7f644ec996
bookmaker bot checked in more md files with the wrong fiddle hashes. Ravi is landing a CL to preventing it from checking in more errors, for now. Sadly, creating this CL also corrupted the md output -- luckily it was an error that could be detected. But perhaps other errors are going undetected. TMI: The call to fiddlecli wrote the wrong "text" string to SKIRect_isEmpty, first time I've seen that. Running it again generated the correct output. TBR=rmistry@google.com,jcgregario@google.com No-Try: true Docs-Preview: https://skia.org/?cl=142329 Bug: skia:6818 Change-Id: I6b57a4a070991b76a1acc44fb024439defc2d977 Reviewed-on: https://skia-review.googlesource.com/142329 Commit-Queue: Cary Clark <caryclark@google.com> Auto-Submit: Cary Clark <caryclark@google.com> Reviewed-by: Cary Clark <caryclark@google.com>
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SkImageInfo Reference
Image Info
Image Info specifies the dimensions and encoding of the pixels in a Bitmap. The dimensions are integral width and height. The encoding is how pixel bits describe Color Alpha, transparency; Color components red, blue, and green; and Color Space, the range and linearity of colors.
Image Info describes an uncompressed raster pixels. In contrast, Image additionally describes compressed pixels like PNG, and Surface describes destinations on the GPU. Image and Surface may be specified by Image Info, but Image and Surface may not contain Image Info.
Overview
| Topic | Description |
|---|---|
| Constructors | functions that construct SkImageInfo |
| Functions | global and class member functions |
| Operators | operator overloading methods |
| Related Functions | similar member functions grouped together |
Constant
SkImageInfo related constants are defined by enum, enum class, #define, const, and constexpr.
| Topic | Description |
|---|---|
| SkAlphaType | encoding for pixel transparency |
| SkColorType | encoding for pixel color |
| SkYUVColorSpace | color range of YUV pixels |
| kARGB_4444_SkColorType | pixel with 4 bits for alpha, red, green, blue; in 16-bit word |
| kAlpha_8_SkColorType | pixel with Alpha in 8-bit byte |
| kBGRA_8888_SkColorType | pixel with 8 bits for blue, green, red, alpha; in 32-bit word |
| kGray_8_SkColorType | pixel with Grayscale level in 8-bit byte |
| kJPEG_SkYUVColorSpace | describes full range |
| kLastEnum_SkAlphaType | last valid value |
| kLastEnum_SkColorType | last valid value |
| kLastEnum_SkYUVColorSpace | last valid value |
| kN32_SkColorType | native ARGB 32-bit encoding |
| kOpaque_SkAlphaType | pixel is opaque |
| kPremul_SkAlphaType | pixel components are Premultiplied by Alpha |
| kRGBA_1010102_SkColorType | 10 bits for red, green, blue; 2 bits for alpha; in 32-bit word |
| kRGBA_8888_SkColorType | pixel with 8 bits for red, green, blue, alpha; in 32-bit word |
| kRGBA_F16_SkColorType | pixel with half floats for red, green, blue, alpha; in 64-bit word |
| kRGBA_F32_SkColorType | pixel using C float for red, green, blue, alpha; in 128-bit word |
| kRGB_101010x_SkColorType | pixel with 10 bits each for red, green, blue; in 32-bit word |
| kRGB_565_SkColorType | pixel with 5 bits red, 6 bits green, 5 bits blue, in 16-bit word |
| kRGB_888x_SkColorType | pixel with 8 bits each for red, green, blue; in 32-bit word |
| kRec601_SkYUVColorSpace | describes SDTV range |
| kRec709_SkYUVColorSpace | describes HDTV range |
| kUnknown_SkAlphaType | uninitialized |
| kUnknown_SkColorType | uninitialized |
| kUnpremul_SkAlphaType | pixel components are independent of Alpha |
Alpha Type
Enum SkAlphaType
enum SkAlphaType { kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType, kLastEnum_SkAlphaType = kUnpremul_SkAlphaType, };
Describes how to interpret the alpha component of a pixel. A pixel may be opaque, or Color Alpha, describing multiple levels of transparency.
In simple blending, Color Alpha weights the draw color and the destination color to create a new color. If alpha describes a weight from zero to one:
new color = draw color * alpha + destination color * (1 - alpha)
In practice alpha is encoded in two or more bits, where 1.0 equals all bits set.
RGB may have Color Alpha included in each component value; the stored value is the original RGB multiplied by Color Alpha. Premultiplied color components improve performance.
Constants
| Const | Value | Details | Description |
|---|---|---|---|
kUnknown_SkAlphaType |
0 | Alpha Type is uninitialized. | |
kOpaque_SkAlphaType |
1 | Opaque | Pixels are opaque. The Color Type must have no explicit alpha component, or all alpha components must be set to their maximum value. |
kPremul_SkAlphaType |
2 | Premul | Pixels have Alpha Premultiplied into color components. Surface pixels must be Premultiplied. |
kUnpremul_SkAlphaType |
3 | Unpremul | Pixel color component values are independent of alpha value. Images generated from encoded data like PNG do not Premultiply pixel color components. kUnpremul_SkAlphaType is supported for Image pixels, but not for Surface pixels. |
kLastEnum_SkAlphaType |
3 | Used by tests to iterate through all valid values. |
See Also
Alpha Type Opaque
Use kOpaque_SkAlphaType as a hint to optimize drawing when Alpha component of all pixel is set to its maximum value of 1.0; all alpha component bits are set. If Image Info is set to kOpaque_SkAlphaType but all alpha values are not 1.0, results are undefined.
