5538c13906
explict substitutions are required to distiguish words that preserve underscores R=caryclark@google.com Docs-Preview: https://skia.org/?cl=134841 Bug: skia:6898 Change-Id: Id1a5669c180e03e048de3c0251882bd06b297283 Reviewed-on: https://skia-review.googlesource.com/134841 Reviewed-by: Cary Clark <caryclark@skia.org> Commit-Queue: Cary Clark <caryclark@skia.org> Auto-Submit: Cary Clark <caryclark@skia.org>
216 KiB
SkBitmap Reference
Bitmap
Class SkBitmap
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.
Row Bytes
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.
Overview
| Topic | Description |
|---|---|
| Class Declarations | embedded class members |
| Constants | enum and enum class, and their const values |
| Constructors | functions that construct SkBitmap |
| Functions | global and class member functions |
| Operators | operator overloading methods |
| Related Functions | similar member functions grouped together |
Related Function
SkBitmap global, struct, and class related member functions share a topic.
| Topic | Description |
|---|---|
| Allocate | allocates storage for pixels |
| Draw | sets pixels to Color |
| Pixels | read and write pixel values |
| Property | metrics and attributes |
| Row Bytes | interval from one row to the next |
| Set | updates values and attributes |
| Utility | rarely called management functions |
Constant
SkBitmap related constants are defined by enum, enum class, #define, const, and constexpr.
| Topic | Description |
|---|---|
| AllocFlags | zero pixel memory |
| kZeroPixels AllocFlag | zero pixel memory |
Class
SkBitmap uses C++ classes to declare the public data structures and interfaces.
| Topic | Description |
|---|---|
| Allocator | abstract subclass of HeapAllocator |
| HeapAllocator | allocates pixel memory from heap |
Constructor
SkBitmap can be constructed or initialized by these functions, including C++ class constructors.
| Topic | Description |
|---|---|
| SkBitmap() | constructs with default values |
| SkBitmap(SkBitmap&& src) | takes ownership of pixels |
| SkBitmap(const SkBitmap& src) | shares ownership of pixels |
| extractAlpha | creates Bitmap containing Alpha of pixels |
| extractAlpha(SkBitmap* dst) const | |
| extractAlpha(SkBitmap* dst, const SkPaint* paint, SkIPoint* offset) const | |
| extractAlpha(SkBitmap* dst, const SkPaint* paint, Allocator* allocator, SkIPoint* offset) const | |
| extractSubset | creates Bitmap, sharing pixels if possible |
| reset | sets to default values, releases pixel ownership |
| ~SkBitmap() | releases ownership of pixels |
Operator
SkBitmap operators inline class member functions with arithmetic equivalents.
| Topic | Description |
|---|---|
| operator=(SkBitmap&& src) | takes ownership of pixels |
| operator=(const SkBitmap& src) | shares ownership of pixels |
Member Function
SkBitmap member functions read and modify the structure properties.
| Topic | Description |
|---|---|
| ComputeIsOpaque | returns true if all pixels are opaque |
| allocN32Pixels | allocates compatible ARGB pixels, or aborts |
| allocPixels | allocates pixels from Image Info, or aborts |
| allocPixelsFlags | allocates pixels from Image Info with options, or aborts |
| alphaType | returns Image Info Alpha Type |
| bounds | returns width and height as Rectangle |
| bytesPerPixel | returns number of bytes in pixel based on Color Type |
| colorSpace | returns Image Info Color Space |
| colorType | returns Image Info Color Type |
| computeByteSize | returns size required for pixels |
| dimensions | returns width and height |
| drawsNothing | returns true if no width, no height, or no Pixel Ref |
| empty | returns true if Image Info has zero width or height |
| erase | writes Color to rectangle of pixels |
| eraseARGB | writes Color to pixels |
| eraseColor | writes Color to pixels |
| extractAlpha | creates Bitmap containing Alpha of pixels |
| extractSubset | creates Bitmap, sharing pixels if possible |
| getAddr | returns readable pixel address as void pointer |
| getAddr16 | returns readable pixel address as 16-bit pointer |
| getAddr32 | returns readable pixel address as 32-bit pointer |
| getAddr8 | returns readable pixel address as 8-bit pointer |
| getBounds | returns width and height as Rectangle |
| getColor | returns one pixel as Unpremultiplied Color |
| getGenerationID | returns unique ID |
| getPixels | returns address of pixels |
| getSubset | returns bounds offset by origin |
| hasHardwareMipMap | returns Mip Map support present; Android only |
| height | returns pixel row count |
| info | returns Image Info |
| installPixels | creates Pixel Ref, with optional release function |
| isImmutable | returns true if pixels will not change |
| isNull | returns true if Pixel Ref is nullptr |
| isOpaque | returns true if Image Info describes opaque pixels |
| isVolatile | returns true if pixels should not be cached |
| notifyPixelsChanged | marks pixels as changed, altering the unique ID |
| peekPixels | returns Pixmap if possible |
| pixelRef | returns Pixel Ref, or nullptr |
| pixelRefOrigin | returns offset within Pixel Ref |
| pixmap | returns Pixmap |
| readPixels | copies and converts pixels |
| readyToDraw | returns true if address of pixels is not nullptr |
| refColorSpace | returns Image Info Color Space |
| reset | sets to default values, releases pixel ownership |
| rowBytes | returns interval between rows in bytes |
| rowBytesAsPixels | returns interval between rows in pixels |
| setAlphaType | sets Alpha Type of shared pixels |
| setHasHardwareMipMap | sets Mip Map support present; Android only |
| setImmutable | marks that pixels will not change |
| setInfo | sets height, width, Color Type, and so on, releasing pixels |
| setIsVolatile | marks if pixels should not be cached |
| setPixelRef | sets Pixel Ref and offset |
| setPixels | sets Pixel Ref without an offset |
| shiftPerPixel | returns bit shift from pixels to bytes |
| swap | exchanges Bitmap pair |
| tryAllocN32Pixels | allocates compatible ARGB pixels if possible |
| tryAllocPixels | allocates pixels from Image Info if possible |
| tryAllocPixelsFlags | allocates pixels from Image Info with options if possible |
| validate | asserts if Bitmap is invalid (debug only) |
| width | returns pixel column count |
| writePixels | copies and converts pixels |
Class SkBitmap::Allocator
Member_Function
SkBitmap member functions read and modify the structure properties.
| Topic | Description |
|---|
class Allocator : public SkRefCnt { public: virtual bool allocPixelRef(SkBitmap* bitmap) = 0; };
Abstract subclass of HeapAllocator.
allocPixelRef
virtual bool allocPixelRef(SkBitmap* bitmap) = 0
Allocates the pixel memory for the bitmap, given its dimensions and Color Type. Returns true on success, where success means either setPixels or setPixelRef was called.
