Cary Clark 2dc84ad3ef working on global enum and image info

Added global enum support. That exposed one
big hole in bookmaker: The topic overview
should not be in the class or struct if
the topic includes multiple objects, which
is the case for SkImageInfo and enums like
SkColorType.

This straightens that out, and then used that
knowledge to strengthen the topics in
SkRect as a test. Now SkRect has more
groups of methods, and can expose and link
to sets of methods with the same name.

This work also is getting ready for tightening
SeeAlso data, to be checked as part of the
bots' tasks soon.

Also, remove links from markup for lowercase
method names unless the reference has
trailing parentheses.

TBR=caryclark@google.com
Docs-Preview: https://skia.org/?cl=98782
Bug: skia:6898
Change-Id: I35419c9789da17e272047bf7b9c95b1cf44bb7fe
Reviewed-on: https://skia-review.googlesource.com/98782
Commit-Queue: Cary Clark <caryclark@google.com>
Reviewed-by: Cary Clark <caryclark@skia.org>
Reviewed-by: Cary Clark <caryclark@google.com>

2018-01-26 18:22:10 +00:00

129 KiB

Raw Blame History

SkImage Reference

Image

Class SkImage

Image describes a two dimensional array of pixels to draw. The pixels may be unencoded 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 encodings details vary with platform.

Raster Image

Raster Image pixels are unencoded 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.

Texture Image

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.

Lazy Image

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.

Overview

Subtopics

topics	description

Constructors

name	description
MakeBackendTextureFromSkImage	Creates GPU Texture from Image.
MakeCrossContextFromEncoded	Creates Image from encoded data, and uploads to GPU.
MakeCrossContextFromPixmap	Creates Image from Pixmap, and uploads to GPU.
MakeFromAHardwareBuffer	Creates Image from Android hardware buffer.
MakeFromAdoptedTexture	Creates Image from GPU Texture, managed internally.
MakeFromBitmap	Creates Image from Bitmap, sharing or copying pixels.
MakeFromDeferredTextureImageData	To be deprecated.
MakeFromEncoded	Creates Image from encoded data.
MakeFromGenerator	Creates Image from a stream of data.
MakeFromNV12TexturesCopy	Creates Image from YUV ColorSpace data in two planes.
MakeFromPicture	Creates Image from Picture.
MakeFromRaster	Creates Image from Pixmap, with release.
MakeFromTexture	Creates Image from GPU Texture, managed externally.
MakeFromYUVTexturesCopy	Creates Image from YUV ColorSpace data in three planes.
MakeRasterCopy	Creates Image from Pixmap and copied pixels.
MakeRasterData	Creates Image from Image Info and shared pixels.
SkSurface::makeImageSnapshot	Creates Image capturing Surface contents.
makeColorSpace	Creates Image matching Color Space if possible.
makeNonTextureImage	Creates Image without dependency on GPU Texture.
makeRasterImage	Creates Image compatible with Raster Surface if possible.
makeSubset	Creates Image containing part of original.
makeTextureImage	Creates Image matching Color Space if possible.
makeWithFilter	Creates filtered, clipped Image.

