skia2/site/user/api/SkPixmap_Reference.md

SkPixmap Reference

Pixmap

Class SkPixmap

Pixmap provides a utility to pair SkImageInfo with pixels and row bytes. Pixmap is a low level class which provides convenience functions to access raster destinations. Canvas can not draw Pixmap, nor does Pixmap provide a direct drawing destination.

Use Bitmap to draw pixels referenced by Pixmap; use Surface to draw into pixels referenced by Pixmap.

Pixmap does not try to manage the lifetime of the pixel memory. Use Pixel Ref to manage pixel memory; Pixel Ref is safe across threads.

Overview

Subtopics

topics	description
Image Info Access	Returns all or part of Image Info.
Initialization	Sets fields for use.
Reader	Examine pixel value.
Writer	Copy to pixel values.
Readable Address	Returns read only pixels.
Writable Address	Returns writable pixels.

Constructors

	description
SkPixmap()	Constructs with default values.
SkPixmap(const SkImageInfo& info, const void* addr, size t rowBytes)	Constructs from Image Info, pixels.

Member Functions

function	description
addr	Returns readable pixel address as void pointer.
addr16	Returns readable pixel address as 16-bit pointer.
addr32	Returns readable pixel address as 32-bit pointer.
addr64	Returns readable pixel address as 64-bit pointer.
addr8	Returns readable pixel address as 8-bit pointer.
addrF16	Returns readable pixel component address as 16-bit pointer.
alphaType	Returns Image Info Alpha Type.
bounds	Returns width and height as Rectangle.
colorSpace	Returns Image Info Color Space.
colorType	Returns Image Info Color Type.
computeByteSize	Returns size required for pixels.
computeIsOpaque	Returns true if all pixels are opaque.
erase	Writes Color to pixels.
extractSubset	Sets pointer to portion of original.
getColor	Returns one pixel as Unpremultiplied Color.
height	Returns pixel row count.
info	Returns Image Info.
isOpaque	Returns true if Image Info describes opaque pixels.
readPixels	Copies and converts pixels.
reset	Reuses existing Pixmap with replacement values.
rowBytes	Returns interval between rows in bytes.
rowBytesAsPixels	Returns interval between rows in pixels.
scalePixels	Scales and converts pixels.
setColorSpace	Sets Image Info Color Space.
shiftPerPixel	Returns bit shift from pixels to bytes.
width	Returns pixel column count.
writable addr	Returns writable pixel address as void pointer.
writable addr16	Returns writable pixel address as 16-bit pointer.
writable addr32	Returns writable pixel address as 32-bit pointer.
writable addr64	Returns writable pixel address as 64-bit pointer.
writable addr8	Returns writable pixel address as 8-bit pointer.
writable addrF16	Returns writable pixel component address as 16-bit pointer.

Initialization

SkPixmap

SkPixmap()

Creates an empty Pixmap without pixels, with kUnknown SkColorType, with kUnknown SkAlphaType, and with a width and height of zero. Use reset to associate pixels, SkColorType, SkAlphaType, width, and height after Pixmap has been created.

Return Value

empty Pixmap

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

SkPixmap(const SkImageInfo& info, const void* addr, size t rowBytes) reset SkAlphaType SkColorType

---

SkPixmap

SkPixmap(const SkImageInfo& info, const void* addr, size_t rowBytes)

Creates Pixmap from info width, height, SkAlphaType, and SkColorType. addr points to pixels, or nullptr. rowBytes should be info.width times info.bytesPerPixel(), or larger.

No parameter checking is performed; it is up to the caller to ensure that addr and rowBytes agree with info.

The memory lifetime of pixels is managed by the caller. When Pixmap goes out of scope, addr is unaffected.

Pixmap may be later modified by reset to change its size, pixel type, or storage.

Parameters

info	width, height, SkAlphaType, SkColorType of Image Info
addr	pointer to pixels allocated by caller; may be nullptr
rowBytes	size of one row of addr; width times pixel size, or larger

Return Value

initialized Pixmap

Example

SkImage::MakeRasterCopy takes const SkPixmap& as an argument. The example constructs a SkPixmap from the brace-delimited parameters.

Example Output

image alpha only = false
copy alpha only = true

See Also

SkPixmap() reset SkAlphaType SkColorType

---

reset

void reset()

Sets width, height, row bytes to zero; pixel address to nullptr; SkColorType to kUnknown SkColorType; and SkAlphaType to kUnknown SkAlphaType.