Parameters
bitmap |
Bitmap containing Image Info as input, and Pixel Ref as output |
Return Value
true if Pixel Ref was allocated
See Also
Class SkBitmap::HeapAllocator
Member_Function
SkBitmap member functions read and modify the structure properties.
| Topic | Description |
|---|
class HeapAllocator : public Allocator { public: bool allocPixelRef(SkBitmap* bitmap) override; };
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.
allocPixelRef
bool allocPixelRef(SkBitmap* bitmap) override
Allocates the pixel memory for the bitmap, given its dimensions and Color Type. Returns true on success, where success means either setPixels or setPixelRef was called.
Parameters
bitmap |
Bitmap containing Image Info as input, and Pixel Ref as output |
Return Value
true if pixels are allocated
Example
Example Output
#Volatile
pixel address = (nil)
pixel address = 0x560ddd0ac670
See Also
SkBitmap::Allocator tryAllocPixels[2][3][4]
SkBitmap
SkBitmap()
Creates an empty Bitmap without pixels, with kUnknown_SkColorType, kUnknown_SkAlphaType, and with a width and height of zero. Pixel Ref origin is set to (0, 0). Bitmap is not volatile.
Use setInfo to associate SkColorType, SkAlphaType, width, and height after Bitmap has been created.
Return Value
empty Bitmap
Example
Example Output
width: 0 height: 0 color: kUnknown_SkColorType alpha: kUnknown_SkAlphaType
width: 25 height: 35 color: kRGBA_8888_SkColorType alpha: kOpaque_SkAlphaType
See Also
SkBitmap
SkBitmap(const SkBitmap& src)
Copies settings from src to returned Bitmap. Shares pixels if src has pixels allocated, so both bitmaps reference the same pixels.
Parameters
src |
Bitmap to copy Image Info, and share Pixel Ref |
Return Value
copy of src
Example
Example Output
original has pixels before copy: true
original has pixels after copy: true
copy has pixels: true
See Also
setInfo setPixelRef setPixels swap
SkBitmap
SkBitmap(SkBitmap&& src)
Copies settings from src to returned Bitmap. Moves ownership of src pixels to Bitmap.
Parameters
src |
Bitmap to copy Image Info, and reassign Pixel Ref |
Return Value
copy of src
Example
Example Output
original has pixels before move: true
original has pixels after move: false
copy has pixels: true
See Also
setInfo setPixelRef setPixels swap
~SkBitmap
~SkBitmap()
Decrements Pixel Ref reference count, if Pixel Ref is not nullptr.
See Also
operator=
SkBitmap& operator=(const SkBitmap& src)
Copies settings from src to returned Bitmap. Shares pixels if src has pixels allocated, so both bitmaps reference the same pixels.
Parameters
src |
Bitmap to copy Image Info, and share Pixel Ref |
Return Value
copy of src
Example
Example Output
original has pixels before copy: true
original has pixels after copy: true
copy has pixels: true
See Also
setInfo setPixelRef setPixels swap
operator=
SkBitmap& operator=(SkBitmap&& src)
Copies settings from src to returned Bitmap. Moves ownership of src pixels to Bitmap.
Parameters
src |
Bitmap to copy Image Info, and reassign Pixel Ref |
Return Value
copy of src
Example
Example Output
original has pixels before move: true
original has pixels after move: false
copy has pixels: true
See Also
setInfo setPixelRef setPixels swap
swap
void swap(SkBitmap& other)
Swaps the fields of the two bitmaps.
Parameters
other |
Bitmap exchanged with original |
Example
Example Output
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
See Also
SkBitmap(SkBitmap&& src) operator=(SkBitmap&& src)
Property
| Topic | Description |
|---|---|
| alphaType | returns Image Info Alpha Type |
| bounds | returns width and height as Rectangle |
| bytesPerPixel | returns number of bytes in pixel based on Color Type |
| colorSpace | returns Image Info Color Space |
| colorType | returns Image Info Color Type |
| dimensions | returns width and height |
| drawsNothing | returns true if no width, no height, or no Pixel Ref |
| empty | returns true if Image Info has zero width or height |
| getAddr | returns readable pixel address as void pointer |
| getAddr16 | returns readable pixel address as 16-bit pointer |
| getAddr32 | returns readable pixel address as 32-bit pointer |
| getAddr8 | returns readable pixel address as 8-bit pointer |
| getBounds | returns width and height as Rectangle |
| getBounds(SkRect* bounds) const | |
| getBounds(SkIRect* bounds) const | |
| getColor | returns one pixel as Unpremultiplied Color |
| getPixels | returns address of pixels |
| getSubset | returns bounds offset by origin |
| hasHardwareMipMap | returns Mip Map support present; Android only |
| height | returns pixel row count |
| info | returns Image Info |
| isImmutable | returns true if pixels will not change |
| isNull | returns true if Pixel Ref is nullptr |
| isOpaque | returns true if Image Info describes opaque pixels |
| isVolatile | returns true if pixels should not be cached |
| pixelRef | returns Pixel Ref, or nullptr |
| pixelRefOrigin | returns offset within Pixel Ref |
| pixmap | returns Pixmap |
| refColorSpace | returns Image Info Color Space |
| rowBytes | returns interval between rows in bytes |
| rowBytesAsPixels | returns interval between rows in pixels |
| shiftPerPixel | returns bit shift from pixels to bytes |
| width | returns pixel column count |
pixmap
const SkPixmap& pixmap() const
Returns a constant reference to the Pixmap holding the Bitmap pixel address, row bytes, and Image Info.
