docs/SkImage_Reference.bmh

#Topic Image
#Alias Image_Reference

#Subtopic Overview
    #Subtopic Subtopic
    #Populate
    ##
##

#Class SkImage

Image describes a two dimensional array of pixels to draw. The pixels may be
decoded in a Raster_Bitmap, encoded in a Picture or compressed data stream,
or located in GPU memory as a GPU_Texture.

Image cannot be modified after it is created. Image may allocate additional
storage as needed; for instance, an encoded Image may decode when drawn.

Image width and height are greater than zero. Creating an Image with zero width
or height returns Image equal to nullptr.

Image may be created from Bitmap, Pixmap, Surface, Picture, encoded streams,
GPU_Texture, YUV_ColorSpace data, or hardware buffer. Encoded streams supported
include BMP, GIF, HEIF, ICO, JPEG, PNG, WBMP, WebP. Supported encoding details
vary with platform.

#Subtopic Raster_Image
#Alias Raster_Image
#Line # pixels decoded in Raster_Bitmap ##
Raster_Image pixels are decoded in a Raster_Bitmap. These pixels may be read
directly and in most cases written to, although edited pixels may not be drawn
if Image has been copied internally.
##

#Subtopic Texture_Image
#Line # pixels located on GPU ##
Texture_Image are located on GPU and pixels are not accessible. Texture_Image
are allocated optimally for best performance. Raster_Image may
be drawn to GPU_Surface, but pixels are uploaded from CPU to GPU downgrading
performance.
##

#Subtopic Lazy_Image
#Line # deferred pixel buffer ##
Lazy_Image defer allocating buffer for Image pixels and decoding stream until
Image is drawn. Lazy_Image caches result if possible to speed up repeated
drawing.
##

#Subtopic Related_Function
#Populate
##

#Subtopic Class_or_Struct
#Populate
##

#Subtopic Constructor
#Populate
##

#Subtopic Member_Function
#Populate
##

#Typedef SkImageInfo Info

##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeRasterCopy(const SkPixmap& pixmap)
#In Constructor
#Line # creates Image from Pixmap and copied pixels ##
Creates Image from Pixmap and copy of pixels. Since pixels are copied, Pixmap
pixels may be modified or deleted without affecting Image.

Image is returned if Pixmap is valid. Valid Pixmap parameters include:
dimensions are greater than zero;
each dimension fits in 29 bits;
Color_Type and Alpha_Type are valid, and Color_Type is not kUnknown_SkColorType;
row bytes are large enough to hold one row of pixels;
pixel address is not nullptr.

#Param pixmap  Image_Info, pixel address, and row bytes ##

#Return copy of Pixmap pixels, or nullptr  ##

#Example
#Height 50
#Description
Draw a five by five bitmap, and draw a copy in an Image. Editing the pixmap
alters the bitmap draw, but does not alter the Image draw since the Image
contains a copy of the pixels.
##
    uint8_t storage[][5] = {{ 0xCA, 0xDA, 0xCA, 0xC9, 0xA3 },
                            { 0xAC, 0xA8, 0x89, 0xA7, 0x87 },
                            { 0x9B, 0xB5, 0xE5, 0x95, 0x46 },
                            { 0x90, 0x81, 0xC5, 0x71, 0x33 },
                            { 0x75, 0x55, 0x44, 0x40, 0x30 }};
    SkImageInfo imageInfo = SkImageInfo::Make(5, 5, kGray_8_SkColorType, kOpaque_SkAlphaType);
    SkPixmap pixmap(imageInfo, storage[0], sizeof(storage) / 5);
    SkBitmap bitmap;
    bitmap.installPixels(pixmap);
    sk_sp<SkImage> image = SkImage::MakeRasterCopy(pixmap);
    *pixmap.writable_addr8(2, 2) = 0x00;
    canvas->scale(10, 10);
    canvas->drawBitmap(bitmap, 0, 0);
    canvas->drawImage(image, 10, 0);
##

#SeeAlso MakeRasterData MakeFromGenerator

#Method ##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeRasterData(const Info& info, sk_sp<SkData> pixels, size_t rowBytes)
#In Constructor
#Line # creates Image from Image_Info and shared pixels ##
Creates Image from Image_Info, sharing pixels.

Image is returned if Image_Info is valid. Valid Image_Info parameters include:
dimensions are greater than zero;
each dimension fits in 29 bits;
Color_Type and Alpha_Type are valid, and Color_Type is not kUnknown_SkColorType;
rowBytes are large enough to hold one row of pixels;
pixels is not nullptr, and contains enough data for Image.

#Param info  contains width, height, Alpha_Type, Color_Type, Color_Space ##
#Param pixels  address or pixel storage ##
#Param rowBytes  size of pixel row or larger ##

#Return Image sharing pixels, or nullptr ##

#Example
#Image 3
    size_t rowBytes = image->width() * SkColorTypeBytesPerPixel(kRGBA_8888_SkColorType);
    sk_sp<SkData> data = SkData::MakeUninitialized(rowBytes * image->height());
    SkImageInfo dstInfo = SkImageInfo::MakeN32(image->width(), image->height(), 
                                               kPremul_SkAlphaType);
    image->readPixels(dstInfo, data->writable_data(), rowBytes, 0, 0, SkImage::kAllow_CachingHint);
    sk_sp<SkImage> raw = SkImage::MakeRasterData(dstInfo.makeColorType(kRGBA_8888_SkColorType),
                                                 data, rowBytes);
    canvas->drawImage(image, 0, 0);
    canvas->drawImage(raw.get(), 128, 0);
##

#SeeAlso MakeRasterCopy MakeFromGenerator

#Method ##

# ------------------------------------------------------------------------------

#Typedef void* ReleaseContext

Caller data passed to RasterReleaseProc; may be nullptr.

#SeeAlso MakeFromRaster RasterReleaseProc

##

#Typedef void (*RasterReleaseProc)(const void* pixels, ReleaseContext)

Function called when Image no longer shares pixels. ReleaseContext is
provided by caller when Image is created, and may be nullptr.   

#SeeAlso ReleaseContext MakeFromRaster

##

#Method static sk_sp<SkImage> MakeFromRaster(const SkPixmap& pixmap,
                                         RasterReleaseProc rasterReleaseProc,
                                         ReleaseContext releaseContext)
#In Constructor
#Line # creates Image from Pixmap, with release ##

Creates Image from pixmap, sharing Pixmap pixels. Pixels must remain valid and
unchanged until rasterReleaseProc is called. rasterReleaseProc is passed
releaseContext when Image is deleted or no longer refers to pixmap pixels.

Pass nullptr for rasterReleaseProc to share Pixmap without requiring a callback
when Image is released. Pass nullptr for releaseContext if rasterReleaseProc
does not require state.

Image is returned if pixmap is valid. Valid Pixmap parameters include:
dimensions are greater than zero;
each dimension fits in 29 bits;
Color_Type and Alpha_Type are valid, and Color_Type is not kUnknown_SkColorType;
row bytes are large enough to hold one row of pixels;
pixel address is not nullptr.

#Param pixmap  Image_Info, pixel address, and row bytes ##
#Param rasterReleaseProc  function called when pixels can be released; or nullptr ##
#Param releaseContext  state passed to rasterReleaseProc; or nullptr ##

#Return Image sharing pixmap ##

#Example
#Function
static void releaseProc(const void* pixels, SkImage::ReleaseContext context) {
     int* countPtr = static_cast<int*>(context);
     *countPtr += 1;
}
##

void draw(SkCanvas* canvas) {
    SkColor color = 0;
    SkPixmap pixmap(SkImageInfo::MakeN32(1, 1, kPremul_SkAlphaType), &color, 4);
    int releaseCount = 0;
    sk_sp<SkImage> image(SkImage::MakeFromRaster(pixmap, releaseProc, &releaseCount));
    SkDebugf("before reset: %d\n", releaseCount);
    image.reset();
    SkDebugf("after reset: %d\n", releaseCount);
}
#StdOut
before reset: 0
after reset: 1
##
##

#SeeAlso MakeRasterCopy MakeRasterData MakeFromGenerator RasterReleaseProc ReleaseContext

#Method ##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeFromBitmap(const SkBitmap& bitmap)
#In Constructor
#Line # creates Image from Bitmap, sharing or copying pixels ##
Creates Image from bitmap, sharing or copying bitmap pixels. If the bitmap 
is marked immutable, and its pixel memory is shareable, it may be shared
instead of copied.

Image is returned if bitmap is valid. Valid Bitmap parameters include:
dimensions are greater than zero;
each dimension fits in 29 bits;
Color_Type and Alpha_Type are valid, and Color_Type is not kUnknown_SkColorType;
row bytes are large enough to hold one row of pixels;
pixel address is not nullptr.

#Param bitmap  Image_Info, row bytes, and pixels ##

#Return created Image, or nullptr ##

#Example
#Description
The first Bitmap is shared; writing to the pixel memory changes the first
Image.
The second Bitmap is marked immutable, and is copied; writing to the pixel
memory does not alter the second Image.
##
#Height 50
    uint8_t storage[][5] = {{ 0xCA, 0xDA, 0xCA, 0xC9, 0xA3 },
                            { 0xAC, 0xA8, 0x89, 0xA7, 0x87 },
                            { 0x9B, 0xB5, 0xE5, 0x95, 0x46 },
                            { 0x90, 0x81, 0xC5, 0x71, 0x33 },
                            { 0x75, 0x55, 0x44, 0x40, 0x30 }};
    SkImageInfo imageInfo = SkImageInfo::Make(5, 5, kGray_8_SkColorType, kOpaque_SkAlphaType);
    SkPixmap pixmap(imageInfo, storage[0], sizeof(storage) / 5);
    SkBitmap bitmap;
    bitmap.installPixels(pixmap);
    sk_sp<SkImage> image1 = SkImage::MakeFromBitmap(bitmap);
    bitmap.setImmutable();
    sk_sp<SkImage> image2 = SkImage::MakeFromBitmap(bitmap);
    *pixmap.writable_addr8(2, 2) = 0x00;
    canvas->scale(10, 10);
    canvas->drawImage(image1, 0, 0);
    canvas->drawImage(image2, 10, 0);
##

#SeeAlso MakeFromRaster MakeRasterCopy MakeFromGenerator MakeRasterData

#Method ##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeFromGenerator(std::unique_ptr<SkImageGenerator> imageGenerator,
                                            const SkIRect* subset = nullptr)
#In Constructor
#Line # creates Image from a stream of data ##

Creates Image from data returned by imageGenerator. Generated data is owned by Image and may not
be shared or accessed.

subset allows selecting a portion of the full image. Pass nullptr to select the entire image;
otherwise, subset must be contained by image bounds.

