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80 lines
3.0 KiB
C++
80 lines
3.0 KiB
C++
// Copyright (c) 2011 The Chromium Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef UI_GFX_CODEC_JPEG_CODEC_H_
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#define UI_GFX_CODEC_JPEG_CODEC_H_
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#include <stddef.h>
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#include <vector>
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#include "ui/gfx/gfx_export.h"
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class SkBitmap;
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namespace gfx {
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// Interface for encoding/decoding JPEG data. This is a wrapper around libjpeg,
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// which has an inconvenient interface for callers. This is only used for UI
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// elements, WebKit has its own more complicated JPEG decoder which handles,
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// among other things, partially downloaded data.
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class GFX_EXPORT JPEGCodec {
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public:
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enum ColorFormat {
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// 3 bytes per pixel (packed), in RGB order regardless of endianness.
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// This is the native JPEG format.
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FORMAT_RGB,
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// 4 bytes per pixel, in RGBA order in mem regardless of endianness.
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FORMAT_RGBA,
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// 4 bytes per pixel, in BGRA order in mem regardless of endianness.
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// This is the default Windows DIB order.
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FORMAT_BGRA,
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// 4 bytes per pixel, it can be either RGBA or BGRA. It depends on the bit
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// order in kARGB_8888_Config skia bitmap.
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FORMAT_SkBitmap
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};
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enum LibraryVariant {
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SYSTEM_LIBJPEG = 0,
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LIBJPEG_TURBO,
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IJG_LIBJPEG,
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};
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// This method helps identify at run time which library chromium is using.
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static LibraryVariant JpegLibraryVariant();
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// Encodes the given raw 'input' data, with each pixel being represented as
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// given in 'format'. The encoded JPEG data will be written into the supplied
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// vector and true will be returned on success. On failure (false), the
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// contents of the output buffer are undefined.
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//
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// w, h: dimensions of the image
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// row_byte_width: the width in bytes of each row. This may be greater than
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// w * bytes_per_pixel if there is extra padding at the end of each row
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// (often, each row is padded to the next machine word).
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// quality: an integer in the range 0-100, where 100 is the highest quality.
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static bool Encode(const unsigned char* input, ColorFormat format,
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int w, int h, int row_byte_width,
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int quality, std::vector<unsigned char>* output);
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// Decodes the JPEG data contained in input of length input_size. The
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// decoded data will be placed in *output with the dimensions in *w and *h
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// on success (returns true). This data will be written in the'format'
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// format. On failure, the values of these output variables is undefined.
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static bool Decode(const unsigned char* input, size_t input_size,
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ColorFormat format, std::vector<unsigned char>* output,
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int* w, int* h);
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// Decodes the JPEG data contained in input of length input_size. If
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// successful, a SkBitmap is created and returned. It is up to the caller
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// to delete the returned bitmap.
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static SkBitmap* Decode(const unsigned char* input, size_t input_size);
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};
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} // namespace gfx
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#endif // UI_GFX_CODEC_JPEG_CODEC_H_
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