Return Value
reference to Pixmap describing this Bitmap
Example
Example Output
----------
---xx-----
--x--x----
--x-------
--xx------
--x-x---x-
-x---x--x-
-x----xx--
-xx---x---
--xxxx-xx-
----------
See Also
peekPixels installPixels[2][3] readPixels[2][3][4] writePixels[2][3]
info
const SkImageInfo& info() const
Returns width, height, Alpha Type, Color Type, and Color Space.
Return Value
reference to Image Info
Example
Example Output
width: 56 height: 56 color: BGRA_8888 alpha: Opaque
See Also
width
int width() const
Returns pixel count in each row. Should be equal or less than:
rowBytes / info.bytesPerPixel.
Maybe be less than pixelRef.width. Will not exceed pixelRef.width less pixelRefOrigin.fX.
Return Value
pixel width in Image Info
Example
Example Output
bitmap width: 16 info width: 16
See Also
height SkPixelRef::width() SkImageInfo::width()
height
int height() const
Returns pixel row count.
Maybe be less than pixelRef.height. Will not exceed pixelRef.height less pixelRefOrigin.fY.
Return Value
pixel height in Image Info
Example
Example Output
bitmap height: 32 info height: 32
See Also
width SkPixelRef::height() SkImageInfo::height()
colorType
SkColorType colorType() const
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.
Return Value
Example
Example Output
color type: kAlpha_8_SkColorType
See Also
alphaType SkImageInfo::colorType
alphaType
SkAlphaType alphaType() const
Returns Alpha Type, one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType.
Return Value
Example
Example Output
alpha type: kPremul_SkAlphaType
See Also
colorType SkImageInfo::alphaType
colorSpace
SkColorSpace* colorSpace() const
Returns Color Space, the range of colors, associated with Image Info. The reference count of Color Space is unchanged. The returned Color Space is immutable.
Return Value
Color Space in Image Info, or nullptr
Example
Example Output
gammaCloseToSRGB: false gammaIsLinear: true isSRGB: false
See Also
Color Space SkImageInfo::colorSpace
refColorSpace
sk sp<SkColorSpace> refColorSpace() const
Returns smart pointer to Color Space, the range of colors, associated with Image Info. The smart pointer tracks the number of objects sharing this Color Space reference so the memory is released when the owners destruct.
The returned Color Space is immutable.
Return Value
Color Space in Image Info wrapped in a smart pointer
Example
Example Output
gammaCloseToSRGB: false gammaIsLinear: true isSRGB: false
See Also
Color Space SkImageInfo::colorSpace
bytesPerPixel
int bytesPerPixel() const
Returns number of bytes per pixel required by Color Type. Returns zero if colorType( is kUnknown_SkColorType.
Return Value
bytes in pixel
Example
Example Output
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
See Also
rowBytes rowBytesAsPixels width shiftPerPixel SkImageInfo::bytesPerPixel
rowBytesAsPixels
int rowBytesAsPixels() const
Returns number of pixels that fit on row. Should be greater than or equal to width.
Return Value
maximum pixels per row
Example
Example Output
rowBytes: 4 rowBytesAsPixels: 1
rowBytes: 5 rowBytesAsPixels: 1
rowBytes: 6 rowBytesAsPixels: 1
rowBytes: 7 rowBytesAsPixels: 1
rowBytes: 8 rowBytesAsPixels: 2
See Also
rowBytes shiftPerPixel width bytesPerPixel
shiftPerPixel
int shiftPerPixel() const
Returns bit shift converting row bytes to row pixels. Returns zero for kUnknown_SkColorType.
Return Value
one of: 0, 1, 2, 3; left shift to convert pixels to bytes
Example
Example Output
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
See Also
rowBytes rowBytesAsPixels width bytesPerPixel
empty
bool empty() const
Returns true if either width or height are zero.
Does not check if Pixel Ref is nullptr; call drawsNothing to check width, height, and Pixel Ref.
Return Value
true if dimensions do not enclose area
Example
Example Output
width: 0 height: 0 empty: true
width: 0 height: 2 empty: true
width: 2 height: 0 empty: true
width: 2 height: 2 empty: false
See Also
isNull
bool isNull() const
Return true if Pixel Ref is nullptr.
Does not check if width or height are zero; call drawsNothing to check width, height, and Pixel Ref.
Return Value
true if no Pixel Ref is associated
Example
Example Output
empty bitmap does not have pixels
bitmap with dimensions does not have pixels
allocated bitmap does have pixels
See Also
drawsNothing
bool drawsNothing() const
Return true if width or height are zero, or if Pixel Ref is nullptr. If true, Bitmap has no effect when drawn or drawn into.
Return Value
true if drawing has no effect
Example
Example Output
empty:true isNull:true drawsNothing:true
empty:true isNull:false drawsNothing:true
empty:false isNull:true drawsNothing:true
empty:false isNull:false drawsNothing:false
See Also
rowBytes
size_t rowBytes() const
Returns row bytes, the interval from one pixel row to the next. Row bytes is at least as large aswidth * 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.
Return Value
byte length of pixel row
Example
Example Output
setInfo returned:false rowBytes:0
setInfo returned:true rowBytes:8
See Also
info setInfo SkImageInfo::minRowBytes
setAlphaType
bool setAlphaType(SkAlphaType alphaType)
Sets Alpha Type, if alphaType is compatible with Color Type. Returns true unless alphaType is kUnknown_SkAlphaType and current Alpha Type is not kUnknown_SkAlphaType.
Returns true if Color Type is kUnknown_SkColorType. alphaType is ignored, and Alpha Type remains kUnknown_SkAlphaType.
Returns true if Color Type is kRGB_565_SkColorType or kGray_8_SkColorType. alphaType is ignored, and Alpha Type remains kOpaque_SkAlphaType.
If Color Type is kARGB_4444_SkColorType, kRGBA_8888_SkColorType, kBGRA_8888_SkColorType, or kRGBA_F16_SkColorType: returns true unless alphaType is kUnknown_SkAlphaType and Alpha Type is not kUnknown_SkAlphaType. If Alpha Type is kUnknown_SkAlphaType, alphaType is ignored.