The prior pixels are unaffected; it is up to the caller to release pixels memory if desired.

Example

Example Output

width: 25  height: 35  color: kRGBA_8888_SkColorType  alpha: kOpaque_SkAlphaType
width:  0  height:  0  color: kUnknown_SkColorType  alpha: kUnknown_SkAlphaType

See Also

SkPixmap() SkAlphaType SkColorType

---

void reset(const SkImageInfo& info, const void* addr, size_t rowBytes)

Sets width, height, SkAlphaType, and SkColorType from info. Sets pixel address from addr, which may be nullptr. Sets row bytes from rowBytes, which should be info.width times info.bytesPerPixel(), or larger.

Does not check addr. Asserts if built with SK_DEBUG defined and if rowBytes is too small to hold one row of pixels.

The memory lifetime pixels are managed by the caller. When Pixmap goes out of scope, addr is unaffected.

Parameters

info	width, height, SkAlphaType, SkColorType of Image Info
addr	pointer to pixels allocated by caller; may be nullptr
rowBytes	size of one row of addr; width times pixel size, or larger

Example

See Also

SkPixmap(const SkImageInfo& info, const void* addr, size t rowBytes) reset SkAlphaType SkColorType

---

setColorSpace

void setColorSpace(sk_sp<SkColorSpace> colorSpace)

Changes Color Space in Image Info; preserves width, height, SkAlphaType, and SkColorType in Image, and leaves pixel address and row bytes unchanged. Color Space reference count is incremented.

Parameters

colorSpace

Color Space moved to Image Info

Example

Example Output

is unique
is not unique

See Also

Color Space SkImageInfo::makeColorSpace

---

bool SK_WARN_UNUSED_RESULT reset(const SkMask& mask)

Sets width, height, pixel address, and row bytes to Mask properties, if Mask format is SkMask::kA8 Format; and returns true. Otherwise sets width, height, row bytes to zero; pixel address to nullptr; SkColorType to kUnknown SkColorType; and SkAlphaType to kUnknown SkAlphaType; and returns false.

Failing to read the return value generates a compile time warning.

Parameters

mask	Mask containing pixels and dimensions

Return Value

true if set to Mask properties

Example

Example Output

success: true  width: 2 height: 2
success: false width: 0 height: 0

See Also

Mask reset

---

extractSubset

bool SK_WARN_UNUSED_RESULT extractSubset(SkPixmap* subset, const SkIRect& area) const

Sets subset width, height, pixel address to intersection of Pixmap with area, if intersection is not empty; and return true. Otherwise, leave subset unchanged and return false.

Failing to read the return value generates a compile time warning.

Parameters

subset	storage for width, height, pixel address of intersection
area	bounds to intersect with Pixmap

Return Value

true if intersection of Pixmap and area is not empty

Example

See Also

reset SkIRect::intersect

---

Image Info Access

info

const SkImageInfo& info() const

Returns width, height, Alpha Type, Color Type, and Color Space.

Return Value

reference to ImageInfo

Example

Example Output

width: 384 height: 384 color: BGRA_8888 alpha: Opaque

See Also

Image Info

---

rowBytes

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. It is up to the Bitmap creator to ensure that row bytes is a useful value.

Return Value

byte length of pixel row

Example

Example Output

rowBytes: 2 minRowBytes: 4
rowBytes: 8 minRowBytes: 4

See Also

addr info SkImageInfo::minRowBytes

---

addr

const void* addr() const

Returns pixel address, the base address corresponding to the pixel origin.

It is up to the Pixmap creator to ensure that pixel address is a useful value.

Return Value

pixel address

Example

Example Output

#Volatile
pixels address: 0x7f2a440bb010
inset address:  0x7f2a440fb210

See Also

addr(int x, int y) addr8 addr16 addr32 addr64 info rowBytes

---

width

int width() const

Returns pixel count in each pixel row. Should be equal or less than:

rowBytes / info.bytesPerPixel().

Return Value

pixel width in Image Info

Example

Example Output

pixmap width: 16  info width: 16

See Also

height SkImageInfo::width()

---

height

int height() const

Returns pixel row count.