Example
Alpha Type Premul
Use kPremul_SkAlphaType when stored color components are the original color multiplied by the alpha component. The alpha component range of 0.0 to 1.0 is achieved by dividing the integer bit value by the maximum bit value.
stored color = original color * alpha / max alpha
The color component must be equal to or smaller than the alpha component, or the results are undefined.
Example
Alpha Type Unpremul
Use kUnpremul_SkAlphaType if stored color components are not divided by the alpha component. Some drawing destinations may not support kUnpremul_SkAlphaType.
Example
SkAlphaTypeIsOpaque
static inline bool SkAlphaTypeIsOpaque(SkAlphaType at)
Returns true if Alpha Type equals kOpaque_SkAlphaType. kOpaque_SkAlphaType is a hint that the Color Type is opaque, or that all Color Alpha values are set to their 1.0 equivalent. If Alpha Type is kOpaque_SkAlphaType, and Color Type is not opaque, then the result of drawing any pixel with a Color Alpha value less than 1.0 is undefined.
Parameters
at |
one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType |
Return Value
true if at equals kOpaque_SkAlphaType
Color Type
Enum SkColorType
enum SkColorType { 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, kRGBA_F32_SkColorType, kLastEnum_SkColorType = kRGBA_F32_SkColorType, #if SK_PMCOLOR_BYTE_ORDER(B,G,R,A) kN32_SkColorType = kBGRA_8888_SkColorType, #elif SK_PMCOLOR_BYTE_ORDER(R,G,B,A) kN32_SkColorType = kRGBA_8888_SkColorType, #else #error #endif };
Describes how pixel bits encode color. A pixel may be an alpha mask, a Grayscale, RGB, or ARGB.
kN32_SkColorType selects the native 32-bit ARGB format. On Little Endian processors, pixels containing 8-bit ARGB components pack into 32-bit kBGRA_8888_SkColorType. On Big Endian processors, pixels pack into 32-bit kRGBA_8888_SkColorType.
Constants
| Const | Value | Details | Description |
|---|---|---|---|
kUnknown_SkColorType |
0 | Color Type is set to kUnknown_SkColorType by default. If set, encoding format and size is unknown. | |
kAlpha_8_SkColorType |
1 | Alpha 8 | Stores 8-bit byte pixel encoding that represents transparency. Value of zero is completely transparent; a value of 255 is completely opaque. |
kRGB_565_SkColorType |
2 | RGB 565 | Stores 16-bit word pixel encoding that contains five bits of blue, six bits of green, and five bits of red. |
kARGB_4444_SkColorType |
3 | ARGB 4444 | Stores 16-bit word pixel encoding that contains four bits of alpha, four bits of blue, four bits of green, and four bits of red. |
kRGBA_8888_SkColorType |
4 | RGBA 8888 | Stores 32-bit word pixel encoding that contains eight bits of red, eight bits of green, eight bits of blue, and eight bits of alpha. |
kRGB_888x_SkColorType |
5 | RGB 888 | Stores 32-bit word pixel encoding that contains eight bits of red, eight bits of green, eight bits of blue, and eight unused bits. |
kBGRA_8888_SkColorType |
6 | BGRA 8888 | Stores 32-bit word pixel encoding that contains eight bits of blue, eight bits of green, eight bits of red, and eight bits of alpha. |
kRGBA_1010102_SkColorType |
7 | RGBA 1010102 | Stores 32-bit word pixel encoding that contains ten bits of red, ten bits of green, ten bits of blue, and two bits of alpha. |
kRGB_101010x_SkColorType |
8 | RGB 101010 | Stores 32-bit word pixel encoding that contains ten bits of red, ten bits of green, ten bits of blue, and two unused bits. |
kGray_8_SkColorType |
9 | Gray 8 | Stores 8-bit byte pixel encoding that equivalent to equal values for red, blue, and green, representing colors from black to white. |
kRGBA_F16_SkColorType |
10 | RGBA F16 | Stores 64-bit word pixel encoding that contains 16 bits of blue, 16 bits of green, 16 bits of red, and 16 bits of alpha. Each component is encoded as a half float. |
kRGBA_F32_SkColorType |
11 | RGBA F32 | Stores 128-bit word pixel encoding that contains 32 bits of blue, 32 bits of green, 32 bits of red, and 32 bits of alpha. Each component is encoded as a single precision float. |
kLastEnum_SkColorType |
11 | Used by tests to iterate through all valid values. | |
kN32_SkColorType |
4 or 6 | Encodes ARGB as either kRGBA_8888_SkColorType or kBGRA_8888_SkColorType, whichever is native to the platform. |
See Also
Color Type Alpha 8
Alpha pixels encode transparency without color information. Value of zero is completely transparent; a value of 255 is completely opaque. Bitmap pixels do not visibly draw, because its pixels have no color information. When SkColorType is set to kAlpha_8_SkColorType, the paired SkAlphaType is ignored.
Example
See Also
Color Type RGB 565
kRGB_565_SkColorType encodes RGB to fit in a 16-bit word. Red and blue components use five bits describing 32 levels. Green components, more sensitive to the eye, use six bits describing 64 levels. kRGB_565_SkColorType has no bits for Alpha. Pixels are fully opaque as if its Color Alpha was set to one, and should always be paired with kOpaque_SkAlphaType.