If Color Type is kAlpha_8_SkColorType, returns true unless alphaType is kUnknown_SkAlphaType and Alpha Type is not kUnknown_SkAlphaType. If Alpha Type is kUnknown_SkAlphaType, alphaType is ignored. If alphaType is kUnpremul_SkAlphaType, it is treated as kPremul_SkAlphaType.
This changes Alpha Type in Pixel Ref; all bitmaps sharing Pixel Ref are affected.
Parameters
alphaType |
one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType |
Return Value
true if Alpha Type is set
Example
See Also
Alpha Type Color Type Image Info setInfo
getPixels
void* getPixels() const
Returns pixel address, the base address corresponding to the pixel origin.
Return Value
pixel address
Example
Example Output
bitmap.getColor(0, 1) == 0x00000000
bitmap.getColor(0, 0) == 0xFFFFFFFF
See Also
computeByteSize
size_t computeByteSize() const
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.
Return Value
size in bytes of image buffer
Example
Example Output
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
See Also
isImmutable
bool isImmutable() const
Returns true if pixels can not change.
Most immutable Bitmap checks trigger an assert only on debug builds.
Return Value
true if pixels are immutable
Example
Example Output
original is immutable
copy is immutable
See Also
setImmutable SkPixelRef::isImmutable SkImage
setImmutable
void setImmutable()
Sets internal flag to mark Bitmap as immutable. Once set, pixels can not change. Any other bitmap sharing the same Pixel Ref are also marked as immutable. Once Pixel Ref is marked immutable, the setting cannot be cleared.
Writing to immutable Bitmap pixels triggers an assert on debug builds.
Example
See Also
isImmutable SkPixelRef::setImmutable SkImage
isOpaque
bool isOpaque() const
Returns true if Alpha Type is set to hint that all pixels are opaque; their Color Alpha value is implicitly or explicitly 1.0. If true, and all pixels are not opaque, Skia may draw incorrectly.
Does not check if Color Type allows Alpha, or if any pixel value has transparency.
Return Value
true if Image Info Alpha Type is kOpaque_SkAlphaType
Example
Example Output
isOpaque: false
isOpaque: false
isOpaque: true
isOpaque: true
See Also
ComputeIsOpaque SkImageInfo::isOpaque
isVolatile
bool isVolatile() const
If true, 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 Pixel Ref.
Return Value
true if marked volatile
Example
Example Output
original is volatile
copy is not volatile
See Also
setIsVolatile
void setIsVolatile(bool isVolatile)
Sets if pixels should be read from Pixel Ref on every access. Bitmaps are not volatile by default; a GPU back end may upload pixel values expecting them to be accessed repeatedly. Marking temporary Bitmaps as volatile provides a hint to Device that the Bitmap pixels should not be cached. This can improve performance by avoiding overhead and reducing resource consumption on Device.
Parameters
isVolatile |
true if backing pixels are temporary |
Example
See Also
reset
void reset()
Resets to its initial state; all fields are set to zero, as if Bitmap 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 Pixel Ref is allocated, its reference count is decreased by one, releasing its memory if Bitmap is the sole owner.
Example
Example Output
width:1 height:1 isNull:false
width:0 height:0 isNull:true
See Also
SkBitmap() SkAlphaType SkColorType
ComputeIsOpaque
static bool ComputeIsOpaque(const SkBitmap& bm)
Returns true if all pixels are opaque. Color Type determines how pixels are encoded, and whether pixel describes Alpha. Returns true for Color Types without alpha in each pixel; for other Color Types, returns true if all pixels have alpha values equivalent to 1.0 or greater.
For Color Types kRGB_565_SkColorType or kGray_8_SkColorType: always returns true. For Color Types kAlpha_8_SkColorType, kBGRA_8888_SkColorType, kRGBA_8888_SkColorType: returns true if all pixel Alpha values are 255. For Color Type kARGB_4444_SkColorType: returns true if all pixel Alpha values are 15. For kRGBA_F16_SkColorType: returns true if all pixel Alpha values are 1.0 or greater.
Returns false for kUnknown_SkColorType.
Parameters
bm |
Bitmap to check |
Return Value
true if all pixels have opaque values or Color Type is opaque
Example
Example Output
computeIsOpaque: false
computeIsOpaque: true
computeIsOpaque: false
computeIsOpaque: true
See Also
getBounds
void getBounds(SkRect* bounds) const
Returns Rect { 0, 0, width, height }.
Parameters
bounds |
container for floating point rectangle |
Example
See Also
void getBounds(SkIRect* bounds) const
Returns IRect { 0, 0, width, height }.
Parameters
bounds |
container for integral rectangle |
Example
See Also
bounds
SkIRect bounds() const
Returns IRect { 0, 0, width, height }.
Return Value
integral rectangle from origin to width and height
Example
See Also
dimensions
SkISize dimensions() const
Returns ISize { width, height }.
Return Value
integral size of width and height
Example
See Also
getSubset
SkIRect getSubset() const
Returns the bounds of this bitmap, offset by its Pixel Ref origin.
Return Value
bounds within Pixel Ref bounds
Example
Example Output
source: 0, 0, 512, 512
subset: 100, 100, 412, 412
See Also
setInfo
bool setInfo(const SkImageInfo& imageInfo, size_t rowBytes = 0)
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:
| rowBytes exceeds 31 bits |
| imageInfo.width is negative |
| imageInfo.height is negative |
| rowBytes is positive and less than imageInfo.width times imageInfo.bytesPerPixel |
Parameters
imageInfo |
contains width, height, Alpha Type, Color Type, Color Space |
rowBytes |
imageInfo.minRowBytes or larger; or zero |
Return Value
true if Image Info set successfully
Example
See Also
Alpha Type Color Type Color Space height rowBytes width
Enum SkBitmap::AllocFlags
enum AllocFlags { kZeroPixels AllocFlag = 1 << 0, };
AllocFlags provides the option to zero pixel memory when allocated.
Constants
| Const | Value | Description |
|---|---|---|
SkBitmap::kZeroPixels_AllocFlag |
1 | Instructs tryAllocPixelsFlags and allocPixelsFlags to zero pixel memory. |
See Also
tryAllocPixelsFlags allocPixelsFlags erase eraseColor
Allocate
tryAllocPixelsFlags
bool SK_WARN_UNUSED_RESULT tryAllocPixelsFlags(const SkImageInfo& info, uint32_t flags)
Sets Image Info 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 Image Info 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.
