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skia2/site/user/api/SkBitmap_Reference.md
Cary Clark 77b3f3aeee Check every word in docs 
This enables checking all text to see if it
either represents a valid reference or is a
word in docs/spelling.txt . Expressions are
checked for validity as well.

There are a few shortcuts (marked with TODO):
- typedefs aren't resolved, so cheats are
added for SkVector and SkIVector.
- operator overload detection is incomplete
- constructor detection is incomplete
- formula definitions aren't detected

Found and fixed a bunch of spelling, usage,
and incorrect or obsolete references.

A few comment changes are needed in
include/core to get this to work, mostly
centered around recent SkPaint/SkFont edits.

TBR=reed@google.com
Docs-Preview: https://skia.org/?cl=167541
Bug: skia:
Change-Id: I2e0d5990105c5a8482b0c0d3e50fd0b330996dd6
Reviewed-on: https://skia-review.googlesource.com/c/167541
Reviewed-by: Cary Clark <caryclark@skia.org>
Auto-Submit: Cary Clark <caryclark@skia.org>
Commit-Queue: Cary Clark <caryclark@skia.org>
2018-11-08 13:27:57 +00:00

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SkBitmap Reference

class SkBitmap {
public:
    SkBitmap();
    SkBitmap(const SkBitmap& src);
    SkBitmap(SkBitmap&& src);
    ~SkBitmap();
    SkBitmap& operator=(const SkBitmap& src);
    SkBitmap& operator=(SkBitmap&& src);
    void swap(SkBitmap& other);
    const SkPixmap& pixmap() const;
    const SkImageInfo& info() const;
    int width() const;
    int height() const;
    SkColorType colorType() const;
    SkAlphaType alphaType() const;
    SkColorSpace* colorSpace() const;
    sk_sp<SkColorSpace> refColorSpace() const;
    int bytesPerPixel() const;
    int rowBytesAsPixels() const;
    int shiftPerPixel() const;
    bool empty() const;
    bool isNull() const;
    bool drawsNothing() const;
    size_t rowBytes() const;
    bool setAlphaType(SkAlphaType alphaType);
    void* getPixels() const;
    size_t computeByteSize() const;
    bool isImmutable() const;
    void setImmutable();
    bool isOpaque() const;
    bool isVolatile() const;
    void setIsVolatile(bool isVolatile);
    void reset();
    static bool ComputeIsOpaque(const SkBitmap& bm);
    void getBounds(SkRect* bounds) const;
    void getBounds(SkIRect* bounds) const;
    SkIRect bounds() const;
    SkISize dimensions() const;
    SkIRect getSubset() const;
    bool setInfo(const SkImageInfo& imageInfo, size_t rowBytes = 0);

    enum AllocFlags {
        kZeroPixels_AllocFlag = 1 << 0,
    };

    bool tryAllocPixelsFlags(const SkImageInfo& info, uint32_t flags);
    void allocPixelsFlags(const SkImageInfo& info, uint32_t flags);
    bool tryAllocPixels(const SkImageInfo& info, size_t rowBytes);
    void allocPixels(const SkImageInfo& info, size_t rowBytes);
    bool tryAllocPixels(const SkImageInfo& info);
    void allocPixels(const SkImageInfo& info);
    bool tryAllocN32Pixels(int width, int height, bool isOpaque = false);
    void allocN32Pixels(int width, int height, bool isOpaque = false);
    bool installPixels(const SkImageInfo& info, void* pixels, size_t rowBytes,
                       void (*releaseProc)(void* addr, void* context), void* context);
    bool installPixels(const SkImageInfo& info, void* pixels, size_t rowBytes);
    bool installPixels(const SkPixmap& pixmap);
    bool installMaskPixels(const SkMask& mask);
    void setPixels(void* pixels);
    bool tryAllocPixels();
    void allocPixels();
    bool tryAllocPixels(Allocator* allocator);
    void allocPixels(Allocator* allocator);
    SkPixelRef* pixelRef() const;
    SkIPoint pixelRefOrigin() const;
    void setPixelRef(sk_sp<SkPixelRef> pixelRef, int dx, int dy);
    bool readyToDraw() const;
    uint32_t getGenerationID() const;
    void notifyPixelsChanged() const;
    void eraseColor(SkColor c) const;
    void eraseARGB(U8CPU a, U8CPU r, U8CPU g, U8CPU b) const;
    void erase(SkColor c, const SkIRect& area) const;
    void eraseArea(const SkIRect& area, SkColor c) const;
    SkColor getColor(int x, int y) const;
    float getAlphaf(int x, int y) const;
    void* getAddr(int x, int y) const;
    uint32_t* getAddr32(int x, int y) const;
    uint16_t* getAddr16(int x, int y) const;
    uint8_t* getAddr8(int x, int y) const;
    bool extractSubset(SkBitmap* dst, const SkIRect& subset) const;
    bool readPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes,
                    int srcX, int srcY) const;
    bool readPixels(const SkPixmap& dst, int srcX, int srcY) const;
    bool readPixels(const SkPixmap& dst) const;
    bool writePixels(const SkPixmap& src, int dstX, int dstY);
    bool writePixels(const SkPixmap& src);
    bool extractAlpha(SkBitmap* dst) const;
    bool extractAlpha(SkBitmap* dst, const SkPaint* paint,
                      SkIPoint* offset) const;
    bool extractAlpha(SkBitmap* dst, const SkPaint* paint, Allocator* allocator,
                      SkIPoint* offset) const;
    bool peekPixels(SkPixmap* pixmap) const;
    void validate() const;

