1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef UI_GFX_CODEC_PNG_CODEC_H_ 6 #define UI_GFX_CODEC_PNG_CODEC_H_ 7 8 #include <string> 9 #include <vector> 10 11 #include "base/basictypes.h" 12 #include "ui/gfx/gfx_export.h" 13 14 class SkBitmap; 15 16 namespace gfx { 17 18 class Size; 19 20 // Interface for encoding and decoding PNG data. This is a wrapper around 21 // libpng, which has an inconvenient interface for callers. This is currently 22 // designed for use in tests only (where we control the files), so the handling 23 // isn't as robust as would be required for a browser (see Decode() for more). 24 // WebKit has its own more complicated PNG decoder which handles, among other 25 // things, partially downloaded data. 26 class GFX_EXPORT PNGCodec { 27 public: 28 enum ColorFormat { 29 // 3 bytes per pixel (packed), in RGB order regardless of endianness. 30 // This is the native JPEG format. 31 FORMAT_RGB, 32 33 // 4 bytes per pixel, in RGBA order in memory regardless of endianness. 34 FORMAT_RGBA, 35 36 // 4 bytes per pixel, in BGRA order in memory regardless of endianness. 37 // This is the default Windows DIB order. 38 FORMAT_BGRA, 39 40 // SkBitmap format. For Encode() kARGB_8888_Config (4 bytes per pixel) and 41 // kA8_Config (1 byte per pixel) formats are supported. kA8_Config gets 42 // encoded into a grayscale PNG treating alpha as the color intensity. 43 // For Decode() kARGB_8888_Config is always used. 44 FORMAT_SkBitmap 45 }; 46 47 // Represents a comment in the tEXt ancillary chunk of the png. 48 struct GFX_EXPORT Comment { 49 Comment(const std::string& k, const std::string& t); 50 ~Comment(); 51 52 std::string key; 53 std::string text; 54 }; 55 56 // Encodes the given raw 'input' data, with each pixel being represented as 57 // given in 'format'. The encoded PNG data will be written into the supplied 58 // vector and true will be returned on success. On failure (false), the 59 // contents of the output buffer are undefined. 60 // 61 // When writing alpha values, the input colors are assumed to be post 62 // multiplied. 63 // 64 // size: dimensions of the image 65 // row_byte_width: the width in bytes of each row. This may be greater than 66 // w * bytes_per_pixel if there is extra padding at the end of each row 67 // (often, each row is padded to the next machine word). 68 // discard_transparency: when true, and when the input data format includes 69 // alpha values, these alpha values will be discarded and only RGB will be 70 // written to the resulting file. Otherwise, alpha values in the input 71 // will be preserved. 72 // comments: comments to be written in the png's metadata. 73 static bool Encode(const unsigned char* input, 74 ColorFormat format, 75 const Size& size, 76 int row_byte_width, 77 bool discard_transparency, 78 const std::vector<Comment>& comments, 79 std::vector<unsigned char>* output); 80 81 // Call PNGCodec::Encode on the supplied SkBitmap |input|, which is assumed 82 // to be kARGB_8888_Config, 32 bits per pixel. The params 83 // |discard_transparency| and |output| are passed directly to Encode; refer to 84 // Encode for more information. During the call, an SkAutoLockPixels lock 85 // is held on |input|. 86 static bool EncodeBGRASkBitmap(const SkBitmap& input, 87 bool discard_transparency, 88 std::vector<unsigned char>* output); 89 90 // Call PNGCodec::Encode on the supplied SkBitmap |input|. The difference 91 // between this and the previous method is that this restricts compression to 92 // zlib q1, which is just rle encoding. 93 static bool FastEncodeBGRASkBitmap(const SkBitmap& input, 94 bool discard_transparency, 95 std::vector<unsigned char>* output); 96 97 // Call PNGCodec::Encode on the supplied SkBitmap |input|, which is assumed 98 // to be kA8_Config, 8 bits per pixel. The bitmap is encoded as a grayscale 99 // PNG with alpha used for color intensity. The |output| param is passed 100 // directly to Encode; refer to Encode for more information. During the call, 101 // an SkAutoLockPixels lock is held on |input|. 102 static bool EncodeA8SkBitmap(const SkBitmap& input, 103 std::vector<unsigned char>* output); 104 105 // Decodes the PNG data contained in input of length input_size. The 106 // decoded data will be placed in *output with the dimensions in *w and *h 107 // on success (returns true). This data will be written in the 'format' 108 // format. On failure, the values of these output variables are undefined. 109 // 110 // This function may not support all PNG types, and it hasn't been tested 111 // with a large number of images, so assume a new format may not work. It's 112 // really designed to be able to read in something written by Encode() above. 113 static bool Decode(const unsigned char* input, size_t input_size, 114 ColorFormat format, std::vector<unsigned char>* output, 115 int* w, int* h); 116 117 // Decodes the PNG data directly into the passed in SkBitmap. This is 118 // significantly faster than the vector<unsigned char> version of Decode() 119 // above when dealing with PNG files that are >500K, which a lot of theme 120 // images are. (There are a lot of themes that have a NTP image of about ~1 121 // megabyte, and those require a 7-10 megabyte side buffer.) 122 // 123 // Returns true if data is non-null and can be decoded as a png, false 124 // otherwise. 125 static bool Decode(const unsigned char* input, size_t input_size, 126 SkBitmap* bitmap); 127 128 private: 129 DISALLOW_COPY_AND_ASSIGN(PNGCodec); 130 }; 131 132 } // namespace gfx 133 134 #endif // UI_GFX_CODEC_PNG_CODEC_H_ 135