Image is returned if generator data is valid. Valid data parameters vary by type of data
and platform.

imageGenerator may wrap Picture data, codec data, or custom data.

#Param imageGenerator  stock or custom routines to retrieve Image ##
#Param subset  bounds of returned Image; may be nullptr ##

#Return created Image, or nullptr ##

#Example
#Height 128
#Description
The generator returning Picture cannot be shared; std::move transfers ownership to generated Image.
##
    SkPictureRecorder recorder;
    recorder.beginRecording(100, 100)->drawColor(SK_ColorRED);
    auto picture = recorder.finishRecordingAsPicture();
    auto gen = SkImageGenerator::MakeFromPicture({100, 100}, picture, nullptr, nullptr,
                                                 SkImage::BitDepth::kU8, SkColorSpace::MakeSRGB());
    sk_sp<SkImage> image = SkImage::MakeFromGenerator(std::move(gen));
    canvas->drawImage(image, 0, 0);
##

#SeeAlso MakeFromEncoded

#Method ##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeFromEncoded(sk_sp<SkData> encoded, const SkIRect* subset = nullptr)
#In Constructor
#Line # creates Image from encoded data ##
Creates Image from encoded data. 
subset allows selecting a portion of the full image. Pass nullptr to select the entire image;
otherwise, subset must be contained by image bounds.

Image is returned if format of the encoded data is recognized and supported.
Recognized formats vary by platform.

#Param encoded  data of Image to decode ##
#Param subset  bounds of returned Image; may be nullptr ##

#Return created Image, or nullptr ##

#Example
#Image 3
int x = 0;
for (int quality : { 100, 50, 10, 1} ) {
    sk_sp<SkData> encodedData = image->encodeToData(SkEncodedImageFormat::kJPEG, quality);
    sk_sp<SkImage> image = SkImage::MakeFromEncoded(encodedData);
    canvas->drawImage(image, x, 0);
    x += 64;
}
##

#SeeAlso MakeFromGenerator

#Method ##

# ------------------------------------------------------------------------------

#Typedef void (*TextureReleaseProc)(ReleaseContext releaseContext)

##

#Method static sk_sp<SkImage> MakeFromTexture(GrContext* context,
                                          const GrBackendTexture& backendTexture,
                                          GrSurfaceOrigin origin,
                                          SkAlphaType alphaType,
                                          sk_sp<SkColorSpace> colorSpace)
#Deprecated
#Method ##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeFromTexture(GrContext* context,
                                          const GrBackendTexture& backendTexture,
                                          GrSurfaceOrigin origin,
                                          SkAlphaType alphaType,
                                          sk_sp<SkColorSpace> colorSpace,
                                          TextureReleaseProc textureReleaseProc,
                                          ReleaseContext releaseContext)

#Deprecated
#Method ##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeFromTexture(GrContext* context,
                                          const GrBackendTexture& backendTexture,
                                          GrSurfaceOrigin origin,
                                          SkColorType colorType,
                                          SkAlphaType alphaType,
                                          sk_sp<SkColorSpace> colorSpace)
#In Constructor
#Line # creates Image from GPU_Texture ##
Creates Image from GPU_Texture associated with context. Caller is responsible for
managing the lifetime of GPU_Texture.

Image is returned if format of backendTexture is recognized and supported.
Recognized formats vary by GPU back-end.

#Param context  GPU_Context ##
#Param backendTexture  texture residing on GPU ##
#Param origin  one of: kBottomLeft_GrSurfaceOrigin, kTopLeft_GrSurfaceOrigin ##
#Param colorType  one of: #list_of_color_types#
##
#Param alphaType  one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType,
                          kPremul_SkAlphaType, kUnpremul_SkAlphaType
##
#Param colorSpace  range of colors; may be nullptr ##

#Return created Image, or nullptr ##

#Example
#Image 3
#Platform gpu
#Height 128
#Description
A back-end texture has been created and uploaded to the GPU outside of this example.
##
GrContext* context = canvas->getGrContext();
if (!context) {
   return;
}
canvas->scale(.25f, .25f);
int x = 0;
for (auto origin : { kBottomLeft_GrSurfaceOrigin, kTopLeft_GrSurfaceOrigin } ) {
    sk_sp<SkImage> image = SkImage::MakeFromTexture(context, backEndTexture,
           origin, kN32_SkColorType, kOpaque_SkAlphaType, nullptr);
    canvas->drawImage(image, x, 0);
x += 512;
}
##

#SeeAlso MakeFromAdoptedTexture SkSurface::MakeFromBackendTexture

#Method ##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeFromTexture(GrContext* context,
                                          const GrBackendTexture& backendTexture,
                                          GrSurfaceOrigin origin,
                                          SkColorType colorType,
                                          SkAlphaType alphaType,
                                          sk_sp<SkColorSpace> colorSpace,
                                          TextureReleaseProc textureReleaseProc,
                                          ReleaseContext releaseContext)

Creates Image from GPU_Texture associated with context. GPU_Texture must stay
valid and unchanged until textureReleaseProc is called. textureReleaseProc is
passed releaseContext when Image is deleted or no longer refers to texture.

Image is returned if format of backendTexture is recognized and supported.
Recognized formats vary by GPU back-end.

#Param context  GPU_Context ##
#Param backendTexture  texture residing on GPU ##
#Param origin  one of: kBottomLeft_GrSurfaceOrigin, kTopLeft_GrSurfaceOrigin ##
#Param colorType  one of: #list_of_color_types#
##
#Param alphaType  one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType,
                          kPremul_SkAlphaType, kUnpremul_SkAlphaType
##
#Param colorSpace  range of colors; may be nullptr ##
#Param textureReleaseProc  function called when texture can be released ##
#Param releaseContext  state passed to textureReleaseProc ##

#Return created Image, or nullptr ##

#ToDo
This doesn't do anything clever with TextureReleaseProc because it may not get called
fwithin the lifetime of the example
##

#Example
#Platform gpu
#Image 4
GrContext* context = canvas->getGrContext();
if (!context) {
   return;
}
auto debugster = [](SkImage::ReleaseContext releaseContext) -> void {
    *((int *) releaseContext) += 128;
};
int x = 0;
for (auto origin : { kBottomLeft_GrSurfaceOrigin, kTopLeft_GrSurfaceOrigin } ) {
    sk_sp<SkImage> image = SkImage::MakeFromTexture(context, backEndTexture,
           origin, kRGBA_8888_SkColorType, kOpaque_SkAlphaType, nullptr, debugster, &x);
    canvas->drawImage(image, x, 0);
    x += 128;
}
##

#SeeAlso MakeFromAdoptedTexture SkSurface::MakeFromBackendTexture

#Method ##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeCrossContextFromEncoded(GrContext* context, sk_sp<SkData> data,
                                                      bool buildMips,
                                                      SkColorSpace* dstColorSpace)
#In Constructor
#Line # creates Image from encoded data, and uploads to GPU ##

Creates Image from encoded data. Image is uploaded to GPU back-end using context. 

Created Image is available to other GPU contexts, and is available across thread
boundaries. All contexts must be in the same GPU_Share_Group, or otherwise 
share resources.

When Image is no longer referenced, context releases texture memory
asynchronously.

Texture decoded from data is uploaded to match Surface created with
dstColorSpace. Color_Space of Image is determined by encoded data.

Image is returned if format of data is recognized and supported, and if context
supports moving resources. Recognized formats vary by platform and GPU back-end.

Image is returned using MakeFromEncoded if context is nullptr or does not support
moving resources between contexts.

#Param context  GPU_Context ##
#Param data  Image to decode ##
#Param buildMips  create Image as Mip_Map if true ##
#Param dstColorSpace  range of colors of matching Surface on GPU ##

#Return created Image, or nullptr ##

#Example
#Image 4
#Height 64
GrContext* context = canvas->getGrContext();
sk_sp<SkData> encodedData = image->encodeToData(SkEncodedImageFormat::kJPEG, 100);
sk_sp<SkImage> image = SkImage::MakeCrossContextFromEncoded(context,
                                                            encodedData, false, nullptr);
canvas->drawImage(image, 0, 0);
##

#SeeAlso MakeCrossContextFromPixmap

#Method ##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeCrossContextFromPixmap(GrContext* context, const SkPixmap& pixmap,
                                                      bool buildMips,
                                                      SkColorSpace* dstColorSpace)
#In Constructor
#Line # creates Image from Pixmap, and uploads to GPU ##

Creates Image from pixmap. Image is uploaded to GPU back-end using context. 

Created Image is available to other GPU contexts, and is available across thread
boundaries. All contexts must be in the same GPU_Share_Group, or otherwise 
share resources.

When Image is no longer referenced, context releases texture memory
asynchronously.

Texture created from pixmap is uploaded to match Surface created with
dstColorSpace. Color_Space of Image is determined by pixmap.colorSpace().

Image is returned referring to GPU back-end if context is not nullptr, 
format of data is recognized and supported, and if context supports moving
resources between contexts. Otherwise, pixmap pixel data is copied and Image
as returned in raster format if possible; nullptr may be returned.
Recognized GPU formats vary by platform and GPU back-end.