Member Functions

description	function
MakeBackendTextureFromSkImage	Creates GPU Texture from Image.
MakeCrossContextFromEncoded	Creates Image from encoded data, and uploads to GPU.
MakeCrossContextFromPixmap	Creates Image from Pixmap, and uploads to GPU.
MakeFromAHardwareBuffer	Creates Image from Android hardware buffer.
MakeFromAdoptedTexture	Creates Image from GPU Texture, managed internally.
MakeFromBitmap	Creates Image from Bitmap, sharing or copying pixels.
MakeFromDeferredTextureImageData	To be deprecated.
MakeFromEncoded	Creates Image from encoded data.
MakeFromGenerator	Creates Image from a stream of data.
MakeFromNV12TexturesCopy	Creates Image from YUV ColorSpace data in two planes.
MakeFromPicture	Creates Image from Picture.
MakeFromRaster	Creates Image from Pixmap, with release.
MakeFromTexture	Creates Image from GPU Texture, managed externally.
MakeFromYUVTexturesCopy	Creates Image from YUV ColorSpace data in three planes.
MakeRasterCopy	Creates Image from Pixmap and copied pixels.
MakeRasterData	Creates Image from Image Info and shared pixels.
alphaType	Returns Alpha Type.
asLegacyBitmap	Returns as Raster Bitmap.
bounds	Returns width and height as Rectangle.
colorSpace	Returns Color Space.
dimensions	Returns width and height.
encodeToData	Returns encoded Image as SkData.
getDeferredTextureImageData	To be deprecated.
getTexture	Deprecated.
getTextureHandle	Returns GPU reference to Image as texture.
height	Returns pixel row count.
isAlphaOnly	Returns if pixels represent a transparency mask.
isLazyGenerated	Returns if Image is created as needed.
isOpaque	Returns if Alpha Type is kOpaque SkAlphaType.
isTextureBacked	Returns if Image was created from GPU Texture.
isValid	Returns if Image can draw to Raster Surface or GPU Context.
makeColorSpace	Creates Image matching Color Space if possible.
makeNonTextureImage	Creates Image without dependency on GPU Texture.
makeRasterImage	Creates Image compatible with Raster Surface if possible.
makeShader	Creates Shader, Paint element that can tile Image.
makeSubset	Creates Image containing part of original.
makeTextureImage	Creates Image matching Color Space if possible.
makeWithFilter	Creates filtered, clipped Image.
peekPixels	Returns Pixmap if possible.
readPixels	Copies and converts pixels.
refColorSpace	Returns Image Info Color Space.
refEncodedData	Returns Image encoded in SkData if present.
scalePixels	Scales and converts one Image to another.
toString	Converts Image to machine readable form.
uniqueID	Identifier for Image.
width	Returns pixel column count.

MakeRasterCopy

static sk_sp<SkImage> MakeRasterCopy(const SkPixmap& pixmap)

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.

Parameters

pixmap Image Info, pixel address, and row bytes

Return Value

copy of Pixmap pixels, or nullptr

Example

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.

MakeRasterData

static sk_sp<SkImage> MakeRasterData(const Info& info, sk_sp<SkData> pixels, size_t rowBytes)

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.

Parameters

`info`	contains width, height, Alpha Type, Color Type, Color Space
`pixels`	address or pixel storage
`rowBytes`	size of pixel row or larger

Return Value

Image sharing pixels, or nullptr

Example

MakeFromRaster

static sk_sp<SkImage> MakeFromRaster(const SkPixmap& pixmap, RasterReleaseProc rasterReleaseProc,
                                     ReleaseContext releaseContext)

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.

Parameters

`pixmap`	Image Info, pixel address, and row bytes
`rasterReleaseProc`	function called when pixels can be released; or nullptr
`releaseContext`	state passed to rasterReleaseProc; or nullptr

Return Value

Image sharing pixmap

Example

Example Output

before reset: 0
after reset: 1

MakeFromBitmap

static sk_sp<SkImage> MakeFromBitmap(const SkBitmap& bitmap)

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.

Parameters

bitmap Image Info, row bytes, and pixels

Return Value

created Image, or nullptr

Example

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.

MakeFromGenerator

static sk_sp<SkImage> MakeFromGenerator(std::unique_ptr<SkImageGenerator> imageGenerator,
                                 const SkIRect* subset = nullptr)

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.

Parameters

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

Return Value

created Image, or nullptr

Example

The generator returning Picture cannot be shared; std::move transfers ownership to generated Image.

Parameters

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

Return Value

created Image, or nullptr

Example

MakeFromTexture

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

Deprecated.

Parameters

`context`	GPU Context
`backendTexture`	texture residing on GPU
`origin`	one of: kBottomLeft GrSurfaceOrigin, kTopLeft GrSurfaceOrigin
`alphaType`	one of: kUnknown SkAlphaType, kOpaque SkAlphaType, kPremul SkAlphaType, kUnpremul SkAlphaType
`colorSpace`	range of colors; may be nullptr

Return Value

created Image, or nullptr

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

Deprecated.

Parameters

`context`	GPU Context
`backendTexture`	texture residing on GPU
`origin`	one of: kBottomLeft GrSurfaceOrigin, kTopLeft GrSurfaceOrigin
`alphaType`	one of: kUnknown SkAlphaType, kOpaque SkAlphaType, kPremul SkAlphaType, kUnpremul SkAlphaType
`colorSpace`	range of colors; may be nullptr
`textureReleaseProc`	function called when texture can be released
`releaseContext`	state passed to textureReleaseProc

Return Value

created Image, or nullptr

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

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.

