Bitmap describes a two-dimensional raster pixel array. Bitmap is built on Image_Info, containing integer width and height, Color_Type and Alpha_Type describing the pixel format, and Color_Space describing the range of colors. Bitmap points to Pixel_Ref, which describes the physical array of pixels. Image_Info bounds may be located anywhere fully inside Pixel_Ref bounds.
Bitmap can be drawn using Canvas. Bitmap can be a drawing destination for Canvas draw member functions. Bitmap flexibility as a pixel container limits some optimizations available to the target platform.
If pixel array is primarily read-only, use Image for better performance. If pixel array is primarily written to, use Surface for better performance.
Declaring SkBitmap const prevents altering Image_Info: the Bitmap height, width, and so on cannot change. It does not affect Pixel_Ref: a caller may write its pixels. Declaring SkBitmap const affects Bitmap configuration, not its contents.
Bitmap is not thread safe. Each thread must have its own copy of Bitmap fields, although threads may share the underlying pixel array.
Bitmap pixels may be contiguous, or may have a gap at the end of each row. Row_Bytes is the interval from one row to the next. Row_Bytes may be specified; sometimes passing zero will compute the Row_Bytes from the row width and the number of bytes in a pixel. Row_Bytes may be larger than the row requires. This is useful to position one or more Bitmaps within a shared pixel array.
Abstract subclass of HeapAllocator.
Allocates the pixel memory for the bitmap, given its dimensions and SkColorType. Returns true on success, where success means either setPixels() or setPixelRef() was called.
true if SkPixelRef was allocated
HeapAllocator
Subclass of SkBitmap::Allocator that returns a Pixel_Ref that allocates its pixel memory from the heap. This is the default SkBitmap::Allocator invoked by allocPixels.
Allocates the pixel memory for the bitmap, given its dimensions and SkColorType. Returns true on success, where success means either setPixels() or setPixelRef() was called.
true if pixels are allocated
#Volatile pixel address = (nil) pixel address = 0x560ddd0ac670
SkBitmap::Allocator tryAllocPixels
Creates an empty SkBitmap without pixels, with kUnknown_SkColorType, kUnknown_SkAlphaType, and with a width and height of zero. SkPixelRef origin is set to (0, 0). SkBitmap is not volatile.
Use setInfo() to associate SkColorType, SkAlphaType, width, and height after SkBitmap has been created.
empty SkBitmap
width: 0 height: 0 color: kUnknown_SkColorType alpha: kUnknown_SkAlphaType width: 25 height: 35 color: kRGBA_8888_SkColorType alpha: kOpaque_SkAlphaType
setInfo
Copies settings from src to returned SkBitmap. Shares pixels if src has pixels allocated, so both bitmaps reference the same pixels.
copy of src
original has pixels before copy: true original has pixels after copy: true copy has pixels: true
setInfo setPixelRef setPixels swap
Copies settings from src to returned SkBitmap. Moves ownership of src pixels to SkBitmap.
copy of src
original has pixels before move: true original has pixels after move: false copy has pixels: true
setInfo setPixelRef setPixels swap
Decrements SkPixelRef reference count, if SkPixelRef is not nullptr.
Pixel_Ref
Copies settings from src to returned SkBitmap. Shares pixels if src has pixels allocated, so both bitmaps reference the same pixels.
copy of src
original has pixels before copy: true original has pixels after copy: true copy has pixels: true
setInfo setPixelRef setPixels swap
Copies settings from src to returned SkBitmap. Moves ownership of src pixels to SkBitmap.
copy of src
original has pixels before move: true original has pixels after move: false copy has pixels: true
setInfo setPixelRef setPixels swap
Swaps the fields of the two bitmaps.
one width:1 height:1 colorType:kRGBA_8888_SkColorType alphaType:kOpaque_SkAlphaType two width:2 height:2 colorType:kBGRA_8888_SkColorType alphaType:kPremul_SkAlphaType one width:2 height:2 colorType:kBGRA_8888_SkColorType alphaType:kPremul_SkAlphaType two width:1 height:1 colorType:kRGBA_8888_SkColorType alphaType:kOpaque_SkAlphaType
SkBitmap(SkBitmap&& src) SkBitmap(SkBitmap&& src)operator=(SkBitmap&& src)
Returns a constant reference to the SkPixmap holding the SkBitmap pixel address, row bytes, and SkImageInfo.
reference to SkPixmap describing this SkBitmap
---------- ---xx----- --x--x---- --x------- --xx------ --x-x---x- -x---x--x- -x----xx-- -xx---x--- --xxxx-xx- ----------
peekPixels installPixels readPixels writePixels
Returns width, height, SkAlphaType, SkColorType, and SkColorSpace.
reference to SkImageInfo
width: 56 height: 56 color: BGRA_8888 alpha: Opaque
Image_Info
Returns pixel count in each row. Should be equal or less than rowBytes() / info().bytesPerPixel().