Example
See Also
Color Type ARGB 4444
kARGB_4444_SkColorType encodes ARGB to fit in 16-bit word. Each component: alpha, blue, green, and red; use four bits, describing 16 levels. Note that kARGB_4444_SkColorType is misnamed; the acronym does not describe the actual component order.
If paired with kPremul_SkAlphaType: blue, green, and red components are Premultiplied by the alpha value. If blue, green, or red is greater than alpha, the drawn result is undefined.
If paired with kUnpremul_SkAlphaType: alpha, blue, green, and red components may have any value. There may be a performance penalty with Unpremultipled pixels.
If paired with kOpaque_SkAlphaType: all alpha component values are at the maximum; blue, green, and red components are fully opaque. If any alpha component is less than 15, the drawn result is undefined.
Example
See Also
Color Type RGBA 8888
kRGBA_8888_SkColorType encodes ARGB into a 32-bit word. Each component: red, green, blue, alpha; use eight bits, describing 256 levels.
If paired with kPremul_SkAlphaType: red, green, and blue components are Premultiplied by the alpha value. If red, green, or blue is greater than alpha, the drawn result is undefined.
If paired with kUnpremul_SkAlphaType: alpha, red, green, and blue components may have any value. There may be a performance penalty with Unpremultipled pixels.
If paired with kOpaque_SkAlphaType: all alpha component values are at the maximum; red, green, and blue components are fully opaque. If any alpha component is less than 255, the drawn result is undefined.
On Big Endian platforms, kRGBA_8888_SkColorType is the native Color Type, and will have the best performance. Use kN32_SkColorType to choose the best Color Type for the platform at compile time.
Example
See Also
Color Type RGB 888
kRGB_888x_SkColorType encodes RGB into a 32-bit word. Each component: red, green, blue; use eight bits, describing 256 levels. Eight bits are unused. Pixels described by kRGB_888x_SkColorType are fully opaque as if their Color Alpha was set to one, and should always be paired with kOpaque_SkAlphaType.
Example
See Also
Color Type BGRA 8888
kBGRA_8888_SkColorType encodes ARGB into a 32-bit word. Each component: blue, green, red, and alpha; use eight bits, describing 256 levels.
If paired with kPremul_SkAlphaType: blue, green, and red components are Premultiplied by the alpha value. If blue, green, or red is greater than alpha, the drawn result is undefined.
If paired with kUnpremul_SkAlphaType: blue, green, red, and alpha components may have any value. There may be a performance penalty with Unpremultiplied pixels.
If paired with kOpaque_SkAlphaType: all alpha component values are at the maximum; blue, green, and red components are fully opaque. If any alpha component is less than 255, the drawn result is undefined.
On Little Endian platforms, kBGRA_8888_SkColorType is the native Color Type, and will have the best performance. Use kN32_SkColorType to choose the best Color Type for the platform at compile time.
Example
See Also
Color Type RGBA 1010102
kRGBA_1010102_SkColorType encodes ARGB into a 32-bit word. Each Color component: red, green, and blue; use ten bits, describing 1024 levels. Two bits contain alpha, describing four levels. Possible alpha values are zero: fully transparent; one: 33% opaque; two: 67% opaque; three: fully opaque.
At present, Color in Paint does not provide enough precision to draw all colors possible to a kRGBA_1010102_SkColorType Surface.
If paired with kPremul_SkAlphaType: red, green, and blue components are Premultiplied by the alpha value. If red, green, or blue is greater than the alpha replicated to ten bits, the drawn result is undefined.
If paired with kUnpremul_SkAlphaType: alpha, red, green, and blue components may have any value. There may be a performance penalty with Unpremultiplied pixels.
If paired with kOpaque_SkAlphaType: all alpha component values are at the maximum; red, green, and blue components are fully opaque. If any alpha component is less than three, the drawn result is undefined.
Example
See Also
Color Type RGB 101010
kRGB_101010x_SkColorType encodes RGB into a 32-bit word. Each Color component: red, green, and blue; use ten bits, describing 1024 levels. Two bits are unused. Pixels described by kRGB_101010x_SkColorType are fully opaque as if its Color Alpha was set to one, and should always be paired with kOpaque_SkAlphaType.
At present, Color in Paint does not provide enough precision to draw all colors possible to a kRGB_101010x_SkColorType Surface.
Example
See Also
Color Type Gray 8
kGray_8_SkColorType encodes Grayscale level in eight bits that is equivalent to equal values for red, blue, and green, representing colors from black to white. Pixels described by kGray_8_SkColorType are fully opaque as if its Color Alpha was set to one, and should always be paired with kOpaque_SkAlphaType.
Example
See Also
Color Type RGBA F16
kRGBA_F16_SkColorType encodes ARGB into a 64-bit word. Each component: blue, green, red, and alpha; use 16 bits, describing a floating point value, from -65500 to 65000 with 3.31 decimal digits of precision.
At present, Color in Paint does not provide enough precision or range to draw all colors possible to a kRGBA_F16_SkColorType Surface.
Each component encodes a floating point value using Half floats . Meaningful colors are represented by the range 0.0 to 1.0, although smaller and larger values may be useful when used in combination with Transfer Mode.
If paired with kPremul_SkAlphaType: blue, green, and red components are Premultiplied by the alpha value. If blue, green, or red is greater than alpha, the drawn result is undefined.