Parameters
info |
contains width, height, Alpha Type, Color Type, Color Space |
flags |
kZeroPixels AllocFlag, or zero |
Return Value
true if pixels allocation is successful
Example
Example Output
bitmap allocation succeeded!
See Also
allocPixelsFlags tryAllocPixels[2][3][4] SkMallocPixelRef::MakeZeroed
allocPixelsFlags
void allocPixelsFlags(const SkImageInfo& info, uint32_t flags)
Sets Image Info to info following the rules in setInfo and allocates pixel memory. If flags is kZeroPixels AllocFlag, memory is zeroed.
Aborts execution if Image Info 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.
Parameters
info |
contains width, height, Alpha Type, Color Type, Color Space |
flags |
kZeroPixels AllocFlag, or zero |
Example
See Also
tryAllocPixelsFlags allocPixels[2][3][4] SkMallocPixelRef::MakeZeroed
tryAllocPixels
bool SK_WARN_UNUSED_RESULT tryAllocPixels(const SkImageInfo& info, size_t rowBytes)
Sets Image Info 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 Image Info 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().
Parameters
info |
contains width, height, Alpha Type, Color Type, Color Space |
rowBytes |
size of pixel row or larger; may be zero |
Return Value
true if pixel storage is allocated
Example
See Also
tryAllocPixelsFlags allocPixels[2][3][4] SkMallocPixelRef::MakeAllocate
allocPixels
void allocPixels(const SkImageInfo& info, size_t rowBytes)
Sets Image Info 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 Image Info 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().
Parameters
info |
contains width, height, Alpha Type, Color Type, Color Space |
rowBytes |
size of pixel row or larger; may be zero |
Example
See Also
tryAllocPixels[2][3][4] allocPixelsFlags SkMallocPixelRef::MakeAllocate
bool SK_WARN_UNUSED_RESULT tryAllocPixels(const SkImageInfo& info)
Sets Image Info to info following the rules in setInfo and allocates pixel memory.
Returns false and calls reset if Image Info 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().
Parameters
info |
contains width, height, Alpha Type, Color Type, Color Space |
Return Value
true if pixel storage is allocated
Example
See Also
tryAllocPixelsFlags allocPixels[2][3][4] SkMallocPixelRef::MakeAllocate
void allocPixels(const SkImageInfo& info)
Sets Image Info to info following the rules in setInfo and allocates pixel memory.
Aborts execution if Image Info 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().
Parameters
info |
contains width, height, Alpha Type, Color Type, Color Space |
Example
See Also
tryAllocPixels[2][3][4] allocPixelsFlags SkMallocPixelRef::MakeAllocate
tryAllocN32Pixels
bool SK_WARN_UNUSED_RESULT tryAllocN32Pixels(int width, int height, bool isOpaque = false)
Sets Image Info to width, height, and Native_Color_Type; and allocates pixel memory. If isOpaque is true, sets Image Info 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 Bitmap that matches SkPMColor, the native pixel arrangement on the platform. Bitmap drawn to output device skips converting its pixel format.
Parameters
width |
pixel column count; must be zero or greater |
height |
pixel row count; must be zero or greater |
isOpaque |
true if pixels do not have transparency |
Return Value
true if pixel storage is allocated
Example
See Also
tryAllocPixels[2][3][4] allocN32Pixels SkMallocPixelRef::MakeAllocate
allocN32Pixels
void allocN32Pixels(int width, int height, bool isOpaque = false)
Sets Image Info to width, height, and the Native_Color_Type; and allocates pixel memory. If isOpaque is true, sets Image Info 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 Bitmap that matches SkPMColor, the native pixel arrangement on the platform. Bitmap drawn to output device skips converting its pixel format.
Parameters
width |
pixel column count; must be zero or greater |
height |
pixel row count; must be zero or greater |
isOpaque |
true if pixels do not have transparency |
Example
See Also
allocPixels[2][3][4] tryAllocN32Pixels SkMallocPixelRef::MakeAllocate
installPixels
bool installPixels(const SkImageInfo& info, void* pixels, size_t rowBytes, void (*releaseProc) (void* addr, void* context) , void* context)
Sets Image Info to info following the rules in setInfo, and creates Pixel Ref 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 Image Info 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 Image Info, calls releaseProc if present, returns true.
If Image Info 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.
Parameters
info |
contains width, height, Alpha Type, Color Type, Color Space |
pixels |
address or pixel storage; may be nullptr |
rowBytes |
size of pixel row or larger |
releaseProc |
function called when pixels can be deleted; may be nullptr |
context |
caller state passed to releaseProc; may be nullptr |
Return Value
true if Image Info is set to info
Example
Example Output
before installPixels
releaseProc called
install not successful
See Also
bool installPixels(const SkImageInfo& info, void* pixels, size_t rowBytes)
Sets Image Info to info following the rules in setInfo, and creates Pixel Ref containing pixels and rowBytes.
If Image Info could not be set, or rowBytes is less than info.minRowBytes: calls reset, and returns false.
Otherwise, if pixels equals nullptr: sets Image Info, returns true.
Caller must ensure that pixels are valid for the lifetime of Bitmap and Pixel Ref.
Parameters
info |
contains width, height, Alpha Type, Color Type, Color Space |
pixels |
address or pixel storage; may be nullptr |
rowBytes |
size of pixel row or larger |
Return Value
true if Image Info is set to info
Example
See Also
bool installPixels(const SkPixmap& pixmap)
Sets Image Info to pixmap.info following the rules in setInfo, and creates Pixel Ref containing pixmap.addr() and pixmap.rowBytes.
If Image Info could not be set, or pixmap.rowBytes is less than SkImageInfo::minRowBytes: calls reset, and returns false.
Otherwise, if pixmap.addr() equals nullptr: sets Image Info, returns true.
Caller must ensure that pixmap is valid for the lifetime of Bitmap and Pixel Ref.