May be less than pixelRef().width(). Will not exceed pixelRef().width() less pixelRefOrigin().fX.
pixel width in Image_Info
bitmap width: 16 info width: 16
height() SkPixelRef::width() SkImageInfo::width()
Returns pixel row count.
Maybe be less than pixelRef().height(). Will not exceed pixelRef().height() less pixelRefOrigin().fY.
pixel height in SkImageInfo
bitmap height: 32 info height: 32
width() SkPixelRef::height() SkImageInfo::height()
Returns Color_Type, one of: kUnknown_SkColorType, kAlpha_8_SkColorType, kRGB_565_SkColorType, kARGB_4444_SkColorType, kRGBA_8888_SkColorType, kRGB_888x_SkColorType, kBGRA_8888_SkColorType, kRGBA_1010102_SkColorType, kRGB_101010x_SkColorType, kGray_8_SkColorType, kRGBA_F16_SkColorType .
Color_Type in Image_Info
color type: kAlpha_8_SkColorType
alphaType() SkImageInfo::colorType
Returns Alpha_Type, one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType .
Alpha_Type in Image_Info
alpha type: kPremul_SkAlphaType
colorType() SkImageInfo::alphaType
Returns SkColorSpace, the range of colors, associated with SkImageInfo. The reference count of SkColorSpace is unchanged. The returned SkColorSpace is immutable.
SkColorSpace in SkImageInfo, or nullptr
gammaCloseToSRGB: false gammaIsLinear: true isSRGB: false
Color_Space SkImageInfo::colorSpace
Returns smart pointer to SkColorSpace, the range of colors, associated with SkImageInfo. 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.
SkColorSpace in SkImageInfo wrapped in a smart pointer
gammaCloseToSRGB: false gammaIsLinear: true isSRGB: false
Color_Space SkImageInfo::colorSpace
Returns number of bytes per pixel required by SkColorType. Returns zero if colorType( is kUnknown_SkColorType.
bytes in pixel
color: kUnknown_SkColorType bytesPerPixel: 0 color: kAlpha_8_SkColorType bytesPerPixel: 1 color: kRGB_565_SkColorType bytesPerPixel: 2 color: kARGB_4444_SkColorType bytesPerPixel: 2 color: kRGBA_8888_SkColorType bytesPerPixel: 4 color: kRGB_888x_SkColorType bytesPerPixel: 4 color: kBGRA_8888_SkColorType bytesPerPixel: 4 color: kRGBA_1010102_SkColorType bytesPerPixel: 4 color: kRGB_101010x_SkColorType bytesPerPixel: 4 color: kGray_8_SkColorType bytesPerPixel: 1 color: kRGBA_F16_SkColorType bytesPerPixel: 8
rowBytes rowBytesAsPixels width shiftPerPixel SkImageInfo::bytesPerPixel
Returns number of pixels that fit on row. Should be greater than or equal to width().
maximum pixels per row
rowBytes: 4 rowBytesAsPixels: 1 rowBytes: 5 rowBytesAsPixels: 1 rowBytes: 6 rowBytesAsPixels: 1 rowBytes: 7 rowBytesAsPixels: 1 rowBytes: 8 rowBytesAsPixels: 2
rowBytes shiftPerPixel width bytesPerPixel
Returns bit shift converting row bytes to row pixels. Returns zero for kUnknown_SkColorType.
one of: 0, 1, 2, 3; left shift to convert pixels to bytes
color: kUnknown_SkColorType shiftPerPixel: 0 color: kAlpha_8_SkColorType shiftPerPixel: 0 color: kRGB_565_SkColorType shiftPerPixel: 1 color: kARGB_4444_SkColorType shiftPerPixel: 1 color: kRGBA_8888_SkColorType shiftPerPixel: 2 color: kRGB_888x_SkColorType shiftPerPixel: 2 color: kBGRA_8888_SkColorType shiftPerPixel: 2 color: kRGBA_1010102_SkColorType shiftPerPixel: 2 color: kRGB_101010x_SkColorType shiftPerPixel: 2 color: kGray_8_SkColorType shiftPerPixel: 0 color: kRGBA_F16_SkColorType shiftPerPixel: 3
rowBytes rowBytesAsPixels width bytesPerPixel
Returns true if either width() or height() are zero.
Does not check if SkPixelRef is nullptr; call drawsNothing() to check width(), height(), and SkPixelRef.
true if dimensions do not enclose area
width: 0 height: 0 empty: true width: 0 height: 2 empty: true width: 2 height: 0 empty: true width: 2 height: 2 empty: false
height() width() drawsNothing
Returns true if SkPixelRef is nullptr.
Does not check if width() or height() are zero; call drawsNothing() to check width(), height(), and SkPixelRef.
true if no SkPixelRef is associated
empty bitmap does not have pixels bitmap with dimensions does not have pixels allocated bitmap does have pixels
empty() drawsNothing pixelRef
Returns true if width() or height() are zero, or if SkPixelRef is nullptr. If true, SkBitmap has no effect when drawn or drawn into.
true if drawing has no effect
empty:true isNull:true drawsNothing:true empty:true isNull:false drawsNothing:true empty:false isNull:true drawsNothing:true empty:false isNull:false drawsNothing:false
empty() isNull pixelRef
Returns row bytes, the interval from one pixel row to the next. Row bytes is at least as large as: width() * info().bytesPerPixel().