Parameters

`context`	GPU Context
`backendTexture`	texture residing on GPU
`origin`	one of: kBottomLeft GrSurfaceOrigin, kTopLeft GrSurfaceOrigin
`colorType`	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
`alphaType`	one of: kUnknown SkAlphaType, kOpaque SkAlphaType, kPremul SkAlphaType, kUnpremul SkAlphaType
`colorSpace`	range of colors; may be nullptr

Return Value

created Image, or nullptr

Example

A back-end texture has been created and uploaded to the GPU outside of this example.

Parameters

`context`	GPU Context
`backendTexture`	texture residing on GPU
`origin`	one of: kBottomLeft GrSurfaceOrigin, kTopLeft GrSurfaceOrigin
`colorType`	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
`alphaType`	one of: kUnknown SkAlphaType, kOpaque SkAlphaType, kPremul SkAlphaType, kUnpremul SkAlphaType
`colorSpace`	range of colors; may be nullptr
`textureReleaseProc`	function called when texture can be released
`releaseContext`	state passed to textureReleaseProc

Return Value

created Image, or nullptr

Example

MakeCrossContextFromEncoded

static sk_sp<SkImage> MakeCrossContextFromEncoded(GrContext* context, sk_sp<SkData> data,
                                                  bool buildMips, SkColorSpace* dstColorSpace)

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.

Parameters

`context`	GPU Context
`data`	Image to decode
`buildMips`	create Image as Mip Map if true
`dstColorSpace`	range of colors of matching Surface on GPU

Return Value

created Image, or nullptr

Example

Parameters

`context`	GPU Context
`pixmap`	Image Info, pixel address, and row bytes
`buildMips`	create Image as Mip Map if true
`dstColorSpace`	range of colors of matching Surface on GPU

Return Value

created Image, or nullptr

Example

MakeFromAdoptedTexture

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

Deprecated.

Parameters

`context`	GPU Context
`backendTexture`	texture residing on GPU
`surfaceOrigin`	one of: kBottomLeft GrSurfaceOrigin, kTopLeft GrSurfaceOrigin
`alphaType`	one of: kUnknown SkAlphaType, kOpaque SkAlphaType, kPremul SkAlphaType, kUnpremul SkAlphaType
`colorSpace`	range of colors; may be nullptr

Return Value

created Image, or nullptr

Parameters

`context`	GPU Context
`backendTexture`	texture residing on GPU
`surfaceOrigin`	one of: kBottomLeft GrSurfaceOrigin, kTopLeft GrSurfaceOrigin
`colorType`	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
`alphaType`	one of: kUnknown SkAlphaType, kOpaque SkAlphaType, kPremul SkAlphaType, kUnpremul SkAlphaType
`colorSpace`	range of colors; may be nullptr

Return Value

created Image, or nullptr

Example

MakeFromYUVTexturesCopy

static sk_sp<SkImage> MakeFromYUVTexturesCopy(GrContext* context, SkYUVColorSpace yuvColorSpace,
                                              const GrBackendObject yuvTextureHandles[3],
                                              const SkISize yuvSizes[3],
                                              GrSurfaceOrigin surfaceOrigin,
                                              sk_sp<SkColorSpace> colorSpace = nullptr)

Creates Image from copy of yuvTextureHandles, an array of textures on GPU. yuvTextureHandles contain pixels for YUV planes of Image. yuvSizes conain dimensions for each pixel plane. Dimensions must be greater than zero but may differ from plane to plane. Returned Image has the dimensions yuvSizes[0]. yuvColorSpace describes how YUV colors convert to RGB colors.

