf("width: %2d height: %2d", pixmap.width(), pixmap.height());
SkDebugf(" color: k%s_SkColorType", colors[pixmap.colorType()]);
SkDebugf(" alpha: k%s_SkAlphaType\n", alphas[pixmap.alphaType()]);
pixmap.reset();
}
}
#StdOut
width: 25 height: 35 color: kRGBA_8888_SkColorType alpha: kOpaque_SkAlphaType
width: 0 height: 0 color: kUnknown_SkColorType alpha: kUnknown_SkAlphaType
##
##
#SeeAlso SkPixmap() SkAlphaType SkColorType
##
# ------------------------------------------------------------------------------
#Method void reset(const SkImageInfo& info, const void* addr, size_t rowBytes)
Sets width, height, SkAlphaType, and SkColorType from info.
Sets pixel address from addr, which may be nullptr.
Sets row bytes from rowBytes, which should be
#Formula
info.width() * info.bytesPerPixel()
##
or larger.
Does not check addr. Asserts if built with SK_DEBUG defined and if rowBytes is
too small to hold one row of pixels.
The memory lifetime pixels are managed by the caller. When Pixmap goes
out of scope, addr is unaffected.
#Param info width, height, SkAlphaType, SkColorType of Image_Info ##
#Param addr pointer to pixels allocated by caller; may be nullptr ##
#Param rowBytes size of one row of addr; width times pixel size, or larger ##
#Example
#Image 4
#Height 128
void draw(SkCanvas* canvas) {
std::vector<int32_t> pixels;
pixels.resize(image->height() * image->width() * 4);
SkPixmap pixmap(SkImageInfo::Make(image->width(), image->height(), kN32_SkColorType,
image->alphaType()), (const void*) &pixels.front(), image->width() * 4);
image->readPixels(pixmap, 0, 0);
int x = 0;
for (auto colorType : { kRGBA_8888_SkColorType, kBGRA_8888_SkColorType } ) {
pixmap.reset(SkImageInfo::Make(image->width(), image->height(), colorType,
image->alphaType()), (const void*) &pixels.front(), image->width() * 4);
SkBitmap bitmap;
bitmap.installPixels(pixmap);
canvas->drawBitmap(bitmap, x, 0);
x += 128;
}
}
##
#SeeAlso SkPixmap(const SkImageInfo& info, const void* addr, size_t rowBytes) reset() SkAlphaType SkColorType
##
# ------------------------------------------------------------------------------
#Method void setColorSpace(sk_sp<SkColorSpace> colorSpace)
Changes Color_Space in Image_Info; preserves width, height, SkAlphaType, and
SkColorType in Image, and leaves pixel address and row bytes unchanged.
colorSpace reference count is incremented.
#Param colorSpace Color_Space moved to Image_Info ##
#Example
void draw(SkCanvas* canvas) {
SkPixmap pixmap;
sk_sp<SkColorSpace> colorSpace1 = SkColorSpace::MakeRGB(SkColorSpace::kLinear_RenderTargetGamma,
SkColorSpace::kRec2020_Gamut);
SkDebugf("is %sunique\n", colorSpace1->unique() ? "" : "not ");
pixmap.setColorSpace(colorSpace1);
SkDebugf("is %sunique\n", colorSpace1->unique() ? "" : "not ");
}
#StdOut
is unique
is not unique
##
##
#SeeAlso Color_Space SkImageInfo::makeColorSpace
##
# ------------------------------------------------------------------------------
#Method bool SK_WARN_UNUSED_RESULT reset(const SkMask& mask)
Sets width, height, pixel address, and row bytes to Mask properties, if Mask
format is SkMask::kA8_Format; and returns true. Otherwise sets width, height,
row bytes to zero; pixel address to nullptr; SkColorType to kUnknown_SkColorType;
and SkAlphaType to kUnknown_SkAlphaType; and returns false.
Failing to read the return value generates a compile time warning.
#Param mask Mask containing pixels and dimensions ##
#Return true if set to Mask properties ##
#Example
const int width = 2;
const int height = 2;
uint8_t bytes[] = { 0, 1, 2, 3, 4, 5, 6, 7 };
SkMask mask;
mask.fFormat = SkMask::kA8_Format;
mask.fBounds = {0, 0, width, height};
mask.fImage = bytes;
mask.fRowBytes = (width + 7) >> 3;
SkPixmap pixmap;
bool success = pixmap.reset(mask);
SkDebugf("success: %s width: %d height: %d\n", success ? "true " : "false",
pixmap.width(), pixmap.height());
mask.fFormat = SkMask::kBW_Format;
success = pixmap.reset(mask);
SkDebugf("success: %s width: %d height: %d\n", success ? "true " : "false",
pixmap.width(), pixmap.height());
#StdOut
success: true width: 2 height: 2
success: false width: 0 height: 0
##
##
#SeeAlso Mask reset()
##
# ------------------------------------------------------------------------------
#Method bool SK_WARN_UNUSED_RESULT extractSubset(SkPixmap* subset, const SkIRect& area) const
Sets subset width, height, pixel address to intersection of Pixmap with area,
if intersection is not empty; and return true. Otherwise, leave subset unchanged
and return false.
Failing to read the return value generates a compile time warning.
#Param subset storage for width, height, pixel address of intersection ##
#Param area bounds to intersect with Pixmap ##
#Return true if intersection of Pixmap and area is not empty ##
#Example
#Image 3
#Height 128
void draw(SkCanvas* canvas) {
std::vector<int32_t> pixels;
pixels.resize(image->height() * image->width() * 4);
SkPixmap pixmap(SkImageInfo::Make(image->width(), image->height(), kN32_SkColorType,
image->alphaType()), (const void*) &pixels.front(), image->width() * 4);
image->readPixels(pixmap, 0, 0);
SkPixmap inset;
if (pixmap.extractSubset(&inset, {128, 128, 512, 512})) {
SkBitmap bitmap;
bitmap.installPixels(inset);
canvas->drawBitmap(bitmap, 0, 0);
}
}
##
#SeeAlso reset() SkIRect::intersect
##
#Subtopic Initialization ##
#Subtopic Image_Info_Access
# ------------------------------------------------------------------------------
#Method const SkImageInfo& info() const
Returns width, height, SkAlphaType, and SkColorType.
#Return reference to ImageInfo ##
#Example
#Image 3
std::vector<int32_t> pixels;
pixels.resize(image->height() * image->width() * 4);
SkPixmap pixmap(SkImageInfo::Make(image->width(), image->height(), kN32_SkColorType,
image->alphaType()), (const void*) &pixels.front(), image->width() * 4);
image->readPixels(pixmap, 0, 0);
SkPixmap inset;
if (pixmap.extractSubset(&inset, {128, 128, 512, 512})) {
const SkImageInfo& info = inset.info();
const char* alphas[] = {"Unknown", "Opaque", "Premul", "Unpremul"};
const char* colors[] = {"Unknown", "Alpha", "RGB_565", "ARGB_4444",
"RGBA_8888", "BGRA_8888", "Gray_8", "RGBA_F16"};
SkDebugf("width: %d height: %d color: %s alpha: %s\n", info.width(), info.height(),
colors[info.colorType()], alphas[info.alphaType()]);
}
#StdOut
width: 384 height: 384 color: BGRA_8888 alpha: Opaque
##
##
#SeeAlso Image_Info
##
# ------------------------------------------------------------------------------
#Method size_t rowBytes() const
Returns row bytes, the interval from one pixel row to the next. Row bytes
is at least as large as
#Formula
width() * info().bytesPerPixel()
##
.
It is up to the Pixmap creator to ensure that row bytes is a useful value.
#Return byte length of pixel row ##
#Example
SkPixmap badPixmap = {SkImageInfo::MakeA8(4, 4), nullptr, 2};
SkPixmap okPixmap = {SkImageInfo::MakeA8(4, 4), nullptr, 8};
for (auto& pixmap : { badPixmap, okPixmap } ) {
SkDebugf("rowBytes: %d minRowBytes: %d\n", pixmap.rowBytes(),
pixmap.info().minRowBytes());
}
#StdOut
rowBytes: 2 minRowBytes: 4
rowBytes: 8 minRowBytes: 4
##
##
#SeeAlso addr() info() SkImageInfo::minRowBytes
##
# ------------------------------------------------------------------------------
#Method const void* addr() const
Returns pixel address, the base corresponding the pixel origin.
It is up to the Pixmap creator to ensure that pixel address is a useful value.