#Param context  GPU_Context ##
#Param pixmap  Image_Info, pixel address, and row bytes ##
#Param buildMips  create Image as Mip_Map if true ##
#Param dstColorSpace  range of colors of matching Surface on GPU ##

#Return created Image, or nullptr ##

#Example
#Image 4
#Height 64
GrContext* context = canvas->getGrContext();
SkPixmap pixmap;
if (source.peekPixels(&pixmap)) {
    sk_sp<SkImage> image = SkImage::MakeCrossContextFromPixmap(context, pixmap,
                                                               false, nullptr);
    canvas->drawImage(image, 0, 0);
}
##

#SeeAlso MakeCrossContextFromEncoded

#Method ##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeFromAdoptedTexture(GrContext* context,
                                                 const GrBackendTexture& backendTexture,
                                                 GrSurfaceOrigin surfaceOrigin,
                                                 SkAlphaType alphaType = kPremul_SkAlphaType,
                                                 sk_sp<SkColorSpace> colorSpace = nullptr)
#Deprecated
#Method ##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeFromAdoptedTexture(GrContext* context,
                                                 const GrBackendTexture& backendTexture,
                                                 GrSurfaceOrigin surfaceOrigin,
                                                 SkColorType colorType,
                                                 SkAlphaType alphaType = kPremul_SkAlphaType,
                                                 sk_sp<SkColorSpace> colorSpace = nullptr)
#In Constructor
#Line # creates Image from GPU_Texture, managed internally ##
Creates Image from backendTexture associated with context. backendTexture and
returned Image are managed internally, and are released when no longer needed.

Image is returned if format of backendTexture is recognized and supported.
Recognized formats vary by GPU back-end.

#Param context  GPU_Context ##
#Param backendTexture  texture residing on GPU ##
#Param surfaceOrigin  one of: kBottomLeft_GrSurfaceOrigin, kTopLeft_GrSurfaceOrigin ##
#Param colorType  one of: #list_of_color_types#
##
#Param alphaType  one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType,
                          kPremul_SkAlphaType, kUnpremul_SkAlphaType
##
#Param colorSpace  range of colors; may be nullptr ##

#Return created Image, or nullptr ##

#Example
#Image 5
#Platform gpu
   if (!canvas->getGrContext()) {
       return;
   }
   canvas->scale(.5f, .5f);
   canvas->clear(0x7f3f5f7f);
   int x = 0, y = 0;
   for (auto origin : { kBottomLeft_GrSurfaceOrigin, kTopLeft_GrSurfaceOrigin } ) {
       for (auto alpha : { kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType } ) {
           sk_sp<SkImage> image = SkImage::MakeFromAdoptedTexture(canvas->getGrContext(),
                                                                  backEndTexture, origin, 
                                                                  kRGBA_8888_SkColorType, alpha);
           canvas->drawImage(image, x, y);
           x += 160;
       }
       x -= 160 * 3;
       y += 256;
   }
##

#SeeAlso MakeFromTexture MakeFromYUVTexturesCopy

#Method ##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeFromYUVTexturesCopy(GrContext* context, SkYUVColorSpace yuvColorSpace,
                                                  const GrBackendTexture yuvTextures[3],
                                                  GrSurfaceOrigin surfaceOrigin,
                                                  sk_sp<SkColorSpace> colorSpace = nullptr)
#In Constructor
#Line # creates Image from YUV_ColorSpace data in three planes ##

Creates Image from copy of yuvTextures, an array of textures on GPU.
yuvTextures contain pixels for YUV planes of Image. Returned Image has the dimensions
yuvTextures[0]. yuvColorSpace describes how YUV colors convert to RGB colors.

#Param context  GPU_Context ##
#Param yuvColorSpace  one of: kJPEG_SkYUVColorSpace, kRec601_SkYUVColorSpace,
                              kRec709_SkYUVColorSpace
##
#Param yuvTextures  array of YUV textures on GPU ##
#Param surfaceOrigin  one of: kBottomLeft_GrSurfaceOrigin, kTopLeft_GrSurfaceOrigin ##
#Param colorSpace  range of colors; may be nullptr ##

#Return created Image, or nullptr ##

# seems too complicated to create an example for this
#ToDo
should this be moved to chrome only?
##

#NoExample
##

#SeeAlso MakeFromNV12TexturesCopy

#Method ##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeFromYUVTexturesCopy(GrContext* context, SkYUVColorSpace yuvColorSpace,
                                                  const GrBackendTexture yuvTextures[3],
                                                  const SkISize yuvSizes[3],
                                                  GrSurfaceOrigin surfaceOrigin,
                                                  sk_sp<SkColorSpace> colorSpace = nullptr)
This version of MakeFromYUVTexturesCopy is over specified and should not be used.

#Param context  GPU_Context ##
#Param yuvColorSpace  one of: kJPEG_SkYUVColorSpace, kRec601_SkYUVColorSpace,
                              kRec709_SkYUVColorSpace
##
#Param yuvTextures  array of YUV textures on GPU ##
#Param yuvSizes  dimensions of YUV textures ##
#Param surfaceOrigin  one of: kBottomLeft_GrSurfaceOrigin, kTopLeft_GrSurfaceOrigin ##
#Param colorSpace  range of colors; may be nullptr ##

#Return created Image, or nullptr ##

# seems too complicated to create an example for this
#ToDo
should this be moved to chrome only?
##

#NoExample
##

#SeeAlso MakeFromNV12TexturesCopy

#Method ##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeFromNV12TexturesCopy(GrContext* context,
                                                   SkYUVColorSpace yuvColorSpace,
                                                   const GrBackendTexture nv12Textures[2],
                                                   GrSurfaceOrigin surfaceOrigin,
                                                   sk_sp<SkColorSpace> colorSpace = nullptr)
#In Constructor
#Line # creates Image from YUV_ColorSpace data in three planes ##

Creates Image from copy of nv12TextureHandles, an array of textures on GPU.
nv12Textures[0] contains pixels for YUV_Component_Y plane.
nv12Textures[1] contains pixels for YUV_Component_U plane,
followed by pixels for YUV_Component_V plane.
Returned Image has the dimensions
nv12Textures[2]. yuvColorSpace describes how YUV colors convert to RGB colors.

#Param context  GPU_Context ##
#Param yuvColorSpace  one of: kJPEG_SkYUVColorSpace, kRec601_SkYUVColorSpace,
                              kRec709_SkYUVColorSpace
##
#Param nv12Textures  array of YUV textures on GPU ##
#Param surfaceOrigin  one of: kBottomLeft_GrSurfaceOrigin, kTopLeft_GrSurfaceOrigin ##
#Param colorSpace  range of colors; may be nullptr ##

#Return created Image, or nullptr ##

# seems too complicated to create an example for this
#ToDo
should this be moved to chrome only?
##

#NoExample
##

#SeeAlso MakeFromYUVTexturesCopy

#Method ##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeFromNV12TexturesCopy(GrContext* context,
                                                   SkYUVColorSpace yuvColorSpace,
                                                   const GrBackendTexture nv12Textures[2],
                                                   const SkISize nv12Sizes[2],
                                                   GrSurfaceOrigin surfaceOrigin,
                                                   sk_sp<SkColorSpace> colorSpace = nullptr)

This version of MakeFromYUVTexturesCopy is over specified and should not be used.

#Param context  GPU_Context ##
#Param yuvColorSpace  one of: kJPEG_SkYUVColorSpace, kRec601_SkYUVColorSpace,
                              kRec709_SkYUVColorSpace
##
#Param nv12Textures  array of YUV textures on GPU ##
#Param nv12Sizes  dimensions of YUV textures ##
#Param surfaceOrigin  one of: kBottomLeft_GrSurfaceOrigin, kTopLeft_GrSurfaceOrigin ##
#Param colorSpace  range of colors; may be nullptr ##

#Return created Image, or nullptr ##

# seems too complicated to create an example for this
#ToDo
should this be moved to chrome only?
##

#NoExample
##

#SeeAlso MakeFromYUVTexturesCopy

#Method ##

# ------------------------------------------------------------------------------

# currently uncalled by any test or client ##
#Bug 7424

#EnumClass BitDepth

#Code
    enum class BitDepth {
        kU8,
        kF16,
    };
##

#Const kU8 0
Use 8 bits per Color_ARGB component using unsigned integer format.
##
#Const kF16 1
Use 16 bits per Color_ARGB component using half-precision floating point format.  
##

#NoExample
##

#SeeAlso MakeFromPicture

#EnumClass ##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeFromPicture(sk_sp<SkPicture> picture, const SkISize& dimensions,
                                          const SkMatrix* matrix, const SkPaint* paint,
                                          BitDepth bitDepth,
                                          sk_sp<SkColorSpace> colorSpace)
#In Constructor
#Line # creates Image from Picture ##

Creates Image from picture. Returned Image width and height are set by dimensions.
Image draws picture with matrix and paint, set to bitDepth and colorSpace.

If matrix is nullptr, draws with identity Matrix. If paint is nullptr, draws
with default Paint. colorSpace may be nullptr. 

#Param picture  stream of drawing commands ##
#Param dimensions  width and height ##
#Param matrix  Matrix to rotate, scale, translate, and so on; may be nullptr ##
#Param paint  Paint to apply transparency, filtering, and so on; may be nullptr ##
#Param bitDepth  8 bit integer or 16 bit float: per component ##
#Param colorSpace  range of colors; may be nullptr ##

#Return created Image, or nullptr ##

#Example
    SkPaint paint;
    SkPictureRecorder recorder;
    SkCanvas* recordingCanvas = recorder.beginRecording(50, 50);
    for (auto color : { SK_ColorRED, SK_ColorBLUE, 0xff007f00 } ) {
        paint.setColor(color);
        recordingCanvas->drawRect({10, 10, 30, 40}, paint);
        recordingCanvas->translate(10, 10);
        recordingCanvas->scale(1.2f, 1.4f);
    }
    sk_sp<SkPicture> playback = recorder.finishRecordingAsPicture();
    int x = 0, y = 0;
    for (auto alpha : { 70, 140, 210 } ) {
        paint.setAlpha(alpha);
        auto srgbColorSpace = SkColorSpace::MakeSRGB();
        sk_sp<SkImage> image = SkImage::MakeFromPicture(playback, {50, 50}, nullptr, &paint,
                                                        SkImage::BitDepth::kU8, srgbColorSpace);
        canvas->drawImage(image, x, y);
        x += 70; y += 70;
    }
##

#SeeAlso SkCanvas::drawPicture

#Method ##

# ------------------------------------------------------------------------------

#Method static sk_sp<SkImage> MakeFromAHardwareBuffer(AHardwareBuffer* hardwareBuffer,
                                                 SkAlphaType alphaType = kPremul_SkAlphaType,
                                                 sk_sp<SkColorSpace> colorSpace = nullptr)
#In Constructor
#Line # creates Image from Android hardware buffer ##

#Bug 7447

Creates Image from Android hardware buffer.
Returned Image takes a reference on the buffer.