Returns zero if colorType is kUnknown_SkColorType, or if row bytes supplied to setInfo is not large enough to hold a row of pixels.
byte length of pixel row
setInfo returned:false rowBytes:0 setInfo returned:true rowBytes:8
info() setInfo SkImageInfo::minRowBytes
Sets SkAlphaType, if alphaType is compatible with SkColorType. Returns true unless alphaType is kUnknown_SkAlphaType and current SkAlphaType is not kUnknown_SkAlphaType.
Returns true if SkColorType is kUnknown_SkColorType. alphaType is ignored, and SkAlphaType remains kUnknown_SkAlphaType.
Returns true if SkColorType is kRGB_565_SkColorType or kGray_8_SkColorType. alphaType is ignored, and SkAlphaType remains kOpaque_SkAlphaType.
If SkColorType is kARGB_4444_SkColorType, kRGBA_8888_SkColorType, kBGRA_8888_SkColorType, or kRGBA_F16_SkColorType: returns true unless alphaType is kUnknown_SkAlphaType and SkAlphaType is not kUnknown_SkAlphaType. If SkAlphaType is kUnknown_SkAlphaType, alphaType is ignored.
If SkColorType is kAlpha_8_SkColorType, returns true unless alphaType is kUnknown_SkAlphaType and SkAlphaType is not kUnknown_SkAlphaType. If SkAlphaType is kUnknown_SkAlphaType, alphaType is ignored. If alphaType is kUnpremul_SkAlphaType, it is treated as kPremul_SkAlphaType.
This changes SkAlphaType in SkPixelRef; all bitmaps sharing SkPixelRef are affected.
kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType
true if SkAlphaType is set
Alpha_Type Color_Type Image_Info setInfo
Returns pixel address, the base address corresponding to the pixel origin.
pixel address
bitmap.getColor(0, 1) == 0x00000000 bitmap.getColor(0, 0) == 0xFFFFFFFF
isNull drawsNothing
Returns minimum memory required for pixel storage. Does not include unused memory on last row when rowBytesAsPixels() exceeds width(). Returns zero if result does not fit in size_t. Returns zero if height() or width() is 0. Returns height() times rowBytes() if colorType() is kUnknown_SkColorType.
size in bytes of image buffer
width: 1 height: 1 computeByteSize: 4 width: 1 height: 1000 computeByteSize: 4999 width: 1 height: 1000000 computeByteSize: 4999999 width: 1000 height: 1 computeByteSize: 4000 width: 1000 height: 1000 computeByteSize: 4999000 width: 1000 height: 1000000 computeByteSize: 4999999000 width: 1000000 height: 1 computeByteSize: 4000000 width: 1000000 height: 1000 computeByteSize: 4999000000 width: 1000000 height: 1000000 computeByteSize: 4999999000000
SkImageInfo::computeByteSize
Returns true if pixels can not change.
Most immutable SkBitmap checks trigger an assert only on debug builds.
true if pixels are immutable
original is immutable copy is immutable
setImmutable SkPixelRef::isImmutable SkImage
Sets internal flag to mark SkBitmap as immutable. Once set, pixels can not change. Any other bitmap sharing the same SkPixelRef are also marked as immutable. Once SkPixelRef is marked immutable, the setting cannot be cleared.
Writing to immutable SkBitmap pixels triggers an assert on debug builds.
isImmutable SkPixelRef::setImmutable SkImage
Returns true if SkAlphaType is set to hint that all pixels are opaque; their alpha value is implicitly or explicitly 1.0. If true, and all pixels are not opaque, Skia may draw incorrectly.
Does not check if SkColorType allows alpha, or if any pixel value has transparency.
true if SkImageInfo SkAlphaType is kOpaque_SkAlphaType
isOpaque: false isOpaque: false isOpaque: true isOpaque: true
ComputeIsOpaque SkImageInfo::isOpaque
Provides a hint to caller that pixels should not be cached. Only true if setIsVolatile() has been called to mark as volatile.
Volatile state is not shared by other bitmaps sharing the same SkPixelRef.
true if marked volatile
original is volatile copy is not volatile
setIsVolatile
Sets if pixels should be read from SkPixelRef on every access. SkBitmap are not volatile by default; a GPU back end may upload pixel values expecting them to be accessed repeatedly. Marking temporary SkBitmap as volatile provides a hint to SkBaseDevice that the SkBitmap pixels should not be cached. This can improve performance by avoiding overhead and reducing resource consumption on SkBaseDevice.
isVolatile
Resets to its initial state; all fields are set to zero, as if SkBitmap had been initialized by SkBitmap().
