SkSurface is responsible for managing the pixels that a canvas draws into. The pixels can be allocated either in CPU memory (a raster surface) or on the GPU (a GrRenderTarget surface). SkSurface takes care of allocating a SkCanvas that will draw into the surface. Call surface->getCanvas to use that canvas (but don't delete it, it is owned by the surface). SkSurface always has non-zero dimensions. If there is a request for a new surface, and either of the requested dimensions are zero, then nullptr will be returned.
SkSurface related constants are defined by enum, enum class, #define, const, and constexpr.
SkSurface global, struct, and class related member functions share a topic.
SkSurface member functions read and modify the structure properties.
SkSurface can be constructed or initialized by these functions, including C++ class constructors.
Allocates raster Surface. Canvas returned by Surface draws directly into pixels.
Surface is returned if all parameters are valid. Valid parameters include: info dimensions are greater than zero; info contains Color Type and Alpha Type supported by Raster Surface; pixels is not nullptr; rowBytes is large enough to contain info width pixels of Color Type.
Pixel buffer size should be info height times computed rowBytes. Pixels are not initialized. To access pixels after drawing, call flush or peekPixels.
Surface if all parameters are valid; otherwise, nullptr
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MakeRasterDirectReleaseProc MakeRaster[2] MakeRasterN32Premul SkCanvas::MakeRasterDirect
Allocates raster Surface. Canvas returned by Surface draws directly into pixels. releaseProc is called with pixels and context when Surface is deleted.
Surface is returned if all parameters are valid. Valid parameters include: info dimensions are greater than zero; info contains Color Type and Alpha Type supported by Raster Surface; pixels is not nullptr; rowBytes is large enough to contain info width pixels of Color Type.
Pixel buffer size should be info height times computed rowBytes. Pixels are not initialized. To access pixels after drawing, call flush or peekPixels.
Surface if all parameters are valid; otherwise, nullptr
--- -x- --- expected release context
MakeRasterDirect MakeRasterN32Premul MakeRaster[2]
Allocates raster Surface. Canvas returned by Surface draws directly into pixels. Allocates and zeroes pixel memory. Pixel memory size is imageInfo.height times rowBytes, or times imageInfo.minRowBytes() if rowBytes is zero. Pixel memory is deleted when Surface is deleted.
Surface is returned if all parameters are valid. Valid parameters include: info dimensions are greater than zero; info contains Color Type and Alpha Type supported by Raster Surface; rowBytes is large enough to contain info width pixels of Color Type, or is zero.
If rowBytes is not zero, subsequent images returned by makeImageSnapshot have the same rowBytes.
Surface if all parameters are valid; otherwise, nullptr
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MakeRasterDirect MakeRasterN32Premul MakeRasterDirectReleaseProc
Allocates raster Surface. Canvas returned by Surface draws directly into pixels. Allocates and zeroes pixel memory. Pixel memory size is imageInfo.height times imageInfo.minRowBytes(). Pixel memory is deleted when Surface is deleted.
Surface is returned if all parameters are valid. Valid parameters include: info dimensions are greater than zero; info contains Color Type and Alpha Type supported by Raster Surface.
Surface if all parameters are valid; otherwise, nullptr
MakeRasterDirect MakeRasterN32Premul MakeRasterDirectReleaseProc
Allocates raster Surface. Canvas returned by Surface draws directly into pixels. Allocates and zeroes pixel memory. Pixel memory size is height times width times four. Pixel memory is deleted when Surface is deleted.
Internally, sets Image Info to width, height, Native_Color_Type, and kPremul_SkAlphaType.
Surface is returned if width and height are greater than zero.
Use to create Surface that matches SkPMColor, the native pixel arrangement on the platform. Surface drawn to output device skips converting its pixel format.
Surface if all parameters are valid; otherwise, nullptr
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MakeRasterDirect MakeRasterN32Premul MakeRasterDirectReleaseProc
Wraps a GPU-backed texture into Surface. Caller must ensure the texture is valid for the lifetime of returned Surface. If sampleCnt greater than zero, creates an intermediate MSAA Surface which is used for drawing backendTexture.
Surface is returned if all parameters are valid. backendTexture is valid if its pixel configuration agrees with colorSpace and context; for instance, if backendTexture has an sRGB configuration, then context must support sRGB, and colorSpace must be present. Further, backendTexture width and height must not exceed context capabilities, and the context must be able to support back-end textures.
