Documentation ¶
Overview ¶
Package webp implements a decoder and encoder for WEBP images.
WEBP is defined at: https://developers.google.com/speed/webp/docs/riff_container
Install ¶
Install `GCC` or `MinGW` (http://tdm-gcc.tdragon.net/download) at first, and then run these commands:
- `go get github.com/chai2010/webp`
- `go run hello.go`
Examples ¶
This is a simple example:
package main import ( "bytes" "fmt" "io/ioutil" "log" "github.com/chai2010/webp" ) func main() { var buf bytes.Buffer var width, height int var data []byte var err error // Load file data if data, err = ioutil.ReadFile("./testdata/1_webp_ll.webp"); err != nil { log.Fatal(err) } // GetInfo if width, height, _, err = webp.GetInfo(data); err != nil { log.Fatal(err) } fmt.Printf("width = %d, height = %d\n", width, height) // GetMetadata if metadata, err := webp.GetMetadata(data, "ICCP"); err != nil { fmt.Printf("Metadata: err = %v\n", err) } else { fmt.Printf("Metadata: %s\n", string(metadata)) } // Decode webp m, err := webp.Decode(bytes.NewReader(data)) if err != nil { log.Fatal(err) } // Encode lossless webp if err = webp.Encode(&buf, m, &webp.Options{Lossless: true}); err != nil { log.Fatal(err) } if err = ioutil.WriteFile("output.webp", buf.Bytes(), 0666); err != nil { log.Fatal(err) } fmt.Printf("Save output.webp ok\n") }
Decode and Encode as RGB format:
m, err := webp.DecodeRGB(data) if err != nil { log.Fatal(err) } data, err := webp.EncodeRGB(m) if err != nil { log.Fatal(err) }
BUGS ¶
Report bugs to <chaishushan@gmail.com>.
Thanks!
Index ¶
- Constants
- func C_webpFree(p unsafe.Pointer)
- func C_webpMalloc(size C_size_t) unsafe.Pointer
- func ChannelsOf(m image.Image) int
- func ColorModel(channels int, dataType reflect.Kind) color.Model
- func Decode(r io.Reader) (m image.Image, err error)
- func DecodeConfig(r io.Reader) (config image.Config, err error)
- func DecodeGray(data []byte) (m *image.Gray, err error)
- func DecodeGrayToSize(data []byte, width, height int) (m *image.Gray, err error)
- func DecodeRGBA(data []byte) (m *image.RGBA, err error)
- func DecodeRGBAToSize(data []byte, width, height int) (m *image.RGBA, err error)
- func DepthOf(m image.Image) int
- func Encode(w io.Writer, m image.Image, opt *Options) (err error)
- func EncodeExactLosslessRGBA(m image.Image) (data []byte, err error)
- func EncodeGray(m image.Image, quality float32) (data []byte, err error)
- func EncodeLosslessGray(m image.Image) (data []byte, err error)
- func EncodeLosslessRGB(m image.Image) (data []byte, err error)
- func EncodeLosslessRGBA(m image.Image) (data []byte, err error)
- func EncodeRGB(m image.Image, quality float32) (data []byte, err error)
- func EncodeRGBA(m image.Image, quality float32) (data []byte, err error)
- func GetInfo(data []byte) (width, height int, hasAlpha bool, err error)
- func GetMetadata(data []byte, format string) (metadata []byte, err error)
- func Load(name string) (m image.Image, err error)
- func LoadConfig(name string) (config image.Config, err error)
- func Save(name string, m image.Image, opt *Options) (err error)
- func SetMetadata(data, metadata []byte, format string) (newData []byte, err error)
- func SizeofImage(m image.Image) int
- func SizeofKind(dataType reflect.Kind) int