Return Value

pixel height in Image Info

Example

Example Output

pixmap height: 32  info height: 32

See Also

width ImageInfo::height()

---

colorType

SkColorType colorType() const

Returns Color Type, one of: kUnknown SkColorType, kAlpha 8 SkColorType, kRGB 565 SkColorType, kARGB 4444 SkColorType, kRGBA 8888 SkColorType, kBGRA 8888 SkColorType, kGray 8 SkColorType, kRGBA F16 SkColorType.

Return Value

Color Type in Image Info

Example

Example Output

color type: kAlpha_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 associated with Image Info. The reference count of Color Space is unchanged. The returned Color Space is immutable.

Return Value

Color Space, the range of colors, in Image Info

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

---

isOpaque

bool isOpaque() const

Returns true if Alpha Type is kOpaque SkAlphaType. Does not check if Color Type allows Alpha, or if any pixel value has transparency.

Return Value

true if Image Info has opaque Alpha Type

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

---

bounds

SkIRect bounds() const

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

Return Value

integral rectangle from origin to width and height

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 IRect

---

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 SkImageInfo::bytesPerPixel

---

shiftPerPixel

int shiftPerPixel() const

Returns bit shift converting row bytes to row pixels. Returns zero for kUnknown SkColorType.

Return Value

one of: 0, 1, 2, 3; left shift to convert pixels to bytes

Example

Example Output

color: kUnknown_SkColorType   bytesPerPixel: 0 shiftPerPixel: 0
color: kAlpha_SkColorType     bytesPerPixel: 1 shiftPerPixel: 0
color: kRGB_565_SkColorType   bytesPerPixel: 2 shiftPerPixel: 1
color: kARGB_4444_SkColorType bytesPerPixel: 2 shiftPerPixel: 1
color: kRGBA_8888_SkColorType bytesPerPixel: 4 shiftPerPixel: 2
color: kBGRA_8888_SkColorType bytesPerPixel: 4 shiftPerPixel: 2
color: kGray_8_SkColorType    bytesPerPixel: 1 shiftPerPixel: 0
color: kRGBA_F16_SkColorType  bytesPerPixel: 8 shiftPerPixel: 3

See Also

rowBytes rowBytesAsPixels width SkImageInfo::bytesPerPixel

---

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

---

Reader

computeIsOpaque

bool computeIsOpaque() const

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.

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

---

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

addr readPixels

---

Readable Address

const void* addr(int x, int y) const

Returns readable pixel address at (x, y). Returns nullptr if Pixel Ref is nullptr.

Input is not validated: out of bounds values of x or y trigger an assert() if built with SK_DEBUG defined. Returns nullptr if Color Type is kUnknown SkColorType.

Performs a lookup of pixel size; for better performance, call one of: addr8, addr16, addr32, addr64, or addrF16.

Parameters

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

Return Value

readable generic pointer to pixel

Example

Example Output

pixmap.addr(1, 2) == &storage[1 + 2 * w]

See Also

addr8 addr16 addr32 addr64 addrF16 getColor writable addr SkBitmap::getAddr

---

addr8

const uint8_t* addr8() const

Returns readable base pixel address. Result is addressable as unsigned 8-bit bytes. Will trigger an assert() if Color Type is not kAlpha 8 SkColorType or kGray 8 SkColorType, and is built with SK_DEBUG defined.

One byte corresponds to one pixel.

Return Value

readable unsigned 8-bit pointer to pixels

Example

Example Output

pixmap.addr8() == storage

See Also

addr addr16 addr32 addr64 addrF16 getColor writable addr writable addr8

---

addr16

const uint16_t* addr16() const

Returns readable base pixel address. Result is addressable as unsigned 16-bit words. Will trigger an assert() if Color Type is not kRGB 565 SkColorType or kARGB 4444 SkColorType, and is built with SK_DEBUG defined.

One word corresponds to one pixel.

Return Value

readable unsigned 16-bit pointer to pixels

Example

Example Output

pixmap.addr16() == storage

See Also

addr addr8 addr32 addr64 addrF16 getColor writable addr writable addr16

---

addr32

const uint32_t* addr32() const

Returns readable base pixel address. Result is addressable as unsigned 32-bit words. Will trigger an assert() if Color Type is not kRGBA 8888 SkColorType or kBGRA 8888 SkColorType, and is built with SK_DEBUG defined.

One word corresponds to one pixel.