If SK_SUPPORT_GPU is defined as zero, has no effect and returns nullptr.
Surface if all parameters are valid; otherwise, nullptr
GrBackendTexture MakeFromBackendRenderTarget MakeRenderTarget[2][3][4]
Wraps a GPU-backed buffer into Surface. Caller must ensure backendRenderTarget is valid for the lifetime of returned Surface.
Surface is returned if all parameters are valid. backendRenderTarget is valid if its pixel configuration agrees with colorSpace and context; for instance, if backendRenderTarget has an sRGB configuration, then context must support sRGB, and colorSpace must be present. Further, backendRenderTarget width and height must not exceed context capabilities, and the context must be able to support back-end render targets.
If SK_SUPPORT_GPU is defined as zero, has no effect and returns nullptr.
Surface if all parameters are valid; otherwise, nullptr
MakeFromBackendTexture MakeRenderTarget[2][3][4]
Wraps a GPU-backed texture into Surface. Caller must ensure backendTexture is valid for the lifetime of returned Surface. If sampleCnt greater than zero, creates an intermediate MSAA Surface which is used for drawing backendTexture.
Surface is returned if all parameters are valid. backendTexture is valid if its pixel configuration agrees with colorSpace and context; for instance, if backendTexture has an sRGB configuration, then context must support sRGB, and colorSpace must be present. Further, backendTexture width and height must not exceed context capabilities.
Returned Surface is available only for drawing into, and cannot generate an Image.
If SK_SUPPORT_GPU is defined as zero, has no effect and returns nullptr.
Surface if all parameters are valid; otherwise, nullptr
MakeFromBackendRenderTarget MakeRenderTarget[2][3][4]
Returns Surface on GPU indicated by context. Allocates memory for pixels, based on the width, height, and Color Type in ImageInfo. budgeted selects whether allocation for pixels is tracked by context. imageInfo describes the pixel format in Color Type, and transparency in Alpha Type, and color matching in Color Space.
sampleCount requests the number of samples per pixel. Pass zero to disable Multi_Sample_Anti_Aliasing. The request is rounded up to the next supported count, or rounded down if it is larger than the maximum supported count.
surfaceOrigin pins either the top-left or the bottom-left corner to the origin.
shouldCreateWithMips hints that Image returned by makeImageSnapshot is Mip_Map.
If SK_SUPPORT_GPU is defined as zero, has no effect and returns nullptr.
Surface if all parameters are valid; otherwise, nullptr
MakeFromBackendRenderTarget MakeFromBackendTextureAsRenderTarget
Returns Surface on GPU indicated by context. Allocates memory for pixels, based on the width, height, and Color Type in ImageInfo. budgeted selects whether allocation for pixels is tracked by context. imageInfo describes the pixel format in Color Type, and transparency in Alpha Type, and color matching in Color Space.
sampleCount requests the number of samples per pixel. Pass zero to disable Multi_Sample_Anti_Aliasing. The request is rounded up to the next supported count, or rounded down if it is larger than the maximum supported count.
Surface bottom-left corner is pinned to the origin.
Surface if all parameters are valid; otherwise, nullptr
MakeFromBackendRenderTarget MakeFromBackendTextureAsRenderTarget
Returns Surface on GPU indicated by context. Allocates memory for pixels, based on the width, height, and Color Type in ImageInfo. budgeted selects whether allocation for pixels is tracked by context. imageInfo describes the pixel format in Color Type, and transparency in Alpha Type, and color matching in Color Space.
Surface bottom-left corner is pinned to the origin.
Surface if all parameters are valid; otherwise, nullptr
MakeFromBackendRenderTarget MakeFromBackendTextureAsRenderTarget
Returns SkSurface on GPU indicated by context that is compatible with the provided characterization. budgeted selects whether allocation for pixels is tracked by context.
Surface if all parameters are valid; otherwise, nullptr
MakeFromBackendRenderTarget MakeFromBackendTextureAsRenderTarget
Returns Surface without backing pixels. Drawing to Canvas returned from Surface has no effect. Calling makeImageSnapshot on returned Surface returns nullptr.
