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/Color.h"
33 #include "platform/graphics/GraphicsContext.h"
34 #include "platform/graphics/skia/SkiaUtils.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 namespace WebCore {
40
Gradient(const FloatPoint & p0,const FloatPoint & p1)41 Gradient::Gradient(const FloatPoint& p0, const FloatPoint& p1)
42 : m_radial(false)
43 , m_p0(p0)
44 , m_p1(p1)
45 , m_r0(0)
46 , m_r1(0)
47 , m_aspectRatio(1)
48 , m_stopsSorted(false)
49 , m_spreadMethod(SpreadMethodPad)
50 , m_drawInPMColorSpace(false)
51 {
52 }
53
Gradient(const FloatPoint & p0,float r0,const FloatPoint & p1,float r1,float aspectRatio)54 Gradient::Gradient(const FloatPoint& p0, float r0, const FloatPoint& p1, float r1, float aspectRatio)
55 : m_radial(true)
56 , m_p0(p0)
57 , m_p1(p1)
58 , m_r0(r0)
59 , m_r1(r1)
60 , m_aspectRatio(aspectRatio)
61 , m_stopsSorted(false)
62 , m_spreadMethod(SpreadMethodPad)
63 , m_drawInPMColorSpace(false)
64 {
65 }
66
~Gradient()67 Gradient::~Gradient()
68 {
69 }
70
addColorStop(float value,const Color & color)71 void Gradient::addColorStop(float value, const Color& color)
72 {
73 float r;
74 float g;
75 float b;
76 float a;
77 color.getRGBA(r, g, b, a);
78 m_stops.append(ColorStop(value, r, g, b, a));
79
80 m_stopsSorted = false;
81 m_gradient.clear();
82 }
83
addColorStop(const Gradient::ColorStop & stop)84 void Gradient::addColorStop(const Gradient::ColorStop& stop)
85 {
86 m_stops.append(stop);
87
88 m_stopsSorted = false;
89 m_gradient.clear();
90 }
91
compareStops(const Gradient::ColorStop & a,const Gradient::ColorStop & b)92 static inline bool compareStops(const Gradient::ColorStop& a, const Gradient::ColorStop& b)
93 {
94 return a.stop < b.stop;
95 }
96
sortStopsIfNecessary()97 void Gradient::sortStopsIfNecessary()
98 {
99 if (m_stopsSorted)
100 return;
101
102 m_stopsSorted = true;
103
104 if (!m_stops.size())
105 return;
106
107 std::stable_sort(m_stops.begin(), m_stops.end(), compareStops);
108 }
109
hasAlpha() const110 bool Gradient::hasAlpha() const
111 {
112 for (size_t i = 0; i < m_stops.size(); i++) {
113 if (m_stops[i].alpha < 1)
114 return true;
115 }
116
117 return false;
118 }
119
setSpreadMethod(GradientSpreadMethod spreadMethod)120 void Gradient::setSpreadMethod(GradientSpreadMethod spreadMethod)
121 {
122 // FIXME: Should it become necessary, allow calls to this method after m_gradient has been set.
123 ASSERT(!m_gradient);
124
125 if (m_spreadMethod == spreadMethod)
126 return;
127
128 m_spreadMethod = spreadMethod;
129 }
130
setDrawsInPMColorSpace(bool drawInPMColorSpace)131 void Gradient::setDrawsInPMColorSpace(bool drawInPMColorSpace)
132 {
133 if (drawInPMColorSpace == m_drawInPMColorSpace)
134 return;
135
136 m_drawInPMColorSpace = drawInPMColorSpace;
137 m_gradient.clear();
138 }
139
setGradientSpaceTransform(const AffineTransform & gradientSpaceTransformation)140 void Gradient::setGradientSpaceTransform(const AffineTransform& gradientSpaceTransformation)
141 {
142 if (m_gradientSpaceTransformation == gradientSpaceTransformation)
143 return;
144
145 m_gradientSpaceTransformation = gradientSpaceTransformation;
146 if (m_gradient)
147 m_gradient->setLocalMatrix(affineTransformToSkMatrix(m_gradientSpaceTransformation));
148 }
149
F2B(float x)150 static inline U8CPU F2B(float x)
151 {
152 return static_cast<int>(x * 255);
153 }
154
makeSkColor(float a,float r,float g,float b)155 static SkColor makeSkColor(float a, float r, float g, float b)
156 {
157 return SkColorSetARGB(F2B(a), F2B(r), F2B(g), F2B(b));
158 }
159
160 // Determine the total number of stops needed, including pseudo-stops at the
161 // ends as necessary.
totalStopsNeeded(const Gradient::ColorStop * stopData,size_t count)162 static size_t totalStopsNeeded(const Gradient::ColorStop* stopData, size_t count)
163 {
164 // N.B.: The tests in this function should kept in sync with the ones in
165 // fillStops(), or badness happens.
