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 39typedef Vector<SkScalar, 8> ColorStopOffsetVector; 40typedef Vector<SkColor, 8> ColorStopColorVector; 41 42namespace blink { 43 44Gradient::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 57Gradient::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 70Gradient::~Gradient() 71{ 72} 73 74static inline bool compareStops(const Gradient::ColorStop& a, const Gradient::ColorStop& b) 75{ 76 return a.stop < b.stop; 77} 78 79void 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 91void 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 104bool 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 114void 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 125void Gradient::setDrawsInPMColorSpace(bool drawInPMColorSpace) 126{ 127 if (drawInPMColorSpace == m_drawInPMColorSpace) 128 return; 129 130 m_drawInPMColorSpace = drawInPMColorSpace; 131 m_gradient.clear(); 132} 133 134void 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. 145static 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. 160static 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. 169static 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 203SkShader* 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 blink 269