#Return pixel address ##
#Example
#Image 3
std::vector<int32_t> pixels;
pixels.resize(image->height() * image->width() * 4);
SkPixmap pixmap(SkImageInfo::Make(image->width(), image->height(), kN32_SkColorType,
image->alphaType()), (const void*) &pixels.front(), image->width() * 4);
image->readPixels(pixmap, 0, 0);
SkDebugf("pixels address: 0x%llx\n", pixmap.addr());
SkPixmap inset;
if (pixmap.extractSubset(&inset, {128, 128, 512, 512})) {
SkDebugf("inset address: 0x%llx\n", inset.addr());
}
#StdOut
#Volatile
pixels address: 0x7f2a440bb010
inset address: 0x7f2a440fb210
##
##
#SeeAlso addr(int x, int y) addr8 addr16 addr32 addr64 info() rowBytes()
##
# ------------------------------------------------------------------------------
#Method int width() const
Returns pixel count in each pixel row. Should be equal or less than:
#Formula
rowBytes() / info.bytesPerPixel()
##
.
#Return pixel width in Image_Info ##
#Example
SkImageInfo info = SkImageInfo::MakeA8(16, 32);
SkPixmap pixmap(info, nullptr, 64);
SkDebugf("pixmap width: %d info width: %d\n", pixmap.width(), info.width());
#StdOut
pixmap width: 16 info width: 16
##
##
#SeeAlso height()
##
# ------------------------------------------------------------------------------
#Method int height() const
Returns pixel row count.
#Return pixel height in Image_Info ##
#Example
SkImageInfo info = SkImageInfo::MakeA8(16, 32);
SkPixmap pixmap(info, nullptr, 64);
SkDebugf("pixmap height: %d info height: %d\n", pixmap.height(), info.height());
#StdOut
pixmap height: 32 info height: 32
##
##
#SeeAlso width()
##
# ------------------------------------------------------------------------------
#Method SkColorType colorType() const
Returns Color_Type, one of: kUnknown_SkColorType, kAlpha_8_SkColorType,
kRGB_565_SkColorType, kARGB_4444_SkColorType, kRGBA_8888_SkColorType,
kBGRA_8888_SkColorType, kGray_8_SkColorType, kRGBA_F16_SkColorType.
#Return Color_Type in Image_Info ##
#Example
const char* colors[] = {"Unknown", "Alpha", "RGB_565", "ARGB_4444",
"RGBA_8888", "BGRA_8888", "Gray_8", "RGBA_F16"};
SkPixmap pixmap(SkImageInfo::MakeA8(16, 32), nullptr, 64);
SkDebugf("color type: k" "%s" "_SkColorType\n", colors[pixmap.colorType()]);
#StdOut
color type: kAlpha_SkColorType
##
##
#SeeAlso alphaType()
##
# ------------------------------------------------------------------------------
#Method SkAlphaType alphaType() const
Returns Alpha_Type, one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType,
kPremul_SkAlphaType, kUnpremul_SkAlphaType.
#Return Alpha_Type in Image_Info ##
#Example
const char* alphas[] = {"Unknown", "Opaque", "Premul", "Unpremul"};
SkPixmap pixmap(SkImageInfo::MakeA8(16, 32), nullptr, 64);
SkDebugf("alpha type: k" "%s" "_SkAlphaType\n", alphas[pixmap.alphaType()]);
#StdOut
alpha type: kPremul_SkAlphaType
##
##
#SeeAlso colorType()
##
# ------------------------------------------------------------------------------
#Method SkColorSpace* colorSpace() const
Returns Color_Space associated with Image_Info.
#Return Color_Space in Image_Info ##
#Example
#Description
SkColorSpace::MakeSRGBLinear creates Color_Space with linear gamma
and an sRGB gamut. This Color_Space gamma is not close to sRGB gamma.
##
SkPixmap pixmap(SkImageInfo::MakeN32(16, 32, kPremul_SkAlphaType,
SkColorSpace::MakeSRGBLinear()), nullptr, 64);
SkColorSpace* colorSpace = pixmap.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
##
# ------------------------------------------------------------------------------
#Method bool isOpaque() const
Returns true if Alpha_Type is kOpaque_SkAlphaType.
Does not check if Color_Type allows Alpha, or Alpha in pixel values.
#Return true if Image_Info has opaque Alpha_Type ##
#Example
#Description
isOpaque ignores whether all pixels are opaque or not.
##
std::vector<uint32_t> pixels;
const int height = 2;
const int width = 2;
pixels.resize(height * width * 4);
SkPixmap pixmap(SkImageInfo::Make(width, height, kN32_SkColorType,
kPremul_SkAlphaType), (const void*) &pixels.front(), width * 4);
for (int index = 0; index < 2; ++index) {
pixmap.erase(0x00000000);
SkDebugf("isOpaque: %s\n", pixmap.isOpaque() ? "true" : "false");
pixmap.erase(0xFFFFFFFF);
SkDebugf("isOpaque: %s\n", pixmap.isOpaque() ? "true" : "false");
pixmap.reset(pixmap.info().makeAlphaType(kOpaque_SkAlphaType),
(const void*) &pixels.front(), width * 4);
}
#StdOut
isOpaque: false
isOpaque: false
isOpaque: true
isOpaque: true
##
##
#SeeAlso computeIsOpaque SkImageInfo::isOpaque
##
# ------------------------------------------------------------------------------
#Method SkIRect bounds() const
Returns IRect
#Formula
{ 0, 0, width(), height() }
##
.
#Return integral rectangle from origin to width() and height() ##
#Example
for (int width : { 0, 2 } ) {
for (int height : { 0, 2 } ) {
SkPixmap pixmap(SkImageInfo::MakeA8(width, height), nullptr, width);
SkDebugf("width: %d height: %d empty: %s\n", width, height,
pixmap.bounds().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 height() width() IRect
##
# ------------------------------------------------------------------------------
#Method int rowBytesAsPixels() const
Returns number of pixels that fit on row. Should be greater than or equal to
width().
#Return maximum pixels per row ##
#Example
for (int rowBytes : { 4, 5, 6, 7, 8} ) {
SkPixmap pixmap(SkImageInfo::MakeN32(1, 1, kPremul_SkAlphaType), nullptr, rowBytes);
SkDebugf("rowBytes: %d rowBytesAsPixels: %d\n", rowBytes, pixmap.rowBytesAsPixels());
}
#StdOut
rowBytes: 4 rowBytesAsPixels: 1
rowBytes: 5 rowBytesAsPixels: 1
rowBytes: 6 rowBytesAsPixels: 1
rowBytes: 7 rowBytesAsPixels: 1
rowBytes: 8 rowBytesAsPixels: 2
##
##
#SeeAlso rowBytes shiftPerPixel width SkImageInfo::bytesPerPixel
##
# ------------------------------------------------------------------------------
#Method int shiftPerPixel() const
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", "RGB_565", "ARGB_4444",
"RGBA_8888", "BGRA_8888", "Gray_8", "RGBA_F16"};
SkImageInfo info = SkImageInfo::MakeA8(1, 1);
for (SkColorType colorType : { kUnknown_SkColorType, kAlpha_8_SkColorType,
kRGB_565_SkColorType, kARGB_4444_SkColorType,
kRGBA_8888_SkColorType, kBGRA_8888_SkColorType,
kGray_8_SkColorType, kRGBA_F16_SkColorType } ) {
SkPixmap pixmap(info.makeColorType(colorType), nullptr, 4);
SkDebugf("color: k" "%s" "_SkColorType" "%*s" "bytesPerPixel: %d shiftPerPixel: %d\n",
colors[colorType], 10 - strlen(colors[colorType]), " ",
pixmap.info().bytesPerPixel(), pixmap.shiftPerPixel());
}
#StdOut
color: kUnknown_SkColorType bytesPerPixel: 0 shiftPerPixel: 0
color: kAlpha_SkColorType bytesPerPixel: 1 shiftPerPixel: 0
color: kRGB_565_SkColorType bytesPerPixel: 2 shiftPerPixel: 1
color: kARGB_4444_SkColorType bytesPerPixel: 2 shiftPerPixel: 1
color: kRGBA_8888_SkColorType bytesPerPixel: 4 shiftPerPixel: 2
color: kBGRA_8888_SkColorType bytesPerPixel: 4 shiftPerPixel: 2
color: kGray_8_SkColorType bytesPerPixel: 1 shiftPerPixel: 0
color: kRGBA_F16_SkColorType bytesPerPixel: 8 shiftPerPixel: 3
##
##
#SeeAlso rowBytes rowBytesAsPixels width SkImageInfo::bytesPerPixel
##
# ------------------------------------------------------------------------------
#Method uint64_t getSize64() const
Returns conservative memory required for pixel storage.
