1 /*
2 * Copyright (C) 2006, 2007, 2008, 2010 Apple Inc. All rights reserved.
3 * Copyright (C) 2007 Alp Toker <alp@atoker.com>
4 * Copyright (C) 2013 Google Inc. 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
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
16 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
18 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR
19 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
20 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
22 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
23 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
25 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28 #include "config.h"
29 #include "platform/graphics/Gradient.h"
30
31 #include "platform/geometry/FloatRect.h"
32 #include "platform/graphics/GraphicsContext.h"
33 #include "platform/graphics/skia/SkiaUtils.h"
34 #include "third_party/skia/include/core/SkColor.h"
35 #include "third_party/skia/include/core/SkColorShader.h"
36 #include "third_party/skia/include/core/SkShader.h"
37 #include "third_party/skia/include/effects/SkGradientShader.h"
38
39 typedef Vector<SkScalar, 8> ColorStopOffsetVector;
40 typedef Vector<SkColor, 8> ColorStopColorVector;
41
42 namespace WebCore {
43
Gradient(const FloatPoint & p0,const FloatPoint & p1)44 Gradient::Gradient(const FloatPoint& p0, const FloatPoint& p1)
45 : m_p0(p0)
46 , m_p1(p1)
47 , m_r0(0)
48 , m_r1(0)
49 , m_aspectRatio(1)
50 , m_radial(false)
51 , m_stopsSorted(false)
52 , m_drawInPMColorSpace(false)
53 , m_spreadMethod(SpreadMethodPad)
54 {
55 }
56
Gradient(const FloatPoint & p0,float r0,const FloatPoint & p1,float r1,float aspectRatio)57 Gradient::Gradient(const FloatPoint& p0, float r0, const FloatPoint& p1, float r1, float aspectRatio)
58 : m_p0(p0)
59 , m_p1(p1)
60 , m_r0(r0)
61 , m_r1(r1)
62 , m_aspectRatio(aspectRatio)
63 , m_radial(true)
64 , m_stopsSorted(false)
65 , m_drawInPMColorSpace(false)
66 , m_spreadMethod(SpreadMethodPad)
67 {
68 }
69
~Gradient()70 Gradient::~Gradient()
71 {
72 }
73
compareStops(const Gradient::ColorStop & a,const Gradient::ColorStop & b)74 static inline bool compareStops(const Gradient::ColorStop& a, const Gradient::ColorStop& b)
75 {
76 return a.stop < b.stop;
77 }
78
addColorStop(const Gradient::ColorStop & stop)79 void Gradient::addColorStop(const Gradient::ColorStop& stop)
80 {
81 if (m_stops.isEmpty()) {
82 m_stopsSorted = true;
83 } else {
84 m_stopsSorted = m_stopsSorted && compareStops(m_stops.last(), stop);
85 }
86
87 m_stops.append(stop);
88 m_gradient.clear();
89 }
90
sortStopsIfNecessary()91 void Gradient::sortStopsIfNecessary()
92 {
93 if (m_stopsSorted)
94 return;
95
96 m_stopsSorted = true;
97
98 if (!m_stops.size())
99 return;
100
101 std::stable_sort(m_stops.begin(), m_stops.end(), compareStops);
102 }
103
hasAlpha() const104 bool Gradient::hasAlpha() const
105 {
106 for (size_t i = 0; i < m_stops.size(); i++) {
107 if (m_stops[i].color.hasAlpha())
108 return true;
109 }
110
111 return false;
112 }
113
setSpreadMethod(GradientSpreadMethod spreadMethod)114 void Gradient::setSpreadMethod(GradientSpreadMethod spreadMethod)
115 {
116 // FIXME: Should it become necessary, allow calls to this method after m_gradient has been set.
117 ASSERT(!m_gradient);
118
119 if (m_spreadMethod == spreadMethod)
120 return;
121
122 m_spreadMethod = spreadMethod;
123 }
124
setDrawsInPMColorSpace(bool drawInPMColorSpace)125 void Gradient::setDrawsInPMColorSpace(bool drawInPMColorSpace)
126 {
127 if (drawInPMColorSpace == m_drawInPMColorSpace)
128 return;
129
130 m_drawInPMColorSpace = drawInPMColorSpace;
131 m_gradient.clear();
132 }
133
setGradientSpaceTransform(const AffineTransform & gradientSpaceTransformation)134 void Gradient::setGradientSpaceTransform(const AffineTransform& gradientSpaceTransformation)
135 {
136 if (m_gradientSpaceTransformation == gradientSpaceTransformation)
137 return;
138
139 m_gradientSpaceTransformation = gradientSpaceTransformation;
140 m_gradient.clear();
141 }
142
143 // Determine the total number of stops needed, including pseudo-stops at the
144 // ends as necessary.
totalStopsNeeded(const Gradient::ColorStop * stopData,size_t count)145 static size_t totalStopsNeeded(const Gradient::ColorStop* stopData, size_t count)
146 {
147 // N.B.: The tests in this function should kept in sync with the ones in
148 // fillStops(), or badness happens.