Parameters
pixmap |
Image Info, pixel address, and rowBytes |
Return Value
true if Image Info was set to pixmap.info
Example
See Also
installMaskPixels
bool installMaskPixels(const SkMask& mask)
Deprecated.
soon
Pixels
| Topic | Description |
|---|---|
| notifyPixelsChanged | marks pixels as changed, altering the unique ID |
| peekPixels | returns Pixmap if possible |
| readPixels | copies and converts pixels |
| readPixels(const SkImageInfo& dstInfo, void* dstPixels, size t dstRowBytes, int srcX, int srcY, SkTransferFunctionBehavior behavior) const | |
| readPixels(const SkImageInfo& dstInfo, void* dstPixels, size t dstRowBytes, int srcX, int srcY) const | |
| readPixels(const SkPixmap& dst, int srcX, int srcY) const | |
| readPixels(const SkPixmap& dst) const | |
| setPixels | sets Pixel Ref without an offset |
| writePixels | copies and converts pixels |
| writePixels(const SkPixmap& src, int dstX, int dstY) | |
| writePixels(const SkPixmap& src) | |
| writePixels(const SkPixmap& src, int x, int y, SkTransferFunctionBehavior behavior) |
setPixels
void setPixels(void* pixels)
Replaces Pixel Ref with pixels, preserving Image Info and rowBytes. Sets Pixel Ref origin to (0, 0).
If pixels is nullptr, or if info.colorType equals kUnknown_SkColorType; release reference to Pixel Ref, and set Pixel Ref to nullptr.
Caller is responsible for handling ownership pixel memory for the lifetime of Bitmap and Pixel Ref.
Parameters
pixels |
address of pixel storage, managed by caller |
Example
See Also
installPixels[2][3] allocPixels[2][3][4]
bool SK_WARN_UNUSED_RESULT tryAllocPixels()
Allocates pixel memory with HeapAllocator, and replaces existing Pixel Ref. The allocation size is determined by Image Info width, height, and Color Type.
Returns false if info.colorType is kUnknown_SkColorType, or allocation fails.
Return Value
true if the allocation succeeds
Example
See Also
allocPixels[2][3][4] installPixels[2][3] setPixels
void allocPixels()
Allocates pixel memory with HeapAllocator, and replaces existing Pixel Ref. The allocation size is determined by Image Info width, height, and Color Type.
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.
Example
See Also
tryAllocPixels[2][3][4] installPixels[2][3] setPixels
bool SK_WARN_UNUSED_RESULT tryAllocPixels(Allocator* allocator)
Allocates pixel memory with allocator, and replaces existing Pixel Ref. The allocation size is determined by Image Info width, height, and Color Type. If allocator is nullptr, use HeapAllocator instead.
Returns false if Allocator::allocPixelRef return false.
Parameters
allocator |
instance of SkBitmap::Allocator instantiation |
Return Value
true if custom allocator reports success
Example
See Also
allocPixels[2][3][4] Allocator Pixel Ref
void allocPixels(Allocator* allocator)
Allocates pixel memory with allocator, and replaces existing Pixel Ref. The allocation size is determined by Image Info width, height, and Color Type. 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.
Parameters
allocator |
instance of SkBitmap::Allocator instantiation |
Example
See Also
allocPixels[2][3][4] Allocator Pixel Ref
pixelRef
SkPixelRef* pixelRef() const
Returns Pixel Ref, which contains: pixel base address; its dimensions; and rowBytes, the interval from one row to the next. Does not change Pixel Ref reference count. Pixel Ref may be shared by multiple bitmaps. If Pixel Ref has not been set, returns nullptr.
Return Value
Pixel Ref, or nullptr
Example
See Also
pixelRefOrigin
SkIPoint pixelRefOrigin() const
Returns origin of pixels within Pixel Ref. Bitmap bounds is always contained by Pixel Ref bounds, which may be the same size or larger. Multiple Bitmaps can share the same Pixel Ref, where each Bitmap has different bounds.
The returned origin added to Bitmap dimensions equals or is smaller than the Pixel Ref dimensions.
Returns (0, 0) if Pixel Ref is nullptr.
Return Value
pixel origin within Pixel Ref
Example
Example Output
source origin: 0, 0
subset origin: 32, 64
See Also
SkPixelRef getSubset setPixelRef
Set
| Topic | Description |
|---|---|
| setAlphaType | sets Alpha Type of shared pixels |
| setHasHardwareMipMap | sets Mip Map support present; Android only |
| setImmutable | marks that pixels will not change |
| setInfo | sets height, width, Color Type, and so on, releasing pixels |
| setIsVolatile | marks if pixels should not be cached |
| setPixelRef | sets Pixel Ref and offset |
setPixelRef
void setPixelRef(sk sp<SkPixelRef> pixelRef, int dx, int dy)
Replaces pixelRef and origin in Bitmap. dx and dy specify the offset within the Pixel Ref 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 Color Type and Alpha Type in Image Info.
Parameters
pixelRef |
Pixel Ref describing pixel address and rowBytes |
dx |
column offset in Pixel Ref for bitmap origin |
dy |
row offset in Pixel Ref for bitmap origin |
Example
See Also
readyToDraw
bool readyToDraw() const
Returns true if Bitmap is can be drawn.
Return Value
true if getPixels is not nullptr
Example
See Also
getGenerationID
uint32_t getGenerationID() const
Returns a unique value corresponding to the pixels in Pixel Ref. Returns a different value after notifyPixelsChanged has been called. Returns zero if Pixel Ref is nullptr.
Determines if pixels have changed since last examined.
Return Value
unique value for pixels in Pixel Ref
Example
Example Output
#Volatile
empty id 0
alloc id 4
erase id 6
See Also
notifyPixelsChanged
void notifyPixelsChanged() const
Marks that pixels in Pixel Ref have changed. Subsequent calls to getGenerationID return a different value.
Example
See Also
getGenerationID isVolatile Pixel Ref
Draw
| Topic | Description |
|---|---|
| erase | writes Color to rectangle of pixels |
| eraseARGB | writes Color to pixels |
| eraseColor | writes Color to pixels |
eraseColor
void eraseColor(SkColor c) const
Replaces pixel values with c. All pixels contained by bounds are affected. If the colorType is kGray_8_SkColorType or k565_SkColorType, then Color Alpha is ignored; RGB is treated as opaque. If colorType is kAlpha_8_SkColorType, then RGB is ignored.