Parameters

`context`	GPU Context
`yuvColorSpace`	one of: kJPEG SkYUVColorSpace, kRec601 SkYUVColorSpace, kRec709 SkYUVColorSpace
`yuvTextureHandles`	array of YUV textures on GPU
`yuvSizes`	dimensions of YUV textures
`surfaceOrigin`	one of: kBottomLeft GrSurfaceOrigin, kTopLeft GrSurfaceOrigin
`colorSpace`	range of colors; may be nullptr

Return Value

created Image, or nullptr

Parameters

`context`	GPU Context
`yuvColorSpace`	one of: kJPEG SkYUVColorSpace, kRec601 SkYUVColorSpace, kRec709 SkYUVColorSpace
`yuvTextureHandles`	array of YUV textures on GPU
`yuvSizes`	dimensions of YUV textures
`surfaceOrigin`	one of: kBottomLeft GrSurfaceOrigin, kTopLeft GrSurfaceOrigin
`colorSpace`	range of colors; may be nullptr

Return Value

created Image, or nullptr

MakeFromNV12TexturesCopy

static sk_sp<SkImage> MakeFromNV12TexturesCopy(GrContext* context, SkYUVColorSpace yuvColorSpace,
                                               const GrBackendObject nv12TextureHandles[2],
                                               const SkISize nv12Sizes[2],
                                               GrSurfaceOrigin surfaceOrigin,
                                               sk_sp<SkColorSpace> colorSpace = nullptr)

Creates Image from copy of nv12TextureHandles, an array of textures on GPU. nv12TextureHandles[0] contains pixels for YUV_Component_Y plane. nv12TextureHandles[1] contains pixels for YUV_Component_U plane, followed by pixels for YUV_Component_V plane. nv12Sizes conain dimensions for each pixel plane. Dimensions must be greater than zero but may differ from plane to plane. Returned Image has the dimensions nv12Sizes[0]. yuvColorSpace describes how YUV colors convert to RGB colors.

Parameters

`context`	GPU Context
`yuvColorSpace`	one of: kJPEG SkYUVColorSpace, kRec601 SkYUVColorSpace, kRec709 SkYUVColorSpace
`nv12TextureHandles`	array of YUV textures on GPU
`nv12Sizes`	dimensions of YUV textures
`surfaceOrigin`	one of: kBottomLeft GrSurfaceOrigin, kTopLeft GrSurfaceOrigin
`colorSpace`	range of colors; may be nullptr

Return Value

created Image, or nullptr

Parameters

`context`	GPU Context
`yuvColorSpace`	one of: kJPEG SkYUVColorSpace, kRec601 SkYUVColorSpace, kRec709 SkYUVColorSpace
`nv12TextureHandles`	array of YUV textures on GPU
`nv12Sizes`	dimensions of YUV textures
`surfaceOrigin`	one of: kBottomLeft GrSurfaceOrigin, kTopLeft GrSurfaceOrigin
`colorSpace`	range of colors; may be nullptr

Return Value

created Image, or nullptr

Enum SkImage::BitDepth

enum class BitDepth {
kU8,
kF16,
};

Constants

`SkImage::kU8`	0	Use 8 bits per Color ARGB component using unsigned integer format.
`SkImage::kF16`	1	Use 16 bits per Color ARGB component using half-precision floating point format.

Parameters

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

Return Value

created Image, or nullptr

Example

MakeFromAHardwareBuffer

static sk_sp<SkImage> MakeFromAHardwareBuffer(AHardwareBuffer* hardwareBuffer,
                                            SkAlphaType alphaType = kPremul_SkAlphaType,
                                            sk_sp<SkColorSpace> colorSpace = nullptr)

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.

Parameters

`hardwareBuffer`	AHardwareBuffer Android hardware buffer
`alphaType`	one of: kUnknown SkAlphaType, kOpaque SkAlphaType, kPremul SkAlphaType, kUnpremul SkAlphaType
`colorSpace`	range of colors; may be nullptr

Return Value

created Image, or nullptr

width

int width() const

Returns pixel count in each row.

Return Value

pixel width in Image

Example

height

int height() const

Returns pixel row count.

Return Value

pixel height in Image

Example

dimensions

SkISize dimensions() const

Returns ISize { width, height }.

Return Value

integral size of width and height

Example

bounds

SkIRect bounds() const

Returns IRect { 0, 0, width, height }.

Return Value

integral rectangle from origin to width and height

Example

uniqueID

uint32_t uniqueID() const

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 Value

unique identifier

Example

alphaType

SkAlphaType alphaType() const

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 Value

Alpha Type in Image

Example

colorSpace

SkColorSpace* colorSpace() const

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 Value

Color Space in Image, or nullptr

Example

refColorSpace

sk_sp<SkColorSpace> refColorSpace() const

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.