Only available on Android, when __ANDROID_API__ is defined to be 26 or greater.

#Param hardwareBuffer  AHardwareBuffer Android hardware buffer ##
#Param alphaType  one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType,
                          kPremul_SkAlphaType, kUnpremul_SkAlphaType
##
#Param colorSpace  range of colors; may be nullptr ##

#Return created Image, or nullptr ##

#NoExample
##

#SeeAlso MakeFromRaster

#Method ##

# ------------------------------------------------------------------------------
#Subtopic Property
#Populate
#Line # values and attributes ##
##

#Method int width() const
#In Property
#Line # returns pixel column count ##
Returns pixel count in each row.

#Return pixel width in Image ##

#Example
#Image 4
#Height 96
   canvas->translate(10, 10);
   canvas->drawImage(image, 0, 0);
   canvas->translate(0, image->height());
   SkPaint paint;
   paint.setTextAlign(SkPaint::kCenter_Align);
   canvas->drawLine(0, 10, image->width(), 10, paint);
   canvas->drawString("width", image->width() / 2, 25, paint);
##

#SeeAlso dimensions() height()

#Method ##

# ------------------------------------------------------------------------------

#Method int height() const
#In Property
#Line # returns pixel row count ##
Returns pixel row count.

#Return pixel height in Image ##

#Example
#Image 4
#Height 96
   canvas->translate(10, 10);
   canvas->drawImage(image, 0, 0);
   canvas->translate(image->width(), 0);
   SkPaint paint;
   paint.setTextAlign(SkPaint::kCenter_Align);
   paint.setVerticalText(true);
   canvas->drawLine(10, 0, 10, image->height(), paint);
   canvas->drawString("height", 25, image->height() / 2, paint);
##

#SeeAlso dimensions() width()

#Method ##

# ------------------------------------------------------------------------------

#Method SkISize dimensions() const
#In Property
#Line # returns width() and height() ##
Returns ISize { width(), height() }.

#Return integral size of width() and height() ##

#Example
#Image 4
    SkISize dimensions = image->dimensions();
    SkIRect bounds = image->bounds();
    SkIRect dimensionsAsBounds = SkIRect::MakeSize(dimensions);
    SkDebugf("dimensionsAsBounds %c= bounds\n", dimensionsAsBounds == bounds ? '=' : '!');
##

#SeeAlso height() width() bounds()

#Method ##

# ------------------------------------------------------------------------------

#Method SkIRect bounds() const
#In Property
#Line # returns width() and height() as Rectangle ##
Returns IRect { 0, 0, width(), height() }.

#Return integral rectangle from origin to width() and height() ##

#Example
#Height 128
#Image 4
    SkIRect bounds = image->bounds();
    for (int x : { 0, bounds.width() } ) {
        for (int y : { 0, bounds.height() } ) {
            canvas->drawImage(image, x, y);
        }
    }
##

#SeeAlso dimensions() 

#Method ##

# ------------------------------------------------------------------------------

#Method uint32_t uniqueID() const
#In Property
#Line # identifier for Image ##
Returns value unique to image. Image contents cannot change after Image is
created. Any operation to create a new Image will receive generate a new
unique number.

#Return unique identifier ##

#Example
#Image 5
#Height 156
 sk_sp<SkImage> subset = image->makeSubset({10, 20, 90, 100});
 canvas->drawImage(image, 0, 0);
 canvas->drawImage(subset, 128, 0);
 SkPaint paint;
 SkString s;
 s.printf("original id: %d", image->uniqueID());
 canvas->drawString(s, 20, image->height() + 20, paint);
 s.printf("subset id: %d", subset->uniqueID());
 canvas->drawString(s, 148, subset->height() + 20, paint);
##

#SeeAlso isLazyGenerated

#Method ##

# ------------------------------------------------------------------------------

#Method SkAlphaType alphaType() const
#In Property
#Line # returns Alpha_Type ##
Returns Alpha_Type, one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType,
kPremul_SkAlphaType, kUnpremul_SkAlphaType.

Alpha_Type returned was a parameter to an Image constructor,
or was parsed from encoded data.

#Return Alpha_Type in Image ##

#Example
#Image 4
#Height 96
  const char* alphaTypeStr[] = { "Unknown", "Opaque", "Premul", "Unpremul" };
  SkAlphaType alphaType = image->alphaType();
  canvas->drawImage(image, 16, 0);
  SkPaint paint;
  canvas->drawString(alphaTypeStr[(int) alphaType], 20, image->height() + 20, paint);
##

#SeeAlso SkImageInfo::alphaType

#Method ##

# ------------------------------------------------------------------------------

#Method SkColorType colorType() const
#In Property
#Line # returns Color_Type ##

Returns Color_Type if known; otherwise, returns kUnknown_SkColorType.

#Return Color_Type of Image ##

#Example
// incomplete
##

#SeeAlso SkImageInfo::colorType

#Method ##

# ------------------------------------------------------------------------------

#Method SkColorSpace* colorSpace() const
#In Property
#Line # returns Color_Space ##
Returns Color_Space, the range of colors, associated with Image.  The
reference count of Color_Space is unchanged. The returned Color_Space is
immutable.

Color_Space returned was passed to an Image constructor,
or was parsed from encoded data. Color_Space returned may be ignored when Image
is drawn, depending on the capabilities of the Surface receiving the drawing.

#Return Color_Space in Image, or nullptr ##

#Example
#Image 3
#Set sRGB
    SkPixmap pixmap;
    source.peekPixels(&pixmap);
    canvas->scale(.25f, .25f);
    int y = 0;
    for (auto gamma : { SkColorSpace::kLinear_RenderTargetGamma,
                        SkColorSpace::kSRGB_RenderTargetGamma } ) {
        int x = 0;
        sk_sp<SkColorSpace> colorSpace = SkColorSpace::MakeRGB(gamma, SkColorSpace::kSRGB_Gamut);
        for (int index = 0; index < 2; ++index) {
            pixmap.setColorSpace(colorSpace);
            sk_sp<SkImage> image = SkImage::MakeRasterCopy(pixmap);
            canvas->drawImage(image, x, y);
            colorSpace = image->colorSpace()->makeColorSpin();
            x += 512;
        }
        y += 512;
    }
##

#SeeAlso refColorSpace makeColorSpace

#Method ##

# ------------------------------------------------------------------------------

#Method sk_sp<SkColorSpace> refColorSpace() const
#In Property
#Line # returns Image_Info Color_Space ##
Returns a smart pointer to Color_Space, the range of colors, associated with
Image.  The smart pointer tracks the number of objects sharing this
SkColorSpace reference so the memory is released when the owners destruct.

The returned SkColorSpace is immutable.

Color_Space returned was passed to an Image constructor,
or was parsed from encoded data. Color_Space returned may be ignored when Image
is drawn, depending on the capabilities of the Surface receiving the drawing.

#Return Color_Space in Image, or nullptr, wrapped in a smart pointer ##

#Example
#Image 3
#Set sRGB
    SkPixmap pixmap;
    source.peekPixels(&pixmap);
    canvas->scale(.25f, .25f);
    int y = 0;
    for (auto gamma : { SkColorSpace::kLinear_RenderTargetGamma,
                        SkColorSpace::kSRGB_RenderTargetGamma } ) {
        int x = 0;
        sk_sp<SkColorSpace> colorSpace = SkColorSpace::MakeRGB(gamma, SkColorSpace::kSRGB_Gamut);
        for (int index = 0; index < 2; ++index) {
            pixmap.setColorSpace(colorSpace);
            sk_sp<SkImage> image = SkImage::MakeRasterCopy(pixmap);
            canvas->drawImage(image, x, y);
            colorSpace = image->refColorSpace()->makeColorSpin();
            x += 512;
        }
        y += 512;
    }
##

#SeeAlso colorSpace makeColorSpace

#Method ##

# ------------------------------------------------------------------------------

#Method bool isAlphaOnly() const
#In Property
#Line # returns if pixels represent a transparency mask ##
Returns true if Image pixels represent transparency only. If true, each pixel
is packed in 8 bits as defined by kAlpha_8_SkColorType.

#Return true if pixels represent a transparency mask ##

#Example
    uint8_t pmColors = 0;
    sk_sp<SkImage> image = SkImage::MakeRasterCopy({SkImageInfo::MakeA8(1, 1), &pmColors, 1});
    SkDebugf("alphaOnly = %s\n", image->isAlphaOnly() ? "true" : "false");
#StdOut
alphaOnly = true
##
##

#SeeAlso alphaType isOpaque

#Method ##

# ------------------------------------------------------------------------------

#Method bool isOpaque() const
#In Property
#Line # returns if Alpha_Type is kOpaque_SkAlphaType ##
Returns true if pixels ignore their Alpha value and are treated as fully opaque.

#Return true if Alpha_Type is kOpaque_SkAlphaType ##

#Example
    auto check_isopaque = [](const SkImageInfo& imageInfo) -> void {
        auto surface(SkSurface::MakeRaster(imageInfo));
        auto image(surface->makeImageSnapshot());
        SkDebugf("isOpaque = %s\n", image->isOpaque() ? "true" : "false");
    };

    check_isopaque(SkImageInfo::MakeN32Premul(5, 5));
    check_isopaque(SkImageInfo::MakeN32(5, 5, kOpaque_SkAlphaType));
#StdOut
isOpaque = false
isOpaque = true
##
##

#SeeAlso alphaType isAlphaOnly

#Method ##

# ------------------------------------------------------------------------------

#Method sk_sp<SkShader> makeShader(SkShader::TileMode tileMode1, SkShader::TileMode tileMode2,
                               const SkMatrix* localMatrix = nullptr) const
#In Constructor
#Line # creates Shader, Paint element that can tile Image ##

Creates Shader from Image. Shader dimensions are taken from Image. Shader uses
SkShader::TileMode rules to fill drawn area outside Image. localMatrix permits
transforming Image before Canvas_Matrix is applied.