Includes unused memory on last row when rowBytesAsPixels exceeds width().
#Return conservative pixel storage size ##
#Example
SkPixmap pixmap;
for (int width : { 1, 1000, 1000000 } ) {
for (int height: { 1, 1000, 1000000 } ) {
SkImageInfo imageInfo = SkImageInfo::MakeN32(width, height, kPremul_SkAlphaType);
pixmap.reset(imageInfo , nullptr, width * 5);
SkDebugf("width: %7d height: %7d getSize64: %13lld\n", width, height, pixmap.getSize64());
}
}
#StdOut
width: 1 height: 1 getSize64: 5
width: 1 height: 1000 getSize64: 5000
width: 1 height: 1000000 getSize64: 5000000
width: 1000 height: 1 getSize64: 5000
width: 1000 height: 1000 getSize64: 5000000
width: 1000 height: 1000000 getSize64: 5000000000
width: 1000000 height: 1 getSize64: 5000000
width: 1000000 height: 1000 getSize64: 5000000000
width: 1000000 height: 1000000 getSize64: 5000000000000
##
##
#SeeAlso getSafeSize64 getSafeSize height() rowBytes width() SkImageInfo::bytesPerPixel
##
# ------------------------------------------------------------------------------
#Method uint64_t getSafeSize64() const
Returns minimum memory required for pixel storage.
Does not include unused memory on last row when rowBytesAsPixels exceeds width().
#Return exact pixel storage size ##
#Example
SkPixmap pixmap;
for (int width : { 1, 1000, 1000000 } ) {
for (int height: { 1, 1000, 1000000 } ) {
SkImageInfo imageInfo = SkImageInfo::MakeN32(width, height, kPremul_SkAlphaType);
pixmap.reset(imageInfo , nullptr, width * 5);
SkDebugf("width: %7d height: %7d getSafeSize64: %13lld\n", width, height,
pixmap.getSafeSize64());
}
}
#StdOut
width: 1 height: 1 getSafeSize64: 4
width: 1 height: 1000 getSafeSize64: 4999
width: 1 height: 1000000 getSafeSize64: 4999999
width: 1000 height: 1 getSafeSize64: 4000
width: 1000 height: 1000 getSafeSize64: 4999000
width: 1000 height: 1000000 getSafeSize64: 4999999000
width: 1000000 height: 1 getSafeSize64: 4000000
width: 1000000 height: 1000 getSafeSize64: 4999000000
width: 1000000 height: 1000000 getSafeSize64: 4999999000000
##
##
#SeeAlso getSize64 getSafeSize height() rowBytes width() SkImageInfo::bytesPerPixel
##
# ------------------------------------------------------------------------------
#Method size_t getSafeSize() const
Returns minimum memory required for pixel storage.
Does not include unused memory on last row when rowBytesAsPixels exceeds width().
Returns zero if value is does not fit in a signed 32-bit integer.
The largest value than can be returned is 2,147,483,647.
#Return exact pixel storage size if size fits in signed 32 bits ##
#Example
void draw(SkCanvas* canvas) {
SkPixmap pixmap;
for (int width : { 1, 1000, 1000000 } ) {
for (int height: { 1, 1000, 1000000 } ) {
SkImageInfo imageInfo = SkImageInfo::MakeN32(width, height, kPremul_SkAlphaType);
pixmap.reset(imageInfo , nullptr, width * 5);
SkDebugf("width: %7d height: %7d getSafeSize: %7d\n", width, height, pixmap.getSafeSize());
}
}
}
#StdOut
width: 1 height: 1 getSafeSize: 4
width: 1 height: 1000 getSafeSize: 4999
width: 1 height: 1000000 getSafeSize: 4999999
width: 1000 height: 1 getSafeSize: 4000
width: 1000 height: 1000 getSafeSize: 4999000
width: 1000 height: 1000000 getSafeSize: 0
width: 1000000 height: 1 getSafeSize: 4000000
width: 1000000 height: 1000 getSafeSize: 0
width: 1000000 height: 1000000 getSafeSize: 0
##
##
#SeeAlso getSize64 getSafeSize64 height() rowBytes width() SkImageInfo::bytesPerPixel sk_64_isS32
##
#Subtopic Image_Info_Access ##
#Subtopic Reader
# ------------------------------------------------------------------------------
#Method bool computeIsOpaque() const
Returns true if all pixels are opaque. Color_Type determines how pixels
are encoded, and whether pixel describes Alpha. Returns true for Color_Types
without alpha for each pixel; for other Color_Types, returns true if all
pixels have alpha values equivalent to 1.0 or greater.
For Color_Types kRGB_565_SkColorType or kGray_8_SkColorType: always
returns true. For Color_Types kAlpha_8_SkColorType, kBGRA_8888_SkColorType,
kRGBA_8888_SkColorType: returns true if all pixel Alpha values are 255.
For Color_Type kARGB_4444_SkColorType: returns true if all pixel Alpha values are 15.
For kRGBA_F16_SkColorType: returns true if all pixel Alpha values are 1.0 or
greater.
Returns false for any other Color_Type.
#Return true all pixels have opaque values or Color_Type is opaque ##
#Example
std::vector<uint32_t> pixels;
const int height = 2;
const int width = 2;
pixels.resize(height * width * 4);
SkPixmap pixmap(SkImageInfo::Make(width, height, kN32_SkColorType,
kPremul_SkAlphaType), (const void*) &pixels.front(), width * 4);
for (int index = 0; index < 2; ++index) {
pixmap.erase(0x00000000);
SkDebugf("computeIsOpaque: %s\n", pixmap.computeIsOpaque() ? "true" : "false");
pixmap.erase(0xFFFFFFFF);
SkDebugf("computeIsOpaque: %s\n", pixmap.computeIsOpaque() ? "true" : "false");
pixmap.reset(pixmap.info().makeAlphaType(kOpaque_SkAlphaType),
(const void*) &pixels.front(), width * 4);
}
#StdOut
computeIsOpaque: false
computeIsOpaque: true
computeIsOpaque: false
computeIsOpaque: true
##
##
#SeeAlso isOpaque Color_Type Alpha
##
# ------------------------------------------------------------------------------
#Method SkColor getColor(int x, int y) const
Returns pixel at (x, y) as Unpremultiplied Color.
Returns black with Alpha if Color_Type is kAlpha_8_SkColorType.
Input is not validated: out of bounds values of x or y trigger an assert() if
built with SK_DEBUG defined; and returns undefined values or may crash if
SK_RELEASE is defined. Fails if Color_Type is kUnknown_SkColorType or
pixel address is nullptr.
Color_Space in Image_Info is ignored. Some Color precision may be lost in the
conversion to Unpremultiplied Color; original pixel data may have additional
precision.
#Param x positive column index less than width() ##
#Param y positive row index less than height() ##
#Return pixel converted to Unpremultiplied Color ##
#Example
const int w = 4;
const int h = 4;
std::vector<SkPMColor> storage;
storage.resize(w * h);
SkDebugf("Premultiplied:\n");
for (int y = 0; y < h; ++y) {
SkDebugf("(0, %d) ", y);
for (int x = 0; x < w; ++x) {
int a = 0xFF * (x + y) / (w - 1 + h - 1);
storage[x + y * w] = SkPackARGB32(a, a * x / (w - 1), a * y / (h - 1), a);
SkDebugf("0x%08x%c", storage[x + y * w], x == w - 1 ? '\n' : ' ');
}
}
SkPixmap pixmap(SkImageInfo::MakeN32(w, h, kPremul_SkAlphaType), &storage.front(), w * 4);
SkDebugf("Unpremultiplied:\n");
for (int y = 0; y < h; ++y) {
SkDebugf("(0, %d) ", y);
for (int x = 0; x < w; ++x) {
SkDebugf("0x%08x%c", pixmap.getColor(x, y), x == w - 1 ? '\n' : ' ');
}
}
#StdOut
Premultiplied:
(0, 0) 0x00000000 0x2a0e002a 0x55380055 0x7f7f007f
(0, 1) 0x2a000e2a 0x551c1c55 0x7f542a7f 0xaaaa38aa
(0, 2) 0x55003855 0x7f2a547f 0xaa7171aa 0xd4d48dd4
(0, 3) 0x7f007f7f 0xaa38aaaa 0xd48dd4d4 0xffffffff
Unpremultiplied:
(0, 0) 0x00000000 0x2a5500ff 0x55a800ff 0x7fff00ff
(0, 1) 0x2a0055ff 0x555454ff 0x7fa954ff 0xaaff54ff
(0, 2) 0x5500a8ff 0x7f54a9ff 0xaaaaaaff 0xd4ffaaff
(0, 3) 0x7f00ffff 0xaa54ffff 0xd4aaffff 0xffffffff
##
##
#SeeAlso addr() readPixels
##
#Subtopic Reader ##
#Subtopic Readable_Address
# ------------------------------------------------------------------------------
#Method const void* addr(int x, int y) const
Returns readable pixel address at (x, y).
