SkWebpCodec.h

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/*
 * Copyright 2015 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
#ifndef SkWebpCodec_DEFINED
#define SkWebpCodec_DEFINED
 
#include "include/codec/SkEncodedImageFormat.h"
#include "include/codec/SkEncodedOrigin.h"
#include "include/core/SkData.h"
#include "include/core/SkRefCnt.h"
#include "include/core/SkTypes.h"
#include "include/private/SkEncodedInfo.h"
#include "include/private/base/SkTemplates.h"
#include "src/codec/SkFrameHolder.h"
#include "src/codec/SkScalingCodec.h"
 
#include <cstddef>
#include <memory>
#include <vector>
 
class SkStream;
class SkCodec;
struct SkIRect;
struct SkImageInfo;
 
extern "C" {
    struct WebPDemuxer;
    void WebPDemuxDelete(WebPDemuxer* dmux);
}
 
class SkWebpCodec final : public SkScalingCodec {
public:
    // Assumes IsWebp was called and returned true.
    static std::unique_ptr<SkCodec> MakeFromStream(std::unique_ptr<SkStream>, Result*);
    static bool IsWebp(const void*, size_t);
protected:
    Result onGetPixels(const SkImageInfo&, void*, size_t, const Options&, int*) override;
    SkEncodedImageFormat onGetEncodedFormat() const override { return SkEncodedImageFormat::kWEBP; }
 
    bool onGetValidSubset(SkIRect* /* desiredSubset */) const override;
 
    int onGetFrameCount() override;
    bool onGetFrameInfo(int, FrameInfo*) const override;
    int onGetRepetitionCount() override;
 
    const SkFrameHolder* getFrameHolder() const override {
        return &fFrameHolder;
    }
 
private:
    SkWebpCodec(SkEncodedInfo&&, std::unique_ptr<SkStream>, WebPDemuxer*, sk_sp<SkData>,
                SkEncodedOrigin);
 
    SkAutoTCallVProc<WebPDemuxer, WebPDemuxDelete> fDemux;
 
    // fDemux has a pointer into this data.
    // This should not be freed until the decode is completed.
    sk_sp<SkData> fData;
 
    class Frame : public SkFrame {
    public:
        Frame(int i, SkEncodedInfo::Alpha alpha)
            : INHERITED(i)
            , fReportedAlpha(alpha)
        {}
 
    protected:
        SkEncodedInfo::Alpha onReportedAlpha() const override {
            return fReportedAlpha;
        }
 
    private:
        const SkEncodedInfo::Alpha fReportedAlpha;
 
        using INHERITED = SkFrame;
    };
 
    class FrameHolder : public SkFrameHolder {
    public:
        ~FrameHolder() override {}
        void setScreenSize(int w, int h) {
            fScreenWidth = w;
            fScreenHeight = h;
        }
        Frame* appendNewFrame(bool hasAlpha);
        const Frame* frame(int i) const;
        int size() const {
            return static_cast<int>(fFrames.size());
        }
        void reserve(int size) {
            fFrames.reserve(size);
        }
 
    protected:
        const SkFrame* onGetFrame(int i) const override;
 
    private:
        std::vector<Frame> fFrames;
    };
 
    FrameHolder fFrameHolder;
    // Set to true if WebPDemuxGetFrame fails. This only means
    // that we will cap the frame count to the frames that
    // succeed.
    bool        fFailed;
 
    using INHERITED = SkScalingCodec;
};
#endif // SkWebpCodec_DEFINED