- func SizeofPixel(channels int, dataType reflect.Kind) int
- type C_double
- type C_float
- type C_int
- func C_webpDecodeGrayToSize(data *C_uint8_t, data_size C_size_t, width C_int, height C_int, ...) C_int
- func C_webpDecodeRGBAToSize(data *C_uint8_t, data_size C_size_t, width C_int, height C_int, ...) C_int
- func C_webpDecodeRGBToSize(data *C_uint8_t, data_size C_size_t, width C_int, height C_int, ...) C_int
- func C_webpGetInfo(data *C_uint8_t, data_size C_size_t, width *C_int, height *C_int, ...) C_int
- type C_int16_t
- type C_int32_t
- type C_int64_t
- type C_int8_t
- type C_size_t
- type C_uint
- type C_uint16_t
- type C_uint32_t
- type C_uint64_t
- type C_uint8_t
- func C_webpDecodeGray(data *C_uint8_t, data_size C_size_t, width *C_int, height *C_int) *C_uint8_t
- func C_webpDecodeRGB(data *C_uint8_t, data_size C_size_t, width *C_int, height *C_int) *C_uint8_t
- func C_webpDecodeRGBA(data *C_uint8_t, data_size C_size_t, width *C_int, height *C_int) *C_uint8_t
- func C_webpEncodeGray(pix *C_uint8_t, width C_int, height C_int, stride C_int, ...) *C_uint8_t
- func C_webpEncodeLosslessGray(pix *C_uint8_t, width C_int, height C_int, stride C_int, output_size *C_size_t) *C_uint8_t
- func C_webpEncodeLosslessRGB(pix *C_uint8_t, width C_int, height C_int, stride C_int, output_size *C_size_t) *C_uint8_t
- func C_webpEncodeLosslessRGBA(exact C_int, pix *C_uint8_t, width C_int, height C_int, stride C_int, ...) *C_uint8_t
- func C_webpEncodeRGB(pix *C_uint8_t, width C_int, height C_int, stride C_int, ...) *C_uint8_t
- func C_webpEncodeRGBA(pix *C_uint8_t, width C_int, height C_int, stride C_int, ...) *C_uint8_t
- type ColorModelInterface
- type MemP
- type MemPColor
- type MemPImage
- func (p *MemPImage) AsStdImage() (m image.Image, ok bool)
- func (p *MemPImage) At(x, y int) color.Color
- func (p *MemPImage) Bounds() image.Rectangle
- func (p *MemPImage) Channels() int
- func (p *MemPImage) Clone() *MemPImage
- func (p *MemPImage) ColorModel() color.Model
- func (p *MemPImage) DataType() reflect.Kind
- func (p *MemPImage) MemPMagic() string
- func (p *MemPImage) Pix() []byte
- func (p *MemPImage) PixOffset(x, y int) int
- func (p *MemPImage) PixelAt(x, y int) []byte
- func (p *MemPImage) Set(x, y int, c color.Color)
- func (p *MemPImage) SetPixel(x, y int, c []byte)
- func (p *MemPImage) StdImage() image.Image
- func (p *MemPImage) Stride() int
- func (p *MemPImage) SubImage(r image.Rectangle) image.Image
- type Options
- type PixSlice
- func (d PixSlice) Bytes() (v []byte)
- func (d PixSlice) Complex128s() (v []complex128)
- func (d PixSlice) Complex64s() (v []complex64)
- func (d PixSlice) Float32s() (v []float32)
- func (d PixSlice) Float64s() (v []float64)
- func (d PixSlice) Int16s() (v []int16)
- func (d PixSlice) Int32s() (v []int32)
- func (d PixSlice) Int64s() (v []int64)
- func (d PixSlice) Int8s() (v []int8)
- func (d PixSlice) SetValue(i int, dataType reflect.Kind, v float64)
- func (d PixSlice) Slice(newSliceType reflect.Type) interface{}
- func (d PixSlice) SwapEndian(dataType reflect.Kind)
- func (d PixSlice) Uint16s() (v []uint16)
- func (d PixSlice) Uint32s() (v []uint32)
- func (d PixSlice) Uint64s() (v []uint64)
- func (d PixSlice) Uint8s() []uint8