Return Value

readable unsigned 32-bit pointer to pixels

Example

Example Output

pixmap.addr32() == storage

See Also

addr addr8 addr16 addr64 addrF16 getColor writable addr writable addr32

---

addr64

const uint64_t* addr64() const

Returns readable base pixel address. Result is addressable as unsigned 64-bit words. Will trigger an assert() if Color Type is not kRGBA F16 SkColorType and is built with SK_DEBUG defined.

One word corresponds to one pixel.

Return Value

readable unsigned 64-bit pointer to pixels

Example

Example Output

pixmap.addr64() == storage

See Also

addr addr8 addr16 addr32 addrF16 getColor writable addr writable addr64

---

addrF16

const uint16_t* addrF16() const

Returns readable base pixel address. Result is addressable as unsigned 16-bit words. Will trigger an assert() if Color Type is not kRGBA F16 SkColorType and is built with SK_DEBUG defined.

Each word represents one color component encoded as a half float. Four words correspond to one pixel.

Return Value

readable unsigned 16-bit pointer to first component of pixels

Example

Example Output

pixmap.addrF16() == storage

See Also

addr addr8 addr16 addr32 addr64 getColor writable addr writable addrF16

---

const uint8_t* addr8(int x, int y) const

Returns readable pixel address at (x, y).

Input is not validated: out of bounds values of x or y trigger an assert() if built with SK_DEBUG defined.

Will trigger an assert() if Color Type is not kAlpha 8 SkColorType or kGray 8 SkColorType, and is built with SK_DEBUG defined.

Parameters

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

Return Value

readable unsigned 8-bit pointer to pixel at (x, y)

Example

Example Output

pixmap.addr8(1, 2) == &storage[1 + 2 * w]

See Also

addr addr16 addr32 addr64 addrF16 getColor writable addr writable addr8

---

const uint16_t* addr16(int x, int y) const

Returns readable pixel address at (x, y).

Input is not validated: out of bounds values of x or y trigger an assert() if built with SK_DEBUG defined.

Will trigger an assert() if Color Type is not kRGB 565 SkColorType or kARGB 4444 SkColorType, and is built with SK_DEBUG defined.

Parameters

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

Return Value

readable unsigned 16-bit pointer to pixel at (x, y)

Example

Example Output

pixmap.addr16(1, 2) == &storage[1 + 2 * w]

See Also

addr addr8 addr32 addr64 addrF16 getColor writable addr writable addr16

---

const uint32_t* addr32(int x, int y) const

Returns readable pixel address at (x, y).

Input is not validated: out of bounds values of x or y trigger an assert() if built with SK_DEBUG defined.

Will trigger an assert() if Color Type is not kRGBA 8888 SkColorType or kBGRA 8888 SkColorType, and is built with SK_DEBUG defined.

Parameters

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

Return Value

readable unsigned 32-bit pointer to pixel at (x, y)

Example

Example Output

pixmap.addr32(1, 2) == &storage[1 + 2 * w]

See Also

addr addr8 addr16 addr64 addrF16 getColor writable addr writable addr64

---

const uint64_t* addr64(int x, int y) const

Returns readable pixel address at (x, y).

Input is not validated: out of bounds values of x or y trigger an assert() if built with SK_DEBUG defined.

Will trigger an assert() if Color Type is not kRGBA F16 SkColorType and is built with SK_DEBUG defined.

Parameters

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

Return Value

readable unsigned 64-bit pointer to pixel at (x, y)

Example

Example Output

pixmap.addr64(1, 2) == &storage[1 + 2 * w]

See Also

addr addr8 addr16 addr32 addrF16 getColor writable addr writable addr64

---

const uint16_t* addrF16(int x, int y) const

Returns readable pixel address at (x, y).

Input is not validated: out of bounds values of x or y trigger an assert() if built with SK_DEBUG defined.

Will trigger an assert() if Color Type is not kRGBA F16 SkColorType and is built with SK_DEBUG defined.

Each unsigned 16-bit word represents one color component encoded as a half float. Four words correspond to one pixel.

Parameters

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

Return Value

readable unsigned 16-bit pointer to pixel component at (x, y)

Example

Example Output

pixmap.addrF16(1, 2) == &storage[1 * wordsPerPixel + 2 * rowWords]

See Also

addr addr8 addr16 addr32 addr64 getColor writable addr writable addrF16

---

Writable Address

writable_addr

void* writable_addr() const

Returns writable base pixel address.