#Param tileMode1  tiling in x, one of: SkShader::kClamp_TileMode, SkShader::kRepeat_TileMode,
                  SkShader::kMirror_TileMode
##
#Param tileMode2  tiling in y, one of: SkShader::kClamp_TileMode, SkShader::kRepeat_TileMode,
                  SkShader::kMirror_TileMode
##
#Param localMatrix  Image transformation, or nullptr ##

#Return Shader containing Image ##

#Example
#Image 4
SkMatrix matrix;
matrix.setRotate(45);
SkPaint paint;
paint.setShader(image->makeShader(SkShader::kRepeat_TileMode, SkShader::kMirror_TileMode,
                                  &matrix));
canvas->drawPaint(paint);
##

#SeeAlso scalePixels

#Method ##

# ------------------------------------------------------------------------------

#Method sk_sp<SkShader> makeShader(const SkMatrix* localMatrix = nullptr) const

Creates Shader from Image. Shader dimensions are taken from Image. Shader uses
SkShader::kClamp_TileMode to fill drawn area outside Image. localMatrix permits
transforming Image before Canvas_Matrix is applied.

#Param localMatrix  Image transformation, or nullptr ##

#Return Shader containing Image ##

#Example
#Image 5
SkMatrix matrix;
matrix.setRotate(45);
matrix.postTranslate(125, 30);
SkPaint paint;
paint.setShader(image->makeShader(&matrix));
canvas->drawPaint(paint);
##

#SeeAlso scalePixels

#Method ##

# ------------------------------------------------------------------------------
#Subtopic Pixels
#Populate
#Line # read and write pixel values ##
##

#Method bool peekPixels(SkPixmap* pixmap) const
#In Pixels
#Line # returns Pixmap if possible ##
Copies Image pixel address, row bytes, and Image_Info to pixmap, if address
is available, and returns true. If pixel address is not available, return
false and leave pixmap unchanged.

#Param pixmap  storage for pixel state if pixels are readable; otherwise, ignored ##

#Return true if Image has direct access to pixels ##

#Example
    SkBitmap bitmap;
    bitmap.allocPixels(SkImageInfo::MakeN32Premul(12, 11));
    SkCanvas offscreen(bitmap);
    offscreen.clear(SK_ColorWHITE);
    SkPaint paint;
    offscreen.drawString("%", 1, 10, paint);
    sk_sp<SkImage> image = SkImage::MakeFromBitmap(bitmap);
    SkPixmap pixmap;
    if (image->peekPixels(&pixmap)) {
        const SkPMColor* pixels = pixmap.addr32();
        SkPMColor pmWhite = pixels[0];
        for (int y = 0; y < image->height(); ++y) {
            for (int x = 0; x < image->width(); ++x) {
                SkDebugf("%c", *pixels++ == pmWhite ? '-' : 'x');
            }
            SkDebugf("\n");
        }
    }
#StdOut
------------
--xx----x---
-x--x--x----
-x--x--x----
-x--x-x-----
--xx-xx-xx--
-----x-x--x-
----x--x--x-
----x--x--x-
---x----xx--
------------
##
##

#SeeAlso readPixels

#Method ##

# ------------------------------------------------------------------------------

#Method GrTexture* getTexture() const
#Deprecated 
#Method ##

# ------------------------------------------------------------------------------

#Method bool isTextureBacked() const
#In Property
#Line # returns if Image was created from GPU_Texture ##
Returns true the contents of Image was created on or uploaded to GPU memory,
and is available as a GPU_Texture.

#Return true if Image is a GPU_Texture ##

#Example
#Image 5
#Platform gpu
auto drawImage = [=](sk_sp<SkImage> image, const char* label) -> void {
    if (nullptr == image) {
        return;
    }
    SkPaint paint;
    paint.setAntiAlias(true);
    paint.setTextAlign(SkPaint::kCenter_Align);
    canvas->drawImage(image, 0, 0);
    canvas->drawString(label, image->width() / 2, image->height() / 4, paint);
    canvas->drawString(image->isTextureBacked() ? "is GPU texture" : "not GPU texture",
                       image->width() / 2, image->height() * 3 / 4, paint);
};
sk_sp<SkImage> bitmapImage(SkImage::MakeFromBitmap(source));
sk_sp<SkImage> textureImage(SkImage::MakeFromTexture(canvas->getGrContext(), backEndTexture,
                            kTopLeft_GrSurfaceOrigin, kOpaque_SkAlphaType, nullptr));
drawImage(image, "image");
canvas->translate(image->width(), 0);
drawImage(bitmapImage, "source");
canvas->translate(-image->width(), image->height());
drawImage(textureImage, "backEndTexture");
##

#SeeAlso MakeFromTexture isValid

#Method ##

# ------------------------------------------------------------------------------

#Method bool isValid(GrContext* context) const
#In Property
#Line # returns if Image can draw to Raster_Surface or GPU_Context ##
Returns true if Image can be drawn on either Raster_Surface or GPU_Surface.
If context is nullptr, tests if Image draws on Raster_Surface;
otherwise, tests if Image draws on GPU_Surface associated with context.

Image backed by GPU_Texture may become invalid if associated GrContext is
invalid. Lazy_Image may be invalid and may not draw to Raster_Surface or
GPU_Surface or both.

#Param context  GPU_Context ##

#Return true if Image can be drawn  ##

#Example
#Image 5
#Platform gpu
auto drawImage = [=](sk_sp<SkImage> image, const char* label) -> void {
    if (nullptr == image) {
        return;
    }
    SkPaint paint;
    paint.setAntiAlias(true);
    paint.setTextAlign(SkPaint::kCenter_Align);
    canvas->drawImage(image, 0, 0);
    canvas->drawString(label, image->width() / 2, image->height() / 4, paint);
    if (canvas->getGrContext()) {
        canvas->drawString(image->isValid(canvas->getGrContext()) ? "is valid on GPU" :
                "not valid on GPU", image->width() / 2, image->height() * 5 / 8, paint);
    }
    canvas->drawString(image->isValid(nullptr) ? "is valid on CPU" :
            "not valid on CPU", image->width() / 2, image->height() * 7 / 8, paint);
};
sk_sp<SkImage> bitmapImage(SkImage::MakeFromBitmap(source));
sk_sp<SkImage> textureImage(SkImage::MakeFromTexture(canvas->getGrContext(), backEndTexture,
                            kTopLeft_GrSurfaceOrigin, kOpaque_SkAlphaType, nullptr));
drawImage(image, "image");
canvas->translate(image->width(), 0);
drawImage(bitmapImage, "source");
canvas->translate(-image->width(), image->height());
drawImage(textureImage, "backEndTexture");
##

#SeeAlso isTextureBacked isLazyGenerated

#Method ##

# ------------------------------------------------------------------------------

#Method GrBackendObject getTextureHandle(bool flushPendingGrContextIO,
                                     GrSurfaceOrigin* origin = nullptr) const
#In Property
#Line # returns GPU reference to Image as texture ##

Retrieves the back-end API handle of texture. If flushPendingGrContextIO is true,
complete deferred I/O operations.

If origin in not nullptr, copies location of content drawn into Image.

#Param flushPendingGrContextIO  flag to flush outstanding requests ##
#Param origin  storage for one of: kTopLeft_GrSurfaceOrigin,
               kBottomLeft_GrSurfaceOrigin; or nullptr 
##

#Return back-end API texture handle, or nullptr ##

#Example
#Image 4
#Platform gpu
GrContext* context = canvas->getGrContext();
if (!context) {
   return;
}
SkPaint paint;
paint.setAntiAlias(true);
SkString str;
int y = -10;
for (auto origin : { kTopLeft_GrSurfaceOrigin, kBottomLeft_GrSurfaceOrigin } ) {
    sk_sp<SkImage> srcImage(SkImage::MakeFromTexture(context,
            backEndTexture, origin, kPremul_SkAlphaType, nullptr));
    GrSurfaceOrigin readBackOrigin;
    GrBackendObject readBackHandle = srcImage->getTextureHandle(false, &readBackOrigin);
    str.printf("readBackHandle: 0x%x", readBackHandle);
    canvas->drawString(str, 5, y += 30, paint);
    canvas->drawImage(srcImage, 80, y += 10);
    str.printf("origin: k%s_GrSurfaceOrigin", readBackOrigin ? "BottomLeft" : "TopLeft");
    canvas->drawString(str, 5, y += srcImage->height() + 10, paint);
}
##

#Example
#Image 5
#Platform gpu
    auto drawImage = [=](sk_sp<SkImage> image, const char* label) -> void {
        if (nullptr == image) {
            return;
        }
        SkPaint paint;
        paint.setAntiAlias(true);
        paint.setTextAlign(SkPaint::kCenter_Align);
        canvas->drawImage(image, 0, image->height() / 4);
        canvas->drawString(label, image->width() / 2, image->height() / 8, paint);
        GrSurfaceOrigin readBackOrigin;
        GrBackendObject readBackHandle = image->getTextureHandle(false, &readBackOrigin);
        canvas->drawString(readBackHandle ? "has readBackHandle" : "no readBackHandle",
                           image->width() / 2, image->height() * 11 / 8, paint);
    };
    drawImage(image, "image");
    canvas->translate(image->width(), 0);
    sk_sp<SkImage> textureImage(SkImage::MakeFromTexture(canvas->getGrContext(), backEndTexture,
                                kTopLeft_GrSurfaceOrigin, kOpaque_SkAlphaType, nullptr));
    drawImage(textureImage, "backEndTexture");
##

#SeeAlso MakeFromTexture isTextureBacked

#Method ##

# ------------------------------------------------------------------------------

#Enum CachingHint

#Code
    enum CachingHint {
        kAllow_CachingHint,
        kDisallow_CachingHint,
    };
##

CachingHint selects whether Skia may internally cache Bitmaps generated by
decoding Image, or by copying Image from GPU to CPU. The default behavior
allows caching Bitmaps. 

Choose kDisallow_CachingHint if Image pixels are to be used only once, or
if Image pixels reside in a cache outside of Skia, or to reduce memory pressure.

Choosing kAllow_CachingHint does not ensure that pixels will be cached.
Image pixels may not be cached if memory requirements are too large or
pixels are not accessible.

