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1 /*
2  * Copyright (c) 2008, Google Inc. All rights reserved.
3  * Copyright (C) 2009 Dirk Schulze <krit@webkit.org>
4  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions are
8  * met:
9  *
10  *     * Redistributions of source code must retain the above copyright
11  * notice, this list of conditions and the following disclaimer.
12  *     * Redistributions in binary form must reproduce the above
13  * copyright notice, this list of conditions and the following disclaimer
14  * in the documentation and/or other materials provided with the
15  * distribution.
16  *     * Neither the name of Google Inc. nor the names of its
17  * contributors may be used to endorse or promote products derived from
18  * this software without specific prior written permission.
19  *
20  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
23  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
24  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
25  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
26  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
30  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31  */
32 
33 #include "config.h"
34 #include "platform/graphics/ColorSpace.h"
35 
36 #include "wtf/MathExtras.h"
37 
38 namespace blink {
39 
40 namespace ColorSpaceUtilities {
41 
getLinearRgbLUT()42 static const uint8_t* getLinearRgbLUT()
43 {
44     static uint8_t linearRgbLUT[256];
45     static bool initialized;
46     if (!initialized) {
47         for (unsigned i = 0; i < 256; i++) {
48             float color = i  / 255.0f;
49             color = (color <= 0.04045f ? color / 12.92f : pow((color + 0.055f) / 1.055f, 2.4f));
50             color = std::max(0.0f, color);
51             color = std::min(1.0f, color);
52             linearRgbLUT[i] = static_cast<uint8_t>(round(color * 255));
53         }
54         initialized = true;
55     }
56     return linearRgbLUT;
57 }
58 
getDeviceRgbLUT()59 static const uint8_t* getDeviceRgbLUT()
60 {
61     static uint8_t deviceRgbLUT[256];
62     static bool initialized;
63     if (!initialized) {
64         for (unsigned i = 0; i < 256; i++) {
65             float color = i / 255.0f;
66             color = (powf(color, 1.0f / 2.4f) * 1.055f) - 0.055f;
67             color = std::max(0.0f, color);
68             color = std::min(1.0f, color);
69             deviceRgbLUT[i] = static_cast<uint8_t>(round(color * 255));
70         }
71         initialized = true;
72     }
73     return deviceRgbLUT;
74 }
75 
getConversionLUT(ColorSpace dstColorSpace,ColorSpace srcColorSpace)76 const uint8_t* getConversionLUT(ColorSpace dstColorSpace, ColorSpace srcColorSpace)
77 {
78     // Identity.
79     if (srcColorSpace == dstColorSpace)
80         return 0;
81 
82     // Only sRGB/DeviceRGB <-> linearRGB are supported at the moment.
83     if ((srcColorSpace != ColorSpaceLinearRGB && srcColorSpace != ColorSpaceDeviceRGB)
84         || (dstColorSpace != ColorSpaceLinearRGB && dstColorSpace != ColorSpaceDeviceRGB))
85         return 0;
86 
87     if (dstColorSpace == ColorSpaceLinearRGB)
88         return getLinearRgbLUT();
89     if (dstColorSpace == ColorSpaceDeviceRGB)
90         return getDeviceRgbLUT();
91 
92     ASSERT_NOT_REACHED();
93     return 0;
94 }
95 
convertColor(const Color & srcColor,ColorSpace dstColorSpace,ColorSpace srcColorSpace)96 Color convertColor(const Color& srcColor, ColorSpace dstColorSpace, ColorSpace srcColorSpace)
97 {
98     const uint8_t* lookupTable = getConversionLUT(dstColorSpace, srcColorSpace);
99     if (!lookupTable)
100         return srcColor;
101 
102     return Color(lookupTable[srcColor.red()], lookupTable[srcColor.green()], lookupTable[srcColor.blue()], srcColor.alpha());
103 }
104 
105 } // namespace ColorSpaceUtilities
106 
107 } // namespace blink
108