Input is not validated: out of bounds values of x or y trigger an assert() if
built with SK_DEBUG defined. Returns zero if Color_Type is kUnknown_SkColorType.
#Param x positive column index less than width() ##
#Param y positive row index less than height() ##
#Return readable generic pointer to pixel ##
#Example
const int w = 4;
const int h = 4;
std::vector<SkPMColor> storage;
storage.resize(w * h);
SkPixmap pixmap(SkImageInfo::MakeN32(w, h, kPremul_SkAlphaType), &storage.front(), w * 4);
SkDebugf("pixmap.addr(1, 2) %c= &storage[1 + 2 * w]\n",
pixmap.addr(1, 2) == &storage[1 + 2 * w] ? '=' : '!');
#StdOut
pixmap.addr(1, 2) == &storage[1 + 2 * w]
##
##
#SeeAlso addr8 addr16 addr32 addr64 addrF16 getColor writable_addr
##
# ------------------------------------------------------------------------------
#Method const uint8_t* addr8() const
Returns readable base pixel address. Result is addressable as unsigned 8-bit bytes.
Will trigger an assert() if Color_Type is not kAlpha_8_SkColorType or
kGray_8_SkColorType, and is built with SK_DEBUG defined.
One byte corresponds to one pixel.
#Return readable unsigned 8-bit pointer to pixels ##
#Example
const int w = 4;
const int h = 4;
uint8_t storage[w * h];
SkPixmap pixmap(SkImageInfo::Make(w, h, kGray_8_SkColorType, kPremul_SkAlphaType),
storage, w * sizeof(storage[0]));
SkDebugf("pixmap.addr8() %c= storage\n",
pixmap.addr8() == storage ? '=' : '!');
#StdOut
pixmap.addr8() == storage
##
##
#SeeAlso addr() addr16 addr32 addr64 addrF16 getColor writable_addr writable_addr8
##
# ------------------------------------------------------------------------------
#Method const uint16_t* addr16() const
Returns readable base pixel address. Result is addressable as unsigned 16-bit words.
Will trigger an assert() if Color_Type is not kRGB_565_SkColorType or
kARGB_4444_SkColorType, and is built with SK_DEBUG defined.
One word corresponds to one pixel.
#Return readable unsigned 16-bit pointer to pixels ##
#Example
const int w = 4;
const int h = 4;
uint16_t storage[w * h];
SkPixmap pixmap(SkImageInfo::Make(w, h, kARGB_4444_SkColorType, kPremul_SkAlphaType),
storage, w * sizeof(storage[0]));
SkDebugf("pixmap.addr16() %c= storage\n",
pixmap.addr16() == storage ? '=' : '!');
#StdOut
pixmap.addr16() == storage
##
##
#SeeAlso addr() addr8 addr32 addr64 addrF16 getColor writable_addr writable_addr16
##
# ------------------------------------------------------------------------------
#Method const uint32_t* addr32() const
Returns readable base pixel address. Result is addressable as unsigned 32-bit words.
Will trigger an assert() if Color_Type is not kRGBA_8888_SkColorType or
kBGRA_8888_SkColorType, and is built with SK_DEBUG defined.
One word corresponds to one pixel.
#Return readable unsigned 32-bit pointer to pixels ##
#Example
const int w = 4;
const int h = 4;
uint32_t storage[w * h];
SkPixmap pixmap(SkImageInfo::MakeN32(w, h, kPremul_SkAlphaType),
storage, w * sizeof(storage[0]));
SkDebugf("pixmap.addr32() %c= storage\n",
pixmap.addr32() == storage ? '=' : '!');
#StdOut
pixmap.addr32() == storage
##
##
#SeeAlso addr() addr8 addr16 addr64 addrF16 getColor writable_addr writable_addr32
##
# ------------------------------------------------------------------------------
#Method const uint64_t* addr64() const
Returns readable base pixel address. Result is addressable as unsigned 64-bit words.
Will trigger an assert() if Color_Type is not kRGBA_F16_SkColorType and is built
with SK_DEBUG defined.
One word corresponds to one pixel.
#Return readable unsigned 64-bit pointer to pixels ##
#Example
const int w = 4;
const int h = 4;
uint64_t storage[w * h];
SkPixmap pixmap(SkImageInfo::Make(w, h, kRGBA_F16_SkColorType, kPremul_SkAlphaType),
storage, w * sizeof(storage[0]));
SkDebugf("pixmap.addr64() %c= storage\n",
pixmap.addr64() == storage ? '=' : '!');
#StdOut
pixmap.addr64() == storage
##
##
#SeeAlso addr() addr8 addr16 addr32 addrF16 getColor writable_addr writable_addr64
##
# ------------------------------------------------------------------------------
#Method const uint16_t* addrF16() const
Returns readable base pixel address. Result is addressable as unsigned 16-bit words.
Will trigger an assert() if Color_Type is not kRGBA_F16_SkColorType and is built
with SK_DEBUG defined.
Each word represents one color component encoded as a half float.
Four words correspond to one pixel.
#Return readable unsigned 16-bit pointer to first component of pixels ##
#Example
const int w = 4;
const int h = 4;
uint16_t storage[w * h * 4];
SkPixmap pixmap(SkImageInfo::Make(w, h, kRGBA_F16_SkColorType, kPremul_SkAlphaType),
storage, w * 4 * sizeof(storage[0]));
SkDebugf("pixmap.addrF16() %c= storage\n",
pixmap.addrF16() == storage ? '=' : '!');
#StdOut
pixmap.addrF16() == storage
##
##
#SeeAlso addr() addr8 addr16 addr32 addr64 getColor writable_addr writable_addrF16
##
# ------------------------------------------------------------------------------
#Method const uint8_t* addr8(int x, int y) const
Returns readable pixel address at (x, y).
Input is not validated: out of bounds values of x or y trigger an assert() if
built with SK_DEBUG defined.
Will trigger an assert() if Color_Type is not kAlpha_8_SkColorType or
kGray_8_SkColorType, and is built with SK_DEBUG defined.
#Param x positive column index less than width() ##
#Param y positive row index less than height() ##
#Return readable unsigned 8-bit pointer to pixel at (x, y) ##
#Example
const int w = 4;
const int h = 4;
uint8_t storage[w * h];
SkPixmap pixmap(SkImageInfo::Make(w, h, kGray_8_SkColorType, kPremul_SkAlphaType),
storage, w * sizeof(storage[0]));
SkDebugf("pixmap.addr8(1, 2) %c= &storage[1 + 2 * w]\n",
pixmap.addr8(1, 2) == &storage[1 + 2 * w] ? '=' : '!');
#StdOut
pixmap.addr8(1, 2) == &storage[1 + 2 * w]
##
##
#SeeAlso addr() addr16 addr32 addr64 addrF16 getColor writable_addr writable_addr8
##
# ------------------------------------------------------------------------------
#Method const uint16_t* addr16(int x, int y) const
Returns readable pixel address at (x, y).
Input is not validated: out of bounds values of x or y trigger an assert() if
built with SK_DEBUG defined.
Will trigger an assert() if Color_Type is not kRGB_565_SkColorType or
kARGB_4444_SkColorType, and is built with SK_DEBUG defined.
#Param x positive column index less than width() ##
#Param y positive row index less than height() ##
#Return readable unsigned 16-bit pointer to pixel at (x, y) ##
#Example
const int w = 4;
const int h = 4;
uint16_t storage[w * h];
SkPixmap pixmap(SkImageInfo::Make(w, h, kARGB_4444_SkColorType, kPremul_SkAlphaType),
storage, w * sizeof(storage[0]));
SkDebugf("pixmap.addr16(1, 2) %c= &storage[1 + 2 * w]\n",
pixmap.addr16(1, 2) == &storage[1 + 2 * w] ? '=' : '!');
#StdOut
pixmap.addr16(1, 2) == &storage[1 + 2 * w]
##
##
#SeeAlso addr() addr8 addr32 addr64 addrF16 getColor writable_addr writable_addr16
##
# ------------------------------------------------------------------------------
#Method const uint32_t* addr32(int x, int y) const
Returns readable pixel address at (x, y).