#Const kAllow_CachingHint 0
Allows Skia to internally cache decoded and copied pixels.
##
#Const kDisallow_CachingHint 1
Disallows Skia from internally caching decoded and copied pixels.
##

#NoExample
##

#SeeAlso readPixels scalePixels

#Enum ##

# ------------------------------------------------------------------------------

#Method bool readPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes,
                    int srcX, int srcY, CachingHint cachingHint = kAllow_CachingHint) const
#In Pixels
#Line # copies and converts pixels ##

Copies Rect of pixels from Image to dstPixels. Copy starts at offset (srcX, srcY),
and does not exceed Image (width(), 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:
#List
# dstInfo.addr() equals nullptr ##
# dstRowBytes is less than dstInfo.minRowBytes ##
# Pixel_Ref is nullptr ##
##

Pixels are copied only if pixel conversion is possible. If Image Color_Type is
kGray_8_SkColorType, or kAlpha_8_SkColorType; dstInfo.colorType must match.
If Image Color_Type is kGray_8_SkColorType, dstInfo.colorSpace must match.
If Image Alpha_Type is kOpaque_SkAlphaType, dstInfo.alphaType must
match. If Image Color_Space 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) >= Image width()
##
, or if
#Formula
abs(srcY) >= Image height()
##
.

If cachingHint is kAllow_CachingHint, pixels may be retained locally.
If cachingHint is kDisallow_CachingHint, pixels are not added to the local cache.

#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 cachingHint  one of: kAllow_CachingHint, kDisallow_CachingHint ##

#Return true if pixels are copied to dstPixels ##

#Example
#Image 3
    canvas->scale(.5f, .5f);
    const int width = 32;
    const int height = 32;
    std::vector<int32_t> dstPixels;
    dstPixels.resize(height * width * 4);
    SkImageInfo info = SkImageInfo::MakeN32Premul(width, height);
    for (int y = 0; y < 512; y += height ) {
        for (int x = 0; x < 512; x += width ) {
            if (image->readPixels(info, &dstPixels.front(), width * 4, x, y)) {
                SkPixmap dstPixmap(info, &dstPixels.front(), width * 4);
                SkBitmap bitmap;
                bitmap.installPixels(dstPixmap);
                canvas->drawBitmap(bitmap, 0, 0);
            }
            canvas->translate(48, 0);
        }
        canvas->translate(-16 * 48, 48);
    }
##

#SeeAlso scalePixels SkBitmap::readPixels SkPixmap::readPixels SkCanvas::readPixels SkSurface::readPixels

#Method ##

# ------------------------------------------------------------------------------

#Method bool readPixels(const SkPixmap& dst, int srcX, int srcY,
                    CachingHint cachingHint = kAllow_CachingHint) const

Copies a Rect of pixels from Image to dst. Copy starts at (srcX, srcY), and
does not exceed Image (width(), height()). 

dst specifies width, height, Color_Type, Alpha_Type, Color_Space, pixel storage,
and row bytes of destination. dst.rowBytes specifics the gap from one destination
row to the next. Returns true if pixels are copied. Returns false if:
#List
# dst pixel storage equals nullptr ##
# dst.rowBytes is less than SkImageInfo::minRowBytes ##
# Pixel_Ref is nullptr ##
##

Pixels are copied only if pixel conversion is possible. If Image Color_Type is
kGray_8_SkColorType, or kAlpha_8_SkColorType; dst.colorType must match.
If Image Color_Type is kGray_8_SkColorType, dst.colorSpace must match.
If Image Alpha_Type is kOpaque_SkAlphaType, dst.alphaType must
match. If Image Color_Space is nullptr, dst.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) >= Image width()
##
, or if
#Formula
abs(srcY) >= Image height()
##
.

If cachingHint is kAllow_CachingHint, pixels may be retained locally.
If cachingHint is kDisallow_CachingHint, pixels are not added to the local cache.

#Param dst  destination Pixmap: Image_Info, pixels, row bytes ##
#Param srcX  column index whose absolute value is less than width() ##
#Param srcY  row index whose absolute value is less than height() ##
#Param cachingHint  one of: kAllow_CachingHint, kDisallow_CachingHint ##

#Return true if pixels are copied to dst ##

#Example
#Image 3
    std::vector<int32_t> srcPixels;
    int rowBytes = image->width() * 4;
    int quarterWidth = image->width() / 4;
    int quarterHeight = image->height() / 4;
    srcPixels.resize(image->height() * rowBytes);
    for (int y = 0; y < 4; ++y) {
        for (int x = 0; x < 4; ++x) {
            SkPixmap pixmap(SkImageInfo::MakeN32Premul(quarterWidth, quarterHeight),
                    &srcPixels.front() + x * image->height() * quarterWidth +
                    y * quarterWidth, rowBytes);
            image->readPixels(pixmap, x * quarterWidth, y * quarterHeight);
        }
    }
    canvas->scale(.5f, .5f);
    SkBitmap bitmap;
    bitmap.installPixels(SkImageInfo::MakeN32Premul(image->width(), image->height()),
                             &srcPixels.front(), rowBytes);
    canvas->drawBitmap(bitmap, 0, 0);
##

#SeeAlso scalePixels SkBitmap::readPixels SkPixmap::readPixels SkCanvas::readPixels SkSurface::readPixels

#Method ##

# ------------------------------------------------------------------------------

#Method bool scalePixels(const SkPixmap& dst, SkFilterQuality filterQuality,
                     CachingHint cachingHint = kAllow_CachingHint) const
#In Pixels
#Line # scales and converts one Image to another ##

Copies Image 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 Image Color_Type is
kGray_8_SkColorType, or kAlpha_8_SkColorType; dst.colorType must match.
If Image Color_Type is kGray_8_SkColorType, dst.colorSpace must match.
If Image Alpha_Type is kOpaque_SkAlphaType, dst.alphaType must
match. If Image Color_Space is nullptr, dst.colorSpace must match. Returns
false if pixel conversion is not possible.

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.

If cachingHint is kAllow_CachingHint, pixels may be retained locally.
If cachingHint is kDisallow_CachingHint, pixels are not added to the local cache.

#Param dst  destination Pixmap: Image_Info, pixels, row bytes ##
#Param filterQuality  one of: kNone_SkFilterQuality, kLow_SkFilterQuality,
                      kMedium_SkFilterQuality, kHigh_SkFilterQuality
##
#Param cachingHint  one of: kAllow_CachingHint, kDisallow_CachingHint ##

#Return true if pixels are scaled to fit dst ##

#Example
#Image 3
#Height 128
    std::vector<int32_t> srcPixels;
    int quarterWidth = image->width() / 16;
    int rowBytes = quarterWidth * 4;
    int quarterHeight = image->height() / 16;
    srcPixels.resize(quarterHeight * rowBytes);
    SkPixmap pixmap(SkImageInfo::MakeN32Premul(quarterWidth, quarterHeight),
                    &srcPixels.front(), rowBytes);
    canvas->scale(4, 4);
    SkFilterQuality qualities[] = { kNone_SkFilterQuality, kLow_SkFilterQuality,
                     kMedium_SkFilterQuality, kHigh_SkFilterQuality };
    for (unsigned index = 0; index < SK_ARRAY_COUNT(qualities); ++index) {
        image->scalePixels(pixmap, qualities[index]);
        sk_sp<SkImage> filtered = SkImage::MakeFromRaster(pixmap, nullptr, nullptr);
        canvas->drawImage(filtered, 16 * index, 0);
    }
##

#SeeAlso SkCanvas::drawImage readPixels SkPixmap::scalePixels

#Method ##

# ------------------------------------------------------------------------------

#Method sk_sp<SkData> encodeToData(SkEncodedImageFormat encodedImageFormat, int quality) const
#In Utility
#Line # returns encoded Image as SkData ##
Encodes Image pixels, returning result as SkData. 

Returns nullptr if encoding fails, or if encodedImageFormat is not supported.

Image encoding in a format requires both building with one or more of:
SK_HAS_JPEG_LIBRARY, SK_HAS_PNG_LIBRARY, SK_HAS_WEBP_LIBRARY; and platform support
for the encoded format.

If SK_BUILD_FOR_MAC or SK_BUILD_FOR_IOS is defined, encodedImageFormat can
additionally be one of: SkEncodedImageFormat::kICO, SkEncodedImageFormat::kBMP,
SkEncodedImageFormat::kGIF.

quality is a platform and format specific metric trading off size and encoding
error. When used, quality equaling 100 encodes with the least error. quality may
be ignored by the encoder.

#Param encodedImageFormat  one of: SkEncodedImageFormat::kJPEG, SkEncodedImageFormat::kPNG,
    SkEncodedImageFormat::kWEBP
 ##
#Param quality  encoder specific metric with 100 equaling best ##

#Return encoded Image, or nullptr ##

#Example
#Image 3
    canvas->scale(4, 4);
    SkIRect subset = {0, 0, 16, 64};
    int x = 0;
    for (int quality : { 0, 10, 50, 100 } ) {
        sk_sp<SkData> data(image->encodeToData(SkEncodedImageFormat::kJPEG, quality));
        sk_sp<SkImage> filtered = SkImage::MakeFromEncoded(data, &subset);
        canvas->drawImage(filtered, x, 0);
        x += 16;
    }
##

#SeeAlso refEncodedData MakeFromEncoded

#Method ##

# ------------------------------------------------------------------------------

#Method sk_sp<SkData> encodeToData() const

Encodes Image pixels, returning result as SkData. Returns existing encoded data
if present; otherwise, Image is encoded with SkEncodedImageFormat::kPNG. Skia
must be built with SK_HAS_PNG_LIBRARY to encode Image.

Returns nullptr if existing encoded data is missing or invalid, and 
encoding fails.

#Return encoded Image, or nullptr ##

#Example
#Image 3
    canvas->scale(4, 4);
    SkIRect subset = {136, 32, 200, 96};
    sk_sp<SkData> data(image->encodeToData());
    sk_sp<SkImage> eye = SkImage::MakeFromEncoded(data, &subset);
    canvas->drawImage(eye, 0, 0);
##

#SeeAlso refEncodedData MakeFromEncoded

#Method ##

# ------------------------------------------------------------------------------

#Method sk_sp<SkData> refEncodedData() const
#In Utility
#Line # returns Image encoded in SkData if present ##
Returns encoded Image pixels as SkData, if Image was created from supported
encoded stream format. Platform support for formats vary and may require building
with one or more of: SK_HAS_JPEG_LIBRARY, SK_HAS_PNG_LIBRARY, SK_HAS_WEBP_LIBRARY.

