skia2/site/user/api/SkImageInfo_Reference.md

SkImageInfo Reference

enum SkAlphaType {
    kUnknown_SkAlphaType,
    kOpaque_SkAlphaType,
    kPremul_SkAlphaType,
    kUnpremul_SkAlphaType,
    kLastEnum_SkAlphaType = kUnpremul_SkAlphaType,
};

static bool SkAlphaTypeIsOpaque(SkAlphaType at);

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,
    kN32_SkColorType = kBGRA_8888_SkColorType,
    kN32_SkColorType = kRGBA_8888_SkColorType,
};

int SkColorTypeBytesPerPixel(SkColorType ct);

bool SkColorTypeIsAlwaysOpaque(SkColorType ct);

bool SkColorTypeValidateAlphaType(SkColorType colorType, SkAlphaType alphaType,
                                  SkAlphaType* canonical = nullptr);

enum SkYUVColorSpace {
    kJPEG_SkYUVColorSpace,
    kRec601_SkYUVColorSpace,
    kRec709_SkYUVColorSpace,
    kLastEnum_SkYUVColorSpace = kRec709_SkYUVColorSpace,
};

struct SkImageInfo {
    // SkImageInfo interface
};

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.

---

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 is set to: 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

SkColorType SkColorSpace

---

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

SkPreMultiplyARGB parameter a is set to 255, its maximum value, and is interpreted as Color Alpha of 1.0. kOpaque_SkAlphaType may be set to improve performance. If SkPreMultiplyARGB parameter a is set to a value smaller than 255, kPremul_SkAlphaType must be used instead to avoid undefined results. The four displayed values are the original component values, though not necessarily in the same order.

---

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

SkPreMultiplyARGB parameter a is set to 150, less than its maximum value, and is interpreted as Color Alpha of about 0.6. kPremul_SkAlphaType must be set, since SkPreMultiplyARGB parameter a is set to a value smaller than 255, to avoid undefined results. The four displayed values reflect that the alpha component has been multiplied by the original color.

---

Use kUnpremul_SkAlphaType if stored color components are not divided by the alpha component. Some drawing destinations may not support kUnpremul_SkAlphaType.

Example

SkColorSetARGB parameter a is set to 150, less than its maximum value, and is interpreted as Color Alpha of about 0.6. color is not Premultiplied; color components may have values greater than color alpha. The four displayed values are the original component values, though not necessarily in the same order.

---

static inline bool SkAlphaTypeIsOpaque(SkAlphaType at)

Returns true if SkAlphaType equals kOpaque_SkAlphaType. kOpaque_SkAlphaType is a hint that the SkColorType is opaque, or that all alpha values are set to their 1.0 equivalent. If SkAlphaType is kOpaque_SkAlphaType, and SkColorType is not opaque, then the result of drawing any pixel with a 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

---

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,
    kN32_SkColorType = kBGRA_8888_SkColorType,
    kN32_SkColorType = kRGBA_8888_SkColorType,
};

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

SkAlphaType SkColorSpace

---

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

Alpha pixels can modify another draw. orangePaint fills the bounds of bitmap, with its transparency set to alpha8 pixel value.

See Also

Alpha Gray 8

---

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

ARGB 4444 RGBA 8888

---

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

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

RGB 888 BGRA 8888

---

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

RGBA 8888 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

RGBA 8888

---

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

RGB 101010 RGBA 8888

---

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

RGBA 1010102

---

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

Alpha 8

---

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

SkColor4f

---

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

SkColor4f

---

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

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

Return Value

bytes per pixel

Example

kUnknown_SkColorType, kAlpha_8_SkColorType, kRGB_565_SkColorType, kARGB_4444_SkColorType, kRGBA_8888_SkColorType, kRGB_888x_SkColorType, kBGRA_8888_SkColorType, kRGBA_1010102_SkColorType, kRGB_101010x_SkColorType, kGray_8_SkColorType, kRGBA_F16_SkColorType

See Also

SkImageInfo::bytesPerPixel

---

bool SkColorTypeIsAlwaysOpaque(SkColorType ct)

Returns true if SkColorType always decodes alpha to 1.0, making the pixel fully opaque. If true, SkColorType does not reserve bits to encode alpha.