Sets width, height, row bytes to zero; pixel address to nullptr; SkColorType to kUnknown_SkColorType; and SkAlphaType to kUnknown_SkAlphaType.
If SkPixelRef is allocated, its reference count is decreased by one, releasing its memory if SkBitmap is the sole owner.
width:1 height:1 isNull:false width:0 height:0 isNull:true
SkBitmap() SkAlphaType SkColorType
Returns true if all pixels are opaque. SkColorType determines how pixels are encoded, and whether pixel describes alpha. Returns true for SkColorType without alpha in each pixel; for other SkColorType, returns true if all pixels have alpha values equivalent to 1.0 or greater.
For SkColorType kRGB_565_SkColorType or kGray_8_SkColorType: always returns true. For SkColorType kAlpha_8_SkColorType, kBGRA_8888_SkColorType, kRGBA_8888_SkColorType: returns true if all pixel alpha values are 255. For SkColorType kARGB_4444_SkColorType: returns true if all pixel alpha values are 15. For kRGBA_F16_SkColorType: returns true if all pixel alpha values are 1.0 or greater.
Returns false for kUnknown_SkColorType.
true if all pixels have opaque values or SkColorType is opaque
computeIsOpaque: false computeIsOpaque: true computeIsOpaque: false computeIsOpaque: true
isOpaque Color_Type Alpha
Returns SkRect { 0, 0, width(), height() }.
bounds()
Returns SkIRect { 0, 0, width(), height() }.
bounds()
Returns SkIRect { 0, 0, width(), height() }.
integral rectangle from origin to width() and height()
getBounds
Returns SkISize { width(), height() }.
integral size of width() and height()
height width
Returns the bounds of this bitmap, offset by its SkPixelRef origin.
bounds within SkPixelRef bounds
source: 0, 0, 512, 512 subset: 100, 100, 412, 412
extractSubset getBounds
Sets width, height, Alpha_Type, Color_Type, Color_Space, and optional rowBytes. Frees pixels, and returns true if successful.
imageInfo.alphaType() may be altered to a value permitted by imageInfo.colorSpace(). If imageInfo.colorType() is kUnknown_SkColorType, imageInfo.alphaType() is set to kUnknown_SkAlphaType. If imageInfo.colorType() is kAlpha_8_SkColorType and imageInfo.alphaType() is kUnpremul_SkAlphaType, imageInfo.alphaType() is replaced by kPremul_SkAlphaType. If imageInfo.colorType() is kRGB_565_SkColorType or kGray_8_SkColorType, imageInfo.alphaType() is set to kOpaque_SkAlphaType. If imageInfo.colorType() is kARGB_4444_SkColorType, kRGBA_8888_SkColorType, kBGRA_8888_SkColorType, or kRGBA_F16_SkColorType: imageInfo.alphaType() remains unchanged.
rowBytes must equal or exceed imageInfo.minRowBytes(). If imageInfo.colorSpace() is kUnknown_SkColorType, rowBytes is ignored and treated as zero; for all other Color_Space values, rowBytes of zero is treated as imageInfo.minRowBytes().
Calls reset() and returns false if:
true if Image_Info set successfully
Alpha_Type Color_Type Color_Space height rowBytes width
AllocFlags provides the option to zero pixel memory when allocated.
tryAllocPixelsFlags allocPixelsFlags erase eraseColor
Sets SkImageInfo to info following the rules in setInfo() and allocates pixel memory. If flags is kZeroPixels_AllocFlag, memory is zeroed.
Returns false and calls reset() if SkImageInfo could not be set, or memory could not be allocated, or memory could not optionally be zeroed.
On most platforms, allocating pixel memory may succeed even though there is not sufficient memory to hold pixels; allocation does not take place until the pixels are written to. The actual behavior depends on the platform implementation of malloc(), if flags is zero, and calloc(), if flags is kZeroPixels_AllocFlag.
flags set to kZeroPixels_AllocFlag offers equal or better performance than subsequently calling eraseColor() with SK_ColorTRANSPARENT.
true if pixels allocation is successful
bitmap allocation succeeded!
allocPixelsFlags tryAllocPixels SkMallocPixelRef::MakeZeroed
Sets SkImageInfo to info following the rules in setInfo() and allocates pixel memory. If flags is kZeroPixels_AllocFlag, memory is zeroed.
Aborts execution if SkImageInfo could not be set, or memory could not be allocated, or memory could not optionally be zeroed. Abort steps may be provided by the user at compile time by defining SK_ABORT.
On most platforms, allocating pixel memory may succeed even though there is not sufficient memory to hold pixels; allocation does not take place until the pixels are written to. The actual behavior depends on the platform implementation of malloc(), if flags is zero, and calloc(), if flags is kZeroPixels_AllocFlag.
flags set to kZeroPixels_AllocFlag offers equal or better performance than subsequently calling eraseColor() with SK_ColorTRANSPARENT.
tryAllocPixelsFlags allocPixels SkMallocPixelRef::MakeZeroed
Sets SkImageInfo to info following the rules in setInfo() and allocates pixel memory. rowBytes must equal or exceed info.width() times info.bytesPerPixel(), or equal zero. Pass in zero for rowBytes to compute the minimum valid value.