    class Allocator : public SkRefCnt {
    public:
        virtual bool allocPixelRef(SkBitmap* bitmap) = 0;
    };

    class HeapAllocator : public Allocator {
    public:
        bool allocPixelRef(SkBitmap* bitmap) override;
    };
};

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.

    class Allocator : public SkRefCnt {
    public:
        virtual bool allocPixelRef(SkBitmap* bitmap) = 0;
    };

Abstract subclass of HeapAllocator.

virtual bool allocPixelRef(SkBitmap* bitmap) = 0

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.

Parameters

bitmap SkBitmap containing SkImageInfo as input, and SkPixelRef as output

Return Value

true if SkPixelRef was allocated

See Also

HeapAllocator

    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.

bool allocPixelRef(SkBitmap* bitmap) override

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.

Parameters

bitmap SkBitmap containing SkImageInfo as input, and SkPixelRef as output

Return Value

true if pixels are allocated

Example

Example Output

#Volatile
pixel address = (nil)
pixel address = 0x560ddd0ac670

See Also

SkBitmap::Allocator tryAllocPixels

SkBitmap()

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.

Return Value

empty SkBitmap

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

setInfo

SkBitmap(const SkBitmap& src)

Copies settings from src to returned SkBitmap. Shares pixels if src has pixels allocated, so both bitmaps reference the same pixels.

Parameters

src SkBitmap to copy SkImageInfo, and share SkPixelRef

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&& src)

Copies settings from src to returned SkBitmap. Moves ownership of src pixels to SkBitmap.

Parameters

src SkBitmap to copy SkImageInfo, and reassign SkPixelRef

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()

Decrements SkPixelRef reference count, if SkPixelRef is not nullptr.

See Also

Pixel_Ref

SkBitmap& operator=(const SkBitmap& src)

Copies settings from src to returned SkBitmap. Shares pixels if src has pixels allocated, so both bitmaps reference the same pixels.

Parameters

src SkBitmap to copy SkImageInfo, and share SkPixelRef

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& operator=(SkBitmap&& src)

Copies settings from src to returned SkBitmap. Moves ownership of src pixels to SkBitmap.

Parameters

src SkBitmap to copy SkImageInfo, and reassign SkPixelRef

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

void swap(SkBitmap& other)

Swaps the fields of the two bitmaps.

Parameters

other SkBitmap 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) SkBitmap(SkBitmap&& src)operator=(SkBitmap&& src)

const SkPixmap& pixmap() const

Returns a constant reference to the SkPixmap holding the SkBitmap pixel address, row bytes, and SkImageInfo.

Return Value

reference to SkPixmap describing this SkBitmap

Example

Example Output

----------
---xx-----
--x--x----
--x-------
--xx------
--x-x---x-
-x---x--x-
-x----xx--
-xx---x---
--xxxx-xx-
----------

See Also

peekPixels installPixels readPixels writePixels

const SkImageInfo& info() const

Returns width, height, SkAlphaType, SkColorType, and SkColorSpace.

Return Value

reference to SkImageInfo

Example

Example Output

width: 56 height: 56 color: BGRA_8888 alpha: Opaque

See Also

Image_Info

int width() const

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.