- func (d PixSlice) Value(i int, dataType reflect.Kind) float64
- type RGB48Image
- func (p *RGB48Image) At(x, y int) color.Color
- func (p *RGB48Image) Bounds() image.Rectangle
- func (p *RGB48Image) Channels() int
- func (p *RGB48Image) ColorModel() color.Model
- func (p *RGB48Image) DataType() reflect.Kind
- func (p *RGB48Image) MemPMagic() string
- func (p *RGB48Image) Opaque() bool
- func (p *RGB48Image) Pix() []byte
- func (p *RGB48Image) PixOffset(x, y int) int
- func (p *RGB48Image) RGB48At(x, y int) [3]uint16
- func (p *RGB48Image) Set(x, y int, c color.Color)
- func (p *RGB48Image) SetRGB48(x, y int, c [3]uint16)
- func (p *RGB48Image) Stride() int
- func (p *RGB48Image) SubImage(r image.Rectangle) image.Image
- type RGBImage
- func (p *RGBImage) At(x, y int) color.Color
- func (p *RGBImage) Bounds() image.Rectangle
- func (p *RGBImage) Channels() int
- func (p *RGBImage) ColorModel() color.Model
- func (p *RGBImage) DataType() reflect.Kind
- func (p *RGBImage) MemPMagic() string
- func (p *RGBImage) Opaque() bool
- func (p *RGBImage) Pix() []byte
- func (p *RGBImage) PixOffset(x, y int) int
- func (p *RGBImage) RGBAt(x, y int) [3]uint8
- func (p *RGBImage) Set(x, y int, c color.Color)
- func (p *RGBImage) SetRGB(x, y int, c [3]uint8)
- func (p *RGBImage) Stride() int
- func (p *RGBImage) SubImage(r image.Rectangle) image.Image
- type SizeofImager
Examples ¶
Constants ¶
const DefaulQuality = 90
const (
MemPMagic = "MemP" // See https://github.com/chai2010/image
)
Variables ¶
This section is empty.
Functions ¶
func C_webpFree ¶
func C_webpMalloc ¶
func ChannelsOf ¶
func ColorModel ¶
Example ¶
rgba := color.RGBA{R: 101, G: 102, B: 103, A: 104} c := ColorModel(4, reflect.Uint8).Convert(rgba).(MemPColor) fmt.Printf("c = %v\n", c)
Output: c = {4 uint8 [101 102 103 104]}
func DecodeConfig ¶
DecodeConfig returns the color model and dimensions of a WEBP image without decoding the entire image.
func DecodeGrayToSize ¶
DecodeGrayToSize decodes a Gray image scaled to the given dimensions. For large images, the DecodeXXXToSize methods are significantly faster and require less memory compared to decoding a full-size image and then resizing it.
func DecodeRGBAToSize ¶
DecodeRGBAToSize decodes a Gray image scaled to the given dimensions.
func Encode ¶
Encode writes the image m to w in WEBP format.
Example ¶
m, err := Load("./testdata/1_webp_ll.webp") if err != nil { log.Fatal(err) } var buf bytes.Buffer if err := Encode(&buf, m, nil); err != nil { log.Fatal(err) } _ = buf.Bytes()
Output:
Example (Lossless) ¶
m, err := Load("./testdata/1_webp_ll.webp") if err != nil { log.Fatal(err) } var buf bytes.Buffer if err := Encode(&buf, m, &Options{Lossless: true}); err != nil { log.Fatal(err) } _ = buf.Bytes()
Output:
Example (Rgb) ¶
rgb := NewRGBImage(image.Rect(0, 0, 400, 300)) var buf bytes.Buffer if err := Encode(&buf, rgb, nil); err != nil { log.Fatal(err) } _ = buf.Bytes()
Output:
Example (Rgb48MemP) ¶
rgb48 := NewMemPImage(image.Rect(0, 0, 400, 300), 3, reflect.Uint16) var buf bytes.Buffer if err := Encode(&buf, rgb48, nil); err != nil { log.Fatal(err) } _ = buf.Bytes()
Output:
func EncodeExactLosslessRGBA ¶
EncodeExactLosslessRGBA Encode lossless RGB mode with exact. exact: preserve RGB values in transparent area.
