third_party/WebKit/Source/platform/image-encoders/JPEGImageEncoder.h

/*
 * Copyright (c) 2010, Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
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 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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 */

#ifndef JPEGImageEncoder_h
#define JPEGImageEncoder_h

#include "platform/geometry/IntSize.h"
#include "wtf/Allocator.h"
#include "wtf/PassOwnPtr.h"
#include "wtf/Vector.h"

namespace blink {

struct ImageDataBuffer;

class PLATFORM_EXPORT JPEGImageEncoderState {
    USING_FAST_MALLOC(JPEGImageEncoderState);
    WTF_MAKE_NONCOPYABLE(JPEGImageEncoderState);
public:
    static PassOwnPtr<JPEGImageEncoderState> create(const IntSize& imageSize, const double& quality, Vector<unsigned char>* output);
    JPEGImageEncoderState() {}
    virtual ~JPEGImageEncoderState() {}
};

class PLATFORM_EXPORT JPEGImageEncoder {
    STATIC_ONLY(JPEGImageEncoder);
public:
    enum {
        ProgressiveEncodeFailed = -1
    };

    // Encode the image data with a compression quality in [0-100].
    // Warning: Calling this method off the main thread may result in data race
    // problems; instead, call JPEGImageEncoderState::create on main thread
    // first followed by encodeWithPreInitializedState off the main thread will
    // be safer.
    static bool encode(const ImageDataBuffer&, const double& quality, Vector<unsigned char>*);

    static bool encodeWithPreInitializedState(PassOwnPtr<JPEGImageEncoderState>, const unsigned char*, int numRowsCompleted = 0);
    static int progressiveEncodeRowsJpegHelper(JPEGImageEncoderState*, unsigned char*, int, const double, double);
    static int computeCompressionQuality(const double& quality);

private:
    // For callers: provide a reasonable compression quality default.
    enum Quality { DefaultCompressionQuality = 92 };
};

} // namespace blink

#endif