Return Value

writable generic base pointer to pixels

Example

Example Output

pixmap.writable_addr() == (void *)storage
pixmap.getColor(0, 1) == 0x00000000
pixmap.getColor(0, 0) == 0xFFFFFFFF

See Also

writable addr8 writable addr16 writable addr32 writable addr64 writable addrF16 addr

---

void* writable_addr(int x, int y) const

Returns writable pixel address at (x, y).

Input is not validated: out of bounds values of x or y trigger an assert() if built with SK_DEBUG defined. Returns zero if Color Type is kUnknown SkColorType.

Parameters

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

Return Value

writable generic pointer to pixel

Example

Example Output

pixmap.writable_addr() == (void *)storage
pixmap.getColor(0, 0) == 0x00000000
pixmap.getColor(1, 2) == 0xFFFFFFFF

See Also

writable addr8 writable addr16 writable addr32 writable addr64 writable addrF16 addr

---

writable_addr8

uint8_t* writable_addr8(int x, int y) const

Returns writable pixel address at (x, y). Result is addressable as unsigned 8-bit bytes. Will trigger an assert() if Color Type is not kAlpha 8 SkColorType or kGray 8 SkColorType, and is built with SK_DEBUG defined.

One byte corresponds to one pixel.

Parameters

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

Return Value

writable unsigned 8-bit pointer to pixels

Example

Altering pixels after drawing Bitmap is not guaranteed to affect subsequent drawing on all platforms. Adding a second SkBitmap::installPixels after editing pixel memory is safer.

See Also

writable addr writable addr16 writable addr32 writable addr64 writable addrF16 addr addr8

---

writable_addr16

uint16_t* writable_addr16(int x, int y) const

Returns writable addr pixel address at (x, y). Result is addressable as unsigned 16-bit words. Will trigger an assert() if Color Type is not kRGB 565 SkColorType or kARGB 4444 SkColorType, and is built with SK_DEBUG defined.

One word corresponds to one pixel.

Parameters

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

Return Value

writable unsigned 16-bit pointer to pixel

Example

Draw a five by five bitmap, and draw it again with a center black pixel. The low nibble of the 16-bit word is Alpha.

See Also

writable addr writable addr8 writable addr32 writable addr64 writable addrF16 addr addr16

---

writable_addr32

uint32_t* writable_addr32(int x, int y) const

Returns writable pixel address at (x, y). Result is addressable as unsigned 32-bit words. Will trigger an assert() if Color Type is not kRGBA 8888 SkColorType or kBGRA 8888 SkColorType, and is built with SK_DEBUG defined.

One word corresponds to one pixel.

Parameters

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

Return Value

writable unsigned 32-bit pointer to pixel

Example

See Also

writable addr writable addr8 writable addr16 writable addr64 writable addrF16 addr addr32

---

writable_addr64

uint64_t* writable_addr64(int x, int y) const

Returns writable pixel address at (x, y). Result is addressable as unsigned 64-bit words. Will trigger an assert() if Color Type is not kRGBA F16 SkColorType and is built with SK_DEBUG defined.

One word corresponds to one pixel.

Parameters

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

Return Value

writable unsigned 64-bit pointer to pixel

Example

See Also

writable addr writable addr8 writable addr16 writable addr32 writable addrF16 addr addr64

---

writable_addrF16

uint16_t* writable_addrF16(int x, int y) const

Returns writable pixel address at (x, y). Result is addressable as unsigned 16-bit words. Will trigger an assert() if Color Type is not kRGBA F16 SkColorType and is built with SK_DEBUG defined.

Each word represents one color component encoded as a half float. Four words correspond to one pixel.

Parameters

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

Return Value

writable unsigned 16-bit pointer to first component of pixel

Example

Left bitmap is drawn with two pixels defined in half float format. Right bitmap is drawn after overwriting bottom half float color with top half float color.

See Also

writable addr writable addr8 writable addr16 writable addr32 writable addr64 addr addrF16

---

Writer

readPixels

bool readPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes, int srcX, int srcY,
                SkTransferFunctionBehavior behavior) const

Copies a Rect of pixels to dstPixels. Copy starts at (srcX, srcY), and does not exceed (this->width, this->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, or dstRowBytes is less than dstInfo.minRowBytes.