Returns false and calls reset() if SkImageInfo could not be set, or memory could not be allocated.
On most platforms, allocating pixel memory may succeed even though there is not sufficient memory to hold pixels; allocation does not take place until the pixels are written to. The actual behavior depends on the platform implementation of malloc().
true if pixel storage is allocated
tryAllocPixelsFlags allocPixels SkMallocPixelRef::MakeAllocate
Sets SkImageInfo to info following the rules in setInfo() and allocates pixel memory. rowBytes must equal or exceed info.width() times info.bytesPerPixel(), or equal zero. Pass in zero for rowBytes to compute the minimum valid value.
Aborts execution if SkImageInfo could not be set, or memory could not be allocated. Abort steps may be provided by the user at compile time by defining SK_ABORT.
On most platforms, allocating pixel memory may succeed even though there is not sufficient memory to hold pixels; allocation does not take place until the pixels are written to. The actual behavior depends on the platform implementation of malloc().
tryAllocPixels allocPixelsFlags SkMallocPixelRef::MakeAllocate
Sets SkImageInfo to info following the rules in setInfo() and allocates pixel memory.
Returns false and calls reset() if SkImageInfo could not be set, or memory could not be allocated.
On most platforms, allocating pixel memory may succeed even though there is not sufficient memory to hold pixels; allocation does not take place until the pixels are written to. The actual behavior depends on the platform implementation of malloc().
true if pixel storage is allocated
tryAllocPixelsFlags allocPixels SkMallocPixelRef::MakeAllocate
Sets SkImageInfo to info following the rules in setInfo() and allocates pixel memory.
Aborts execution if SkImageInfo could not be set, or memory could not be allocated. Abort steps may be provided by the user at compile time by defining SK_ABORT.
On most platforms, allocating pixel memory may succeed even though there is not sufficient memory to hold pixels; allocation does not take place until the pixels are written to. The actual behavior depends on the platform implementation of malloc().
tryAllocPixels allocPixelsFlags SkMallocPixelRef::MakeAllocate
Sets SkImageInfo to width, height, and native color type; and allocates pixel memory. If isOpaque is true, sets SkImageInfo to kOpaque_SkAlphaType; otherwise, sets to kPremul_SkAlphaType.
Calls reset() and returns false if width exceeds 29 bits or is negative, or height is negative.
Returns false if allocation fails.
Use to create SkBitmap that matches SkPMColor, the native pixel arrangement on the platform. SkBitmap drawn to output device skips converting its pixel format.
true if pixel storage is allocated
tryAllocPixels allocN32Pixels SkMallocPixelRef::MakeAllocate
Sets SkImageInfo to width, height, and the native color type; and allocates pixel memory. If isOpaque is true, sets SkImageInfo to kPremul_SkAlphaType; otherwise, sets to kOpaque_SkAlphaType.
Aborts if width exceeds 29 bits or is negative, or height is negative, or allocation fails. Abort steps may be provided by the user at compile time by defining SK_ABORT.
Use to create SkBitmap that matches SkPMColor, the native pixel arrangement on the platform. SkBitmap drawn to output device skips converting its pixel format.
allocPixels tryAllocN32Pixels SkMallocPixelRef::MakeAllocate
Sets SkImageInfo to info following the rules in setInfo(), and creates SkPixelRef containing pixels and rowBytes. releaseProc, if not nullptr, is called immediately on failure or when pixels are no longer referenced. context may be nullptr.
If SkImageInfo could not be set, or rowBytes is less than info.minRowBytes(): calls releaseProc if present, calls reset(), and returns false.
Otherwise, if pixels equals nullptr: sets SkImageInfo, calls releaseProc if present, returns true.
If SkImageInfo is set, pixels is not nullptr, and releaseProc is not nullptr: when pixels are no longer referenced, calls releaseProc with pixels and context as parameters.
true if SkImageInfo is set to info
before installPixels releaseProc called install not successful
allocPixels
Sets SkImageInfo to info following the rules in setInfo(), and creates SkPixelRef containing pixels and rowBytes.
If SkImageInfo could not be set, or rowBytes is less than info.minRowBytes(): calls reset(), and returns false.
Otherwise, if pixels equals nullptr: sets SkImageInfo, returns true.
Caller must ensure that pixels are valid for the lifetime of SkBitmap and SkPixelRef.
true if SkImageInfo is set to info
allocPixels
Sets SkImageInfo to pixmap.info() following the rules in setInfo(), and creates SkPixelRef containing pixmap.addr() and pixmap.rowBytes().
If SkImageInfo could not be set, or pixmap.rowBytes() is less than SkImageInfo::minRowBytes(): calls reset(), and returns false.