Input is not validated: out of bounds values of x or y trigger an assert() if
built with SK_DEBUG defined.
Will trigger an assert() if Color_Type is not kRGBA_8888_SkColorType or
kBGRA_8888_SkColorType, and is built with SK_DEBUG defined.
#Param x positive column index less than width() ##
#Param y positive row index less than height() ##
#Return readable unsigned 32-bit pointer to pixel at (x, y) ##
#Example
const int w = 4;
const int h = 4;
uint32_t storage[w * h];
SkPixmap pixmap(SkImageInfo::Make(w, h, kRGBA_8888_SkColorType, kPremul_SkAlphaType),
storage, w * sizeof(storage[0]));
SkDebugf("pixmap.addr32(1, 2) %c= &storage[1 + 2 * w]\n",
pixmap.addr32(1, 2) == &storage[1 + 2 * w] ? '=' : '!');
#StdOut
pixmap.addr32(1, 2) == &storage[1 + 2 * w]
##
##
#ToDo incomplete ##
##
# ------------------------------------------------------------------------------
#Method const uint64_t* addr64(int x, int y) const
Returns readable pixel address at (x, y).
Input is not validated: out of bounds values of x or y trigger an assert() if
built with SK_DEBUG defined.
Will trigger an assert() if Color_Type is not kRGBA_F16_SkColorType and is built
with SK_DEBUG defined.
#Param x positive column index less than width() ##
#Param y positive row index less than height() ##
#Return readable unsigned 64-bit pointer to pixel at (x, y) ##
#Example
const int w = 4;
const int h = 4;
uint64_t storage[w * h];
SkPixmap pixmap(SkImageInfo::Make(w, h, kRGBA_F16_SkColorType, kPremul_SkAlphaType),
storage, w * sizeof(storage[0]));
SkDebugf("pixmap.addr64(1, 2) %c= &storage[1 + 2 * w]\n",
pixmap.addr64(1, 2) == &storage[1 + 2 * w] ? '=' : '!');
#StdOut
pixmap.addr64(1, 2) == &storage[1 + 2 * w]
##
##
#SeeAlso addr() addr8 addr16 addr32 addrF16 getColor writable_addr writable_addr64
##
# ------------------------------------------------------------------------------
#Method const uint16_t* addrF16(int x, int y) const
Returns readable pixel address at (x, y).
Input is not validated: out of bounds values of x or y trigger an assert() if
built with SK_DEBUG defined.
Will trigger an assert() if Color_Type is not kRGBA_F16_SkColorType and is built
with SK_DEBUG defined.
Each unsigned 16-bit word represents one color component encoded as a half float.
Four words correspond to one pixel.
#Param x positive column index less than width() ##
#Param y positive row index less than height() ##
#Return readable unsigned 16-bit pointer to pixel component at (x, y) ##
#Example
const int w = 4;
const int h = 4;
const int wordsPerPixel = 4;
const int rowWords = w * wordsPerPixel;
uint16_t storage[rowWords * h];
SkPixmap pixmap(SkImageInfo::Make(w, h, kRGBA_F16_SkColorType, kPremul_SkAlphaType),
storage, rowWords * sizeof(storage[0]));
SkDebugf("pixmap.addrF16(1, 2) %c= &storage[1 * wordsPerPixel + 2 * rowWords]\n",
pixmap.addrF16(1, 2) == &storage[1 * wordsPerPixel + 2 * rowWords] ? '=' : '!');
#StdOut
pixmap.addrF16(1, 2) == &storage[1 * wordsPerPixel + 2 * rowWords]
##
##
#SeeAlso addr() addr8 addr16 addr32 addr64 getColor writable_addr writable_addrF16
##
#Subtopic Readable_Address ##
#Subtopic Writable_Address
# ------------------------------------------------------------------------------
#Method void* writable_addr() const
Returns writable base pixel address.
#Return writable generic base pointer to pixels ##
#Example
const int w = 4;
const int h = 4;
SkPMColor storage[w * h * 4];
SkPixmap pixmap(SkImageInfo::MakeN32(w, h, kPremul_SkAlphaType), storage, w * 4);
SkDebugf("pixmap.writable_addr() %c= (void *)storage\n",
pixmap.writable_addr() == (void *)storage ? '=' : '!');
pixmap.erase(0x00000000);
*(SkPMColor*)pixmap.writable_addr() = 0xFFFFFFFF;
SkDebugf("pixmap.getColor(0, 1) %c= 0x00000000\n",
pixmap.getColor(0, 1) == 0x00000000 ? '=' : '!');
SkDebugf("pixmap.getColor(0, 0) %c= 0xFFFFFFFF\n",
pixmap.getColor(0, 0) == 0xFFFFFFFF ? '=' : '!');
#StdOut
pixmap.writable_addr() == (void *)storage
pixmap.getColor(0, 1) == 0x00000000
pixmap.getColor(0, 0) == 0xFFFFFFFF
##
##
#SeeAlso writable_addr8 writable_addr16 writable_addr32 writable_addr64 writable_addrF16 addr()
##
# ------------------------------------------------------------------------------
#Method void* writable_addr(int x, int y) const
Returns writable pixel address at (x, y).
Input is not validated: out of bounds values of x or y trigger an assert() if
built with SK_DEBUG defined. Returns zero if Color_Type is kUnknown_SkColorType.
#Param x positive column index less than width() ##
#Param y positive row index less than height() ##
#Return writable generic pointer to pixel ##
#Example
const int w = 4;
const int h = 4;
SkPMColor storage[w * h * 4];
SkPixmap pixmap(SkImageInfo::MakeN32(w, h, kPremul_SkAlphaType), storage, w * 4);
SkDebugf("pixmap.writable_addr() %c= (void *)storage\n",
pixmap.writable_addr() == (void *)storage ? '=' : '!');
pixmap.erase(0x00000000);
*(SkPMColor*)pixmap.writable_addr(1, 2) = 0xFFFFFFFF;
SkDebugf("pixmap.getColor(0, 0) %c= 0x00000000\n",
pixmap.getColor(0, 0) == 0x00000000 ? '=' : '!');
SkDebugf("pixmap.getColor(1, 2) %c= 0xFFFFFFFF\n",
pixmap.getColor(1, 2) == 0xFFFFFFFF ? '=' : '!');
#StdOut
pixmap.writable_addr() == (void *)storage
pixmap.getColor(0, 0) == 0x00000000
pixmap.getColor(1, 2) == 0xFFFFFFFF
##
##
#SeeAlso writable_addr8 writable_addr16 writable_addr32 writable_addr64 writable_addrF16 addr()
##
# ------------------------------------------------------------------------------
#Method uint8_t* writable_addr8(int x, int y) const
Returns writable base pixel address. Result is addressable as unsigned 8-bit bytes.
Will trigger an assert() if Color_Type is not kAlpha_8_SkColorType or
kGray_8_SkColorType, and is built with SK_DEBUG defined.
One byte corresponds to one pixel.
#Param x positive column index less than width() ##
#Param y positive row index less than height() ##
#Return writable unsigned 8-bit pointer to pixels ##
#Example
#Height 64
#Description
Altering pixels after drawing Bitmap is not guaranteed to affect subsequent
drawing on all platforms. Adding a second SkBitmap::installPixels after editing
pixel memory is safer.
##
void draw(SkCanvas* canvas) {
uint8_t storage[][5] = {{ 0, 0, 64, 0, 0},
{ 0, 128, 255, 128, 0},
{64, 255, 255, 255, 64},
{ 0, 128, 255, 128, 0},
{ 0, 0, 64, 0, 0}};
SkImageInfo imageInfo = SkImageInfo::Make(5, 5, kGray_8_SkColorType, kPremul_SkAlphaType);
SkPixmap pixmap(imageInfo, storage[0], 5);
SkBitmap bitmap;
bitmap.installPixels(pixmap);
canvas->scale(10, 10);
canvas->drawBitmap(bitmap, 0, 0);
*pixmap.writable_addr8(2, 2) = 0;
// bitmap.installPixels(pixmap); // uncomment to fix on GPU
canvas->drawBitmap(bitmap, 10, 0);
}
##
#SeeAlso writable_addr writable_addr16 writable_addr32 writable_addr64 writable_addrF16 addr() addr8
##
# ------------------------------------------------------------------------------
#Method uint16_t* writable_addr16(int x, int y) const
Returns writable_addr base pixel address. Result is addressable as unsigned 16-bit words.
