// DecodeRGBA decodes WebP image into RGBA image and returns it as an *image.RGBA.
func DecodeRGBA(data []byte, options *DecoderOptions) (img *image.RGBA, err error) {
config, err := initDecoderConfig(options)
if err != nil {
return nil, err
}
cDataPtr := (*C.uint8_t)(&data[0])
cDataSize := (C.size_t)(len(data))
// Retrive WebP features
if status := C.WebPGetFeatures(cDataPtr, cDataSize, &config.input); status != C.VP8_STATUS_OK {
return nil, fmt.Errorf("Could not get features from the data stream, return %s", statusString(status))
}
// Allocate output image
outWidth, outHeight := calcOutputSize(config)
img = image.NewRGBA(image.Rect(0, 0, outWidth, outHeight))
// Set up output configurations
config.output.colorspace = C.MODE_RGBA
config.output.is_external_memory = 1
// Allocate WebPRGBABuffer and fill in the pointers to output image
buf := (*C.WebPRGBABuffer)(unsafe.Pointer(&config.output.u[0]))
buf.rgba = (*C.uint8_t)(&img.Pix[0])
buf.stride = C.int(img.Stride)
buf.size = (C.size_t)(len(img.Pix))
// Decode
if status := C.WebPDecode(cDataPtr, cDataSize, config); status != C.VP8_STATUS_OK {
return nil, fmt.Errorf("Could not decode data stream, return %s", statusString(status))
}
return
}
// DecodeYUVA decodes WebP image into YUV image with alpha channel, and returns
// it as *YUVAImage.
func DecodeYUVA(data []byte, options *DecoderOptions) (img *YUVAImage, err error) {
config, err := initDecoderConfig(options)
if err != nil {
return nil, err
}
cDataPtr := (*C.uint8_t)(&data[0])
cDataSize := (C.size_t)(len(data))
// Retrive WebP features from data stream
if status := C.WebPGetFeatures(cDataPtr, cDataSize, &config.input); status != C.VP8_STATUS_OK {
return nil, fmt.Errorf("Could not get features from the data stream, return %s", statusString(status))
}
outWidth, outHeight := calcOutputSize(config)
buf := (*C.WebPYUVABuffer)(unsafe.Pointer(&config.output.u[0]))
// Set up output configurations
colorSpace := YUV420
config.output.colorspace = C.MODE_YUV
if config.input.has_alpha > 0 {
colorSpace = YUV420A
config.output.colorspace = C.MODE_YUVA
}
config.output.is_external_memory = 1
// Allocate image and fill into buffer
img = NewYUVAImage(image.Rect(0, 0, outWidth, outHeight), colorSpace)
buf.y = (*C.uint8_t)(&img.Y[0])
buf.u = (*C.uint8_t)(&img.Cb[0])
buf.v = (*C.uint8_t)(&img.Cr[0])
buf.a = nil
buf.y_stride = C.int(img.YStride)
buf.u_stride = C.int(img.CStride)
buf.v_stride = C.int(img.CStride)
buf.a_stride = 0
buf.y_size = C.size_t(len(img.Y))
buf.u_size = C.size_t(len(img.Cb))
buf.v_size = C.size_t(len(img.Cr))
buf.a_size = 0
if config.input.has_alpha > 0 {
buf.a = (*C.uint8_t)(&img.A[0])
buf.a_stride = C.int(img.AStride)
buf.a_size = C.size_t(len(img.A))
}
if status := C.WebPDecode(cDataPtr, cDataSize, config); status != C.VP8_STATUS_OK {
return nil, fmt.Errorf("Could not decode data stream, return %s", statusString(status))
}
return
}
// GetFeatures returns features as BitstreamFeatures retrived from data stream.
func GetFeatures(data []byte) (f *BitstreamFeatures, err error) {
var cf C.WebPBitstreamFeatures
status := C.WebPGetFeatures((*C.uint8_t)(&data[0]), (C.size_t)(len(data)), &cf)
if status != C.VP8_STATUS_OK {
return nil, fmt.Errorf("WebPGetFeatures returns unexpected status: %s", statusString(status))
}
f = &BitstreamFeatures{
Width: int(cf.width), // TODO: use Rectangle instaed?
Height: int(cf.height),
HasAlpha: cf.has_alpha > 0,
HasAnimation: cf.has_animation > 0,
Format: int(cf.format),
}
return
}