Otherwise, if pixmap.addr() equals nullptr: sets SkImageInfo, returns true.
Caller must ensure that pixmap is valid for the lifetime of SkBitmap and SkPixelRef.
true if SkImageInfo was set to pixmap.info()
allocPixels
Replaces SkPixelRef with pixels, preserving SkImageInfo and rowBytes(). Sets SkPixelRef origin to (0, 0).
If pixels is nullptr, or if info().colorType() equals kUnknown_SkColorType; release reference to SkPixelRef, and set SkPixelRef to nullptr.
Caller is responsible for handling ownership pixel memory for the lifetime of SkBitmap and SkPixelRef.
installPixels allocPixels
Allocates pixel memory with HeapAllocator, and replaces existing SkPixelRef. The allocation size is determined by SkImageInfo width, height, and SkColorType.
Returns false if info().colorType() is kUnknown_SkColorType, or allocation fails.
true if the allocation succeeds
allocPixels installPixels setPixels
Allocates pixel memory with HeapAllocator, and replaces existing SkPixelRef. The allocation size is determined by SkImageInfo width, height, and SkColorType.
Aborts if info().colorType() is kUnknown_SkColorType, or allocation fails. Abort steps may be provided by the user at compile time by defining SK_ABORT.
tryAllocPixels installPixels setPixels
Allocates pixel memory with allocator, and replaces existing SkPixelRef. The allocation size is determined by SkImageInfo width, height, and SkColorType. If allocator is nullptr, use HeapAllocator instead.
Returns false if Allocator::allocPixelRef return false.
true if custom allocator reports success
allocPixels Allocator Pixel_Ref
Allocates pixel memory with allocator, and replaces existing SkPixelRef. The allocation size is determined by SkImageInfo width, height, and SkColorType. If allocator is nullptr, use HeapAllocator instead.
Aborts if Allocator::allocPixelRef return false. Abort steps may be provided by the user at compile time by defining SK_ABORT.
allocPixels Allocator Pixel_Ref
Returns SkPixelRef, which contains: pixel base address; its dimensions; and rowBytes(), the interval from one row to the next. Does not change SkPixelRef reference count. SkPixelRef may be shared by multiple bitmaps. If SkPixelRef has not been set, returns nullptr.
SkPixelRef, or nullptr
getPixels getAddr
Returns origin of pixels within SkPixelRef. SkBitmap bounds is always contained by SkPixelRef bounds, which may be the same size or larger. Multiple SkBitmap can share the same SkPixelRef, where each SkBitmap has different bounds.
The returned origin added to SkBitmap dimensions equals or is smaller than the SkPixelRef dimensions.
Returns (0, 0) if SkPixelRef is nullptr.
pixel origin within SkPixelRef
source origin: 0, 0 subset origin: 32, 64
SkPixelRef getSubset setPixelRef
Replaces pixelRef and origin in SkBitmap. dx and dy specify the offset within the SkPixelRef pixels for the top-left corner of the bitmap.
Asserts in debug builds if dx or dy are out of range. Pins dx and dy to legal range in release builds.
The caller is responsible for ensuring that the pixels match the SkColorType and SkAlphaType in SkImageInfo.
setInfo
Returns true if SkBitmap is can be drawn.
true if getPixels() is not nullptr
getPixels drawsNothing
Returns a unique value corresponding to the pixels in SkPixelRef. Returns a different value after notifyPixelsChanged() has been called. Returns zero if SkPixelRef is nullptr.
Determines if pixels have changed since last examined.
unique value for pixels in SkPixelRef
#Volatile empty id 0 alloc id 4 erase id 6
notifyPixelsChanged Pixel_Ref
Marks that pixels in SkPixelRef have changed. Subsequent calls to getGenerationID() return a different value.
getGenerationID isVolatile Pixel_Ref
Replaces pixel values with c. All pixels contained by bounds() are affected. If the colorType() is kGray_8_SkColorType or kRGB_565_SkColorType, then alpha is ignored; RGB is treated as opaque. If colorType() is kAlpha_8_SkColorType, then RGB is ignored.
eraseARGB erase
Replaces pixel values with unpremultiplied color built from a, r, g, and b. All pixels contained by bounds() are affected. If the colorType() is kGray_8_SkColorType or kRGB_565_SkColorType, then a is ignored; r, g, and b are treated as opaque. If colorType() is kAlpha_8_SkColorType, then r, g, and b are ignored.
eraseColor erase
Replaces pixel values inside area with c. If area does not intersect bounds(), call has no effect.
If the colorType() is kGray_8_SkColorType or kRGB_565_SkColorType, then alpha is ignored; RGB is treated as opaque. If colorType() is kAlpha_8_SkColorType, then RGB is ignored.
eraseColor eraseARGB SkCanvas::drawRect
Returns pixel at (x, y) as unpremultiplied color. Returns black with alpha if SkColorType is kAlpha_8_SkColorType.