func GetInfo ¶
Example ¶
data := xLoadData("1_webp_a.webp") width, height, hasAlpha, err := GetInfo(data) if err != nil { log.Fatal(err) } fmt.Printf("width: %v\n", width) fmt.Printf("height: %v\n", height) fmt.Printf("hasAlpha: %v\n", hasAlpha)
Output: width: 400 height: 301 hasAlpha: true
Example (NoAlpha) ¶
data := xLoadData("video-001.webp") width, height, hasAlpha, err := GetInfo(data) if err != nil { log.Fatal(err) } fmt.Printf("width: %v\n", width) fmt.Printf("height: %v\n", height) fmt.Printf("hasAlpha: %v\n", hasAlpha)
Output: width: 150 height: 103 hasAlpha: false
func GetMetadata ¶
GetMetadata return EXIF/ICCP/XMP format metadata.
func Load ¶
Example ¶
m, err := Load("./testdata/1_webp_ll.webp") if err != nil { log.Fatal(err) } fmt.Printf("Bounds = %v\n", m.Bounds())
Output: Bounds = (0,0)-(400,301)
func LoadConfig ¶
Example ¶
cfg, err := LoadConfig("./testdata/1_webp_ll.webp") if err != nil { log.Fatal(err) } fmt.Printf("Width = %d\n", cfg.Width) fmt.Printf("Height = %d\n", cfg.Height)
Output: Width = 400 Height = 301
func Save ¶
Example ¶
tmpname := "z_test_ExampleSave.webp" defer os.Remove(tmpname) gray := NewMemPImage(image.Rect(0, 0, 400, 300), 1, reflect.Uint8) if err := Save(tmpname, gray, &Options{Quality: 75}); err != nil { log.Fatal(err) }
Output:
func SetMetadata ¶
SetMetadata set EXIF/ICCP/XMP format metadata.
func SizeofImage ¶
func SizeofKind ¶
Example ¶
fmt.Printf("%v = %v\n", reflect.Uint8, SizeofKind(reflect.Uint8)) fmt.Printf("%v = %v\n", reflect.Uint16, SizeofKind(reflect.Uint16)) fmt.Printf("%v = %v\n", reflect.Uint32, SizeofKind(reflect.Uint32)) fmt.Printf("%v = %v\n", reflect.Float32, SizeofKind(reflect.Float32)) fmt.Printf("%v = %v\n", reflect.Float64, SizeofKind(reflect.Float64))
Output: uint8 = 1 uint16 = 2 uint32 = 4 float32 = 4 float64 = 8
func SizeofPixel ¶
Example ¶
fmt.Printf("sizeof(gray) = %d\n", SizeofPixel(1, reflect.Uint8)) fmt.Printf("sizeof(gray16) = %d\n", SizeofPixel(1, reflect.Uint16)) fmt.Printf("sizeof(rgb) = %d\n", SizeofPixel(3, reflect.Uint8)) fmt.Printf("sizeof(rgb48) = %d\n", SizeofPixel(3, reflect.Uint16)) fmt.Printf("sizeof(rgba) = %d\n", SizeofPixel(4, reflect.Uint8)) fmt.Printf("sizeof(rgba64) = %d\n", SizeofPixel(4, reflect.Uint16)) fmt.Printf("sizeof(float32) = %d\n", SizeofPixel(1, reflect.Float32))
Output: sizeof(gray) = 1 sizeof(gray16) = 2 sizeof(rgb) = 3 sizeof(rgb48) = 6 sizeof(rgba) = 4 sizeof(rgba64) = 8 sizeof(float32) = 4
Types ¶
type C_int ¶
func C_webpDecodeGrayToSize ¶
func C_webpDecodeRGBAToSize ¶
func C_webpDecodeRGBToSize ¶
type C_uint16_t ¶
type C_uint32_t ¶
type C_uint64_t ¶
type C_uint8_t ¶
func C_webpDecodeGray ¶
func C_webpDecodeRGB ¶
func C_webpDecodeRGBA ¶
func C_webpEncodeGray ¶
func C_webpEncodeLosslessRGB ¶
func C_webpEncodeRGB ¶
type ColorModelInterface ¶
type MemP ¶
type MemP interface { MemPMagic() string Bounds() image.Rectangle Channels() int DataType() reflect.Kind Pix() []byte // PixSilce type // Stride is the Pix stride (in bytes, must align with SizeofKind(p.DataType)) // between vertically adjacent pixels. Stride() int }
MemP Image Spec (Native Endian), see https://github.com/chai2010/image.
