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1 /*
2  * Copyright (c) 2010, Google Inc. All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions are
6  * met:
7  *
8  *     * Redistributions of source code must retain the above copyright
9  * notice, this list of conditions and the following disclaimer.
10  *     * Redistributions in binary form must reproduce the above
11  * copyright notice, this list of conditions and the following disclaimer
12  * in the documentation and/or other materials provided with the
13  * distribution.
14  *     * Neither the name of Google Inc. nor the names of its
15  * contributors may be used to endorse or promote products derived from
16  * this software without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
29  */
30 
31 #include "config.h"
32 #include "platform/image-encoders/skia/PNGImageEncoder.h"
33 
34 #include "SkBitmap.h"
35 #include "SkColorPriv.h"
36 #include "SkUnPreMultiply.h"
37 #include "platform/geometry/IntSize.h"
38 #include "platform/graphics/ImageBuffer.h"
39 extern "C" {
40 #include "png.h"
41 }
42 
43 namespace blink {
44 
writeOutput(png_structp png,png_bytep data,png_size_t size)45 static void writeOutput(png_structp png, png_bytep data, png_size_t size)
46 {
47     static_cast<Vector<unsigned char>*>(png_get_io_ptr(png))->append(data, size);
48 }
49 
preMultipliedBGRAtoRGBA(const void * pixels,int pixelCount,unsigned char * output)50 static void preMultipliedBGRAtoRGBA(const void* pixels, int pixelCount, unsigned char* output)
51 {
52     static const SkUnPreMultiply::Scale* scale = SkUnPreMultiply::GetScaleTable();
53     const SkPMColor* input = static_cast<const SkPMColor*>(pixels);
54 
55     for (; pixelCount-- > 0; ++input) {
56         const unsigned alpha = SkGetPackedA32(*input);
57         if ((alpha != 0) && (alpha != 255)) {
58             *output++ = SkUnPreMultiply::ApplyScale(scale[alpha], SkGetPackedR32(*input));
59             *output++ = SkUnPreMultiply::ApplyScale(scale[alpha], SkGetPackedG32(*input));
60             *output++ = SkUnPreMultiply::ApplyScale(scale[alpha], SkGetPackedB32(*input));
61             *output++ = alpha;
62         } else {
63             *output++ = SkGetPackedR32(*input);
64             *output++ = SkGetPackedG32(*input);
65             *output++ = SkGetPackedB32(*input);
66             *output++ = alpha;
67         }
68     }
69 }
70 
encodePixels(IntSize imageSize,unsigned char * inputPixels,bool premultiplied,Vector<unsigned char> * output)71 static bool encodePixels(IntSize imageSize, unsigned char* inputPixels, bool premultiplied, Vector<unsigned char>* output)
72 {
73     imageSize.clampNegativeToZero();
74     Vector<unsigned char> row;
75 
76     png_struct* png = png_create_write_struct(PNG_LIBPNG_VER_STRING, 0, 0, 0);
77     png_info* info = png_create_info_struct(png);
78     if (!png || !info || setjmp(png_jmpbuf(png))) {
79         png_destroy_write_struct(png ? &png : 0, info ? &info : 0);
80         return false;
81     }
82 
83     // Optimize compression for speed.
84     // The parameters are the same as what libpng uses by default for RGB and RGBA images, except:
85     // - the zlib compression level is 3 instead of 6, to avoid the lazy Ziv-Lempel match searching;
86     // - the delta filter is 1 ("sub") instead of 5 ("all"), to reduce the filter computations.
87     // The zlib memory level (8) and strategy (Z_FILTERED) will be set inside libpng.
88     //
89     // Avoid the zlib strategies Z_HUFFMAN_ONLY or Z_RLE.
90     // Although they are the fastest for poorly-compressible images (e.g. photographs),
91     // they are very slow for highly-compressible images (e.g. text, drawings or business graphics).
92     png_set_compression_level(png, 3);
93     png_set_filter(png, PNG_FILTER_TYPE_BASE, PNG_FILTER_SUB);
94 
95     png_set_write_fn(png, output, writeOutput, 0);
96     png_set_IHDR(png, info, imageSize.width(), imageSize.height(),
97                  8, PNG_COLOR_TYPE_RGB_ALPHA, 0, 0, 0);
98     png_write_info(png, info);
99 
100     unsigned char* pixels = inputPixels;
101     row.resize(imageSize.width() * sizeof(SkPMColor));
102     const size_t pixelRowStride = imageSize.width() * 4;
103     for (int y = 0; y < imageSize.height(); ++y) {
104         if (premultiplied) {
105             preMultipliedBGRAtoRGBA(pixels, imageSize.width(), row.data());
106             png_write_row(png, row.data());
107         } else
108             png_write_row(png, pixels);
109         pixels += pixelRowStride;
110     }
111 
112     png_write_end(png, info);
113     png_destroy_write_struct(&png, &info);
114     return true;
115 }
116 
encode(const SkBitmap & bitmap,Vector<unsigned char> * output)117 bool PNGImageEncoder::encode(const SkBitmap& bitmap, Vector<unsigned char>* output)
118 {
119     SkAutoLockPixels bitmapLock(bitmap);
120 
121     if (bitmap.colorType() != kN32_SkColorType || !bitmap.getPixels())
122         return false; // Only support 32 bit/pixel skia bitmaps.
123 
124     return encodePixels(IntSize(bitmap.width(), bitmap.height()), static_cast<unsigned char*>(bitmap.getPixels()), true, output);
125 }
126 
encode(const ImageDataBuffer & imageData,Vector<unsigned char> * output)127 bool PNGImageEncoder::encode(const ImageDataBuffer& imageData, Vector<unsigned char>* output)
128 {
129     return encodePixels(imageData.size(), imageData.data(), false, output);
130 }
131 
132 } // namespace blink
133