Parameters

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

Return Value

true if alpha is always set to 1.0

Example

kUnknown_SkColorType, kAlpha_8_SkColorType, kRGB_565_SkColorType, kARGB_4444_SkColorType, kRGBA_8888_SkColorType, kRGB_888x_SkColorType, kBGRA_8888_SkColorType, kRGBA_1010102_SkColorType, kRGB_101010x_SkColorType, kGray_8_SkColorType, kRGBA_F16_SkColorType

See Also

SkColorTypeValidateAlphaType

---

bool SkColorTypeValidateAlphaType(SkColorType colorType, SkAlphaType alphaType,
                                  SkAlphaType* canonical = nullptr)

Returns true if canonical can be set to a valid SkAlphaType for colorType. If there is more than one valid canonical SkAlphaType, set to alphaType, if valid. If true is returned and canonical is not nullptr, store valid SkAlphaType.

Returns false only if alphaType is kUnknown_SkAlphaType, color type is not kUnknown_SkColorType, and SkColorType 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

colorType

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

Parameters

alphaType

one of:

kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType

Parameters

canonical

storage for SkAlphaType

Return Value

true if valid SkAlphaType can be associated with colorType

Example

kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType kUnknown_SkColorType, kAlpha_8_SkColorType, kRGB_565_SkColorType, kARGB_4444_SkColorType, kRGBA_8888_SkColorType, kRGB_888x_SkColorType, kBGRA_8888_SkColorType, kRGBA_1010102_SkColorType, kRGB_101010x_SkColorType, kGray_8_SkColorType, kRGBA_F16_SkColorType

See Also

SkColorTypeIsAlwaysOpaque

---

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 {
public:
    SkImageInfo();
    static SkImageInfo Make(int width, int height, SkColorType ct, SkAlphaType at,
                     sk_sp<SkColorSpace> cs = nullptr);
    static SkImageInfo MakeN32(int width, int height, SkAlphaType at,
                        sk_sp<SkColorSpace> cs = nullptr);
    static SkImageInfo MakeS32(int width, int height, SkAlphaType at);
    static SkImageInfo MakeN32Premul(int width, int height, sk_sp<SkColorSpace> cs = nullptr);
    static SkImageInfo MakeN32Premul(const SkISize& size);
    static SkImageInfo MakeA8(int width, int height);
    static SkImageInfo MakeUnknown(int width, int height);
    static SkImageInfo MakeUnknown();
    int width() const;
    int height() const;
    SkColorType colorType() const;
    SkAlphaType alphaType() const;
    SkColorSpace* colorSpace() const;
    sk_sp<SkColorSpace> refColorSpace() const;
    bool isEmpty() const;
    bool isOpaque() const;
    SkISize dimensions() const;
    SkIRect bounds() const;
    bool gammaCloseToSRGB() const;
    SkImageInfo makeWH(int newWidth, int newHeight) const;
    SkImageInfo makeAlphaType(SkAlphaType newAlphaType) const;
    SkImageInfo makeColorType(SkColorType newColorType) const;
    SkImageInfo makeColorSpace(sk_sp<SkColorSpace> cs) const;
    int bytesPerPixel() const;
    int shiftPerPixel() const;
    uint64_t minRowBytes64() const;
    size_t minRowBytes() const;
    size_t computeOffset(int x, int y, size_t rowBytes) const;
    bool operator==(const SkImageInfo& other)_const;
    bool operator!=(const SkImageInfo& other)_const;
    size_t computeByteSize(size_t rowBytes) const;
    size_t computeMinByteSize() const;
    static bool ByteSizeOverflowed(size_t byteSize);
    bool validRowBytes(size_t rowBytes) const;
    void reset();
    void validate() const;
};

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.

---

SkImageInfo()

Creates an empty SkImageInfo with kUnknown_SkColorType, kUnknown_SkAlphaType, a width and height of zero, and no SkColorSpace.

Return Value

empty SkImageInfo

Example

An empty Image Info may be passed to SkCanvas::accessTopLayerPixels as storage for the Canvas actual Image Info.