Returns nullptr if Image contents are not encoded.

#Return encoded Image, or nullptr ##

#Example
#Image 3
#Platform gpu
    struct {
        const char* name;
        sk_sp<SkImage> image;
    } tests[] = { { "image", image }, { "bitmap", SkImage::MakeFromBitmap(source) },
          { "texture", SkImage::MakeFromTexture(canvas->getGrContext(), backEndTexture,
                            kTopLeft_GrSurfaceOrigin, kOpaque_SkAlphaType, nullptr) } };
    SkString string;
    SkPaint paint;
    for (const auto& test : tests ) {
        if (!test.image) {
            string.printf("no %s", test.name);
        } else {
            string.printf("%s" "encoded %s", test.image->refEncodedData() ? "" : "no ", test.name);
        }
        canvas->drawString(string, 10, 20, paint);
        canvas->translate(0, 20);
    }
##

#SeeAlso encodeToData MakeFromEncoded

#Method ##

# ------------------------------------------------------------------------------
#Subtopic Utility
#Populate
#Line # rarely called management functions ##
##

#Method const char* toString(SkString* string) const
#In Utility
#Line # converts Image to machine readable form ##
Appends Image description to string, including unique ID, width, height, and
whether the image is opaque.

#Param string  storage for description; existing content is preserved ##

#Return string appended with Image description ##

#Example
#Image 4
    struct {
        const char* name;
        sk_sp<SkImage> image;
    } tests[] = { { "image", image }, { "bitmap", SkImage::MakeFromBitmap(source) },
          { "texture", SkImage::MakeFromTexture(canvas->getGrContext(), backEndTexture,
                            kTopLeft_GrSurfaceOrigin, kOpaque_SkAlphaType, nullptr) } };
    SkString string;
    SkPaint paint;
    for (const auto& test : tests ) {
        string.printf("%s: ", test.name);
        test.image ? (void) test.image->toString(&string) : string.append("no image");
        canvas->drawString(string, 10, 20, paint);
        canvas->translate(0, 20);
    }
##

#SeeAlso SkPaint::toString

#Method ##

# ------------------------------------------------------------------------------

#Method sk_sp<SkImage> makeSubset(const SkIRect& subset) const
#In Constructor
#Line # creates Image containing part of original ##
Returns subset of Image. subset must be fully contained by Image dimensions().
The implementation may share pixels, or may copy them.

Returns nullptr if subset is empty, or subset is not contained by bounds, or
pixels in Image could not be read or copied.

#Param subset  bounds of returned Image ##

#Return partial or full Image, or nullptr ##

#Example
#Image 3
    canvas->scale(.5f, .5f);
    const int width = 32;
    const int height = 32;
    for (int y = 0; y < 512; y += height ) {
        for (int x = 0; x < 512; x += width ) {
            sk_sp<SkImage> subset(image->makeSubset({x, y, x + width, y + height}));
            canvas->drawImage(subset, x * 3 / 2, y * 3 / 2);
        }
    }
##

#SeeAlso MakeFromEncoded

#Method ##

# ------------------------------------------------------------------------------

#Method sk_sp<SkImage> makeTextureImage(GrContext* context, SkColorSpace* dstColorSpace) const
#In Constructor
#Line # creates Image matching Color_Space if possible ##
Returns Image backed by GPU_Texture associated with context. Returned Image is
compatible with Surface created with dstColorSpace. Returns original
Image if context and dstColorSpace match.

Returns nullptr if context is nullptr, or if Image was created with another
GrContext.

#Param context  GPU_Context ##
#Param dstColorSpace  range of colors of matching Surface on GPU ##

#Return created Image, or nullptr ##

#Example
#Platform gpu
#Image 5
    auto drawImage = [=](sk_sp<SkImage> image, GrContext* context, const char* label) -> void {
        if (nullptr == image || nullptr == context) {
            return;
        }
        SkPaint paint;
        paint.setAntiAlias(true);
        paint.setTextAlign(SkPaint::kCenter_Align);
        sk_sp<SkImage> texture(image->makeTextureImage(context, nullptr));
        canvas->drawImage(texture, 0, 0);
        canvas->drawString(label, texture->width() / 2, texture->height() / 4, paint);
    };
    sk_sp<SkImage> bitmapImage(SkImage::MakeFromBitmap(source));
    GrContext* context = canvas->getGrContext();
    sk_sp<SkImage> textureImage(SkImage::MakeFromTexture(context, backEndTexture,
                                kTopLeft_GrSurfaceOrigin, kOpaque_SkAlphaType, nullptr));
    drawImage(image, context, "image");
    canvas->translate(image->width(), 0);
    drawImage(bitmapImage, context, "source");
    canvas->translate(-image->width(), image->height());
    drawImage(textureImage, context, "backEndTexture");
##

#SeeAlso MakeFromTexture

#Method ##

# ------------------------------------------------------------------------------

#Method sk_sp<SkImage> makeNonTextureImage() const
#In Constructor
#Line # creates Image without dependency on GPU_Texture ##
Returns Raster_Image or Lazy_Image. Copies Image backed by GPU_Texture into
CPU memory if needed. Returns original Image if decoded in Raster_Bitmap,
or if encoded in a stream.

Returns nullptr if backed by GPU_Texture and copy fails.

#Return Raster_Image, Lazy_Image, or nullptr ##

#Example
#Image 5
#Platform gpu
    auto drawImage = [=](sk_sp<SkImage> image, const char* label) -> void {
        if (nullptr == image) {
            return;
        }
        SkPaint paint;
        paint.setAntiAlias(true);
        paint.setTextAlign(SkPaint::kCenter_Align);
        sk_sp<SkImage> nonTexture(image->makeNonTextureImage());
        canvas->drawImage(nonTexture, 0, 0);
        canvas->drawString(label, nonTexture->width() / 2, nonTexture->height() / 4, paint);
    };
    sk_sp<SkImage> bitmapImage(SkImage::MakeFromBitmap(source));
    sk_sp<SkImage> textureImage(SkImage::MakeFromTexture(canvas->getGrContext(), backEndTexture,
                                kTopLeft_GrSurfaceOrigin, kOpaque_SkAlphaType, nullptr));
    drawImage(image, "image");
    canvas->translate(image->width(), 0);
    drawImage(bitmapImage, "source");
    canvas->translate(-image->width(), image->height());
    drawImage(textureImage, "backEndTexture");
##

#SeeAlso makeTextureImage makeRasterImage MakeBackendTextureFromSkImage

#Method ##

# ------------------------------------------------------------------------------

#Method sk_sp<SkImage> makeRasterImage() const
#In Constructor
#Line # creates Image compatible with Raster_Surface if possible ##
Returns Raster_Image. Copies Image backed by GPU_Texture into CPU memory,
or decodes Image from Lazy_Image. Returns original Image if decoded in
Raster_Bitmap.

Returns nullptr if copy, decode, or pixel read fails.

#Return Raster_Image, or nullptr ##

#Bug 7479
#Example
#Image 5
#Platform gpu
    auto drawImage = [=](sk_sp<SkImage> image, const char* label) -> void {
        if (nullptr == image) {
            return;
        }
        SkPaint paint;
        paint.setAntiAlias(true);
        paint.setTextAlign(SkPaint::kCenter_Align);
        sk_sp<SkImage> raster(image->makeRasterImage());
        canvas->drawImage(raster, 0, 0);
        canvas->drawString(label, raster->width() / 2, raster->height() / 4, paint);
    };
    sk_sp<SkImage> bitmapImage(SkImage::MakeFromBitmap(source));
    sk_sp<SkImage> textureImage(SkImage::MakeFromTexture(canvas->getGrContext(), backEndTexture,
                                kTopLeft_GrSurfaceOrigin, kOpaque_SkAlphaType, nullptr));
    drawImage(image, "image");
    canvas->translate(image->width(), 0);
    drawImage(bitmapImage, "source");
    canvas->translate(-image->width(), image->height());
    drawImage(textureImage, "backEndTexture");
##

#SeeAlso isTextureBacked isLazyGenerated MakeFromRaster

#Method ##

# ------------------------------------------------------------------------------

#Method sk_sp<SkImage> makeWithFilter(const SkImageFilter* filter, const SkIRect& subset,
                                  const SkIRect& clipBounds, SkIRect* outSubset,
                                  SkIPoint* offset) const
#In Constructor
#Line # creates filtered, clipped Image ##

Creates filtered Image. filter processes original Image, potentially changing
color, position, and size. subset is the bounds of original Image processed
by filter. clipBounds is the expected bounds of the filtered Image. outSubset
is required storage for the actual bounds of the filtered Image. offset is
required storage for translation of returned Image.

Returns nullptr if Image could not be created. If nullptr is returned, outSubset
and offset are undefined.

Useful for animation of SkImageFilter that varies size from frame to frame.
Returned Image is created larger than required by filter so that GPU_Texture
can be reused with different sized effects. outSubset describes the valid bounds
of GPU_Texture returned. offset translates the returned Image to keep subsequent
animation frames aligned with respect to each other.

