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 SkSafeUnref(m_gradient);
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
platformGradient()113 SkShader* Gradient::platformGradient()
114 {
115 if (m_gradient)
116 return m_gradient;
117
118 sortStopsIfNecessary();
119 ASSERT(m_stopsSorted);
120
121 size_t countUsed = totalStopsNeeded(m_stops.data(), m_stops.size());
122 ASSERT(countUsed >= 2);
123 ASSERT(countUsed >= m_stops.size());
124
125 // FIXME: Why is all this manual pointer math needed?!
126 SkAutoMalloc storage(countUsed * (sizeof(SkColor) + sizeof(SkScalar)));
127 SkColor* colors = (SkColor*)storage.get();
128 SkScalar* pos = (SkScalar*)(colors + countUsed);
129
130 fillStops(m_stops.data(), m_stops.size(), pos, colors);
131
132 SkShader::TileMode tile = SkShader::kClamp_TileMode;
133 switch (m_spreadMethod) {
134 case SpreadMethodReflect:
135 tile = SkShader::kMirror_TileMode;
136 break;
137 case SpreadMethodRepeat:
138 tile = SkShader::kRepeat_TileMode;
139 break;
140 case SpreadMethodPad:
141 tile = SkShader::kClamp_TileMode;
142 break;
143 }
144
145 if (m_radial) {
146 // Since the two-point radial gradient is slower than the plain radial,
147 // only use it if we have to.
148 if (m_p0 == m_p1 && m_r0 <= 0.0f) {
149 // The radius we give to Skia must be positive (and non-zero). If
150 // we're given a zero radius, just ask for a very small radius so
151 // Skia will still return an object.
152 SkScalar radius = m_r1 > 0 ? WebCoreFloatToSkScalar(m_r1) : SK_ScalarMin;
153 m_gradient = SkGradientShader::CreateRadial(m_p1, radius, colors, pos, static_cast<int>(countUsed), tile);
154 } else {
155 // The radii we give to Skia must be positive. If we're given a
156 // negative radius, ask for zero instead.
157 SkScalar radius0 = m_r0 >= 0.0f ? WebCoreFloatToSkScalar(m_r0) : 0;
158 SkScalar radius1 = m_r1 >= 0.0f ? WebCoreFloatToSkScalar(m_r1) : 0;
159 m_gradient = SkGradientShader::CreateTwoPointRadial(m_p0, radius0, m_p1, radius1, colors, pos, static_cast<int>(countUsed), tile);
160 }
161
162 if (aspectRatio() != 1) {
163 // CSS3 elliptical gradients: apply the elliptical scaling at the
164 // gradient center point.
165 m_gradientSpaceTransformation.translate(m_p0.x(), m_p0.y());
166 m_gradientSpaceTransformation.scale(1, 1 / aspectRatio());
167 m_gradientSpaceTransformation.translate(-m_p0.x(), -m_p0.y());
168 ASSERT(m_p0 == m_p1);
169 }
170 } else {
171 SkPoint pts[2] = { m_p0, m_p1 };
172 m_gradient = SkGradientShader::CreateLinear(pts, colors, pos, static_cast<int>(countUsed), tile);
173 }
174
175 ASSERT(m_gradient);
176 SkMatrix matrix = m_gradientSpaceTransformation;
177 m_gradient->setLocalMatrix(matrix);
178 return m_gradient;
179 }
180
fill(GraphicsContext * context,const FloatRect & rect)181 void Gradient::fill(GraphicsContext* context, const FloatRect& rect)
182 {
183 context->setFillGradient(this);
184 context->fillRect(rect);
185 }
186
setPlatformGradientSpaceTransform(const AffineTransform & matrix)187 void Gradient::setPlatformGradientSpaceTransform(const AffineTransform& matrix)
188 {
189 if (m_gradient)
190 m_gradient->setLocalMatrix(m_gradientSpaceTransformation);
191 }
192
193 } // namespace WebCore
194