Pixels are copied only if pixel conversion is possible. If this->colorType is kGray 8 SkColorType, or kAlpha 8 SkColorType; dstInfo.colorType must match. If this->colorType is kGray 8 SkColorType, dstInfo.colorSpace must match. If this->alphaType is kOpaque SkAlphaType, dstInfo.alphaType must match. If this->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) >= this->width, or ifabs(srcY) >= this->height.

If behavior is SkTransferFunctionBehavior::kRespect: converts source pixels to a linear space before converting to dstInfo. If behavior is SkTransferFunctionBehavior::kIgnore: source pixels are treated as if they are linear, regardless of how they are encoded.

Parameters

dstInfo	destination width, height, Color Type, Alpha Type, Color Space
dstPixels	destination pixel storage
dstRowBytes	destination row length
srcX	column index whose absolute value is less than width
srcY	row index whose absolute value is less than height
behavior	one of: SkTransferFunctionBehavior::kRespect, SkTransferFunctionBehavior::kIgnore

Return Value

true if pixels are copied to dstPixels

Example

See Also

erase SkBitmap::readPixels SkCanvas::drawBitmap SkCanvas::readPixels SkImage::readPixels SkSurface::readPixels

---

bool readPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes) const

Copies a Rect of pixels to dstPixels. Copy starts at (0, 0), and does not exceed (this->width, this->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, or dstRowBytes is less than dstInfo.minRowBytes.

Pixels are copied only if pixel conversion is possible. If this->colorType is kGray 8 SkColorType, or kAlpha 8 SkColorType; dstInfo.colorType must match. If this->colorType is kGray 8 SkColorType, dstInfo.colorSpace must match. If this->alphaType is kOpaque SkAlphaType, dstInfo.alphaType must match. If this->colorSpace is nullptr, dstInfo.colorSpace must match. Returns false if pixel conversion is not possible.

Returns false if this->width or this->height is zero or negative.

Parameters

dstInfo	destination width, height, Color Type, Alpha Type, Color Space
dstPixels	destination pixel storage
dstRowBytes	destination row length

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

erase SkBitmap::readPixels SkCanvas::drawBitmap SkCanvas::readPixels SkImage::readPixels SkSurface::readPixels

---

bool readPixels(const SkImageInfo& dstInfo, void* dstPixels, size_t dstRowBytes, int srcX, int srcY) const

Copies a Rect of pixels to dstPixels. Copy starts at (srcX, srcY), and does not exceed (this->width, this->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, or dstRowBytes is less than dstInfo.minRowBytes.

Pixels are copied only if pixel conversion is possible. If this->colorType is kGray 8 SkColorType, or kAlpha 8 SkColorType; dstInfo.colorType must match. If this->colorType is kGray 8 SkColorType, dstInfo.colorSpace must match. If this->alphaType is kOpaque SkAlphaType, dstInfo.alphaType must match. If this->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 this->width or this->height is zero or negative. Returns false if:

abs(srcX) >= this->width, or ifabs(srcY) >= this->height.

Parameters

dstInfo	destination width, height, Color Type, Alpha Type, Color Space
dstPixels	destination pixel storage
dstRowBytes	destination row length
srcX	column index whose absolute value is less than width
srcY	row index whose absolute value is less than height

Return Value

true if pixels are copied to dstPixels

Example

See Also

erase SkBitmap::readPixels SkCanvas::drawBitmap SkCanvas::readPixels SkImage::readPixels SkSurface::readPixels

---

bool readPixels(const SkPixmap& dst, int srcX, int srcY) const

Copies a Rect of pixels to dst. Copy starts at (srcX, srcY), and does not exceed (this->width, this->height). dst specifies width, height, Color Type, Alpha Type, and Color Space of destination. Returns true if pixels are copied. Returns false if dst.addr equals nullptr, or dst.rowBytes is less than dst SkImageInfo::minRowBytes.

Pixels are copied only if pixel conversion is possible. If this->colorType is kGray 8 SkColorType, or kAlpha 8 SkColorType; dst.info.colorType must match. If this->colorType is kGray 8 SkColorType, dst.info.colorSpace must match. If this->alphaType is kOpaque SkAlphaType, dst.info.alphaType must match. If this->colorSpace is nullptr, dst.info.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 this->width or this->height is zero or negative. Returns false if:

abs(srcX) >= this->width, or ifabs(srcY) >= this->height.