Return Value

pixel width in Image_Info

Example

Example Output

bitmap width: 16  info width: 16

See Also

height() SkPixelRef::width() SkImageInfo::width()

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 SkImageInfo

Example

Example Output

bitmap height: 32  info height: 32

See Also

width() SkPixelRef::height() SkImageInfo::height()

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

Color_Type in Image_Info

Example

Example Output

color type: kAlpha_8_SkColorType

See Also

alphaType() SkImageInfo::colorType

SkAlphaType alphaType() const

Returns Alpha_Type, one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType .

Return Value

Alpha_Type in Image_Info

Example

Example Output

alpha type: kPremul_SkAlphaType

See Also

colorType() SkImageInfo::alphaType

SkColorSpace* colorSpace() const

Returns SkColorSpace, the range of colors, associated with SkImageInfo. The reference count of SkColorSpace is unchanged. The returned SkColorSpace is immutable.

Return Value

SkColorSpace in SkImageInfo, or nullptr

Example

Example Output

gammaCloseToSRGB: false  gammaIsLinear: true  isSRGB: false

See Also

Color_Space SkImageInfo::colorSpace

sk_sp&lt;SkColorSpace&gt; refColorSpace() const

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.

Return Value

SkColorSpace in SkImageInfo wrapped in a smart pointer

Example

Example Output

gammaCloseToSRGB: false  gammaIsLinear: true  isSRGB: false

See Also

Color_Space SkImageInfo::colorSpace

int bytesPerPixel() const

Returns number of bytes per pixel required by SkColorType. Returns zero if colorType( is kUnknown_SkColorType.

Return Value

bytes in pixel

Example

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

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

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

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

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

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

bool empty() const

Returns true if either width() or height() are zero.

Does not check if SkPixelRef is nullptr; call drawsNothing() to check width(), height(), and SkPixelRef.

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

height() width() drawsNothing

bool isNull() const

Returns true if SkPixelRef is nullptr.

Does not check if width() or height() are zero; call drawsNothing() to check width(), height(), and SkPixelRef.

Return Value

true if no SkPixelRef 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

empty() drawsNothing pixelRef

bool drawsNothing() const

Returns true if width() or height() are zero, or if SkPixelRef is nullptr. If true, SkBitmap 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

empty() isNull pixelRef

size_t rowBytes() const

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.

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

bool setAlphaType(SkAlphaType alphaType)

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.

Parameters

alphaType one of:

kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType

Return Value

true if SkAlphaType is set

Example

See Also

Alpha_Type Color_Type Image_Info setInfo

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

isNull drawsNothing

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

SkImageInfo::computeByteSize

bool isImmutable() const

Returns true if pixels can not change.

Most immutable SkBitmap 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

void setImmutable()

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.

Example

Triggers assert if SK_DEBUG is true, runs fine otherwise.

See Also

isImmutable SkPixelRef::setImmutable SkImage

bool isOpaque() const

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.

Return Value

true if SkImageInfo SkAlphaType is kOpaque_SkAlphaType

Example

Example Output

isOpaque: false
isOpaque: false
isOpaque: true
isOpaque: true

See Also

ComputeIsOpaque SkImageInfo::isOpaque

bool isVolatile() const

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.

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 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.

Parameters

isVolatile true if backing pixels are temporary

Example

See Also

isVolatile

void reset()

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.

Example

Example Output

width:1 height:1 isNull:false
width:0 height:0 isNull:true

See Also

SkBitmap() SkAlphaType SkColorType

static bool ComputeIsOpaque(const SkBitmap& bm)

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.

Parameters

bm SkBitmap to check

Return Value

true if all pixels have opaque values or SkColorType is opaque

Example

Example Output

computeIsOpaque: false
computeIsOpaque: true
computeIsOpaque: false
computeIsOpaque: true

See Also

isOpaque Color_Type Alpha

void getBounds(SkRect* bounds) const

Returns SkRect { 0, 0, width(), height() }.

Parameters

bounds container for floating point rectangle

Example

See Also

bounds()

void getBounds(SkIRect* bounds) const

Returns SkIRect { 0, 0, width(), height() }.

Parameters

bounds container for integral rectangle

Example

See Also

bounds()

SkIRect bounds() const

Returns SkIRect { 0, 0, width(), height() }.

Return Value

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

Example

See Also

getBounds

SkISize dimensions() const

Returns SkISize { width(), height() }.

