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
## Related Function
SkPixmap global, struct, and class related member functions share a topic.
## Constructor
SkPixmap can be constructed or initialized by these functions, including C++ class constructors.
## Member Function
SkPixmap member functions read and modify the structure properties.
## 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[2][3] 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
### Return Value
initialized Pixmap
### Example
#### Example Output
~~~~
image alpha only = false
copy alpha only = true
~~~~
### See Also
SkPixmap() reset[2][3] 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
### Example
### See Also
SkPixmap(const SkImageInfo& info, const void* addr, size t rowBytes) reset[2][3] 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
### Example
#### Example Output
~~~~
is unique
is not unique
~~~~
### See Also
Color Space SkImageInfo::makeColorSpace
---
bool SK_WARN_UNUSED_RESULT reset(const SkMask& mask)
Deprecated.
soon
---
## 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[2][3] SkIRect::intersect[2][3]
---
## 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[2] 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[2] addr16[2] addr32[2] addr64[2] 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, 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
#### 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
~~~~
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_8_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[2] readPixels[2][3][4]
---
## 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[2] addr16[2] addr32[2] addr64[2] addrF16[2] getColor writable addr[2] 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[2] addr16[2] addr32[2] addr64[2] addrF16[2] getColor writable addr[2] 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[2] addr8[2] addr32[2] addr64[2] addrF16[2] getColor writable addr[2] 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[2] addr8[2] addr16[2] addr64[2] addrF16[2] getColor writable addr[2] 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[2] addr8[2] addr16[2] addr32[2] addrF16[2] getColor writable addr[2] 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[2] addr8[2] addr16[2] addr32[2] addr64[2] getColor writable addr[2] 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[2] addr16[2] addr32[2] addr64[2] addrF16[2] getColor writable addr[2] 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[2] addr8[2] addr32[2] addr64[2] addrF16[2] getColor writable addr[2] 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[2] addr8[2] addr16[2] addr64[2] addrF16[2] getColor writable addr[2] 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[2] addr8[2] addr16[2] addr32[2] addrF16[2] getColor writable addr[2] 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[2] addr8[2] addr16[2] addr32[2] addr64[2] getColor writable addr[2] 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[2]
---
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[2]
---
## 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.
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.
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[2] writable addr8 writable addr16 writable addr64 writable addrF16 addr[2] addr32[2]
---
## 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[2] writable addr8 writable addr16 writable addr32 writable addrF16 addr[2] addr64[2]
---
## 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.
| Topic |
Description |
|---|
| erase |
writes Color to pixels |
|
erase(SkColor color, const SkIRect& subset) const |
|
erase(SkColor color) const |
|
erase(const SkColor4f& color, const SkIRect* subset = nullptr) const |
| readPixels |
copies and converts pixels |
|
readPixels(const SkImageInfo& dstInfo, void* dstPixels, size t dstRowBytes) const |
|
readPixels(const SkImageInfo& dstInfo, void* dstPixels, size t dstRowBytes, int srcX, int srcY) const |
|
readPixels(const SkPixmap& dst, int srcX, int srcY) const |
|
readPixels(const SkPixmap& dst) const |
| scalePixels |
scales and converts pixels |
## 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 Pixmap (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, or dstRowBytes is less than dstInfo.minRowBytes.
Pixels are copied only if pixel conversion is possible. If Pixmap colorType is
kGray_8_SkColorType, or kAlpha_8_SkColorType; dstInfo.colorType must match.
If Pixmap colorType is kGray_8_SkColorType, dstInfo.colorSpace must match.
If Pixmap alphaType is kOpaque_SkAlphaType, dstInfo.alphaType must
match. If Pixmap colorSpace is nullptr, dstInfo.colorSpace must match. Returns
false if pixel conversion is not possible.
Returns false if Pixmap width or height is zero or negative.
### Parameters
### 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.
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 Pixmap (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, or dstRowBytes is less than dstInfo.minRowBytes.
Pixels are copied only if pixel conversion is possible. If Pixmap colorType is
kGray_8_SkColorType, or kAlpha_8_SkColorType; dstInfo.colorType must match.
If Pixmap colorType is kGray_8_SkColorType, dstInfo.colorSpace must match.
If Pixmap alphaType is kOpaque_SkAlphaType, dstInfo.alphaType must
match. If Pixmap 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 Pixmap width or height is zero or negative. Returns false if:
abs(srcX) >= Pixmap width,
or ifabs(srcY) >= Pixmap height.
### Parameters
### Return Value
true if pixels are copied to dstPixels
### Example
### See Also
erase[2][3] SkBitmap::readPixels[2][3] SkCanvas::drawBitmap 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 to dst. Copy starts at (srcX, srcY), and does not
exceed Pixmap (width, 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 Pixmap colorType is
kGray_8_SkColorType, or kAlpha_8_SkColorType; dst.info.colorType must match.
If Pixmap colorType is kGray_8_SkColorType, dst.info.colorSpace must match.
If Pixmap alphaType is kOpaque_SkAlphaType, dst.info.alphaType must
match. If Pixmap 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 Pixmap width or height is zero or negative. Returns false if:
abs(srcX) >= Pixmap width,
or ifabs(srcY) >= Pixmap height.
### Parameters
### Return Value
true if pixels are copied to dst
### Example
### See Also
erase[2][3] SkBitmap::readPixels[2][3] SkCanvas::drawBitmap SkCanvas::readPixels[2][3] SkImage::readPixels[2] SkSurface::readPixels[2][3]
---
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 Pixmap colorType is
kGray_8_SkColorType, or kAlpha_8_SkColorType; dst Color Type must match.
If Pixmap colorType is kGray_8_SkColorType, dst Color Space must match.
If Pixmap alphaType is kOpaque_SkAlphaType, dst Alpha Type must
match. If Pixmap colorSpace is nullptr, dst Color Space must match. Returns
false if pixel conversion is not possible.
Returns false if Pixmap width or height is zero or negative.
### Parameters
### Return Value
true if pixels are copied to dst
### Example
### See Also
erase[2][3] SkBitmap::readPixels[2][3] SkCanvas::drawBitmap SkCanvas::readPixels[2][3] SkImage::readPixels[2] SkSurface::readPixels[2][3]
---
## scalePixels
bool scalePixels(const SkPixmap& dst, SkFilterQuality filterQuality) const
Copies Bitmap 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 Pixmap colorType is
kGray_8_SkColorType, or kAlpha_8_SkColorType; dst Color Type must match.
If Pixmap colorType is kGray_8_SkColorType, dst Color Space must match.
If Pixmap alphaType is kOpaque_SkAlphaType, dst Alpha Type must
match. If Pixmap colorSpace is nullptr, dst Color Space must match. Returns
false if pixel conversion is not possible.
Returns false if Bitmap width or 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
### Return Value
true if pixels are scaled to fit 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
### 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
### 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
### Return Value
true if pixels are changed
### Example
### See Also
SkBitmap::erase SkCanvas::clear SkCanvas::drawColor
---