Will trigger an assert() if Color_Type is not kRGB_565_SkColorType or
kARGB_4444_SkColorType, and is built with SK_DEBUG defined.
One word corresponds to one pixel.
#Param x positive column index less than width() ##
#Param y positive row index less than height() ##
#Return writable unsigned 16-bit pointer to pixel ##
#Example
#Description
Draw a five by five bitmap, and draw it again with a center black pixel.
The low nibble of the 16-bit word is Alpha.
##
#Height 64
uint16_t storage[][5] = {{ 0xCABF, 0xDABE, 0xCA9D, 0xC96C, 0xA39B },
{ 0xACEE, 0xA87C, 0x893A, 0x4779, 0x8708 },
{ 0x4B7C, 0x255B, 0x2559, 0x2557, 0x4656 },
{ 0x9099, 0x8128, 0x2557, 0x4124, 0x3323 },
{ 0x7547, 0x5505, 0x4434, 0x2012, 0x0000 }};
SkImageInfo imageInfo = SkImageInfo::Make(5, 5, kARGB_4444_SkColorType, kPremul_SkAlphaType);
SkPixmap pixmap(imageInfo, storage[0], sizeof(storage) / 5);
SkBitmap bitmap;
bitmap.installPixels(pixmap);
canvas->scale(10, 10);
canvas->drawBitmap(bitmap, 0, 0);
*pixmap.writable_addr16(2, 2) = 0x000F;
bitmap.installPixels(pixmap);
canvas->drawBitmap(bitmap, 10, 0);
##
#SeeAlso writable_addr writable_addr8 writable_addr32 writable_addr64 writable_addrF16 addr() addr16
##
# ------------------------------------------------------------------------------
#Method uint32_t* writable_addr32(int x, int y) const
Returns writable base pixel address. Result is addressable as unsigned 32-bit words.
Will trigger an assert() if Color_Type is not kRGBA_8888_SkColorType or
kBGRA_8888_SkColorType, and is built with SK_DEBUG defined.
One word corresponds to one pixel.
#Param x positive column index less than width() ##
#Param y positive row index less than height() ##
#Return writable unsigned 32-bit pointer to pixel ##
#Example
#Image 4
#Height 72
std::vector<int32_t> pixels;
pixels.resize(image->height() * image->width() * 4);
SkPixmap pixmap(SkImageInfo::Make(image->width(), image->height(), kN32_SkColorType,
image->alphaType()), (const void*) &pixels.front(), image->width() * 4);
image->readPixels(pixmap, 0, 0);
for (int y = 0; y < pixmap.height() / 2; ++y) {
for (int x = 0; x < pixmap.width(); ++x) {
if ((x & 4) == (y & 4)) {
SkTSwap(*pixmap.writable_addr32(x, y),
*pixmap.writable_addr32(pixmap.width() - x, pixmap.height() - y));
}
}
}
SkBitmap bitmap;
bitmap.installPixels(pixmap);
canvas->drawBitmap(bitmap, 0, 0);
##
#SeeAlso writable_addr writable_addr8 writable_addr16 writable_addr64 writable_addrF16 addr() addr32
##
# ------------------------------------------------------------------------------
#Method uint64_t* writable_addr64(int x, int y) const
Returns writable base pixel address. Result is addressable as unsigned 64-bit words.
Will trigger an assert() if Color_Type is not kRGBA_F16_SkColorType and is built
with SK_DEBUG defined.
One word corresponds to one pixel.
#Param x positive column index less than width() ##
#Param y positive row index less than height() ##
#Return writable unsigned 64-bit pointer to pixel ##
#Example
SkImageInfo info = SkImageInfo::Make(3, 3, kRGBA_F16_SkColorType, kPremul_SkAlphaType);
uint64_t storage[9];
SkPixmap pixmap(info, storage, 3 * sizeof(uint64_t));
SkColor4f c4 { 1, 0.45f, 0.25f, 0.65f };
pixmap.erase(c4);
SkBitmap bitmap;
canvas->scale(10, 10);
bitmap.installPixels(pixmap);
canvas->drawBitmap(bitmap, 0, 0);
*pixmap.writable_addr64(1, 1) |= 0x00ff000000000000LL;
bitmap.installPixels(pixmap);
canvas->drawBitmap(bitmap, 10, 0);
##
#SeeAlso writable_addr writable_addr8 writable_addr16 writable_addr32 writable_addrF16 addr() addr64
##
# ------------------------------------------------------------------------------
#Method uint16_t* writable_addrF16(int x, int y) const
Returns writable base pixel address. Result is addressable as unsigned 16-bit words.
Will trigger an assert() if Color_Type is not kRGBA_F16_SkColorType and is built
with SK_DEBUG defined.
Each word represents one color component encoded as a half float.
Four words correspond to one pixel.
#Param x positive column index less than width() ##
#Param y positive row index less than height() ##
#Return writable unsigned 16-bit pointer to first component of pixel ##
#Example
#Height 64
#Description
Left bitmap is drawn with two pixels defined in half float format. Right bitmap
is drawn after overwriting bottom half float color with top half float color.
##
SkImageInfo info = SkImageInfo::Make(1, 2, kRGBA_F16_SkColorType, kPremul_SkAlphaType);
uint16_t storage[2][4];
SkPixmap pixmap(info, storage[0], sizeof(uint64_t));
SkIRect topPixelBounds = {0, 0, 1, 1};
pixmap.erase({ 0.65f, 0.45f, 0.25f, 1 }, &topPixelBounds);
SkIRect bottomPixelBounds = {0, 1, 1, 2};
pixmap.erase({ 0.25f, 0.65f, 0.45f, 1 }, &bottomPixelBounds);
SkBitmap bitmap;
canvas->scale(20, 20);
bitmap.installPixels(pixmap);
canvas->drawBitmap(bitmap, 0, 0);
uint16_t* pixel2 = pixmap.writable_addrF16(0, 1);
for (int i = 0; i < 4; ++i) {
pixel2[i] = storage[0][i];
}
bitmap.installPixels(pixmap);
canvas->drawBitmap(bitmap, 4, 0);
##
#SeeAlso writable_addr writable_addr8 writable_addr16 writable_addr32 writable_addr64 addr() addrF16
##
#Subtopic Writable_Address ##
#Subtopic Writer
# ------------------------------------------------------------------------------
#Method bool readPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes,
int srcX, int srcY, SkTransferFunctionBehavior behavior) const
Copies a Rect of pixels to dstPixels. Copy starts at (srcX, srcY), and does not
exceed
#Formula
(this->width(), this->height())
##
. dstInfo specifies width, height, Color_Type, Alpha_Type, and
Color_Space of destination. dstRowBytes specifics the gap from one destination
row to the next. Returns true if pixels are copied. Returns false if
dstInfo.addr() equals nullptr, or dstRowBytes is less than dstInfo.minRowBytes.
Pixels are copied only if pixel conversion is possible. If this->colorType is
kGray_8_SkColorType, or kAlpha_8_SkColorType; dstInfo.colorType must match.
If this->colorType is kGray_8_SkColorType, dstInfo.colorSpace must match.
If this->alphaType is kOpaque_SkAlphaType, dstInfo.alphaType must
match. If this->colorSpace is nullptr, dstInfo.colorSpace must match. Returns
false if pixel conversion is not possible.
srcX and srcY may be negative to copy only top or left of source. Returns
false if width() or height() is zero or negative. Returns false if
#Formula
abs(srcX) >= this->width() || abs(scrY) >= this->height()
##
.
If behavior is SkTransferFunctionBehavior::kRespect: converts source
pixels to a linear space before converting to dstInfo.
If behavior is SkTransferFunctionBehavior::kIgnore: source
pixels are treated as if they are linear, regardless of their encoding.
#Param dstInfo destination width, height, Color_Type, Alpha_Type, Color_Space ##
#Param dstPixels destination pixel storage ##
#Param dstRowBytes destination row length ##
#Param srcX column index whose absolute value is less than width() ##
#Param srcY row index whose absolute value is less than height() ##
#Param behavior one of: SkTransferFunctionBehavior::kRespect,
SkTransferFunctionBehavior::kIgnore
##
#Return true if pixels are copied to dstPixels ##
#Example
#Image 3
void draw(SkCanvas* canvas) {
SkImageInfo info = SkImageInfo::MakeN32Premul(image->width(), image->height(),
canvas->imageInfo().colorSpace() ? SkColorSpace::MakeSRGB() : nullptr);
std::vector<int32_t> srcPixels;
srcPixels.resize(image->height() * image->width() * 4);
SkPixmap pixmap(info, (const void*) &srcPixels.front(), image->width() * 4);
image->readPixels(pixmap, 0, 0);
SkTransferFunctionBehavior behavior = canvas->imageInfo().colorSpace() ?