Return Value

integral size of width() and height()

Example

See Also

height width

SkIRect getSubset() const

Returns the bounds of this bitmap, offset by its SkPixelRef origin.

Return Value

bounds within SkPixelRef bounds

Example

Example Output

source: 0, 0, 512, 512
subset: 100, 100, 412, 412

See Also

extractSubset getBounds

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 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

bool tryAllocPixelsFlags(const SkImageInfo& info, uint32_t flags)

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.

Parameters

info contains width, height, SkAlphaType, SkColorType, SkColorSpace
flags kZeroPixels_AllocFlag, or zero

Return Value

true if pixels allocation is successful

Example

Example Output

bitmap allocation succeeded!

See Also

allocPixelsFlags tryAllocPixels SkMallocPixelRef::MakeZeroed

void allocPixelsFlags(const SkImageInfo& info, uint32_t flags)

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.

Parameters

info contains width, height, SkAlphaType, SkColorType, SkColorSpace
flags kZeroPixels_AllocFlag, or zero

Example

See Also

tryAllocPixelsFlags allocPixels SkMallocPixelRef::MakeZeroed

bool tryAllocPixels(const SkImageInfo& info, size_t rowBytes)

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().

Parameters

info contains width, height, SkAlphaType, SkColorType, SkColorSpace
rowBytes size of pixel row or larger; may be zero

Return Value

true if pixel storage is allocated

Example

See Also

tryAllocPixelsFlags allocPixels SkMallocPixelRef::MakeAllocate

void allocPixels(const SkImageInfo& info, size_t rowBytes)

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().

Parameters

info contains width, height, SkAlphaType, SkColorType, SkColorSpace
rowBytes size of pixel row or larger; may be zero

Example

See Also

tryAllocPixels allocPixelsFlags SkMallocPixelRef::MakeAllocate

bool tryAllocPixels(const SkImageInfo& info)

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().

Parameters

info contains width, height, SkAlphaType, SkColorType, SkColorSpace

Return Value

true if pixel storage is allocated

Example

See Also

tryAllocPixelsFlags allocPixels SkMallocPixelRef::MakeAllocate

void allocPixels(const SkImageInfo& info)

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().

Parameters

info contains width, height, SkAlphaType, SkColorType, SkColorSpace

Example

See Also

tryAllocPixels allocPixelsFlags SkMallocPixelRef::MakeAllocate

bool tryAllocN32Pixels(int width, int height, bool isOpaque = false)

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.

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 allocN32Pixels SkMallocPixelRef::MakeAllocate

void allocN32Pixels(int width, int height, bool isOpaque = false)

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.

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 tryAllocN32Pixels SkMallocPixelRef::MakeAllocate

bool installPixels(const SkImageInfo& info, void* pixels, size_t rowBytes, void (*releaseProc)
                   (void* addr, void* context) , void* context)

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.

Parameters

info contains width, height, SkAlphaType, SkColorType, SkColorSpace
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 SkImageInfo is set to info

Example

Example Output

before installPixels
releaseProc called
install not successful

See Also

allocPixels

bool installPixels(const SkImageInfo& info, void* pixels, size_t rowBytes)

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.

Parameters

info contains width, height, SkAlphaType, SkColorType, SkColorSpace
pixels address or pixel storage; may be nullptr
rowBytes size of pixel row or larger

Return Value

true if SkImageInfo is set to info

Example

See Also

allocPixels

bool installPixels(const SkPixmap& pixmap)

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.

Parameters

pixmap SkImageInfo, pixel address, and rowBytes()

Return Value

true if SkImageInfo was set to pixmap.info()

Example

Draw a five by five bitmap, and draw it again with a center white pixel.

See Also

allocPixels

bool installMaskPixels(const SkMask& mask)

To be deprecated soon.

void setPixels(void* pixels)

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.

Parameters

pixels address of pixel storage, managed by caller

Example

See Also

installPixels allocPixels

bool tryAllocPixels()

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.

Return Value

true if the allocation succeeds

Example

See Also

allocPixels installPixels setPixels

void allocPixels()

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.

Example

See Also

tryAllocPixels installPixels setPixels

bool tryAllocPixels(Allocator* allocator)

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.

Parameters

allocator instance of SkBitmap::Allocator instantiation

Return Value

true if custom allocator reports success

Example

See Also

allocPixels Allocator Pixel_Ref

void allocPixels(Allocator* allocator)

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.