If paired with kUnpremul_SkAlphaType: blue, green, red, and alpha components may have any value. There may be a performance penalty with Unpremultiplied pixels.
If paired with kOpaque_SkAlphaType: all alpha component values are at the maximum; blue, green, and red components are fully opaque. If any alpha component is less than one, the drawn result is undefined.
Example
See Also
Color Type RGBA F32
kRGBA_F32_SkColorType encodes ARGB into a 128-bit word. Each component: blue, green, red, and alpha; use 32 bits, describing a floating point value, from -3.402823e+38 to 3.402823e+38 with 7.225 decimal digits of precision.
At present, Color in Paint does not provide enough precision or range to draw all colors possible to a kRGBA_F32_SkColorType Surface.
Each component encodes a floating point value using single-precision floats . Meaningful colors are represented by the range 0.0 to 1.0, although smaller and larger values may be useful when used in combination with Transfer Mode.
If paired with kPremul_SkAlphaType: blue, green, and red components are Premultiplied by the alpha value. If blue, green, or red is greater than alpha, the drawn result is undefined.
If paired with kUnpremul_SkAlphaType: blue, green, red, and alpha components may have any value. There may be a performance penalty with Unpremultiplied pixels.
If paired with kOpaque_SkAlphaType: all alpha component values are at the maximum; blue, green, and red components are fully opaque. If any alpha component is less than one, the drawn result is undefined.
See Also
SkColorTypeBytesPerPixel
int SkColorTypeBytesPerPixel(SkColorType ct)
Returns the number of bytes required to store a pixel, including unused padding. Returns zero if ct is kUnknown_SkColorType or invalid.
Parameters
Return Value
bytes per pixel
Example
See Also
SkColorTypeIsAlwaysOpaque
bool SkColorTypeIsAlwaysOpaque(SkColorType ct)
Returns true if Color Type always decodes Color Alpha to 1.0, making the pixel fully opaque. If true, Color Type does not reserve bits to encode Color Alpha.
Parameters
Return Value
true if Color Alpha is always set to 1.0
Example
See Also
SkColorTypeValidateAlphaType
bool SkColorTypeValidateAlphaType(SkColorType colorType, SkAlphaType alphaType, SkAlphaType* canonical = nullptr)
Returns true if canonical can be set to a valid Alpha Type for colorType. If there is more than one valid canonical Alpha Type, set to alphaType, if valid. If true is returned and canonical is not nullptr, store valid Alpha Type.
Returns false only if alphaType is kUnknown_SkAlphaType, color type is not kUnknown_SkColorType, and Color Type is not always opaque. If false is returned, canonical is ignored.
For kUnknown_SkColorType: set canonical to kUnknown_SkAlphaType and return true. For kAlpha_8_SkColorType: set canonical to kPremul_SkAlphaType or kOpaque_SkAlphaType and return true if alphaType is not kUnknown_SkAlphaType. For kRGB_565_SkColorType, kRGB_888x_SkColorType, kRGB_101010x_SkColorType, and kGray_8_SkColorType: set canonical to kOpaque_SkAlphaType and return true. For kARGB_4444_SkColorType, kRGBA_8888_SkColorType, kBGRA_8888_SkColorType, kRGBA_1010102_SkColorType, and kRGBA_F16_SkColorType: set canonical to alphaType and return true if alphaType is not kUnknown_SkAlphaType.
Parameters
Return Value
true if valid Alpha Type can be associated with colorType
Example
See Also
YUV ColorSpace
Enum SkYUVColorSpace
enum SkYUVColorSpace { kJPEG_SkYUVColorSpace, kRec601_SkYUVColorSpace, kRec709_SkYUVColorSpace, kLastEnum_SkYUVColorSpace = kRec709_SkYUVColorSpace, };
Describes color range of YUV pixels. The color mapping from YUV to RGB varies depending on the source. YUV pixels may be generated by JPEG images, standard video streams, or high definition video streams. Each has its own mapping from YUV and RGB.
JPEG YUV values encode the full range of 0 to 255 for all three components. Video YUV values range from 16 to 235 for all three components. Details of encoding and conversion to RGB are described in YCbCr color space .
Constants
| Const | Value | Description |
|---|---|---|
kJPEG_SkYUVColorSpace |
0 | Describes standard JPEG color space; CCIR 601 with full range of 0 to 255 for components. |
kRec601_SkYUVColorSpace |
1 | Describes standard used by standard definition television; CCIR 601 with studio range of 16 to 235 range for components. |
kRec709_SkYUVColorSpace |
2 | Describes standard used by high definition television; Rec. 709 with studio range of 16 to 235 range for components. |
kLastEnum_SkYUVColorSpace |
2 | Used by tests to iterate through all valid values. |
See Also
SkImage::MakeFromYUVTexturesCopy SkImage::MakeFromNV12TexturesCopy
Struct SkImageInfo
Constant
SkImageInfo related constants are defined by enum, enum class, #define, const, and constexpr.
| Topic | Description |
|---|
Describes pixel dimensions and encoding. Bitmap, Image, PixMap, and Surface can be created from Image Info. Image Info can be retrieved from Bitmap and Pixmap, but not from Image and Surface. For example, Image and Surface implementations may defer pixel depth, so may not completely specify Image Info.