Input is not validated: out of bounds values of x or y trigger an assert() if built with SK_DEBUG defined; and returns undefined values or may crash if SK_RELEASE is defined. Fails if SkColorType is kUnknown_SkColorType or pixel address is nullptr.
SkColorSpace in SkImageInfo is ignored. Some color precision may be lost in the conversion to unpremultiplied color; original pixel data may have additional precision.
pixel converted to unpremultiplied color
Premultiplied: (0, 0) 0x00000000 0x2a0e002a 0x55380055 0x7f7f007f (0, 1) 0x2a000e2a 0x551c1c55 0x7f542a7f 0xaaaa38aa (0, 2) 0x55003855 0x7f2a547f 0xaa7171aa 0xd4d48dd4 (0, 3) 0x7f007f7f 0xaa38aaaa 0xd48dd4d4 0xffffffff Unpremultiplied: (0, 0) 0x00000000 0x2a5500ff 0x55a800ff 0x7fff00ff (0, 1) 0x2a0055ff 0x555454ff 0x7fa954ff 0xaaff54ff (0, 2) 0x5500a8ff 0x7f54a9ff 0xaaaaaaff 0xd4ffaaff (0, 3) 0x7f00ffff 0xaa54ffff 0xd4aaffff 0xffffffff
getAlphaf getAddr readPixels
Looks up the pixel at (x,y) and return its alpha component, normalized to [0..1]. This is roughly equivalent to SkGetColorA(getColor()), but can be more efficient (and more precise if the pixels store more than 8 bits per component).
alpha converted to normalized float
getColor
Returns pixel address at (x, y).
Input is not validated: out of bounds values of x or y, or kUnknown_SkColorType, trigger an assert() if built with SK_DEBUG defined. Returns nullptr if SkColorType is kUnknown_SkColorType, or SkPixelRef is nullptr.
Performs a lookup of pixel size; for better performance, call one of: getAddr8(), getAddr16(), or getAddr32().
generic pointer to pixel
addr interval == rowBytes
getAddr8 getAddr16 getAddr32 readPixels SkPixmap::addr
Returns address at (x, y).
Input is not validated. Triggers an assert() if built with SK_DEBUG defined and:
unsigned 32-bit pointer to pixel at (x, y)
addr interval == rowBytes
getAddr8 getAddr16 getAddr readPixels SkPixmap::addr32
Returns address at (x, y).
Input is not validated. Triggers an assert() if built with SK_DEBUG defined and:
unsigned 16-bit pointer to pixel at (x, y)
addr interval == rowBytes
getAddr8 getAddr getAddr32 readPixels SkPixmap::addr16
Returns address at (x, y).
Input is not validated. Triggers an assert() if built with SK_DEBUG defined and:
unsigned 8-bit pointer to pixel at (x, y)
&pixels[4][2] == bitmap.getAddr8(2, 4)
getAddr getAddr16 getAddr32 readPixels SkPixmap::addr8
Shares Pixel_Ref with dst. Pixels are not copied; Bitmap and dst point to the same pixels; dst bounds() are set to the intersection of subset and the original bounds().
subset may be larger than bounds(). Any area outside of bounds() is ignored.
Any contents of dst are discarded. isVolatile setting is copied to dst. dst is set to colorType, alphaType, and colorSpace.
Return false if:
true if dst is replaced by subset
bounds: 0, 0, 512, 512 subset: -100, 100, 0, 200 success; false subset: -100, 100, 100, 200 success; true subset: 0, 0, 100, 100 subset: -100, 100, 1000, 200 success; true subset: 0, 0, 512, 100 subset: 0, 100, 0, 200 success; false subset: 0, 100, 100, 200 success; true subset: 0, 0, 100, 100 subset: 0, 100, 1000, 200 success; true subset: 0, 0, 512, 100 subset: 100, 100, 0, 200 success; false subset: 100, 100, 100, 200 success; false subset: 100, 100, 1000, 200 success; true subset: 0, 0, 412, 100 subset: 1000, 100, 0, 200 success; false subset: 1000, 100, 100, 200 success; false subset: 1000, 100, 1000, 200 success; false
readPixels writePixels SkCanvas::drawBitmap
Copies a Rect of pixels from Bitmap to dstPixels. Copy starts at (srcX, srcY), and does not exceed Bitmap (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:
Pixels are copied only if pixel conversion is possible. If Bitmap colorType is kGray_8_SkColorType, or kAlpha_8_SkColorType; dstInfo.colorType() must match. If Bitmap colorType is kGray_8_SkColorType, dstInfo.colorSpace() must match. If Bitmap alphaType is kOpaque_SkAlphaType, dstInfo.alphaType() must match. If Bitmap colorSpace is nullptr, dstInfo.colorSpace() must match. Returns false if pixel conversion is not possible.
srcX and srcY may be negative to copy only top or left of source. Returns false if width() or height() is zero or negative. Returns false if abs(srcX) >= Bitmap width(), or if abs(srcY) >= Bitmap height().
