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/*
* Copyright (c) 2008, Google Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above
* copyright notice, this list of conditions and the following disclaimer
* in the documentation and/or other materials provided with the
* distribution.
* * Neither the name of Google Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "Gradient.h"
#include "CSSParser.h"
#include "GraphicsContext.h"
#include "SkGradientShader.h"
#include "SkiaUtils.h"
namespace WebCore {
void Gradient::platformDestroy()
{
if (m_gradient)
SkSafeUnref(m_gradient);
m_gradient = 0;
}
static inline U8CPU F2B(float x)
{
return static_cast<int>(x * 255);
}
static SkColor makeSkColor(float a, float r, float g, float b)
{
return SkColorSetARGB(F2B(a), F2B(r), F2B(g), F2B(b));
}
// Determine the total number of stops needed, including pseudo-stops at the
// ends as necessary.
static size_t totalStopsNeeded(const Gradient::ColorStop* stopData, size_t count)
{
// N.B.: The tests in this function should kept in sync with the ones in
// fillStops(), or badness happens.
const Gradient::ColorStop* stop = stopData;
size_t countUsed = count;
if (count < 1 || stop->stop > 0.0)
countUsed++;
stop += count - 1;
if (count < 1 || stop->stop < 1.0)
countUsed++;
return countUsed;
}
// Collect sorted stop position and color information into the pos and colors
// buffers, ensuring stops at both 0.0 and 1.0. The buffers must be large
// enough to hold information for all stops, including the new endpoints if
// stops at 0.0 and 1.0 aren't already included.
static void fillStops(const Gradient::ColorStop* stopData,
size_t count, SkScalar* pos, SkColor* colors)
{
const Gradient::ColorStop* stop = stopData;
size_t start = 0;
if (count < 1) {
// A gradient with no stops must be transparent black.
pos[0] = WebCoreFloatToSkScalar(0.0);
colors[0] = makeSkColor(0.0, 0.0, 0.0, 0.0);
start = 1;
} else if (stop->stop > 0.0) {
// Copy the first stop to 0.0. The first stop position may have a slight
// rounding error, but we don't care in this float comparison, since
// 0.0 comes through cleanly and people aren't likely to want a gradient
// with a stop at (0 + epsilon).
pos[0] = WebCoreFloatToSkScalar(0.0);
colors[0] = makeSkColor(stop->alpha, stop->red, stop->green, stop->blue);
start = 1;
}
for (size_t i = start; i < start + count; i++) {
pos[i] = WebCoreFloatToSkScalar(stop->stop);
colors[i] = makeSkColor(stop->alpha, stop->red, stop->green, stop->blue);
++stop;
}
// Copy the last stop to 1.0 if needed. See comment above about this float
// comparison.
if (count < 1 || (--stop)->stop < 1.0) {
pos[start + count] = WebCoreFloatToSkScalar(1.0);
colors[start + count] = colors[start + count - 1];
}
}
SkShader* Gradient::platformGradient()
{
if (m_gradient)
return m_gradient;
sortStopsIfNecessary();
ASSERT(m_stopsSorted);
size_t countUsed = totalStopsNeeded(m_stops.data(), m_stops.size());
ASSERT(countUsed >= 2);
ASSERT(countUsed >= m_stops.size());
// FIXME: Why is all this manual pointer math needed?!
SkAutoMalloc storage(countUsed * (sizeof(SkColor) + sizeof(SkScalar)));
SkColor* colors = (SkColor*)storage.get();
SkScalar* pos = (SkScalar*)(colors + countUsed);
fillStops(m_stops.data(), m_stops.size(), pos, colors);
SkShader::TileMode tile = SkShader::kClamp_TileMode;
switch (m_spreadMethod) {
case SpreadMethodReflect:
tile = SkShader::kMirror_TileMode;
break;
case SpreadMethodRepeat:
tile = SkShader::kRepeat_TileMode;
break;
case SpreadMethodPad:
tile = SkShader::kClamp_TileMode;
break;
}
if (m_radial) {
// Since the two-point radial gradient is slower than the plain radial,
// only use it if we have to.
if (m_p0 == m_p1 && m_r0 <= 0.0f) {
// The radius we give to Skia must be positive (and non-zero). If
// we're given a zero radius, just ask for a very small radius so
// Skia will still return an object.
SkScalar radius = m_r1 > 0 ? WebCoreFloatToSkScalar(m_r1) : SK_ScalarMin;
m_gradient = SkGradientShader::CreateRadial(m_p1, radius, colors, pos, static_cast<int>(countUsed), tile);
} else {
// The radii we give to Skia must be positive. If we're given a
// negative radius, ask for zero instead.
SkScalar radius0 = m_r0 >= 0.0f ? WebCoreFloatToSkScalar(m_r0) : 0;
SkScalar radius1 = m_r1 >= 0.0f ? WebCoreFloatToSkScalar(m_r1) : 0;
m_gradient = SkGradientShader::CreateTwoPointRadial(m_p0, radius0, m_p1, radius1, colors, pos, static_cast<int>(countUsed), tile);
}
if (aspectRatio() != 1) {
// CSS3 elliptical gradients: apply the elliptical scaling at the
// gradient center point.
m_gradientSpaceTransformation.translate(m_p0.x(), m_p0.y());
m_gradientSpaceTransformation.scale(1, 1 / aspectRatio());
m_gradientSpaceTransformation.translate(-m_p0.x(), -m_p0.y());
ASSERT(m_p0 == m_p1);
}
} else {
SkPoint pts[2] = { m_p0, m_p1 };
m_gradient = SkGradientShader::CreateLinear(pts, colors, pos, static_cast<int>(countUsed), tile);
}
ASSERT(m_gradient);
SkMatrix matrix = m_gradientSpaceTransformation;
m_gradient->setLocalMatrix(matrix);
return m_gradient;
}
void Gradient::fill(GraphicsContext* context, const FloatRect& rect)
{
context->setFillGradient(this);
context->fillRect(rect);
}
void Gradient::setPlatformGradientSpaceTransform(const AffineTransform& matrix)
{
if (m_gradient)
m_gradient->setLocalMatrix(m_gradientSpaceTransformation);
}
} // namespace WebCore
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