See Also

Make MakeN32 MakeS32 MakeA8

---

static SkImageInfo Make(int width, int height, SkColorType ct, SkAlphaType at,
                        sk sp<SkColorSpace> cs = nullptr)

Creates SkImageInfo from integral dimensions width and height, SkColorType ct, SkAlphaType at, and optionally SkColorSpace cs.

If SkColorSpace cs is nullptr and SkImageInfo is part of drawing source: SkColorSpace defaults to sRGB, mapping into SkSurface SkColorSpace.

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

Parameters

at

one of:

kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType

Parameters

cs	range of colors; may be nullptr

Return Value

created SkImageInfo

Example

See Also

MakeN32 MakeN32Premul^[2] MakeS32 MakeA8

---

static SkImageInfo MakeN32(int width, int height, SkAlphaType at, sk sp<SkColorSpace> cs = nullptr)

Creates SkImageInfo from integral dimensions width and height, kN32_SkColorType, SkAlphaType at, and optionally SkColorSpace cs. kN32_SkColorType will equal either kBGRA_8888_SkColorType or kRGBA_8888_SkColorType, whichever is optimal.

If SkColorSpace cs is nullptr and SkImageInfo is part of drawing source: SkColorSpace defaults to sRGB, mapping into SkSurface SkColorSpace.

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

Parameters

cs	range of colors; may be nullptr

Return Value

created SkImageInfo

Example

See Also

Make MakeN32Premul^[2] MakeS32 MakeA8

---

static SkImageInfo MakeS32(int width, int height, SkAlphaType at)

Creates SkImageInfo from integral dimensions width and height, kN32_SkColorType, SkAlphaType at, with sRGB SkColorSpace.

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 SkImageInfo

Example

Top gradient is drawn to offScreen without Color Space. It is darker than middle gradient, drawn to offScreen with sRGB Color Space. Bottom gradient shares bits with middle, but does not specify the Color Space in noColorSpaceBitmap. A source without Color Space is treated as sRGB; the bottom gradient is identical to the middle gradient.

See Also

Make MakeN32 MakeN32Premul^[2] MakeA8

---

static SkImageInfo MakeN32Premul(int width, int height, sk sp<SkColorSpace> cs = nullptr)

Creates SkImageInfo from integral dimensions width and height, kN32_SkColorType, kPremul_SkAlphaType, with optional SkColorSpace.

If SkColorSpace cs is nullptr and SkImageInfo is part of drawing source: SkColorSpace defaults to sRGB, mapping into SkSurface SkColorSpace.

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 SkImageInfo

Example

See Also

MakeN32 MakeS32 MakeA8 Make

---

static SkImageInfo MakeN32Premul(const SkISize& size)

Creates SkImageInfo from integral dimensions width and height, kN32_SkColorType, kPremul_SkAlphaType, with SkColorSpace set to nullptr.

If SkImageInfo is part of drawing source: SkColorSpace defaults to sRGB, mapping into SkSurface SkColorSpace.

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 SkImageInfo

Example

See Also

MakeN32 MakeS32 MakeA8 Make

---

static SkImageInfo MakeA8(int width, int height)

Creates SkImageInfo from integral dimensions width and height, kAlpha_8_SkColorType, kPremul_SkAlphaType, with SkColorSpace 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 SkImageInfo

Example

See Also

MakeN32 MakeS32 Make

---

static SkImageInfo MakeUnknown(int width, int height)

Creates SkImageInfo from integral dimensions width and height, kUnknown_SkColorType, kUnknown_SkAlphaType, with SkColorSpace set to nullptr.

Returned SkImageInfo 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 SkImageInfo

Example

See Also

SkImageInfo() MakeN32 MakeS32 Make

---

static SkImageInfo MakeUnknown()

Creates SkImageInfo from integral dimensions width and height set to zero, kUnknown_SkColorType, kUnknown_SkAlphaType, with SkColorSpace set to nullptr.

Returned SkImageInfo as part of source does not draw, and as part of destination can not be drawn to.

Return Value

created SkImageInfo

Example

See Also

SkImageInfo() MakeN32 MakeS32 Make

---

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

---

int height() const

Returns pixel row count.