true if pixels are copied to dstPixels
writePixels SkPixmap::readPixels SkCanvas::readPixels SkImage::readPixels SkSurface::readPixels
Copies a Rect of pixels from Bitmap to dst. Copy starts at (srcX, srcY), and does not exceed Bitmap (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:
Pixels are copied only if pixel conversion is possible. If Bitmap colorType is kGray_8_SkColorType, or kAlpha_8_SkColorType; dst Color_Type must match. If Bitmap colorType is kGray_8_SkColorType, dst Color_Space must match. If Bitmap alphaType is kOpaque_SkAlphaType, dst Alpha_Type must match. If Bitmap colorSpace is nullptr, dst Color_Space 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 abs(srcX) >= Bitmap width(), or if abs(srcY) >= Bitmap height().
true if pixels are copied to dst
writePixels SkPixmap::readPixels SkCanvas::readPixels SkImage::readPixels SkSurface::readPixels
Copies a Rect of pixels from Bitmap to dst. Copy starts at (0, 0), and does not exceed Bitmap (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:
Pixels are copied only if pixel conversion is possible. If Bitmap colorType is kGray_8_SkColorType, or kAlpha_8_SkColorType; dst Color_Type must match. If Bitmap colorType is kGray_8_SkColorType, dst Color_Space must match. If Bitmap alphaType is kOpaque_SkAlphaType, dst Alpha_Type must match. If Bitmap colorSpace is nullptr, dst Color_Space must match. Returns false if pixel conversion is not possible.
true if pixels are copied to dst
writePixels SkPixmap::readPixels SkCanvas::readPixels SkImage::readPixels SkSurface::readPixels
Copies a Rect of pixels from src. Copy starts at (dstX, dstY), and does not exceed (src.width(), src.height()).
src specifies width, height, Color_Type, Alpha_Type, Color_Space, pixel storage, and row bytes of source. src.rowBytes() specifics the gap from one source row to the next. Returns true if pixels are copied. Returns false if:
Pixels are copied only if pixel conversion is possible. If Bitmap colorType is kGray_8_SkColorType, or kAlpha_8_SkColorType; src Color_Type must match. If Bitmap colorType is kGray_8_SkColorType, src Color_Space must match. If Bitmap alphaType is kOpaque_SkAlphaType, src Alpha_Type must match. If Bitmap colorSpace is nullptr, src Color_Space must match. Returns false if pixel conversion is not possible.
dstX and dstY may be negative to copy only top or left of source. Returns false if width() or height() is zero or negative. Returns false if abs(dstX) >= Bitmap width(), or if abs(dstY) >= Bitmap height().
true if src pixels are copied to Bitmap
readPixels
Copies a Rect of pixels from src. Copy starts at (0, 0), and does not exceed (src.width(), src.height()).
src specifies width, height, Color_Type, Alpha_Type, Color_Space, pixel storage, and row bytes of source. src.rowBytes() specifics the gap from one source row to the next. Returns true if pixels are copied. Returns false if:
Pixels are copied only if pixel conversion is possible. If Bitmap colorType is kGray_8_SkColorType, or kAlpha_8_SkColorType; src Color_Type must match. If Bitmap colorType is kGray_8_SkColorType, src Color_Space must match. If Bitmap alphaType is kOpaque_SkAlphaType, src Alpha_Type must match. If Bitmap colorSpace is nullptr, src Color_Space must match. Returns false if pixel conversion is not possible.
true if src pixels are copied to Bitmap
readPixels
Sets dst to alpha described by pixels. Returns false if dst cannot be written to or dst pixels cannot be allocated.
Uses HeapAllocator to reserve memory for dst SkPixelRef.
true if alpha layer was constructed in dst SkPixelRef
extractSubset
Sets dst to alpha described by pixels. Returns false if dst cannot be written to or dst pixels cannot be allocated.
If paint is not nullptr and contains SkMaskFilter, SkMaskFilter generates mask alpha from SkBitmap. Uses HeapAllocator to reserve memory for dst SkPixelRef. Sets offset to top-left position for dst for alignment with SkBitmap; (0, 0) unless SkMaskFilter generates mask.
true if alpha layer was constructed in dst SkPixelRef
extractSubset
Sets dst to alpha described by pixels. Returns false if dst cannot be written to or dst pixels cannot be allocated.
If paint is not nullptr and contains SkMaskFilter, SkMaskFilter generates mask alpha from SkBitmap. allocator may reference a custom allocation class or be set to nullptr to use HeapAllocator. Sets offset to top-left position for dst for alignment with SkBitmap; (0, 0) unless SkMaskFilter generates mask.
true if alpha layer was constructed in dst SkPixelRef
extractSubset
Copies SkBitmap pixel address, row bytes, and SkImageInfo 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 SkBitmap.
true if SkBitmap has direct access to pixels
------ -xxx-- x---x- ----x- ---x-- --x--- --x--- ------ --x--- --x--- ------
pixmap installPixels readPixels writePixels
SkImageInfo::validate