Surface if width and height are positive; otherwise, nullptr
SkSurface::MakeNull(0, 0) == nullptr surf->makeImageSnapshot() == nullptr
MakeRaster[2] MakeRenderTarget[2][3][4]
Returns pixel count in each row; may be zero or greater.
number of pixel columns
surface width=37 canvas width=37
height
Returns pixel row count; may be zero or greater.
number of pixel rows
surface height=1000 canvas height=1000
width
Returns unique value identifying the content of Surface. Returned value changes each time the content changes. Content is changed by drawing, or by calling notifyContentWillChange.
unique content identifier
surface generationID: 1 surface generationID: 2 surface generationID: 3
notifyContentWillChange ContentChangeMode getCanvas
ContentChangeMode members are parameters to notifyContentWillChange.
notifyContentWillChange generationID
Notifies that Surface contents will be changed by code outside of Skia. Subsequent calls to generationID return a different value.
mode is normally passed as kRetain ContentChangeMode.
Can we deprecate this?
ContentChangeMode generationID
getBackendTexture getBackendRenderTarget
Deprecated.
Deprecated.
Retrieves the back-end texture. If Surface has no back-end texture, an invalid object is returned. Call GrBackendTexture::isValid to determine if the result is valid.
The returned GrBackendTexture should be discarded if the Surface is drawn to or deleted.
GPU texture reference; invalid on failure
GrBackendTexture BackendHandleAccess getBackendRenderTarget
Retrieves the back-end render target. If Surface has no back-end render target, an invalid object is returned. Call GrBackendRenderTarget::isValid to determine if the result is valid.
The returned GrBackendRenderTarget should be discarded if the Surface is drawn to or deleted.
GPU render target reference; invalid on failure
GrBackendRenderTarget BackendHandleAccess getBackendTexture
Returns Canvas that draws into Surface. Subsequent calls return the same Canvas. Canvas returned is managed and owned by Surface, and is deleted when Surface is deleted.
drawing Canvas for Surface
makeSurface makeImageSnapshot draw[2]
Returns a compatible Surface, or nullptr. Returned Surface contains the same raster, GPU, or null properties as the original. Returned Surface does not share the same pixels.
Returns nullptr if imageInfo width or height are zero, or if imageInfo is incompatible with Surface.
compatible Surface or nullptr
makeImageSnapshot getCanvas draw[2]
Returns Image capturing Surface contents. Subsequent drawing to Surface contents are not captured. Image allocation is accounted for if Surface was created with SkBudgeted::kYes.
Image initialized with Surface contents
draw[2] getCanvas
Draws Surface contents to canvas, with its top-left corner at (x, y).
If Paint paint is not nullptr, apply Color Filter, Color Alpha, Image Filter, Blend Mode, and Draw Looper.
makeImageSnapshot getCanvas
Copies Surface 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.
pixmap contents become invalid on any future change to Surface.
true if Surface has direct access to pixels
readPixels[2][3] writePixels[2]
Copies Rect of pixels to dst.
Source Rect corners are (srcX, srcY) and Surface (width, height). Destination Rect corners are (0, 0) and (dst.width, dst.height). Copies each readable pixel intersecting both rectangles, without scaling, converting to dst.colorType() and dst.alphaType() if required.
Pixels are readable when Surface is raster, or backed by a GPU.
The destination pixel storage must be allocated by the caller.
Pixel values are converted only if Color Type and Alpha Type do not match. Only pixels within both source and destination rectangles are copied. dst contents outside Rect intersection are unchanged.
Pass negative values for srcX or srcY to offset pixels across or down destination.
Does not copy, and returns false if:
true if pixels were copied
peekPixels writePixels[2]
Copies Rect of pixels from Canvas into dstPixels.
Source Rect corners are (srcX, srcY) and Surface (width, height). Destination Rect corners are (0, 0) and (dstInfo.width, dstInfo.height). Copies each readable pixel intersecting both rectangles, without scaling, converting to dstInfo.colorType() and dstInfo.alphaType() if required.
Pixels are readable when Surface is raster, or backed by a GPU.
The destination pixel storage must be allocated by the caller.
Pixel values are converted only if Color Type and Alpha Type do not match. Only pixels within both source and destination rectangles are copied. dstPixels contents outside Rect intersection are unchanged.