Parameters
c |
Unpremultiplied Color |
Example
See Also
eraseARGB
void eraseARGB(U8CPU a, U8CPU r, U8CPU g, U8CPU b) const
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 k565_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.
Parameters
a |
amount of Color Alpha, from fully transparent (0) to fully opaque (255) |
r |
amount of red, from no red (0) to full red (255) |
g |
amount of green, from no green (0) to full green (255) |
b |
amount of blue, from no blue (0) to full blue (255) |
Example
See Also
eraseRGB
void eraseRGB(U8CPU r, U8CPU g, U8CPU b) const
Deprecated.
erase
void erase(SkColor c, const SkIRect& area) const
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 k565_SkColorType, then Color Alpha is ignored; RGB is treated as opaque. If colorType is kAlpha_8_SkColorType, then RGB is ignored.
Parameters
c |
Unpremultiplied Color |
area |
rectangle to fill |
Example
See Also
eraseColor eraseARGB eraseRGB SkCanvas::drawRect
eraseArea
void eraseArea(const SkIRect& area, SkColor c) const
Deprecated.
getColor
SkColor getColor(int x, int y) const
Returns pixel at (x, y) as Unpremultiplied Color. Returns black with Alpha if Color Type is kAlpha_8_SkColorType.
Input is not validated: out of bounds values of x or y trigger an assert() if built with SK_DEBUG defined; and returns undefined values or may crash if SK_RELEASE is defined. Fails if Color Type is kUnknown_SkColorType or pixel address is nullptr.
Color Space in Image Info is ignored. Some Color precision may be lost in the conversion to Unpremultiplied Color; original pixel data may have additional precision.
Parameters
x |
column index, zero or greater, and less than width |
y |
row index, zero or greater, and less than height |
Return Value
pixel converted to Unpremultiplied Color
Example
Example Output
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
See Also
getAddr
void* getAddr(int x, int y) const
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 Color Type is kUnknown_SkColorType, or Pixel Ref is nullptr.
Performs a lookup of pixel size; for better performance, call one of: getAddr8, getAddr16, or getAddr32.
Parameters
x |
column index, zero or greater, and less than width |
y |
row index, zero or greater, and less than height |
Return Value
generic pointer to pixel
Example
Example Output
addr interval == rowBytes
See Also
getAddr8 getAddr16 getAddr32 readPixels[2][3][4] SkPixmap::addr[2]
getAddr32
inline uint32_t* getAddr32(int x, int y) const
Input is not validated. Triggers an assert() if built with SK_DEBUG defined and:
| Pixel Ref is nullptr |
| bytesPerPixel is not four |
| x is negative, or not less than width |
| y is negative, or not less than height |
Parameters
x |
column index, zero or greater, and less than width |
y |
row index, zero or greater, and less than height |
Return Value
unsigned 32-bit pointer to pixel at (x, y)
Example
Example Output
addr interval == rowBytes
See Also
getAddr8 getAddr16 getAddr readPixels[2][3][4] SkPixmap::addr32[2]
getAddr16
inline uint16_t* getAddr16(int x, int y) const
Input is not validated. Triggers an assert() if built with SK_DEBUG defined and:
| Pixel Ref is nullptr |
| bytesPerPixel is not two |
| x is negative, or not less than width |
| y is negative, or not less than height |
Parameters
x |
column index, zero or greater, and less than width |
y |
row index, zero or greater, and less than height |
Return Value
unsigned 16-bit pointer to pixel at (x, y)
Example
Example Output
addr interval == rowBytes
See Also
getAddr8 getAddr getAddr32 readPixels[2][3][4] SkPixmap::addr16[2]
getAddr8
inline uint8_t* getAddr8(int x, int y) const
Input is not validated. Triggers an assert() if built with SK_DEBUG defined and:
| Pixel Ref is nullptr |
| bytesPerPixel is not one |
| x is negative, or not less than width |
| y is negative, or not less than height |
Parameters
x |
column index, zero or greater, and less than width |
y |
row index, zero or greater, and less than height |
Return Value
unsigned 8-bit pointer to pixel at (x, y)
Example
Example Output
&pixels[4][2] == bitmap.getAddr8(2, 4)
See Also
getAddr getAddr16 getAddr32 readPixels[2][3][4] SkPixmap::addr8[2]
extractSubset
bool extractSubset(SkBitmap* dst, const SkIRect& subset) const
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:
| dst is nullptr |
| Pixel Ref is nullptr |
| subset does not intersect bounds |
Parameters
dst |
Bitmap set to subset |
subset |
rectangle of pixels to reference |
Return Value
true if dst is replaced by subset
Example
Example Output
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
See Also
readPixels[2][3][4] writePixels[2][3] SkCanvas::drawBitmap
readPixels
bool readPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes, int srcX, int srcY, SkTransferFunctionBehavior behavior) const
Copies Rect of pixels from Bitmap pixels 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:
| dstInfo.addr() equals nullptr |
| dstRowBytes is less than dstInfo.minRowBytes |
| Pixel Ref is nullptr |
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 ifabs(srcX) >= Bitmap width, or ifabs(srcY) >= Bitmap height.
If behavior is SkTransferFunctionBehavior::kRespect: converts source pixels to a linear space before converting to dstInfo. If behavior is SkTransferFunctionBehavior::kIgnore: source pixels are treated as if they are linear, regardless of how they are encoded.
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 |
behavior |
one of: SkTransferFunctionBehavior::kRespect, SkTransferFunctionBehavior::kIgnore |
Return Value
true if pixels are copied to dstPixels
Example
See Also
writePixels[2][3] SkPixmap::readPixels[2][3][4][5] SkCanvas::readPixels[2][3] SkImage::readPixels[2] SkSurface::readPixels[2][3]
bool readPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes, int srcX, int srcY) const
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:
| dstInfo.addr() equals nullptr |
| dstRowBytes is less than dstInfo.minRowBytes |
| Pixel Ref is nullptr |
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 ifabs(srcX) >= Bitmap width, or ifabs(srcY) >= Bitmap height.