Image Info contains dimensions, the pixel integral width and height. It encodes how pixel bits describe Color Alpha, transparency; Color components red, blue, and green; and Color Space, the range and linearity of colors.
Member Function
SkImageInfo member functions read and modify the structure properties.
Related Function
SkImageInfo global, struct, and class related member functions share a topic.
| Topic | Description |
|---|---|
| Alpha Type | encoding for pixel transparency |
| Alpha Type Opaque | hints all pixels are opaque |
| Alpha Type Premul | stores components scaled by Alpha |
| Alpha Type Unpremul | stores components without Alpha scaling |
| Color Type | encoding for pixel color |
| Color Type ARGB 4444 | encodes ARGB in 16 bits |
| Color Type Alpha 8 | encodes transparency only |
| Color Type BGRA 8888 | encodes ARGB Little Endian in 32 bits |
| Color Type Gray 8 | encodes level of Grayscale in 8 bits |
| Color Type RGBA 1010102 | encodes ARGB ten bits per color component |
| Color Type RGBA 8888 | encodes ARGB Big Endian in 32 bits |
| Color Type RGBA F16 | encodes ARGB as half floats |
| Color Type RGBA F32 | encodes ARGB as single precision floats |
| Color Type RGB 101010 | encodes RGB ten bits per color component |
| Color Type RGB 565 | encodes RGB in 16 bits |
| Color Type RGB 888 | encodes RGB in 32 bits |
| Property | metrics and attributes |
| Utility | rarely called management functions |
| YUV ColorSpace | color range of YUV pixels |
Constructor
SkImageInfo can be constructed or initialized by these functions, including C++ class constructors.
| Topic | Description |
|---|---|
| Make | creates Image Info from dimensions, Color Type, Alpha Type, Color Space |
| MakeA8 | creates Image Info with kAlpha_8_SkColorType, kPremul_SkAlphaType |
| MakeN32 | creates Image Info with Native_Color_Type |
| MakeN32Premul | creates Image Info with Native_Color_Type, kPremul_SkAlphaType |
| MakeN32Premul(int width, int height, sk sp<SkColorSpace> cs = nullptr) | |
| MakeN32Premul(const SkISize& size) | |
| MakeS32 | creates Image Info with Native_Color_Type, sRGB Color Space |
| MakeUnknown | creates Image Info with kUnknown_SkColorType, kUnknown_SkAlphaType |
| MakeUnknown(int width, int height) | |
| MakeUnknown() | |
| SkImageInfo() | creates with zeroed dimensions, kUnknown_SkColorType, kUnknown_SkAlphaType |
| makeAlphaType | creates Image Info with changed Alpha Type |
| makeColorSpace | creates Image Info with changed Color Space |
| makeColorType | creates Image Info with changed Color Type |
| makeWH | creates Image Info with changed dimensions |
| reset | sets zero dimensions, kUnknown_SkColorType, kUnknown_SkAlphaType |
SkImageInfo
SkImageInfo()
Creates an empty Image Info with kUnknown_SkColorType, kUnknown_SkAlphaType, a width and height of zero, and no Color Space.
Return Value
empty Image Info
Example
See Also
Make
static SkImageInfo Make(int width, int height, SkColorType ct, SkAlphaType at, sk sp<SkColorSpace> cs = nullptr)
Creates Image Info from integral dimensions width and height, Color Type ct, Alpha Type at, and optionally Color Space cs.
If Color Space cs is nullptr and Image Info is part of drawing source: Color Space defaults to sRGB, mapping into Surface Color Space.
Parameters are not validated to see if their values are legal, or that the combination is supported.
Parameters
width |
pixel column count; must be zero or greater |
height |
pixel row count; must be zero or greater |
ct |
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 |
at |
one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType |
cs |
range of colors; may be nullptr |
Return Value
created Image Info
Example
See Also
MakeN32 MakeN32Premul[2] MakeS32 MakeA8
MakeN32
static SkImageInfo MakeN32(int width, int height, SkAlphaType at, sk sp<SkColorSpace> cs = nullptr)
Creates Image Info from integral dimensions width and height, kN32_SkColorType, Alpha Type at, and optionally Color Space cs. kN32_SkColorType will equal either kBGRA_8888_SkColorType or kRGBA_8888_SkColorType, whichever is optimal.
If Color Space cs is nullptr and Image Info is part of drawing source: Color Space defaults to sRGB, mapping into Surface Color Space.
Parameters are not validated to see if their values are legal, or that the combination is supported.
Parameters
width |
pixel column count; must be zero or greater |
height |
pixel row count; must be zero or greater |
at |
one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType |
cs |
range of colors; may be nullptr |
Return Value
created Image Info
Example
See Also
Make MakeN32Premul[2] MakeS32 MakeA8
MakeS32
static SkImageInfo MakeS32(int width, int height, SkAlphaType at)
Creates Image Info from integral dimensions width and height, kN32_SkColorType, Alpha Type at, with sRGB Color Space.
Parameters are not validated to see if their values are legal, or that the combination is supported.
Parameters
width |
pixel column count; must be zero or greater |
height |
pixel row count; must be zero or greater |
at |
one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType |
Return Value
created Image Info
Example
See Also
Make MakeN32 MakeN32Premul[2] MakeA8
MakeN32Premul
static SkImageInfo MakeN32Premul(int width, int height, sk sp<SkColorSpace> cs = nullptr)
Creates Image Info from integral dimensions width and height, kN32_SkColorType, kPremul_SkAlphaType, with optional Color Space.