Parameters

allocator instance of SkBitmap::Allocator instantiation

Example

See Also

allocPixels Allocator Pixel_Ref

SkPixelRef* pixelRef() const

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.

Return Value

SkPixelRef, or nullptr

Example

See Also

getPixels getAddr

SkIPoint pixelRefOrigin() const

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.

Return Value

pixel origin within SkPixelRef

Example

Example Output

source origin: 0, 0
subset origin: 32, 64

See Also

SkPixelRef getSubset setPixelRef

void setPixelRef(sk_sp&lt;SkPixelRef&gt; pixelRef, int dx, int dy)

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.

Parameters

pixelRef SkPixelRef describing pixel address and rowBytes()
dx column offset in SkPixelRef for bitmap origin
dy row offset in SkPixelRef for bitmap origin

Example

See Also

setInfo

bool readyToDraw() const

Returns true if SkBitmap is can be drawn.

Return Value

true if getPixels() is not nullptr

Example

See Also

getPixels drawsNothing

uint32_t getGenerationID() const

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.

Return Value

unique value for pixels in SkPixelRef

Example

Example Output

#Volatile
empty id 0
alloc id 4
erase id 6

See Also

notifyPixelsChanged Pixel_Ref

void notifyPixelsChanged() const

Marks that pixels in SkPixelRef have changed. Subsequent calls to getGenerationID() return a different value.

Example

See Also

getGenerationID isVolatile Pixel_Ref

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 kRGB_565_SkColorType, then 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 erase

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 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.

Parameters

a amount of 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

eraseColor 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 kRGB_565_SkColorType, then 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 SkCanvas::drawRect

void eraseArea(const SkIRect& area, SkColor c) const

Deprecated.

SkColor getColor(int x, int y) const

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.

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

getAlphaf getAddr readPixels

float getAlphaf(int x, int y) const

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).

Parameters

x column index, zero or greater, and less than width()
y row index, zero or greater, and less than height()

Return Value

alpha converted to normalized float

See Also

getColor

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 SkColorType is kUnknown_SkColorType, or SkPixelRef 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 SkPixmap::addr

uint32_t* getAddr32(int x, int y) const

Returns address at (x, y).

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 SkPixmap::addr32

uint16_t* getAddr16(int x, int y) const

Returns address at (x, y).

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 SkPixmap::addr16

uint8_t* getAddr8(int x, int y) const

Returns address at (x, y).

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 SkPixmap::addr8

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 writePixels SkCanvas::drawBitmap

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 has no address
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 if abs(srcX) >= Bitmap width(), or if abs(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

Transferring the gradient from 8 bits per component to 4 bits per component creates visible banding.

See Also

writePixels SkPixmap::readPixels SkCanvas::readPixels SkImage::readPixels SkSurface::readPixels

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 if abs(srcX) >= Bitmap width(), or if abs(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 SkPixmap::readPixels SkCanvas::readPixels SkImage::readPixels SkSurface::readPixels

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 SkPixmap::readPixels SkCanvas::readPixels SkImage::readPixels SkSurface::readPixels

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 if abs(dstX) >= Bitmap width(), or if abs(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

readPixels

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

readPixels

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 SkPixelRef.

Parameters

dst holds SkPixelRef to fill with alpha layer

Return Value

true if alpha layer was constructed in dst SkPixelRef

Example

See Also

extractSubset

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 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.

Parameters

dst holds SkPixelRef to fill with alpha layer
paint holds optional SkMaskFilter; may be nullptr
offset top-left position for dst; may be nullptr

Return Value

true if alpha layer was constructed in dst SkPixelRef

Example

See Also

extractSubset

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 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.

Parameters

dst holds SkPixelRef to fill with alpha layer
paint holds optional SkMaskFilter; may be nullptr
allocator function to reserve memory for SkPixelRef; may be nullptr
offset top-left position for dst; may be nullptr

Return Value

true if alpha layer was constructed in dst SkPixelRef

Example

See Also

extractSubset

bool peekPixels(SkPixmap* pixmap) const

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.

Parameters

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

Return Value

true if SkBitmap has direct access to pixels

Example

Example Output

------
-xxx--
x---x-
----x-
---x--
--x---
--x---
------
--x---
--x---
------

See Also

pixmap installPixels readPixels writePixels

void validate() const;

See Also

SkImageInfo::validate