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 |
Return Value
true if pixels are copied to dstPixels
Example
See Also
writePixels[2][3] SkPixmap::readPixels[2][3][4][5] SkCanvas::readPixels[2][3] SkImage::readPixels[2] SkSurface::readPixels[2][3]
bool readPixels(const SkPixmap& dst, int srcX, int srcY) const
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:
| dst pixel storage equals nullptr |
| dst.rowBytes is less than SkImageInfo::minRowBytes |
| Pixel Ref is nullptr |
Pixels are copied only if pixel conversion is possible. If 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 ifabs(srcX) >= Bitmap width, or ifabs(srcY) >= Bitmap height.
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 |
Return Value
true if pixels are copied to dst
Example
See Also
writePixels[2][3] SkPixmap::readPixels[2][3][4][5] SkCanvas::readPixels[2][3] SkImage::readPixels[2] SkSurface::readPixels[2][3]
bool readPixels(const SkPixmap& dst) const
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:
| dst pixel storage equals nullptr |
| dst.rowBytes is less than SkImageInfo::minRowBytes |
| Pixel Ref is nullptr |
Pixels are copied only if pixel conversion is possible. If 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.
Parameters
dst |
destination Pixmap: Image Info, pixels, row bytes |
Return Value
true if pixels are copied to dst
Example
See Also
writePixels[2][3] SkPixmap::readPixels[2][3][4][5] SkCanvas::readPixels[2][3] SkImage::readPixels[2] SkSurface::readPixels[2][3]
writePixels
bool writePixels(const SkPixmap& src, int dstX, int dstY)
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:
| src pixel storage equals nullptr |
| src.rowBytes is less than SkImageInfo::minRowBytes |
| Pixel Ref is nullptr |
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 ifabs(dstX) >= Bitmap width, or ifabs(dstY) >= Bitmap height.
Parameters
src |
source Pixmap: Image Info, pixels, row bytes |
dstX |
column index whose absolute value is less than width |
dstY |
row index whose absolute value is less than height |
Return Value
true if src pixels are copied to Bitmap
Example
See Also
bool writePixels(const SkPixmap& src)
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:
| src pixel storage equals nullptr |
| src.rowBytes is less than SkImageInfo::minRowBytes |
| Pixel Ref is nullptr |
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.
Parameters
src |
source Pixmap: Image Info, pixels, row bytes |
Return Value
true if src pixels are copied to Bitmap
Example
See Also
bool writePixels(const SkPixmap& src, int x, int y, SkTransferFunctionBehavior behavior)
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:
| src pixel storage equals nullptr |
| src.rowBytes is less than SkImageInfo::minRowBytes |
| Pixel Ref is nullptr |
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. Returns false if width or height is zero or negative.
If behavior is SkTransferFunctionBehavior::kRespect: converts src pixels to a linear space before converting to Image Info. If behavior is SkTransferFunctionBehavior::kIgnore: src pixels are treated as if they are linear, regardless of how they are encoded.
Parameters
src |
source Pixmap: Image Info, pixels, row bytes |
x |
column index whose absolute value is less than width |
y |
row index whose absolute value is less than height |
behavior |
one of: SkTransferFunctionBehavior::kRespect, SkTransferFunctionBehavior::kIgnore |
Return Value
true if src pixels are copied to Bitmap
Example
See Also
hasHardwareMipMap
bool hasHardwareMipMap() const
Android framework only.
Return Value
true if setHasHardwareMipMap has been called with true
See Also
setHasHardwareMipMap
void setHasHardwareMipMap(bool hasHardwareMipMap)
Android framework only.
Parameters
hasHardwareMipMap |
sets state |
See Also
extractAlpha
bool extractAlpha(SkBitmap* dst) const
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 Pixel Ref.
Parameters
dst |
holds Pixel Ref to fill with alpha layer |
Return Value
true if Alpha layer was constructed in dst Pixel Ref
Example
See Also
bool extractAlpha(SkBitmap* dst, const SkPaint* paint, SkIPoint* offset) const
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 Mask Filter, SkMaskFilter generates Mask Alpha from Bitmap. Uses HeapAllocator to reserve memory for dst Pixel Ref. Sets offset to top-left position for dst for alignment with Bitmap; (0, 0) unless SkMaskFilter generates mask.
Parameters
dst |
holds Pixel Ref to fill with alpha layer |
paint |
holds optional Mask Filter; may be nullptr |
offset |
top-left position for dst; may be nullptr |
Return Value
true if Alpha layer was constructed in dst Pixel Ref
Example
See Also
bool extractAlpha(SkBitmap* dst, const SkPaint* paint, Allocator* allocator, SkIPoint* offset) const
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 Mask Filter, SkMaskFilter generates Mask Alpha from Bitmap. 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 Bitmap; (0, 0) unless SkMaskFilter generates mask.
Parameters
dst |
holds Pixel Ref to fill with alpha layer |
paint |
holds optional Mask Filter; may be nullptr |
allocator |
function to reserve memory for Pixel Ref; may be nullptr |
offset |
top-left position for dst; may be nullptr |
Return Value
true if Alpha layer was constructed in dst Pixel Ref
Example
See Also
peekPixels
bool peekPixels(SkPixmap* pixmap) const
Copies Bitmap 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 Bitmap.
Parameters
pixmap |
storage for pixel state if pixels are readable; otherwise, ignored |
Return Value
true if Bitmap has direct access to pixels
Example
Example Output
------
-xxx--
x---x-
----x-
---x--
--x---
--x---
------
--x---
--x---
------
See Also
pixmap installPixels[2][3] readPixels[2][3][4] writePixels[2][3]
Utility
| Topic | Description |
|---|---|
| ComputeIsOpaque | returns true if all pixels are opaque |
| computeByteSize | returns size required for pixels |
| getGenerationID | returns unique ID |
| readyToDraw | returns true if address of pixels is not nullptr |
| swap | exchanges Bitmap pair |
| validate | asserts if Bitmap is invalid (debug only) |
validate
void validate() const;
Asserts if internal values are illegal or inconsistent. Only available if SK_DEBUG is defined at compile time.