If Color Space cs is nullptr and Image Info is part of drawing source: Color Space defaults to sRGB, mapping into Surface Color Space.
Parameters are not validated to see if their values are legal, or that the combination is supported.
Parameters
width |
pixel column count; must be zero or greater |
height |
pixel row count; must be zero or greater |
cs |
range of colors; may be nullptr |
Return Value
created Image Info
Example
See Also
static SkImageInfo MakeN32Premul(const SkISize& size)
Creates Image Info from integral dimensions width and height, kN32_SkColorType, kPremul_SkAlphaType, with Color Space set to nullptr.
If Image Info is part of drawing source: Color Space defaults to sRGB, mapping into Surface Color Space.
Parameters are not validated to see if their values are legal, or that the combination is supported.
Parameters
size |
width and height, each must be zero or greater |
Return Value
created Image Info
Example
See Also
MakeA8
static SkImageInfo MakeA8(int width, int height)
Creates Image Info from integral dimensions width and height, kAlpha_8_SkColorType, kPremul_SkAlphaType, with Color Space set to nullptr.
Parameters
width |
pixel column count; must be zero or greater |
height |
pixel row count; must be zero or greater |
Return Value
created Image Info
Example
See Also
MakeUnknown
static SkImageInfo MakeUnknown(int width, int height)
Creates Image Info from integral dimensions width and height, kUnknown_SkColorType, kUnknown_SkAlphaType, with Color Space set to nullptr.
Returned Image Info as part of source does not draw, and as part of destination can not be drawn to.
Parameters
width |
pixel column count; must be zero or greater |
height |
pixel row count; must be zero or greater |
Return Value
created Image Info
Example
See Also
SkImageInfo() MakeN32 MakeS32 Make
static SkImageInfo MakeUnknown()
Creates Image Info from integral dimensions width and height set to zero, kUnknown_SkColorType, kUnknown_SkAlphaType, with Color Space set to nullptr.
Returned Image Info as part of source does not draw, and as part of destination can not be drawn to.
Return Value
created Image Info
Example
See Also
SkImageInfo() MakeN32 MakeS32 Make
Property
| Topic | Description |
|---|---|
| SkAlphaTypeIsOpaque | returns if Alpha Type equals kOpaque_SkAlphaType |
| SkColorTypeBytesPerPixel | returns Color Type byte size |
| SkColorTypeIsAlwaysOpaque | returns if Color Type includes Color Alpha |
| SkColorTypeValidateAlphaType | returns if Alpha Type is valid |
| alphaType | returns Alpha Type |
| bounds | returns width and height as Rectangle |
| bytesPerPixel | returns number of bytes in pixel based on Color Type |
| colorSpace | returns Color Space |
| colorType | returns Color Type |
| dimensions | returns width and height |
| gammaCloseToSRGB | returns if Color Space gamma is approximately the same as sRGB |
| height | returns pixel row count |
| isEmpty | returns if dimensions contain pixels |
| isOpaque | returns if Alpha Type is kOpaque_SkAlphaType |
| minRowBytes | returns width times bytesPerPixel in 32 bits |
| minRowBytes64 | returns width times bytesPerPixel in 64 bits |
| refColorSpace | returns Color Space |
| shiftPerPixel | returns bit shift from pixels to bytes |
| width | returns pixel column count |
width
int width() const
Returns pixel count in each row.
Return Value
pixel width
Example
See Also
height SkBitmap::width SkPixelRef::width SkImage::width SkSurface::width
height
int height() const
Returns pixel row count.
Return Value
pixel height
Example
See Also
width SkBitmap::height SkPixelRef::height SkImage::height SkSurface::height
colorType
SkColorType colorType() const
Returns Color Type, one of: kUnknown_SkColorType, kAlpha_8_SkColorType, kRGB_565_SkColorType, kARGB_4444_SkColorType, kRGBA_8888_SkColorType, kRGB_888x_SkColorType, kBGRA_8888_SkColorType, kRGBA_1010102_SkColorType, kRGB_101010x_SkColorType, kGray_8_SkColorType, kRGBA_F16_SkColorType.
Return Value
Example
Example Output
color type: kAlpha_8_SkColorType
See Also
alphaType SkPixmap::colorType SkBitmap::colorType
alphaType
SkAlphaType alphaType() const
Returns Alpha Type, one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType.
Return Value
Example
Example Output
alpha type: kPremul_SkAlphaType
See Also
colorType SkPixmap::alphaType SkBitmap::alphaType
colorSpace
SkColorSpace* colorSpace() const
Returns Color Space, the range of colors. The reference count of Color Space is unchanged. The returned Color Space is immutable.
Return Value
Color Space, or nullptr
Example
Example Output
gammaCloseToSRGB: false gammaIsLinear: true isSRGB: false
See Also
Color Space SkPixmap::colorSpace SkBitmap::colorSpace
refColorSpace
sk sp<SkColorSpace> refColorSpace() const
Returns smart pointer to Color Space, the range of colors. 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 wrapped in a smart pointer
Example
See Also
Color Space SkBitmap::refColorSpace
isEmpty
bool isEmpty() const
Returns if Image Info describes an empty area of pixels by checking if either width or height is zero or smaller.