SkTransferFunctionBehavior::kRespect : SkTransferFunctionBehavior::kIgnore;
std::vector<int32_t> dstPixels;
dstPixels.resize(image->height() * image->width() * 4);
int offset = 0;
for (auto behavior : { SkTransferFunctionBehavior::kRespect,
SkTransferFunctionBehavior::kIgnore} ) {
pixmap.readPixels(info, &dstPixels.front(), image->width() * 4, offset, 0, behavior);
offset += 128;
}
SkBitmap bitmap;
SkPixmap dstmap(info, &dstPixels.front(), image->width() * 4);
bitmap.installPixels(dstmap);
canvas->drawBitmap(bitmap, 0, 0);
}
##
#SeeAlso erase SkBitmap::readPixels SkCanvas::drawBitmap SkCanvas::readPixels SkImage::readPixels SkSurface::readPixels
##
# ------------------------------------------------------------------------------
#Method bool readPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes) const
Copies a Rect of pixels to dstPixels. Copy starts at (0, 0), and does not
exceed
#Formula
(this->width(), this->height())
##
. dstInfo specifies width, height, Color_Type, Alpha_Type, and
Color_Space of destination. dstRowBytes specifics the gap from one destination
row to the next. Returns true if pixels are copied. Returns false if
dstInfo.addr() equals nullptr, or dstRowBytes is less than dstInfo.minRowBytes.
Pixels are copied only if pixel conversion is possible. If this->colorType is
kGray_8_SkColorType, or kAlpha_8_SkColorType; dstInfo.colorType must match.
If this->colorType is kGray_8_SkColorType, dstInfo.colorSpace must match.
If this->alphaType is kOpaque_SkAlphaType, dstInfo.alphaType must
match. If this->colorSpace is nullptr, dstInfo.colorSpace must match. Returns
false if pixel conversion is not possible.
Returns false if this->width() or this->height() is zero or negative.
#Param dstInfo destination width, height, Color_Type, Alpha_Type, Color_Space ##
#Param dstPixels destination pixel storage ##
#Param dstRowBytes destination row length ##
#Return true if pixels are copied to dstPixels ##
#Example
#Height 128
#Description
Transferring the gradient from 8 bits per component to 4 bits per component
creates visible banding.
##
std::vector<int32_t> pixels;
const int width = 256;
const int height = 64;
pixels.resize(height * width * 4);
SkImageInfo srcInfo = SkImageInfo::MakeN32Premul(width, height);
SkPixmap srcPixmap(srcInfo, (const void*) &pixels.front(), width * 4);
SkColor gradColors[] = { 0xFFAA3300, 0x7F881122 };
SkPoint gradPoints[] = { { 0, 0 }, { 256, 0 } };
SkPaint paint;
paint.setShader(SkGradientShader::MakeLinear(gradPoints, gradColors, nullptr,
SK_ARRAY_COUNT(gradColors), SkShader::kClamp_TileMode));
SkBitmap bitmap;
bitmap.installPixels(srcPixmap);
SkCanvas srcCanvas(bitmap);
srcCanvas.drawRect(SkRect::MakeWH(width, height), paint);
canvas->drawBitmap(bitmap, 0, 0);
std::vector<int32_t> dstPixels;
dstPixels.resize(height * width * 2);
SkImageInfo dstInfo = srcInfo.makeColorType(kARGB_4444_SkColorType);
srcPixmap.readPixels(dstInfo, &dstPixels.front(), width * 2);
SkPixmap dstPixmap(dstInfo, &dstPixels.front(), width * 2);
bitmap.installPixels(dstPixmap);
canvas->drawBitmap(bitmap, 0, 128);
##
#SeeAlso erase SkBitmap::readPixels SkCanvas::drawBitmap SkCanvas::readPixels SkImage::readPixels SkSurface::readPixels
##
# ------------------------------------------------------------------------------
#Method bool readPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes, int srcX,
int srcY) const
Copies a Rect of pixels to dstPixels. Copy starts at (srcX, srcY), and does not
exceed
#Formula
(this->width(), this->height())
##
. dstInfo specifies width, height, Color_Type, Alpha_Type, and
Color_Space of destination. dstRowBytes specifics the gap from one destination
row to the next. Returns true if pixels are copied. Returns false if
dstInfo.addr() equals nullptr, or dstRowBytes is less than dstInfo.minRowBytes.
Pixels are copied only if pixel conversion is possible. If this->colorType is
kGray_8_SkColorType, or kAlpha_8_SkColorType; dstInfo.colorType must match.
If this->colorType is kGray_8_SkColorType, dstInfo.colorSpace must match.
If this->alphaType is kOpaque_SkAlphaType, dstInfo.alphaType must
match. If this->colorSpace is nullptr, dstInfo.colorSpace must match. Returns
false if pixel conversion is not possible.
srcX and srcY may be negative to copy only top or left of source. Returns
false if this->width() or this->height() is zero or negative. Returns false if
#Formula
abs(srcX) >= this->width() || abs(scrY) >= this->height()
##
.
#Param dstInfo destination width, height, Color_Type, Alpha_Type, Color_Space ##
#Param dstPixels destination pixel storage ##
#Param dstRowBytes destination row length ##
#Param srcX column index whose absolute value is less than width() ##
#Param srcY row index whose absolute value is less than height() ##
#Return true if pixels are copied to dstPixels ##
#Example
#Image 3
void draw(SkCanvas* canvas) {
SkImageInfo info = SkImageInfo::MakeN32Premul(image->width(), image->height());
std::vector<int32_t> srcPixels;
const int rowBytes = image->width() * 4;
srcPixels.resize(image->height() * rowBytes);
SkPixmap pixmap(info, (const void*) &srcPixels.front(), rowBytes);
image->readPixels(pixmap, 0, 0);
for (int offset : { 32, 64, 96 } ) {
std::vector<int32_t> dstPixels;
dstPixels.resize(image->height() * rowBytes);
pixmap.readPixels(info, &dstPixels.front(), rowBytes, offset, 0);
SkBitmap bitmap;
SkPixmap dstmap(info, &dstPixels.front(), rowBytes);
bitmap.installPixels(dstmap);
canvas->translate(32, 32);
canvas->drawBitmap(bitmap, 0, 0);
}
}
##
#SeeAlso erase SkBitmap::readPixels SkCanvas::drawBitmap SkCanvas::readPixels SkImage::readPixels SkSurface::readPixels
##
# ------------------------------------------------------------------------------
#Method bool readPixels(const SkPixmap& dst, int srcX, int srcY) const
Copies a Rect of pixels to dst. Copy starts at (srcX, srcY), and does not
exceed (this->width(), this->height()). dst specifies width, height, Color_Type,
Alpha_Type, and Color_Space of destination. Returns true if pixels are copied.
Returns false if dst.addr() equals nullptr, or dst.rowBytes is less than
dst SkImageInfo::minRowBytes.
Pixels are copied only if pixel conversion is possible. If this->colorType is
kGray_8_SkColorType, or kAlpha_8_SkColorType; dst.info().colorType must match.
If this->colorType is kGray_8_SkColorType, dst.info().colorSpace must match.
If this->alphaType is kOpaque_SkAlphaType, dst.info().alphaType must
match. If this->colorSpace is nullptr, dst.info().colorSpace must match. Returns
false if pixel conversion is not possible.
srcX and srcY may be negative to copy only top or left of source. Returns
false this->width() or this->height() is zero or negative. Returns false if
#Formula
abs(srcX) >= this->width() || abs(scrY) >= this->height()
##
.