Pass negative values for srcX or srcY to offset pixels across or down destination.
Does not copy, and returns false if:
true if pixels were copied
peekPixels writePixels[2]
Copies Rect of pixels from Surface into bitmap.
Source Rect corners are (srcX, srcY) and Surface (width, height). Destination Rect corners are (0, 0) and (bitmap.width, bitmap.height). Copies each readable pixel intersecting both rectangles, without scaling, converting to bitmap.colorType() and bitmap.alphaType() if required.
Pixels are readable when Surface is raster, or backed by a GPU.
The destination pixel storage must be allocated by the caller.
Pixel values are converted only if Color Type and Alpha Type do not match. Only pixels within both source and destination rectangles are copied. dst contents outside Rect intersection are unchanged.
Pass negative values for srcX or srcY to offset pixels across or down destination.
Does not copy, and returns false if:
true if pixels were copied
peekPixels writePixels[2]
Copies Rect of pixels from the src Pixmap to the Surface.
Source Rect corners are (0, 0) and (src.width, src.height). Destination Rect corners are (dstX, dstY) and(dstX + Surface width, dstY + Surface height) .
Copies each readable pixel intersecting both rectangles, without scaling, converting to Surface colorType() and Surface alphaType() if required.
readPixels[2][3] peekPixels
Copies Rect of pixels from the src Bitmap to the Surface.
Source Rect corners are (0, 0) and (src.width, src.height). Destination Rect corners are (dstX, dstY) and(dstX + Surface width, dstY + Surface height) .
Copies each readable pixel intersecting both rectangles, without scaling, converting to Surface colorType() and Surface alphaType() if required.
readPixels[2][3] peekPixels
Returns Surface Properties for surface.
LCD striping orientation and setting for device independent fonts
surf.props(): kRGB_H_SkPixelGeometry
SkSurfaceProps
Deprecated.
soon
Issues pending Surface commands to the GPU-backed API and resolves any Surface MSAA.
Skia flushes as needed, so it is not necessary to call this if Skia manages drawing and object lifetime. Call when interleaving Skia calls with native GPU calls.
GrBackendSemaphore
Issues pending Surface commands to the GPU-backed API and resolves any Surface MSAA. After issuing all commands, signalSemaphores of count numSemaphores semaphores are signaled by the GPU.
For each GrBackendSemaphore in signalSemaphores: if GrBackendSemaphore is initialized, the GPU back-end uses the semaphore as is; otherwise, a new semaphore is created and initializes GrBackendSemaphore.
The caller must delete the semaphores created and returned in signalSemaphores. GrBackendSemaphore can be deleted as soon as this function returns.
If the back-end API is OpenGL only uninitialized Backend Semaphores are supported.
If the back-end API is Vulkan semaphores may be initialized or uninitialized. If uninitialized, created semaphores are valid only with the VkDevice with which they were created.
If GrSemaphoresSubmitted::kNo is returned, the GPU back-end did not create or add any semaphores to signal on the GPU; the caller should not instruct the GPU to wait on any of the semaphores.
Pending surface commands are flushed regardless of the return result.
one of: GrSemaphoresSubmitted::kYes, GrSemaphoresSubmitted::kNo
wait GrBackendSemaphore
Inserts a list of GPU semaphores that the current GPU-backed API must wait on before executing any more commands on the GPU for this surface. Skia will take ownership of the underlying semaphores and delete them once they have been signaled and waited on. If this call returns false, then the GPU back-end will not wait on any passed in semaphores, and the client will still own the semaphores.
true if GPU is waiting on semaphores
flushAndSignalSemaphores GrBackendSemaphore
Initializes Surface Characterization that can be used to perform GPU back-end processing in a separate thread. Typically this is used to divide drawing into multiple tiles. DeferredDisplayListRecorder records the drawing commands for each tile.
Return true if Surface supports characterization. Raster Surface returns false.
true if supported
draw[2] SkSurfaceCharacterization SkDeferredDisplayList
Draws deferred display list created using SkDeferredDisplayListRecorder. Has no effect and returns false if Surface Characterization stored in deferredDisplayList is not compatible with Surface.
Raster Surface returns false.
false if deferredDisplayList is not compatible
characterize SkSurfaceCharacterization SkDeferredDisplayList