Return Value

Color Space in Image, or nullptr, wrapped in a smart pointer

Example

isAlphaOnly

bool isAlphaOnly() const

Returns true if Image pixels represent transparency only. If true, each pixel is packed in 8 bits as defined by kAlpha 8 SkColorType.

Return Value

true if pixels represent a transparency mask

Example

Example Output

alphaOnly = true

isOpaque

bool isOpaque() const

Returns true if pixels ignore their Alpha value and are treated as fully opaque.

Return Value

true if Alpha Type is kOpaque SkAlphaType

Example

Example Output

isOpaque = false
isOpaque = true

makeShader

sk_sp<SkShader> makeShader(SkShader::TileMode tileMode1, SkShader::TileMode tileMode2,
                           const SkMatrix* localMatrix = nullptr) const

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.

Parameters

`tileMode1`	tiling in x, one of: SkShader::kClamp TileMode, SkShader::kRepeat TileMode, SkShader::kMirror TileMode
`tileMode2`	tiling in y, one of: SkShader::kClamp TileMode, SkShader::kRepeat TileMode, SkShader::kMirror TileMode
`localMatrix`	Image transformation, or nullptr

Return Value

Shader containing Image

Example

Parameters

localMatrix Image transformation, or nullptr

Return Value

Shader containing Image

Example

peekPixels

bool peekPixels(SkPixmap* pixmap) const

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.

Parameters

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

Return Value

true if Image has direct access to pixels

Example

Example Output

------------
--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--
------------

getTexture

GrTexture* getTexture() const

Deprecated.

isTextureBacked

bool isTextureBacked() const

Returns true the contents of Image was created on or uploaded to GPU memory, and is available as a GPU Texture.

Return Value

true if Image is a GPU Texture

Example

isValid

bool isValid(GrContext* context) const

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.

Parameters

context

GPU Context

Return Value

true if Image can be drawn

Example

getTextureHandle

GrBackendObject getTextureHandle(bool flushPendingGrContextIO, GrSurfaceOrigin* origin = nullptr) const

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.

Parameters

`flushPendingGrContextIO`	flag to flush outstanding requests
`origin`	storage for one of: kTopLeft GrSurfaceOrigin, kBottomLeft GrSurfaceOrigin; or nullptr

Return Value

back-end API texture handle, or nullptr

Example

Enum SkImage::CachingHint

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.

Constants

`SkImage::kAllow_CachingHint`	0	Allows Skia to internally cache decoded and copied pixels.
`SkImage::kDisallow_CachingHint`	1	Disallows Skia from internally caching decoded and copied pixels.

readPixels

bool readPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes, int srcX, int srcY,
                CachingHint cachingHint = kAllow_CachingHint) const

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:

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 ifabs(srcX) >= Image width, or ifabs(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.

Parameters

`dstInfo`	destination width, height, Color Type, Alpha Type, Color Space
`dstPixels`	destination pixel storage
`dstRowBytes`	destination row length
`srcX`	column index whose absolute value is less than width
`srcY`	row index whose absolute value is less than height
`cachingHint`	one of: kAllow CachingHint, kDisallow CachingHint

Return Value

true if pixels are copied to dstPixels

Example

Parameters

`dst`	destination Pixmap: Image Info, pixels, row bytes
`srcX`	column index whose absolute value is less than width
`srcY`	row index whose absolute value is less than height
`cachingHint`	one of: kAllow CachingHint, kDisallow CachingHint

Return Value

true if pixels are copied to dst

Example

scalePixels

bool scalePixels(const SkPixmap& dst, SkFilterQuality filterQuality,
                 CachingHint cachingHint = kAllow_CachingHint) const

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.

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.

Parameters

`dst`	destination Pixmap: Image Info, pixels, row bytes
`filterQuality`	one of: kNone SkFilterQuality, kLow SkFilterQuality, kMedium SkFilterQuality, kHigh SkFilterQuality
`cachingHint`	one of: kAllow CachingHint, kDisallow CachingHint

Return Value

true if pixels are scaled to fit dst

Example

encodeToData

sk_sp<SkData> encodeToData(SkEncodedImageFormat encodedImageFormat, int quality) const

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.

Parameters

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

Return Value

encoded Image, or nullptr

Example

Return Value

encoded Image, or nullptr

Example

refEncodedData

sk_sp<SkData> refEncodedData() const

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 Value

encoded Image, or nullptr

Example

toString

const char* toString(SkString* string) const

Appends Image description to string, including unique ID, width, height, and whether the image is opaque.