149 const Gradient::ColorStop* stop = stopData;
150 size_t countUsed = count;
151 if (count < 1 || stop->stop > 0.0)
152 countUsed++;
153 stop += count - 1;
154 if (count < 1 || stop->stop < 1.0)
155 countUsed++;
156 return countUsed;
157 }
158
159 // FIXME: This would be more at home as Color::operator SkColor.
makeSkColor(const Color & c)160 static inline SkColor makeSkColor(const Color& c)
161 {
162 return SkColorSetARGB(c.alpha(), c.red(), c.green(), c.blue());
163 }
164
165 // Collect sorted stop position and color information into the pos and colors
166 // buffers, ensuring stops at both 0.0 and 1.0. The buffers must be large
167 // enough to hold information for all stops, including the new endpoints if
168 // stops at 0.0 and 1.0 aren't already included.
fillStops(const Gradient::ColorStop * stopData,size_t count,ColorStopOffsetVector & pos,ColorStopColorVector & colors)169 static void fillStops(const Gradient::ColorStop* stopData,
170 size_t count, ColorStopOffsetVector& pos, ColorStopColorVector& colors)
171 {
172 const Gradient::ColorStop* stop = stopData;
173 size_t start = 0;
174 if (count < 1) {
175 // A gradient with no stops must be transparent black.
176 pos[0] = WebCoreFloatToSkScalar(0.0);
177 colors[0] = SK_ColorTRANSPARENT;
178 start = 1;
179 } else if (stop->stop > 0.0) {
180 // Copy the first stop to 0.0. The first stop position may have a slight
181 // rounding error, but we don't care in this float comparison, since
182 // 0.0 comes through cleanly and people aren't likely to want a gradient
183 // with a stop at (0 + epsilon).
184 pos[0] = WebCoreFloatToSkScalar(0.0);
185 colors[0] = makeSkColor(stop->color);
186 start = 1;
187 }
188
189 for (size_t i = start; i < start + count; i++) {
190 pos[i] = WebCoreFloatToSkScalar(stop->stop);
191 colors[i] = makeSkColor(stop->color);
192 ++stop;
193 }
194
195 // Copy the last stop to 1.0 if needed. See comment above about this float
196 // comparison.
197 if (count < 1 || (--stop)->stop < 1.0) {
198 pos[start + count] = WebCoreFloatToSkScalar(1.0);
199 colors[start + count] = colors[start + count - 1];
200 }
201 }
202
shader()203 SkShader* Gradient::shader()
204 {
205 if (m_gradient)
206 return m_gradient.get();
207
208 sortStopsIfNecessary();
209 ASSERT(m_stopsSorted);
210
211 size_t countUsed = totalStopsNeeded(m_stops.data(), m_stops.size());
212 ASSERT(countUsed >= 2);
213 ASSERT(countUsed >= m_stops.size());
214
215 ColorStopOffsetVector pos(countUsed);
216 ColorStopColorVector colors(countUsed);
217 fillStops(m_stops.data(), m_stops.size(), pos, colors);
218
219 SkShader::TileMode tile = SkShader::kClamp_TileMode;
220 switch (m_spreadMethod) {
221 case SpreadMethodReflect:
222 tile = SkShader::kMirror_TileMode;
223 break;
224 case SpreadMethodRepeat:
225 tile = SkShader::kRepeat_TileMode;
226 break;
227 case SpreadMethodPad:
228 tile = SkShader::kClamp_TileMode;
229 break;
230 }
231
232 uint32_t shouldDrawInPMColorSpace = m_drawInPMColorSpace ? SkGradientShader::kInterpolateColorsInPremul_Flag : 0;
233 if (m_radial) {
234 if (aspectRatio() != 1) {
235 // CSS3 elliptical gradients: apply the elliptical scaling at the
236 // gradient center point.
237 m_gradientSpaceTransformation.translate(m_p0.x(), m_p0.y());
238 m_gradientSpaceTransformation.scale(1, 1 / aspectRatio());
239 m_gradientSpaceTransformation.translate(-m_p0.x(), -m_p0.y());
240 ASSERT(m_p0 == m_p1);
241 }
242 SkMatrix localMatrix = affineTransformToSkMatrix(m_gradientSpaceTransformation);
243
244 // Since the two-point radial gradient is slower than the plain radial,
245 // only use it if we have to.
246 if (m_p0 == m_p1 && m_r0 <= 0.0f) {
247 m_gradient = adoptRef(SkGradientShader::CreateRadial(m_p1.data(), m_r1, colors.data(), pos.data(), static_cast<int>(countUsed), tile, shouldDrawInPMColorSpace, &localMatrix));
248 } else {
249 // The radii we give to Skia must be positive. If we're given a
250 // negative radius, ask for zero instead.
251 SkScalar radius0 = m_r0 >= 0.0f ? WebCoreFloatToSkScalar(m_r0) : 0;
252 SkScalar radius1 = m_r1 >= 0.0f ? WebCoreFloatToSkScalar(m_r1) : 0;
253 m_gradient = adoptRef(SkGradientShader::CreateTwoPointConical(m_p0.data(), radius0, m_p1.data(), radius1, colors.data(), pos.data(), static_cast<int>(countUsed), tile, shouldDrawInPMColorSpace, &localMatrix));
254 }
255 } else {
256 SkPoint pts[2] = { m_p0.data(), m_p1.data() };
257 SkMatrix localMatrix = affineTransformToSkMatrix(m_gradientSpaceTransformation);
258 m_gradient = adoptRef(SkGradientShader::CreateLinear(pts, colors.data(), pos.data(), static_cast<int>(countUsed), tile, shouldDrawInPMColorSpace, &localMatrix));
259 }
260
261 if (!m_gradient) {
262 // use last color, since our "geometry" was degenerate (e.g. radius==0)
263 m_gradient = adoptRef(new SkColorShader(colors[countUsed - 1]));
264 }
265 return m_gradient.get();
266 }
267
268 } //namespace
269