#Param filter  how Image is sampled when transformed ##
#Param subset  bounds of Image processed by filter ##
#Param clipBounds  expected bounds of filtered Image ##
#Param outSubset  storage for returned Image bounds ##
#Param offset  storage for returned Image translation ##

#Return filtered Image, or nullptr ##

#Example
#Description
In each frame of the animation, filtered Image is drawn in a different location.
By translating canvas by returned offset, Image appears stationary.
##
#Image 5
#Platform gpu
#Duration 5
    sk_sp<SkImageFilter> shadowFilter = SkDropShadowImageFilter::Make(
                -10.0f * frame, 5.0f * frame, 3.0f, 3.0f, SK_ColorBLUE,
                SkDropShadowImageFilter::kDrawShadowAndForeground_ShadowMode,
                nullptr);
    sk_sp<SkImageFilter> offsetFilter = SkOffsetImageFilter::Make(40, 40, shadowFilter, nullptr);
    SkIRect subset = image->bounds();
    SkIRect clipBounds = image->bounds();
    clipBounds.outset(60, 60);
    SkIRect outSubset;
    SkIPoint offset;
    sk_sp<SkImage> filtered(image->makeWithFilter(offsetFilter.get(), subset, clipBounds,
                            &outSubset, &offset));
    SkPaint paint;
    paint.setAntiAlias(true);
    paint.setStyle(SkPaint::kStroke_Style);
    canvas->drawLine(0, 0, offset.fX, offset.fY, paint);
    canvas->translate(offset.fX, offset.fY);
    canvas->drawImage(filtered, 0, 0);
    canvas->drawRect(SkRect::MakeFromIRect(outSubset), paint);
##

#SeeAlso makeShader SkPaint::setImageFilter

#Method ##

# ------------------------------------------------------------------------------

#Typedef std::function<void(GrBackendTexture)> BackendTextureReleaseProc

##

# ------------------------------------------------------------------------------

#Method static bool MakeBackendTextureFromSkImage(GrContext* context,
                                              sk_sp<SkImage> image,
                                              GrBackendTexture* backendTexture,
                                              BackendTextureReleaseProc* backendTextureReleaseProc)
#In Constructor
#Line # creates GPU_Texture from Image ##

Creates a GrBackendTexture from the provided SkImage. Returns true and
stores result in backendTexture and backendTextureReleaseProc if
texture is created; otherwise, returns false and leaves
backendTexture and backendTextureReleaseProc unmodified.

Call backendTextureReleaseProc after deleting backendTexture.
backendTextureReleaseProc cleans up auxiliary data related to returned
backendTexture. The caller must delete returned backendTexture after use.

If Image is both texture backed and singly referenced, image is returned in
backendTexture without conversion or making a copy. Image is singly referenced
if its was transferred solely using std::move().

If Image is not texture backed, returns texture with Image contents.

#Param context  GPU_Context ##
#Param image  Image used for texture ##
#Param backendTexture  storage for backend texture ##
#Param backendTextureReleaseProc  storage for clean up function ##

#Return true if backend texture was created ##

#Example
#Platform gpu
#Height 64
#Function
static sk_sp<SkImage> create_gpu_image(GrContext* grContext) {
    const SkImageInfo info = SkImageInfo::MakeN32(20, 20, kOpaque_SkAlphaType);
    auto surface(SkSurface::MakeRenderTarget(grContext, SkBudgeted::kNo, info));
    SkCanvas* canvas = surface->getCanvas();
    canvas->clear(SK_ColorWHITE);
    SkPaint paint;
    paint.setColor(SK_ColorBLACK);
    canvas->drawRect(SkRect::MakeXYWH(5, 5, 10, 10), paint);
    return surface->makeImageSnapshot();
}
##

void draw(SkCanvas* canvas) {    
    GrContext* grContext = canvas->getGrContext();
    if (!grContext) {
        return;
    }
    sk_sp<SkImage> backEndImage = create_gpu_image(grContext);
    canvas->drawImage(backEndImage, 0, 0);
    GrBackendTexture texture;
    SkImage::BackendTextureReleaseProc proc;
    if (!SkImage::MakeBackendTextureFromSkImage(grContext, std::move(backEndImage),
            &texture, &proc)) {
        return;
    }
    sk_sp<SkImage> i2 = SkImage::MakeFromTexture(grContext, texture, kTopLeft_GrSurfaceOrigin,
            kN32_SkColorType, kOpaque_SkAlphaType, nullptr);
    canvas->drawImage(i2, 30, 30);
}
##

#SeeAlso MakeFromTexture makeTextureImage

#Method ##

# ------------------------------------------------------------------------------

#Enum LegacyBitmapMode
#Deprecated soon
#Code
    enum LegacyBitmapMode {
        kRO_LegacyBitmapMode,
    };
##

#Const kRO_LegacyBitmapMode 0
Returned bitmap is read-only and immutable.
##

#Enum ##

# ------------------------------------------------------------------------------

#Method bool asLegacyBitmap(SkBitmap* bitmap, LegacyBitmapMode legacyBitmapMode = kRO_LegacyBitmapMode) const
#In Constructor
#Line # returns as Raster_Bitmap ##
Creates raster Bitmap with same pixels as Image. If legacyBitmapMode is
kRO_LegacyBitmapMode, returned bitmap is read-only and immutable.
Returns true if Bitmap is stored in bitmap. Returns false and resets bitmap if
Bitmap write did not succeed.

#Param bitmap  storage for legacy Bitmap ##
#Param legacyBitmapMode  to be deprecated ##

#Return true if Bitmap was created ##

#Example
#Image 4
#Platform gpu
    SkBitmap bitImage;
    if (image->asLegacyBitmap(&bitImage, SkImage::kRO_LegacyBitmapMode)) {
        canvas->drawBitmap(bitImage, 0, 0);
    }
    GrContext* grContext = canvas->getGrContext();
    if (!grContext) {
        return;
    }
    sk_sp<SkImage> textureImage(SkImage::MakeFromTexture(grContext, backEndTexture,
                                kTopLeft_GrSurfaceOrigin, kOpaque_SkAlphaType, nullptr));
    canvas->drawImage(textureImage, 45, 45);
    if (textureImage->asLegacyBitmap(&bitImage, SkImage::kRO_LegacyBitmapMode)) {
        canvas->drawBitmap(bitImage, 90, 90);
    }
##

#SeeAlso MakeRasterData makeRasterImage makeNonTextureImage

#Method ##

# ------------------------------------------------------------------------------

#Method bool isLazyGenerated() const
#In Property
#Line # returns if Image is created as needed ##
Returns true if Image is backed by an image-generator or other service that creates
and caches its pixels or texture on-demand.

#Return true if Image is created as needed ##

#Example
#Height 80
#Function
class TestImageGenerator : public SkImageGenerator {
public:
    TestImageGenerator() : SkImageGenerator(SkImageInfo::MakeN32Premul(10, 10)) {}
    ~TestImageGenerator() override {}
protected:
    bool onGetPixels(const SkImageInfo& info, void* pixelPtr, size_t rowBytes,
                     const Options& options) override {
        SkPMColor* pixels = static_cast<SkPMColor*>(pixelPtr);
        for (int y = 0; y < info.height(); ++y) {
            for (int x = 0; x < info.width(); ++x) {
                pixels[y * info.width() + x] = 0xff223344 + y * 0x000C0811;
            }
        }
        return true;
    }
};
##
void draw(SkCanvas* canvas) {
    auto gen = std::unique_ptr<TestImageGenerator>(new TestImageGenerator());
    sk_sp<SkImage> image(SkImage::MakeFromGenerator(std::move(gen)));
    SkString lazy(image->isLazyGenerated() ? "is lazy" : "not lazy");
    canvas->scale(8, 8);
    canvas->drawImage(image, 0, 0, nullptr);
    SkPaint paint;
    paint.setTextSize(4);
    canvas->drawString(lazy, 2, 5, paint);
}
##

#Example
#Image 5
#Platform gpu
void draw(SkCanvas* canvas) {
    auto drawImage = [=](sk_sp<SkImage> image, const char* label) -> void {
        if (nullptr == image) {
            return;
        }
        SkPaint paint;
        paint.setAntiAlias(true);
        paint.setTextAlign(SkPaint::kCenter_Align);
        canvas->drawImage(image, 0, 0);
        canvas->drawString(label, image->width() / 2, image->height() / 4, paint);
        canvas->drawString(
                image->isLazyGenerated() ? "is lazily generated" : "not lazily generated",
                image->width() / 2, image->height() * 3 / 4, paint);
    };
    sk_sp<SkImage> bitmapImage(SkImage::MakeFromBitmap(source));
    sk_sp<SkImage> textureImage(SkImage::MakeFromTexture(canvas->getGrContext(), backEndTexture,
                                kTopLeft_GrSurfaceOrigin, kOpaque_SkAlphaType, nullptr));
    drawImage(image, "image");
    canvas->translate(image->width(), 0);
    drawImage(bitmapImage, "source");
    canvas->translate(-image->width(), image->height());
    drawImage(textureImage, "backEndTexture");
}
##

#SeeAlso isTextureBacked MakeNonTextureImage

#Method ##

# ------------------------------------------------------------------------------

#Method sk_sp<SkImage> makeColorSpace(sk_sp<SkColorSpace> target,
                                  SkTransferFunctionBehavior premulBehavior) const
#In Constructor
#Line # creates Image matching Color_Space if possible ##

Creates Image in target Color_Space.
Returns nullptr if Image could not be created.

Returns original Image if it is in target Color_Space.
Otherwise, converts pixels from Image Color_Space to target Color_Space.
If Image colorSpace returns nullptr, Image Color_Space is assumed to be sRGB.

SkTransferFunctionBehavior is to be deprecated.

Set premulBehavior to SkTransferFunctionBehavior::kRespect to convert Image
pixels to a linear space, before converting to destination Color_Type
and Color_Space.

Set premulBehavior to SkTransferFunctionBehavior::kIgnore to treat Image
pixels as linear, when converting to destination Color_Type
and Color_Space, ignoring pixel encoding.

#Param target  Color_Space describing color range of returned Image ##
#Param premulBehavior  one of: SkTransferFunctionBehavior::kRespect,
                               SkTransferFunctionBehavior::kIgnore
##

#Return created Image in target Color_Space ##

#Example
#Image 5
#Set sRGB
    sk_sp<SkColorSpace> normalColorSpace = SkColorSpace::MakeRGB(
             SkColorSpace::kSRGB_RenderTargetGamma, SkColorSpace::kSRGB_Gamut);
    sk_sp<SkColorSpace> wackyColorSpace = normalColorSpace->makeColorSpin();
    for (auto colorSpace : { normalColorSpace, wackyColorSpace  } ) {
        for (auto transfer : { SkTransferFunctionBehavior::kRespect,
                               SkTransferFunctionBehavior::kIgnore } ) {
            sk_sp<SkImage> colorSpaced = image->makeColorSpace(colorSpace, transfer);
            canvas->drawImage(colorSpaced, 0, 0);
            canvas->translate(128, 0);
        }
        canvas->translate(-256, 128);
    }
##

#SeeAlso MakeFromPixture MakeFromTexture

#Method ##

#Class SkImage ##

#Topic Image ##