skia2/site/user/api/SkBitmap_Reference.md

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::Allocator member functions read and modify the structure properties.

Topic	Description
allocPixelRef	allocates pixel memory

    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

HeapAllocator

---

Class SkBitmap::HeapAllocator

Member_Function

SkBitmap::HeapAllocator member functions read and modify the structure properties.

Topic	Description
allocPixelRef	allocates pixel memory

    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

setInfo

---

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

Pixel Ref

---

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] writePixels^[2]

---

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

Image Info

---

width

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()

---

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

Color Type in Image Info

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

Alpha Type in Image Info

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

SkColorSpace::MakeSRGBLinear creates Color Space with linear gamma and an sRGB gamut. This Color Space gamma is not close to sRGB gamma.

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

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

---

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

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

---

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

height width drawsNothing

---

isNull

bool isNull() const

Returns 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

empty drawsNothing pixelRef

---

drawsNothing

bool drawsNothing() const

Returns 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

empty isNull pixelRef

---

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

kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType 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

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

isNull drawsNothing

---

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

SkImageInfo::computeByteSize

---

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

Triggers assert if SK_DEBUG is true, runs fine otherwise.

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

isOpaque ignores whether all pixels are opaque or not.

Example Output

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

See Also

ComputeIsOpaque SkImageInfo::isOpaque

---

isVolatile

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 Pixel Ref.

Return Value

true if marked volatile

Example

Example Output

original is volatile
copy is not volatile

See Also

setIsVolatile

---

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

isVolatile

---

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

isOpaque Color Type Alpha

---

getBounds

void getBounds(SkRect* bounds) const

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

Parameters

bounds

container for floating point rectangle

Example

See Also

bounds

---

void getBounds(SkIRect* bounds) const

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

Parameters

bounds

container for integral rectangle

Example

See Also

bounds

---

bounds

SkIRect bounds() const

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

Return Value

integral rectangle from origin to width and height

Example

See Also

getBounds^[2]

---

dimensions

SkISize dimensions() const

Returns ISize { width, height }.

Return Value

integral size of width and height

Example

See Also

height width

---

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

extractSubset getBounds^[2]

---

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

Topic	Description
allocN32Pixels	allocates compatible ARGB pixels, or aborts
allocPixels	allocates pixels from Image Info, or aborts
	allocPixels(const SkImageInfo& info, size t rowBytes)
	allocPixels(const SkImageInfo& info)
	allocPixels
	allocPixels(Allocator* allocator)
allocPixelsFlags	allocates pixels from Image Info with options, or aborts
installPixels	creates Pixel Ref, with optional release function
	installPixels(const SkImageInfo& info, void* pixels, size t rowBytes, void (*releaseProc) (void* addr, void* context) , void* context)
	installPixels(const SkImageInfo& info, void* pixels, size t rowBytes)
	installPixels(const SkPixmap& pixmap)
tryAllocN32Pixels	allocates compatible ARGB pixels if possible
tryAllocPixels	allocates pixels from Image Info if possible
	tryAllocPixels(const SkImageInfo& info, size t rowBytes)
	tryAllocPixels(const SkImageInfo& info)
	tryAllocPixels
	tryAllocPixels(Allocator* allocator)
tryAllocPixelsFlags	allocates pixels from Image Info with options if possible

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

Text is drawn on a transparent background; drawing the bitmap a second time lets the first draw show through.

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

releaseProc is called immediately because rowBytes is too small for Pixel Ref.

Example Output

before installPixels
releaseProc called
install not successful

See Also

allocPixels^[2][3][4]

---

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

GPU does not support kUnpremul_SkAlphaType, does not assert that it does not.

See Also

allocPixels^[2][3][4]

---

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

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

See Also

allocPixels^[2][3][4]

---

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) 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)

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

Bitmap hosts and draws gray values in set1. tryAllocPixels replaces Pixel Ref and erases it to black, but does not alter set1. setPixels replaces black Pixel Ref with set1.

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

Bitmap hosts and draws gray values in set1. allocPixels replaces Pixel Ref and erases it to black, but does not alter set1. setPixels replaces black Pixel Ref with set2.

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

HeapAllocator limits the maximum size of Bitmap to two gigabytes. Using a custom allocator, this limitation may be relaxed. This example can be modified to allocate an eight gigabyte Bitmap on a 64-bit platform with sufficient memory.

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

getPixels getAddr

---

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

Treating 32-bit data as 8-bit data is unlikely to produce useful results.

See Also

setInfo

---

readyToDraw

bool readyToDraw() const

Returns true if Bitmap is can be drawn.

Return Value

true if getPixels is not nullptr

Example

See Also

getPixels drawsNothing

---

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 Pixel Ref

---

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 erase

---

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

eraseColor erase

---

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 readPixels^[2][3]

---

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] SkPixmap::addr^[2]

---

getAddr32

inline 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^[2][3] SkPixmap::addr32^[2]

---

getAddr16

inline 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^[2][3] SkPixmap::addr16^[2]

---

getAddr8

inline 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^[2][3] 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] writePixels^[2] SkCanvas::drawBitmap

---

readPixels

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

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

See Also

writePixels^[2] SkPixmap::readPixels^[2][3][4] 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] SkPixmap::readPixels^[2][3][4] SkCanvas::readPixels^[2][3] SkImage::readPixels^[2] SkSurface::readPixels^[2][3]

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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] SkPixmap::readPixels^[2][3][4] SkCanvas::readPixels^[2][3] SkImage::readPixels^[2] SkSurface::readPixels^[2][3]

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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

readPixels^[2][3]

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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^[2][3]

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hasHardwareMipMap

bool hasHardwareMipMap() const

For use by Android framework only.

Return Value

true if setHasHardwareMipMap has been called with true

See Also

setHasHardwareMipMap

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setHasHardwareMipMap

void setHasHardwareMipMap(bool hasHardwareMipMap)

For use by Android framework only.

Parameters

hasHardwareMipMap

sets state

See Also

hasHardwareMipMap

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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

extractSubset

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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

extractSubset

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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

extractSubset

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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] writePixels^[2]

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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.

See Also

SkImageInfo::validate

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