type MemPImage ¶
type MemPImage struct { XMemPMagic string // MemP XRect image.Rectangle XChannels int XDataType reflect.Kind XPix PixSlice XStride int }
func NewMemPImage ¶
func NewMemPImageFrom ¶
func (*MemPImage) ColorModel ¶
type Options ¶
type Options struct { Lossless bool Quality float32 // 0 ~ 100 Exact bool // Preserve RGB values in transparent area. }
Options are the encoding parameters.
type PixSlice ¶
type PixSlice []byte
func AsPixSilce ¶
func AsPixSilce(slice interface{}) (d PixSlice)
AsPixSilce convert a normal slice to byte slice.
Convert []X to []byte:
x := make([]X, xLen) y := AsPixSilce(x)
func (PixSlice) Complex128s ¶
func (d PixSlice) Complex128s() (v []complex128)
func (PixSlice) Complex64s ¶
func (PixSlice) Slice ¶
Slice convert a normal slice to new type slice.
Convert []byte to []Y:
x := make([]byte, xLen) y := PixSlice(x).Slice(reflect.TypeOf([]Y(nil))).([]Y)
func (PixSlice) SwapEndian ¶
type RGB48Image ¶
type RGB48Image struct { XPix []uint8 // XPix use Native Endian (same as MemP) !!! XStride int XRect image.Rectangle }
func NewRGB48Image ¶
func NewRGB48Image(r image.Rectangle) *RGB48Image
NewRGB48Image returns a new RGB48Image with the given bounds.
func NewRGB48ImageFrom ¶
func NewRGB48ImageFrom(m image.Image) *RGB48Image
func (*RGB48Image) Bounds ¶
func (p *RGB48Image) Bounds() image.Rectangle
func (*RGB48Image) Channels ¶
func (p *RGB48Image) Channels() int
func (*RGB48Image) ColorModel ¶
func (p *RGB48Image) ColorModel() color.Model
func (*RGB48Image) DataType ¶
func (p *RGB48Image) DataType() reflect.Kind
func (*RGB48Image) MemPMagic ¶
func (p *RGB48Image) MemPMagic() string
func (*RGB48Image) Opaque ¶
func (p *RGB48Image) Opaque() bool
Opaque scans the entire image and reports whether it is fully opaque.
func (*RGB48Image) Pix ¶
func (p *RGB48Image) Pix() []byte
func (*RGB48Image) PixOffset ¶
func (p *RGB48Image) PixOffset(x, y int) int
PixOffset returns the index of the first element of XPix that corresponds to the pixel at (x, y).
func (*RGB48Image) RGB48At ¶
func (p *RGB48Image) RGB48At(x, y int) [3]uint16
func (*RGB48Image) SetRGB48 ¶
func (p *RGB48Image) SetRGB48(x, y int, c [3]uint16)
func (*RGB48Image) Stride ¶
func (p *RGB48Image) Stride() int
type RGBImage ¶
func DecodeRGBToSize ¶
DecodeRGBToSize decodes an RGB image scaled to the given dimensions.
func NewRGBImage ¶
NewRGBImage returns a new RGBImage with the given bounds.
func NewRGBImageFrom ¶
func (*RGBImage) ColorModel ¶
type SizeofImager ¶
type SizeofImager interface {
SizeofImage() int
}