Parameters

string storage for description; existing content is preserved

Return Value

string appended with Image description

Example

makeSubset

sk_sp<SkImage> makeSubset(const SkIRect& subset) const

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.

Parameters

subset bounds of returned Image

Return Value

partial or full Image, or nullptr

Example

makeTextureImage

sk_sp<SkImage> makeTextureImage(GrContext* context, SkColorSpace* dstColorSpace) const

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.

Parameters

`context`	GPU Context
`dstColorSpace`	range of colors of matching Surface on GPU

Return Value

created Image, or nullptr

Example

makeNonTextureImage

sk_sp<SkImage> makeNonTextureImage() const

Returns Raster Image or Lazy Image. Copies Image backed by GPU Texture into CPU memory if needed. Returns original Image if unencoded in Raster Bitmap, or if encoded in a stream.

Returns nullptr if backed by GPU Texture and copy fails.

Return Value

Raster Image, Lazy Image, or nullptr

Example

makeRasterImage

sk_sp<SkImage> makeRasterImage() const

Returns Raster Image. Copies Image backed by GPU Texture into CPU memory, or decodes Image from Lazy Image. Returns original Image if unencoded in Raster Bitmap.

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

Return Value

Raster Image, or nullptr

Example

makeWithFilter

sk_sp<SkImage> makeWithFilter(const SkImageFilter* filter, const SkIRect& subset,
                              const SkIRect& clipBounds, SkIRect* outSubset, SkIPoint* offset) const

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.

makeWithFilter is optimized to support Image backed by GPU Texture drawn in an animation with SkImageFilter that vary in size from one frame to the next. The created Image is drawn at an increased size so that GPU Texture can be reused with different sized effects. outSubset describes the valid bounds of GPU Texture returned. The returned Image may be much larger than required for the filter. offset translates the returned Image to keep subsequent animation frames aligned with respect to each other.

Parameters

`filter`	how Image is sampled when transformed
`subset`	incomplete
`clipBounds`	incomplete
`outSubset`	incomplete
`offset`	incomplete

Return Value

filtered Image, or nullptr

Example

In each frame of the animation, filtered Image is drawn in a different location. By translating canvas by returned offset, Image appears stationary.

Struct SkImage::DeferredTextureImageUsageParams

Used only by Chrome; to be deprecated.

struct DeferredTextureImageUsageParams {
DeferredTextureImageUsageParams(const SkMatrix matrix, const SkFilterQuality quality,
int preScaleMipLevel);
SkMatrix        fMatrix;
SkFilterQuality fQuality;
int             fPreScaleMipLevel;
};

SkMatrix fMatrix

SkFilterQuality fQuality

int fPreScaleMipLevel

DeferredTextureImageUsageParams

DeferredTextureImageUsageParams(const SkMatrix matrix, const SkFilterQuality quality,
                                int preScaleMipLevel)

Parameters

`matrix`	incomplete
`quality`	incomplete
`preScaleMipLevel`	incomplete

Return Value

incomplete

Example

getDeferredTextureImageData

size_t getDeferredTextureImageData(const GrContextThreadSafeProxy& contextThreadSafeProxy,
                 const DeferredTextureImageUsageParams deferredTextureImageUsageParams[],
                 int paramCnt, void* buffer, SkColorSpace* dstColorSpace = nullptr,
                 SkColorType dstColorType = kN32_SkColorType) const

Used only by Chrome; to be deprecated.

This method allows clients to capture the data necessary to turn a SkImage into a texture- backed image. If the original image is codec-backed this will decode into a format optimized for the context represented by the proxy. This method is thread safe with respect to the GrContext whence the proxy came. Clients allocate and manage the storage of the deferred texture data and control its lifetime. No cleanup is required, thus it is safe to simply free the memory out from under the data.

The same method is used both for getting the size necessary for pre-uploaded texture data and for retrieving the data. The params array represents the set of draws over which to optimize the pre-upload data.

When called with a null buffer this returns the size that the client must allocate in order to create deferred texture data for this image (or zero if this is an inappropriate candidate). The buffer allocated by the client should be 8 byte aligned.