Return Value

pixel height

Example

See Also

width SkBitmap::height SkPixelRef::height SkImage::height SkSurface::height

---

SkColorType colorType() const

Returns Color Type, one of: kUnknown_SkColorType, kAlpha_8_SkColorType, kRGB_565_SkColorType, kARGB_4444_SkColorType, kRGBA_8888_SkColorType, kRGB_888x_SkColorType, kBGRA_8888_SkColorType, kRGBA_1010102_SkColorType, kRGB_101010x_SkColorType, kGray_8_SkColorType, kRGBA_F16_SkColorType.

Return Value

Color Type

Example

Example Output

color type: kAlpha_8_SkColorType

See Also

alphaType SkPixmap::colorType SkBitmap::colorType

---

SkAlphaType alphaType() const

Returns Alpha Type, one of: kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType.

Return Value

Alpha Type

Example

Example Output

alpha type: kPremul_SkAlphaType

See Also

colorType SkPixmap::alphaType SkBitmap::alphaType

---

SkColorSpace* colorSpace() const

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

Return Value

SkColorSpace, or nullptr

Example

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

Example Output

gammaCloseToSRGB: false  gammaIsLinear: true  isSRGB: false

See Also

Color Space SkPixmap::colorSpace SkBitmap::colorSpace

---

sk sp<SkColorSpace> refColorSpace() const

Returns smart pointer to SkColorSpace, the range of colors. The smart pointer tracks the number of objects sharing this SkColorSpace reference so the memory is released when the owners destruct.

The returned SkColorSpace is immutable.

Return Value

SkColorSpace wrapped in a smart pointer

Example

See Also

Color Space SkBitmap::refColorSpace

---

bool isEmpty() const

Returns if SkImageInfo 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

---

bool isOpaque() const

Returns true if SkAlphaType is set to hint that all pixels are opaque; their alpha value is implicitly or explicitly 1.0. If true, and all pixels are not opaque, Skia may draw incorrectly.

Does not check if SkColorType allows alpha, or if any pixel value has transparency.

Return Value

true if SkAlphaType 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

---

SkISize dimensions() const

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

Return Value

integral size of width() and height()

Example

Example Output

dimensionsAsBounds == bounds

See Also

width height bounds SkBitmap::dimensions

---

SkIRect bounds() const

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

Return Value

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

Example

See Also

width height dimensions

---

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

---

SkImageInfo makeWH(int newWidth, int newHeight) const

Creates SkImageInfo with the same SkColorType, SkColorSpace, and SkAlphaType, 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 SkImageInfo

Example

See Also

Make makeAlphaType makeColorSpace makeColorType

---

SkImageInfo makeAlphaType(SkAlphaType newAlphaType) const

Creates SkImageInfo with same SkColorType, SkColorSpace, width, and height, with SkAlphaType set to newAlphaType.

Created SkImageInfo contains newAlphaType even if it is incompatible with SkColorType, in which case SkAlphaType in SkImageInfo is ignored.

Parameters

newAlphaType

one of:

kUnknown_SkAlphaType, kOpaque_SkAlphaType, kPremul_SkAlphaType, kUnpremul_SkAlphaType

Return Value

created SkImageInfo

Example

See Also

Make MakeA8 makeColorType makeColorSpace

---

SkImageInfo makeColorType(SkColorType newColorType) const

Creates SkImageInfo with same SkAlphaType, SkColorSpace, width, and height, with SkColorType set to newColorType.

Parameters

newColorType

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

created SkImageInfo

Example

See Also

Make makeAlphaType makeColorSpace

---

SkImageInfo makeColorSpace(sk sp<SkColorSpace> cs) const

Creates SkImageInfo with same SkAlphaType, SkColorType, width, and height, with SkColorSpace set to cs.