Parameters

dst	Image Info and pixel address to write to
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

erase SkBitmap::readPixels SkCanvas::drawBitmap SkCanvas::readPixels SkImage::readPixels SkSurface::readPixels

---

bool readPixels(const SkPixmap& dst) const

Copies pixels inside bounds to dst. dst specifies width, height, Color Type, Alpha Type, and Color Space of destination. Returns true if pixels are copied. Returns false if dst.addr equals nullptr, or dst.rowBytes is less than dst SkImageInfo::minRowBytes.

Pixels are copied only if pixel conversion is possible. If this->colorType is kGray 8 SkColorType, or kAlpha 8 SkColorType; dst Color Type must match. If this->colorType is kGray 8 SkColorType, dst Color Space must match. If this->alphaType is kOpaque SkAlphaType, dst Alpha Type must match. If this->colorSpace is nullptr, dst Color Space must match. Returns false if pixel conversion is not possible. Returns false if this->width or this->height is zero or negative.

Parameters

dst	Image Info and pixel address to write to

Return Value

true if pixels are copied to dst

Example

See Also

erase SkBitmap::readPixels SkCanvas::drawBitmap SkCanvas::readPixels SkImage::readPixels SkSurface::readPixels

---

scalePixels

bool scalePixels(const SkPixmap& dst, SkFilterQuality filterQuality) const

Copies this to dst, scaling pixels to fit dst.width and dst.height, and converting pixels to match dst.colorType and dst.alphaType. Returns true if pixels are copied. Returns false if dst.addr is nullptr, or dst.rowBytes is less than dst SkImageInfo::minRowBytes.

Pixels are copied only if pixel conversion is possible. If this->colorType is kGray 8 SkColorType, or kAlpha 8 SkColorType; dst Color Type must match. If this->colorType is kGray 8 SkColorType, dst Color Space must match. If this->alphaType is kOpaque SkAlphaType, dst Alpha Type must match. If this->colorSpace is nullptr, dst Color Space must match. Returns false if pixel conversion is not possible.

Returns false if this->width or this->height is zero or negative.

Scales the image, with filterQuality, to match dst.width and dst.height. filterQuality kNone SkFilterQuality is fastest, typically implemented with Filter Quality Nearest Neighbor. kLow SkFilterQuality is typically implemented with Filter Quality Bilerp. kMedium SkFilterQuality is typically implemented with Filter Quality Bilerp, and Filter Quality MipMap when size is reduced. kHigh SkFilterQuality is slowest, typically implemented with Filter Quality BiCubic.

Parameters

dst	Image Info and pixel address to write to
filterQuality	one of: kNone SkFilterQuality, kLow SkFilterQuality, kMedium SkFilterQuality, kHigh SkFilterQuality

Return Value

true if pixels are copied to dst

Example

See Also

SkCanvas::drawBitmap SkImage::scalePixels

---

erase

bool erase(SkColor color, const SkIRect& subset) const

Writes color to pixels bounded by subset; returns true on success. Returns false if colorType is kUnknown SkColorType, or if subset does not intersect bounds.

Parameters

color	Unpremultiplied Color to write
subset	bounding integer Rect of written pixels

Return Value

true if pixels are changed

Example

See Also

SkBitmap::erase SkCanvas::clear SkCanvas::drawColor

---

bool erase(SkColor color) const

Writes color to pixels inside bounds; returns true on success. Returns false if colorType is kUnknown SkColorType, or if bounds is empty.

Parameters

color

Unpremultiplied Color to write

Return Value

true if pixels are changed

Example

See Also

SkBitmap::erase SkCanvas::clear SkCanvas::drawColor

---

bool erase(const SkColor4f& color, const SkIRect* subset = nullptr) const

Writes color to pixels bounded by subset; returns true on success. if subset is nullptr, writes colors pixels inside bounds. Returns false if colorType is kUnknown SkColorType, if subset is not nullptr and does not intersect bounds, or if subset is nullptr and bounds is empty.

Parameters

color	Unpremultiplied Color to write
subset	bounding integer Rect of pixels to write; may be nullptr

Return Value

true if pixels are changed

Example

See Also

SkBitmap::erase SkCanvas::clear SkCanvas::drawColor

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