When buffer is not null this fills in the deferred texture data for this image in the provided buffer (assuming this is an appropriate candidate image and the buffer is appropriately aligned). Upon success the size written is returned, otherwise 0.

dstColorSpace is the Color Space of the surface where this texture will ultimately be used. If the method determines that mip-maps are needed, this helps determine the correct strategy for building them (gamma-correct or not).

dstColorType is the color type of the surface where this texture will ultimately be used. This determines the format with which the image will be uploaded to the GPU. If dstColorType does not support Color Space (low bit depth types such as kARGB 4444 SkColorType), then dstColorSpace must be null.

Parameters

`contextThreadSafeProxy`	thread safe GPU context
`deferredTextureImageUsageParams`	array of Image transformations
`paramCnt`	entries in deferredTextureImageUsageParams array
`buffer`	storage for GPU Texture data, or nullptr
`dstColorSpace`	Surface Color Space, or nullptr
`dstColorType`	Surface Color Type

Return Value

size of storage for GPU Texture data

Example

Parameters

`context`	GPU Context
`data`	incomplete
`budgeted`	incomplete

Return Value

incomplete

Example

MakeBackendTextureFromSkImage

static bool MakeBackendTextureFromSkImage(GrContext* context, sk_sp<SkImage> image,
                                          GrBackendTexture* backendTexture,
                                          BackendTextureReleaseProc* backendTextureReleaseProc)

Creates a GrBackendTexture from the provided SkImage. Returns true on success. The GrBackendTexture and BackendTextureReleaseProc are populated on success. It is the callers responsibility to call the BackendTextureReleaseProc once they have deleted the texture. Note that the BackendTextureReleaseProc allows Skia to clean up auxiliary data related to the GrBackendTexture, and is not a substitute for the client deleting the GrBackendTexture themselves.

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

If the SkImage is not texture backed, this function will generate a texture with the image's contents and return that.

Parameters

`context`	GPU Context
`image`	incomplete
`backendTexture`	incomplete
`backendTextureReleaseProc`	incomplete

Return Value

incomplete

Example

Enum SkImage::LegacyBitmapMode

enum LegacyBitmapMode {
kRO LegacyBitmapMode,
kRW LegacyBitmapMode,
};

Helper functions to convert to SkBitmap

Constants

`SkImage::kRO_LegacyBitmapMode`	0
`SkImage::kRW_LegacyBitmapMode`	1

Example

asLegacyBitmap

bool asLegacyBitmap(SkBitmap* bitmap, LegacyBitmapMode legacyBitmapMode) const

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.

Parameters

`bitmap`	storage for legacy Bitmap
`legacyBitmapMode`	one of: kRO LegacyBitmapMode, kRW LegacyBitmapMode

Return Value

true if Bitmap was created

Example

isLazyGenerated

bool isLazyGenerated() const

Returns true if Image is backed by an image-generator or other service that creates and caches its pixels or texture on-demand.

Return Value

true if Image is created as needed

Example

makeColorSpace

sk_sp<SkImage> makeColorSpace(sk_sp<SkColorSpace> target, SkTransferFunctionBehavior premulBehavior) const

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.

Parameters

`target`	Color Space describing color range of returned Image
`premulBehavior`	one of: SkTransferFunctionBehavior::kRespect, SkTransferFunctionBehavior::kIgnore

Return Value

created Image in target Color Space

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SkImage Reference

Image

Class SkImage

Raster Image

Texture Image

Lazy Image

Overview

Subtopics

Constructors

Member Functions

MakeRasterCopy

Parameters

Return Value

Example

See Also

MakeRasterData

Parameters

Return Value

Example

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MakeFromRaster

Parameters

Return Value

Example

Example Output

See Also

MakeFromBitmap

Parameters

Return Value

Example

See Also

MakeFromGenerator

Parameters

Return Value

Example

See Also

MakeFromEncoded

Parameters

Return Value

Example

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MakeFromTexture

Parameters

Return Value

Parameters

Return Value

Parameters

Return Value

Example

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Parameters

Return Value

Example

See Also

MakeCrossContextFromEncoded

Parameters

Return Value

Example

See Also

MakeCrossContextFromPixmap

Parameters

Return Value

Example

See Also

MakeFromAdoptedTexture

Parameters

Return Value

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Parameters

Return Value

Example

See Also

MakeFromYUVTexturesCopy

Parameters

Return Value

See Also

Parameters

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