1 /*
2 * Copyright (c) 2008, 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
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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 "Gradient.h"
33
34 #include "CSSParser.h"
35 #include "GraphicsContext.h"
36
37 #include "SkGradientShader.h"
38 #include "SkiaUtils.h"
39
40 namespace WebCore {
41
platformDestroy()42 void Gradient::platformDestroy()
43 {
44 if (m_gradient)
45 m_gradient->safeUnref();
46 m_gradient = 0;
47 }
48
F2B(float x)49 static inline U8CPU F2B(float x)
50 {
51 return static_cast<int>(x * 255);
52 }
53
makeSkColor(float a,float r,float g,float b)54 static SkColor makeSkColor(float a, float r, float g, float b)
55 {
56 return SkColorSetARGB(F2B(a), F2B(r), F2B(g), F2B(b));
57 }
58
59 // Determine the total number of stops needed, including pseudo-stops at the
60 // ends as necessary.
totalStopsNeeded(const Gradient::ColorStop * stopData,size_t count)61 static size_t totalStopsNeeded(const Gradient::ColorStop* stopData, size_t count)
62 {
63 // N.B.: The tests in this function should kept in sync with the ones in
64 // fillStops(), or badness happens.
65 const Gradient::ColorStop* stop = stopData;
66 size_t countUsed = count;
67 if (count < 1 || stop->stop > 0.0)
68 countUsed++;
69 stop += count - 1;
70 if (count < 1 || stop->stop < 1.0)
71 countUsed++;
72 return countUsed;
73 }
74
75 // Collect sorted stop position and color information into the pos and colors
76 // buffers, ensuring stops at both 0.0 and 1.0. The buffers must be large
77 // enough to hold information for all stops, including the new endpoints if
78 // stops at 0.0 and 1.0 aren't already included.
fillStops(const Gradient::ColorStop * stopData,size_t count,SkScalar * pos,SkColor * colors)79 static void fillStops(const Gradient::ColorStop* stopData,
80 size_t count, SkScalar* pos, SkColor* colors)
81 {
82 const Gradient::ColorStop* stop = stopData;
83 size_t start = 0;
84 if (count < 1) {
85 // A gradient with no stops must be transparent black.
86 pos[0] = WebCoreFloatToSkScalar(0.0);
87 colors[0] = makeSkColor(0.0, 0.0, 0.0, 0.0);
88 start = 1;
89 } else if (stop->stop > 0.0) {
90 // Copy the first stop to 0.0. The first stop position may have a slight
91 // rounding error, but we don't care in this float comparison, since
92 // 0.0 comes through cleanly and people aren't likely to want a gradient
93 // with a stop at (0 + epsilon).
94 pos[0] = WebCoreFloatToSkScalar(0.0);
95 colors[0] = makeSkColor(stop->alpha, stop->red, stop->green, stop->blue);
96 start = 1;
97 }
98
99 for (size_t i = start; i < start + count; i++) {
100 pos[i] = WebCoreFloatToSkScalar(stop->stop);
101 colors[i] = makeSkColor(stop->alpha, stop->red, stop->green, stop->blue);
102 ++stop;
103 }
104
105 // Copy the last stop to 1.0 if needed. See comment above about this float
106 // comparison.
107 if (count < 1 || (--stop)->stop < 1.0) {
108 pos[start + count] = WebCoreFloatToSkScalar(1.0);
109 colors[start + count] = colors[start + count - 1];
110 }
111 }
112
compareStops(const Gradient::ColorStop & a,const Gradient::ColorStop & b)113 static inline bool compareStops(const Gradient::ColorStop& a, const Gradient::ColorStop& b)
114 {
115 return a.stop < b.stop;
116 }
117
platformGradient()118 SkShader* Gradient::platformGradient()
119 {
120 if (m_gradient)
121 return m_gradient;
122
123 // FIXME: This and compareStops() are also in Gradient.cpp and
124 // CSSGradientValue.cpp; probably should refactor in WebKit.
125 if (!m_stopsSorted) {
126 if (m_stops.size())
127 std::stable_sort(m_stops.begin(), m_stops.end(), compareStops);
128 m_stopsSorted = true;
129 }
130 size_t countUsed = totalStopsNeeded(m_stops.data(), m_stops.size());
131 ASSERT(countUsed >= 2);
132 ASSERT(countUsed >= m_stops.size());
133
134 // FIXME: Why is all this manual pointer math needed?!
135 SkAutoMalloc storage(countUsed * (sizeof(SkColor) + sizeof(SkScalar)));
136 SkColor* colors = (SkColor*)storage.get();
137 SkScalar* pos = (SkScalar*)(colors + countUsed);
138
139 fillStops(m_stops.data(), m_stops.size(), pos, colors);
140
141 SkShader::TileMode tile = SkShader::kClamp_TileMode;
142 switch (m_spreadMethod) {
143 case SpreadMethodReflect:
144 tile = SkShader::kMirror_TileMode;
145 break;
146 case SpreadMethodRepeat:
147 tile = SkShader::kRepeat_TileMode;
148 break;
149 case SpreadMethodPad:
150 tile = SkShader::kClamp_TileMode;
151 break;
152 }
153
154 if (m_radial) {
155 // FIXME: CSS radial Gradients allow an offset focal point (the
156 // "start circle"), but skia doesn't seem to support that, so this just
157 // ignores m_p0/m_r0 and draws the gradient centered in the "end
158 // circle" (m_p1/m_r1).
159 // See http://webkit.org/blog/175/introducing-css-gradients/ for a
160 // description of the expected behavior.
161
162 // The radius we give to Skia must be positive (and non-zero). If
163 // we're given a zero radius, just ask for a very small radius so
164 // Skia will still return an object.
165 SkScalar radius = m_r1 > 0 ? WebCoreFloatToSkScalar(m_r1) : SK_ScalarMin;
166 m_gradient = SkGradientShader::CreateRadial(m_p1,
167 radius, colors, pos, static_cast<int>(countUsed), tile);
168 } else {
169 SkPoint pts[2] = { m_p0, m_p1 };
170 m_gradient = SkGradientShader::CreateLinear(pts, colors, pos,
171 static_cast<int>(countUsed), tile);
172 }
173
174 ASSERT(m_gradient);
175
176 SkMatrix matrix = m_gradientSpaceTransformation;
177 m_gradient->setLocalMatrix(matrix);
178
179 return m_gradient;
180 }
181
fill(GraphicsContext * context,const FloatRect & rect)182 void Gradient::fill(GraphicsContext* context, const FloatRect& rect)
183 {
184 context->setFillGradient(this);
185 context->fillRect(rect);
186 }
187
setPlatformGradientSpaceTransform(const TransformationMatrix & matrix)188 void Gradient::setPlatformGradientSpaceTransform(const TransformationMatrix& matrix)
189 {
190 if (m_gradient)
191 m_gradient->setLocalMatrix(m_gradientSpaceTransformation);
192 }
193
194 } // namespace WebCore
195