Return Value
true if either dimension is zero or smaller
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
dimensions bounds SkBitmap::empty SkPixmap::bounds
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 Alpha Type is kOpaque_SkAlphaType
Example
Example Output
isOpaque: false
isOpaque: false
isOpaque: true
isOpaque: true
See Also
Color Alpha SkColorTypeValidateAlphaType SkBitmap::isOpaque SkImage::isOpaque SkPixmap::isOpaque
dimensions
SkISize dimensions() const
Returns ISize { width, height }.
Return Value
integral size of width and height
Example
Example Output
dimensionsAsBounds == bounds
See Also
width height bounds SkBitmap::dimensions
bounds
SkIRect bounds() const
Returns IRect { 0, 0, width, height }.
Return Value
integral rectangle from origin to width and height
Example
See Also
gammaCloseToSRGB
bool gammaCloseToSRGB() const
Returns true if associated Color Space is not nullptr, and Color Space gamma is approximately the same as sRGB. This includes the sRGB transfer function as well as a gamma curve described by a 2.2 exponent.
Return Value
true if Color Space gamma is approximately the same as sRGB
Example
See Also
SkColorSpace::gammaCloseToSRGB
makeWH
SkImageInfo makeWH(int newWidth, int newHeight) const
Creates Image Info with the same Color Type, Color Space, and Alpha Type, with dimensions set to width and height.
Parameters
newWidth |
pixel column count; must be zero or greater |
newHeight |
pixel row count; must be zero or greater |
Return Value
created Image Info
Example
See Also
Make makeAlphaType makeColorSpace makeColorType
makeAlphaType
SkImageInfo makeAlphaType(SkAlphaType newAlphaType) const
Creates Image Info with same Color Type, Color Space, width, and height, with Alpha Type set to newAlphaType.
Created Image Info contains newAlphaType even if it is incompatible with Color Type, in which case Alpha Type in Image Info is ignored.
Parameters
newAlphaType |
one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType |
Return Value
created Image Info
Example
See Also
Make MakeA8 makeColorType makeColorSpace
makeColorType
SkImageInfo makeColorType(SkColorType newColorType) const
Creates Image Info with same Alpha Type, Color Space, width, and height, with Color Type set to newColorType.
Parameters
Return Value
created Image Info
Example
See Also
Make makeAlphaType makeColorSpace
makeColorSpace
SkImageInfo makeColorSpace(sk sp<SkColorSpace> cs) const
Creates Image Info with same Alpha Type, Color Type, width, and height, with Color Space set to cs.
Parameters
cs |
range of colors; may be nullptr |
Return Value
created Image Info
Example
See Also
Make MakeS32 makeAlphaType makeColorType
bytesPerPixel
int bytesPerPixel() const
Returns number of bytes per pixel required by Color Type. Returns zero if colorType( is kUnknown_SkColorType.
Return Value
bytes in pixel
Example
Example Output
color: kUnknown_SkColorType bytesPerPixel: 0
color: kAlpha_8_SkColorType bytesPerPixel: 1
color: kRGB_565_SkColorType bytesPerPixel: 2
color: kARGB_4444_SkColorType bytesPerPixel: 2
color: kRGBA_8888_SkColorType bytesPerPixel: 4
color: kRGB_888x_SkColorType bytesPerPixel: 4
color: kBGRA_8888_SkColorType bytesPerPixel: 4
color: kRGBA_1010102_SkColorType bytesPerPixel: 4
color: kRGB_101010x_SkColorType bytesPerPixel: 4
color: kGray_8_SkColorType bytesPerPixel: 1
color: kRGBA_F16_SkColorType bytesPerPixel: 8
See Also
width shiftPerPixel SkBitmap::bytesPerPixel
shiftPerPixel
int shiftPerPixel() const
Returns bit shift converting row bytes to row pixels. Returns zero for kUnknown_SkColorType.
Return Value
one of: 0, 1, 2, 3; left shift to convert pixels to bytes
Example
Example Output
color: kUnknown_SkColorType shiftPerPixel: 0
color: kAlpha_8_SkColorType shiftPerPixel: 0
color: kRGB_565_SkColorType shiftPerPixel: 1
color: kARGB_4444_SkColorType shiftPerPixel: 1
color: kRGBA_8888_SkColorType shiftPerPixel: 2
color: kRGB_888x_SkColorType shiftPerPixel: 2
color: kBGRA_8888_SkColorType shiftPerPixel: 2
color: kRGBA_1010102_SkColorType shiftPerPixel: 2
color: kRGB_101010x_SkColorType shiftPerPixel: 2
color: kGray_8_SkColorType shiftPerPixel: 0
color: kRGBA_F16_SkColorType shiftPerPixel: 3
See Also
bytesPerPixel minRowBytes SkBitmap::shiftPerPixel SkPixmap::shiftPerPixel
minRowBytes64
uint64_t minRowBytes64() const
Returns minimum bytes per row, computed from pixel width and Color Type, which specifies bytesPerPixel. Bitmap maximum value for row bytes must fit in 31 bits.
Return Value
width times bytesPerPixel as unsigned 64-bit integer
Example
Example Output
RGBA_F16 width 16777216 (0x01000000) OK
RGBA_F16 width 33554432 (0x02000000) OK
RGBA_F16 width 67108864 (0x04000000) OK
RGBA_F16 width 134217728 (0x08000000) OK
RGBA_F16 width 268435456 (0x10000000) too large
RGBA_F16 width 536870912 (0x20000000) too large
RGBA_F16 width 1073741824 (0x40000000) too large
RGBA_F16 width -2147483648 (0x80000000) too large
See Also
minRowBytes computeByteSize computeMinByteSize validRowBytes
minRowBytes
size_t minRowBytes() const
Returns minimum bytes per row, computed from pixel width and Color Type, which specifies bytesPerPixel. Bitmap maximum value for row bytes must fit in 31 bits.