#Param dst Image_Info and pixel address to write to ##
#Param srcX column index whose absolute value is less than width() ##
#Param srcY row index whose absolute value is less than height() ##
#Return true if pixels are copied to dst ##
#Example
#Image 3
void draw(SkCanvas* canvas) {
SkImageInfo info = SkImageInfo::MakeN32Premul(image->width(), image->height());
std::vector<int32_t> srcPixels;
const int rowBytes = image->width() * 4;
srcPixels.resize(image->height() * rowBytes);
SkPixmap pixmap(info, (const void*) &srcPixels.front(), rowBytes);
image->readPixels(pixmap, 0, 0);
for (int offset : { 32, 64, 96 } ) {
std::vector<int32_t> dstPixels;
dstPixels.resize(image->height() * rowBytes);
SkPixmap dstmap(info, &dstPixels.front(), rowBytes);
pixmap.readPixels(dstmap, offset, 0);
SkBitmap bitmap;
bitmap.installPixels(dstmap);
canvas->translate(32, 32);
canvas->drawBitmap(bitmap, 0, 0);
}
}
##
#SeeAlso erase SkBitmap::readPixels SkCanvas::drawBitmap SkCanvas::readPixels SkImage::readPixels SkSurface::readPixels
##
# ------------------------------------------------------------------------------
#Method bool readPixels(const SkPixmap& dst) const
Copies pixels inside bounds() to dst. dst specifies width, height, Color_Type,
Alpha_Type, and Color_Space of destination. Returns true if pixels are copied.
Returns false if dst.addr() equals nullptr, or dst.rowBytes is less than
dst SkImageInfo::minRowBytes.
Pixels are copied only if pixel conversion is possible. If this->colorType is
kGray_8_SkColorType, or kAlpha_8_SkColorType; dst Color_Type must match.
If this->colorType is kGray_8_SkColorType, dst Color_Space must match.
If this->alphaType is kOpaque_SkAlphaType, dst Alpha_Type must
match. If this->colorSpace is nullptr, dst Color_Space must match. Returns
false if pixel conversion is not possible.
Returns false if this->width() or this->height() is zero or negative.
#Param dst Image_Info and pixel address to write to ##
#Return true if pixels are copied to dst ##
#Example
#Image 3
void draw(SkCanvas* canvas) {
SkImageInfo info = SkImageInfo::MakeN32Premul(image->width(), image->height());
std::vector<int32_t> srcPixels;
const int rowBytes = image->width() * 4;
srcPixels.resize(image->height() * rowBytes);
SkPixmap pixmap(info, (const void*) &srcPixels.front(), rowBytes);
image->readPixels(pixmap, 0, 0);
for (int index = 0; index < 3; ++index ) {
std::vector<int32_t> dstPixels;
dstPixels.resize(image->height() * rowBytes);
SkPixmap dstmap(info, &dstPixels.front(), rowBytes);
pixmap.readPixels(dstmap);
SkBitmap bitmap;
bitmap.installPixels(dstmap);
canvas->translate(32, 32);
canvas->drawBitmap(bitmap, 0, 0);
}
}
##
#SeeAlso erase SkBitmap::readPixels SkCanvas::drawBitmap SkCanvas::readPixels SkImage::readPixels SkSurface::readPixels
##
# ------------------------------------------------------------------------------
#Method bool scalePixels(const SkPixmap& dst, SkFilterQuality filterQuality) const
Copies this to dst, scaling pixels to fit dst.width() and dst.height(), and
converting pixels to match dst.colorType and dst.alphaType. Returns true if
pixels are copied. Returns false if dst.addr() is nullptr, or dst.rowBytes is
less than dst SkImageInfo::minRowBytes.
Pixels are copied only if pixel conversion is possible. If this->colorType is
kGray_8_SkColorType, or kAlpha_8_SkColorType; dst Color_Type must match.
If this->colorType is kGray_8_SkColorType, dst Color_Space must match.
If this->alphaType is kOpaque_SkAlphaType, dst Alpha_Type must
match. If this->colorSpace is nullptr, dst Color_Space must match. Returns
false if pixel conversion is not possible.
Returns false if this->width() or this->height() is zero or negative.
Scales the image, with filterQuality, to match dst.width() and dst.height().
filterQuality kNone_SkFilterQuality is fastest, typically implemented with
Filter_Quality_Nearest_Neighbor. kLow_SkFilterQuality is typically implemented with
Filter_Quality_Bilerp. kMedium_SkFilterQuality is typically implemented with
Filter_Quality_Bilerp, and Filter_Quality_MipMap when size is reduced.
kHigh_SkFilterQuality is slowest, typically implemented with Filter_Quality_BiCubic.
#Param dst Image_Info and pixel address to write to ##
#Param filterQuality one of: kNone_SkFilterQuality, kLow_SkFilterQuality,
kMedium_SkFilterQuality, kHigh_SkFilterQuality
##
#Return true if pixels are copied to dst ##
#Example
#Image 3
void draw(SkCanvas* canvas) {
SkImageInfo info = SkImageInfo::MakeN32Premul(image->width(), image->height());
std::vector<int32_t> srcPixels;
int rowBytes = image->width() * 4;
srcPixels.resize(image->height() * rowBytes);
SkPixmap pixmap(info, (const void*) &srcPixels.front(), rowBytes);
image->readPixels(pixmap, 0, 0);
for (int offset : { 32, 64, 96 } ) {
info = SkImageInfo::MakeN32Premul(image->width() + offset, image->height());
rowBytes = info.width() * 4;
std::vector<int32_t> dstPixels;
dstPixels.resize(image->height() * rowBytes);
SkPixmap dstmap(info, &dstPixels.front(), rowBytes);
pixmap.scalePixels(dstmap, kMedium_SkFilterQuality);
SkBitmap bitmap;
bitmap.installPixels(dstmap);
canvas->translate(32, 32);
canvas->drawBitmap(bitmap, 0, 0);
}
}
##
#SeeAlso SkCanvas::drawBitmap SkImage::scalePixels
##
# ------------------------------------------------------------------------------
#Method bool erase(SkColor color, const SkIRect& subset) const
Writes color to pixels bounded by subset; returns true on success.
Returns false if colorType is kUnknown_SkColorType, or if subset does
not intersect bounds().
#Param color Unpremultiplied Color to write ##
#Param subset bounding integer Rect of written pixels ##
#Return true if pixels are changed ##
#Example
uint32_t storage[2];
SkImageInfo info = SkImageInfo::MakeN32Premul(1, 2);
SkPixmap pixmap(info, storage, info.minRowBytes());
pixmap.erase(SK_ColorBLUE, {0, 0, 1, 1});
pixmap.erase(SK_ColorRED, {0, 1, 1, 2});
SkBitmap bitmap;
canvas->scale(20, 20);
bitmap.installPixels(pixmap);
canvas->drawBitmap(bitmap, 0, 0);
##
#SeeAlso SkBitmap::erase SkCanvas::clear SkCanvas::drawColor
##
# ------------------------------------------------------------------------------
#Method bool erase(SkColor color) const
Writes color to pixels inside bounds(); returns true on success.
Returns false if colorType is kUnknown_SkColorType, or if bounds()
is empty.
#Param color Unpremultiplied Color to write ##
#Return true if pixels are changed ##
#Example
uint32_t storage[2];
SkImageInfo info = SkImageInfo::MakeN32Premul(1, 2);
SkPixmap pixmap(info, storage, info.minRowBytes());
pixmap.erase(SK_ColorBLUE);
SkBitmap bitmap;
canvas->scale(20, 20);
bitmap.installPixels(pixmap);
canvas->drawBitmap(bitmap, 0, 0);
##
#SeeAlso SkBitmap::erase SkCanvas::clear SkCanvas::drawColor
##
# ------------------------------------------------------------------------------
#Method bool erase(const SkColor4f& color, const SkIRect* subset = nullptr) const
Writes color to pixels bounded by subset; returns true on success.
if subset is nullptr, writes colors pixels inside bounds(). Returns false if
colorType is kUnknown_SkColorType, if subset is not nullptr and does
not intersect bounds(), or if subset is nullptr and bounds() is empty.
#Param color Unpremultiplied Color to write ##
#Param subset bounding integer Rect of pixels to write; may be nullptr ##
#Return true if pixels are changed ##
#Example
uint32_t storage[2];
SkImageInfo info = SkImageInfo::MakeN32Premul(1, 2);
SkPixmap pixmap(info, storage, info.minRowBytes());
SkIRect topPixelBounds = {0, 0, 1, 1};
pixmap.erase({ 0.65f, 0.45f, 0.25f, 1 }, &topPixelBounds);
SkIRect bottomPixelBounds = {0, 1, 1, 2};
pixmap.erase({ 0.25f, 0.65f, 0.45f, 1 }, &bottomPixelBounds);
SkBitmap bitmap;
canvas->scale(20, 20);
bitmap.installPixels(pixmap);
canvas->drawBitmap(bitmap, 0, 0);
##
#SeeAlso SkBitmap::erase SkCanvas::clear SkCanvas::drawColor
##
#Subtopic Writer ##
#Class SkPixmap ##
#Topic Pixmap ##
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