Parameters

cs	range of colors; may be nullptr

Return Value

created SkImageInfo

Example

See Also

Make MakeS32 makeAlphaType makeColorType

---

int bytesPerPixel() const

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

Return Value

bytes in pixel

Example

kUnknown_SkColorType, kAlpha_8_SkColorType, kRGB_565_SkColorType, kARGB_4444_SkColorType, kRGBA_8888_SkColorType, kRGB_888x_SkColorType, kBGRA_8888_SkColorType, kRGBA_1010102_SkColorType, kRGB_101010x_SkColorType, kGray_8_SkColorType, kRGBA_F16_SkColorType

Example Output

color: kUnknown_SkColorType      bytesPerPixel: 0
color: kAlpha_8_SkColorType      bytesPerPixel: 1
color: kRGB_565_SkColorType      bytesPerPixel: 2
color: kARGB_4444_SkColorType    bytesPerPixel: 2
color: kRGBA_8888_SkColorType    bytesPerPixel: 4
color: kRGB_888x_SkColorType     bytesPerPixel: 4
color: kBGRA_8888_SkColorType    bytesPerPixel: 4
color: kRGBA_1010102_SkColorType bytesPerPixel: 4
color: kRGB_101010x_SkColorType  bytesPerPixel: 4
color: kGray_8_SkColorType       bytesPerPixel: 1
color: kRGBA_F16_SkColorType     bytesPerPixel: 8

See Also

width shiftPerPixel SkBitmap::bytesPerPixel

---

int shiftPerPixel() const

Returns bit shift converting row bytes to row pixels. Returns zero for kUnknown_SkColorType.

Return Value

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

Example

kUnknown_SkColorType, kAlpha_8_SkColorType, kRGB_565_SkColorType, kARGB_4444_SkColorType, kRGBA_8888_SkColorType, kRGB_888x_SkColorType, kBGRA_8888_SkColorType, kRGBA_1010102_SkColorType, kRGB_101010x_SkColorType, kGray_8_SkColorType, kRGBA_F16_SkColorType

Example Output

color: kUnknown_SkColorType       shiftPerPixel: 0
color: kAlpha_8_SkColorType       shiftPerPixel: 0
color: kRGB_565_SkColorType       shiftPerPixel: 1
color: kARGB_4444_SkColorType     shiftPerPixel: 1
color: kRGBA_8888_SkColorType     shiftPerPixel: 2
color: kRGB_888x_SkColorType      shiftPerPixel: 2
color: kBGRA_8888_SkColorType     shiftPerPixel: 2
color: kRGBA_1010102_SkColorType  shiftPerPixel: 2
color: kRGB_101010x_SkColorType   shiftPerPixel: 2
color: kGray_8_SkColorType        shiftPerPixel: 0
color: kRGBA_F16_SkColorType      shiftPerPixel: 3

See Also

bytesPerPixel minRowBytes SkBitmap::shiftPerPixel SkPixmap::shiftPerPixel

---

uint64_t minRowBytes64() const

Returns minimum bytes per row, computed from pixel width() and SkColorType, which specifies bytesPerPixel(). SkBitmap 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

---

size_t minRowBytes() const

Returns minimum bytes per row, computed from pixel width() and SkColorType, which specifies bytesPerPixel(). SkBitmap 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

---

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

---

bool operator==(const SkImageInfo& other) const

Compares SkImageInfo with other, and returns true if width, height, SkColorType, SkAlphaType, and SkColorSpace are equivalent.

Parameters

other

SkImageInfo to compare

Return Value

true if SkImageInfo equals other

Example

Example Output

info1 != info2
info1 != info2
info1 != info2
info1 == info2

See Also

operator!=(const SkImageInfo& other) const SkColorSpace::Equals

---

bool operator!=(const SkImageInfo& other) const

Compares SkImageInfo with other, and returns true if width, height, SkColorType, SkAlphaType, and SkColorSpace are not equivalent.

Parameters

other

SkImageInfo to compare

Return Value

true if SkImageInfo 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

---

size_t computeByteSize(size_t rowBytes) const

Returns storage required by pixel array, given SkImageInfo dimensions, SkColorType, 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

---

size_t computeMinByteSize() const

Returns storage required by pixel array, given SkImageInfo dimensions, and SkColorType. 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

computeByteSize validRowBytes

---

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

---

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

---

void reset()

Creates an empty SkImageInfo with kUnknown_SkColorType, kUnknown_SkAlphaType, a width and height of zero, and no SkColorSpace.

Example

Example Output

info == copy
info != reset copy
SkImageInfo() == reset copy

See Also

SkImageInfo()

---

void validate() const

See Also

validRowBytes SkBitmap::validate