Return Value
width times bytesPerPixel as signed 32-bit integer
Example
Example Output
RGBA_F16 width 16777216 (0x01000000) OK
RGBA_F16 width 33554432 (0x02000000) OK
RGBA_F16 width 67108864 (0x04000000) OK
RGBA_F16 width 134217728 (0x08000000) OK
RGBA_F16 width 268435456 (0x10000000) too large
RGBA_F16 width 536870912 (0x20000000) too large
RGBA_F16 width 1073741824 (0x40000000) too large
RGBA_F16 width -2147483648 (0x80000000) too large
See Also
minRowBytes64 computeByteSize computeMinByteSize validRowBytes
computeOffset
size_t computeOffset(int x, int y, size_t rowBytes) const
Returns byte offset of pixel from pixel base address.
Asserts in debug build if x or y is outside of bounds. Does not assert if rowBytes is smaller than minRowBytes, even though result may be incorrect.
Parameters
x |
column index, zero or greater, and less than width |
y |
row index, zero or greater, and less than height |
rowBytes |
size of pixel row or larger |
Return Value
offset within pixel array
Example
See Also
height width minRowBytes computeByteSize
Operator
SkImageInfo operators inline class member functions with arithmetic equivalents.
| Topic | Description |
|---|---|
| operator!=(const SkImageInfo& other) const | compares Image Info for inequality |
| operator==(const SkImageInfo& other) const | compares Image Info for equality |
operator==
bool operator==(const SkImageInfo& other) _const
Compares Image Info with other, and returns true if width, height, Color Type, Alpha Type, and Color Space are equivalent.
Parameters
other |
Image Info to compare |
Return Value
true if Image Info equals other
Example
Example Output
info1 != info2
info1 != info2
info1 != info2
info1 == info2
See Also
operator!=(const SkImageInfo& other) const SkColorSpace::Equals
operator!=
bool operator!=(const SkImageInfo& other) _const
Compares Image Info with other, and returns true if width, height, Color Type, Alpha Type, and Color Space are not equivalent.
Parameters
other |
Image Info to compare |
Return Value
true if Image Info is not equal to other
Example
Example Output
info1 != info2
info1 != info2
info1 != info2
info1 == info2
See Also
operator==(const SkImageInfo& other) const SkColorSpace::Equals
computeByteSize
size_t computeByteSize(size_t rowBytes) const
Returns storage required by pixel array, given Image Info dimensions, Color Type, and rowBytes. rowBytes is assumed to be at least as large as minRowBytes.
Returns zero if height is zero. Returns SIZE_MAX if answer exceeds the range of size_t.
Parameters
rowBytes |
size of pixel row or larger |
Return Value
memory required by pixel buffer
Example
See Also
computeMinByteSize validRowBytes
computeMinByteSize
size_t computeMinByteSize() const
Returns storage required by pixel array, given Image Info dimensions, and Color Type. Uses minRowBytes to compute bytes for pixel row.
Returns zero if height is zero. Returns SIZE_MAX if answer exceeds the range of size_t.
Return Value
least memory required by pixel buffer
Example
See Also
ByteSizeOverflowed
static bool ByteSizeOverflowed(size_t byteSize)
Returns true if byteSize equals SIZE_MAX. computeByteSize and computeMinByteSize return SIZE_MAX if size_t can not hold buffer size.
Parameters
byteSize |
result of computeByteSize or computeMinByteSize |
Return Value
true if computeByteSize or computeMinByteSize result exceeds size_t
Example
Example Output
rowBytes:100000000 size:99999999900000008 overflowed:false
rowBytes:1000000000 size:999999999000000008 overflowed:false
rowBytes:10000000000 size:9999999990000000008 overflowed:false
rowBytes:100000000000 size:18446744073709551615 overflowed:true
rowBytes:1000000000000 size:18446744073709551615 overflowed:true
See Also
computeByteSize computeMinByteSize validRowBytes
validRowBytes
bool validRowBytes(size_t rowBytes) const
Returns true if rowBytes is smaller than width times pixel size.
Parameters
rowBytes |
size of pixel row or larger |
Return Value
true if rowBytes is large enough to contain pixel row
Example
Example Output
validRowBytes(60): false
validRowBytes(64): true
validRowBytes(68): true
See Also
ByteSizeOverflowed computeByteSize computeMinByteSize
reset
void reset()
Creates an empty Image Info with kUnknown_SkColorType, kUnknown_SkAlphaType, a width and height of zero, and no Color Space.
Example
Example Output
info == copy
info != reset copy
SkImageInfo() == reset copy
See Also
Utility
| Topic | Description |
|---|---|
| ByteSizeOverflowed | checks result of computeByteSize and computeMinByteSize |
| computeByteSize | returns memory required by pixel buffer with given row bytes |
| computeMinByteSize | returns least memory required by pixel buffer |
| computeOffset | returns byte offset within pixel array |
| validRowBytes | checks if row bytes is large enough to contain pixel row |
| validate | asserts if Image Info 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
validRowBytes SkBitmap::validate