SkWebpEncoder Namespace Reference

Classes
struct	Options

Enumerations
enum class	Compression { kLossy , kLossless }

Functions
SK_API bool	Encode (SkWStream *dst, const SkPixmap &src, const Options &options)
SK_API sk_sp< SkData >	Encode (GrDirectContext *ctx, const SkImage *img, const Options &options)
SK_API bool	EncodeAnimated (SkWStream *dst, SkSpan< const SkEncoder::Frame > src, const Options &options)

Enumeration Type Documentation

Compression

enum class SkWebpEncoder::Compression

strong

Enumerator
kLossy
kLossless

Definition at line 25 of file SkWebpEncoder.h.

                       {
    kLossy,
    kLossless,
};

Function Documentation

Encode() [1/2]

sk_sp< SkData > SkWebpEncoder::Encode	(	GrDirectContext *	ctx,
		const SkImage *	img,
		const Options &	options
	)

Encode the provided image and return the resulting bytes. If the image was created as a texture-backed image on a GPU context, that |ctx| must be provided so the pixels can be read before being encoded. For raster-backed images, |ctx| can be nullptr. |options| may be used to control the encoding behavior.

Returns nullptr if the pixels could not be read or encoding otherwise fails.

Definition at line 25 of file SkWebpEncoder_none.cpp.

                                                                       {
    SkDEBUGFAIL("Using encoder stub");
    return nullptr;
}

Encode() [2/2]

bool SkWebpEncoder::Encode	(	SkWStream *	dst,
		const SkPixmap &	src,
		const Options &	options
	)

Encode the |src| pixels to the |dst| stream. |options| may be used to control the encoding behavior.

Returns true on success. Returns false on an invalid or unsupported |src|.

Definition at line 20 of file SkWebpEncoder_none.cpp.

                                                         {
    SkDEBUGFAIL("Using encoder stub");
    return false;
}

EncodeAnimated()

bool SkWebpEncoder::EncodeAnimated	(	SkWStream *	dst,
		SkSpan< const SkEncoder::Frame >	src,
		const Options &	options
	)

Encode the |src| frames to the |dst| stream. |options| may be used to control the encoding behavior.

The size of the first frame will be used as the canvas size. If any other frame does not match the canvas size, this is an error.

Returns true on success. Returns false on an invalid or unsupported |src|.

Note: libwebp API also supports set background color, loop limit and customize lossy/lossless for each frame. These could be added later as needed.

Definition at line 191 of file SkWebpEncoderImpl.cpp.

                                                                                                 {
    if (!stream || frames.empty()) {
        return false;
    }
 
    const int canvasWidth = frames.front().pixmap.width();
    const int canvasHeight = frames.front().pixmap.height();
    int timestamp = 0;
 
    std::unique_ptr<WebPAnimEncoder, void (*)(WebPAnimEncoder*)> enc(
            WebPAnimEncoderNew(canvasWidth, canvasHeight, nullptr), WebPAnimEncoderDelete);
    if (!enc) {
        return false;
    }
 
    for (const auto& frame : frames) {
        const auto& pixmap = frame.pixmap;
 
        if (pixmap.width() != canvasWidth || pixmap.height() != canvasHeight) {
            return false;
        }
 
        WebPConfig webp_config;
        if (!WebPConfigPreset(&webp_config, WEBP_PRESET_DEFAULT, opts.fQuality)) {
            return false;
        }
 
        WebPPicture pic;
        if (!WebPPictureInit(&pic)) {
            return false;
        }
        SkAutoTCallVProc<WebPPicture, WebPPictureFree> autoPic(&pic);
 
        if (!preprocess_webp_picture(&pic, &webp_config, pixmap, opts)) {
            return false;
        }
 
        if (!WebPEncode(&webp_config, &pic)) {
            return false;
        }
 
        if (!WebPAnimEncoderAdd(enc.get(), &pic, timestamp, &webp_config)) {
            return false;
        }
 
        timestamp += frame.duration;
    }
 
    // Add a last fake frame to signal the last duration.
    if (!WebPAnimEncoderAdd(enc.get(), nullptr, timestamp, nullptr)) {
        return false;
    }
 
    WebPData assembled;
    SkAutoTCallVProc<WebPData, WebPDataClear> autoWebPData(&assembled);
    if (!WebPAnimEncoderAssemble(enc.get(), &assembled)) {
        return false;
    }
 
    enc.reset();
 
    return stream->write(assembled.bytes, assembled.size);
}