166 const Gradient::ColorStop* stop = stopData;
167 size_t countUsed = count;
168 if (count < 1 || stop->stop > 0.0)
169 countUsed++;
170 stop += count - 1;
171 if (count < 1 || stop->stop < 1.0)
172 countUsed++;
173 return countUsed;
174 }
175
176 // Collect sorted stop position and color information into the pos and colors
177 // buffers, ensuring stops at both 0.0 and 1.0. The buffers must be large
178 // enough to hold information for all stops, including the new endpoints if
179 // stops at 0.0 and 1.0 aren't already included.
fillStops(const Gradient::ColorStop * stopData,size_t count,SkScalar * pos,SkColor * colors)180 static void fillStops(const Gradient::ColorStop* stopData,
181 size_t count, SkScalar* pos, SkColor* colors)
182 {
183 const Gradient::ColorStop* stop = stopData;
184 size_t start = 0;
185 if (count < 1) {
186 // A gradient with no stops must be transparent black.
187 pos[0] = WebCoreFloatToSkScalar(0.0);
188 colors[0] = makeSkColor(0.0, 0.0, 0.0, 0.0);
189 start = 1;
190 } else if (stop->stop > 0.0) {
191 // Copy the first stop to 0.0. The first stop position may have a slight
192 // rounding error, but we don't care in this float comparison, since
193 // 0.0 comes through cleanly and people aren't likely to want a gradient
194 // with a stop at (0 + epsilon).
195 pos[0] = WebCoreFloatToSkScalar(0.0);
196 colors[0] = makeSkColor(stop->alpha, stop->red, stop->green, stop->blue);
197 start = 1;
198 }
199
200 for (size_t i = start; i < start + count; i++) {
201 pos[i] = WebCoreFloatToSkScalar(stop->stop);
202 colors[i] = makeSkColor(stop->alpha, stop->red, stop->green, stop->blue);
203 ++stop;
204 }
205
206 // Copy the last stop to 1.0 if needed. See comment above about this float
207 // comparison.
208 if (count < 1 || (--stop)->stop < 1.0) {
209 pos[start + count] = WebCoreFloatToSkScalar(1.0);
210 colors[start + count] = colors[start + count - 1];
211 }
212 }
213
shader()214 SkShader* Gradient::shader()
215 {
216 if (m_gradient)
217 return m_gradient.get();
218
219 sortStopsIfNecessary();
220 ASSERT(m_stopsSorted);
221
222 size_t countUsed = totalStopsNeeded(m_stops.data(), m_stops.size());
223 ASSERT(countUsed >= 2);
224 ASSERT(countUsed >= m_stops.size());
225
226 // FIXME: Why is all this manual pointer math needed?!
227 SkAutoMalloc storage(countUsed * (sizeof(SkColor) + sizeof(SkScalar)));
228 SkColor* colors = (SkColor*)storage.get();
229 SkScalar* pos = (SkScalar*)(colors + countUsed);
230
231 fillStops(m_stops.data(), m_stops.size(), pos, colors);
232
233 SkShader::TileMode tile = SkShader::kClamp_TileMode;
234 switch (m_spreadMethod) {
235 case SpreadMethodReflect:
236 tile = SkShader::kMirror_TileMode;
237 break;
238 case SpreadMethodRepeat:
239 tile = SkShader::kRepeat_TileMode;
240 break;
241 case SpreadMethodPad:
242 tile = SkShader::kClamp_TileMode;
243 break;
244 }
245
246 uint32_t shouldDrawInPMColorSpace = m_drawInPMColorSpace ? SkGradientShader::kInterpolateColorsInPremul_Flag : 0;
247 if (m_radial) {
248 // Since the two-point radial gradient is slower than the plain radial,
249 // only use it if we have to.
250 if (m_p0 == m_p1 && m_r0 <= 0.0f) {
251 m_gradient = adoptRef(SkGradientShader::CreateRadial(m_p1, m_r1, colors, pos, static_cast<int>(countUsed), tile, 0, shouldDrawInPMColorSpace));
252 } else {
253 // The radii we give to Skia must be positive. If we're given a
254 // negative radius, ask for zero instead.
255 SkScalar radius0 = m_r0 >= 0.0f ? WebCoreFloatToSkScalar(m_r0) : 0;
256 SkScalar radius1 = m_r1 >= 0.0f ? WebCoreFloatToSkScalar(m_r1) : 0;
257 m_gradient = adoptRef(SkGradientShader::CreateTwoPointConical(m_p0, radius0, m_p1, radius1, colors, pos, static_cast<int>(countUsed), tile, 0, shouldDrawInPMColorSpace));
258 }
259
260 if (aspectRatio() != 1) {
261 // CSS3 elliptical gradients: apply the elliptical scaling at the
262 // gradient center point.
263 m_gradientSpaceTransformation.translate(m_p0.x(), m_p0.y());
264 m_gradientSpaceTransformation.scale(1, 1 / aspectRatio());
265 m_gradientSpaceTransformation.translate(-m_p0.x(), -m_p0.y());
266 ASSERT(m_p0 == m_p1);
267 }
268 } else {
269 SkPoint pts[2] = { m_p0, m_p1 };
270 m_gradient = adoptRef(SkGradientShader::CreateLinear(pts, colors, pos, static_cast<int>(countUsed), tile, 0, shouldDrawInPMColorSpace));
271 }
272
273 if (!m_gradient) {
274 // use last color, since our "geometry" was degenerate (e.g. radius==0)
275 m_gradient = adoptRef(new SkColorShader(colors[countUsed - 1]));
276 } else {
277 m_gradient->setLocalMatrix(affineTransformToSkMatrix(m_gradientSpaceTransformation));
278 }
279 return m_gradient.get();
280 }
281
282 } //namespace
283