Merge WebKit at r75315: Initial merge by git.

Change-Id: I570314b346ce101c935ed22a626b48c2af266b84

1 files changed, 266 insertions, 0 deletions

diff --git a/Source/WebCore/platform/graphics/ContextShadow.cpp b/Source/WebCore/platform/graphics/ContextShadow.cpp
new file mode 100644
index 0000000..7becda7
--- /dev/null
+++ b/Source/WebCore/platform/graphics/ContextShadow.cpp
@@ -0,0 +1,266 @@
+/*
+ * Copyright (C) 2010 Sencha, Inc.
+ * Copyright (C) 2010 Igalia S.L.
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``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 APPLE COMPUTER, INC. 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 "ContextShadow.h"
+
+#include "AffineTransform.h"
+#include "FloatQuad.h"
+#include "GraphicsContext.h"
+#include <cmath>
+#include <wtf/MathExtras.h>
+#include <wtf/Noncopyable.h>
+
+using WTF::min;
+using WTF::max;
+
+namespace WebCore {
+
+ContextShadow::ContextShadow()
+    : m_type(NoShadow)
+    , m_blurDistance(0)
+    , m_layerContext(0)
+    , m_shadowsIgnoreTransforms(false)
+{
+}
+
+ContextShadow::ContextShadow(const Color& color, float radius, const FloatSize& offset)
+    : m_color(color)
+    , m_blurDistance(round(radius))
+    , m_offset(offset)
+    , m_layerContext(0)
+    , m_shadowsIgnoreTransforms(false)
+{
+    // See comments in http://webkit.org/b/40793, it seems sensible
+    // to follow Skia's limit of 128 pixels of blur radius
+    m_blurDistance = min(m_blurDistance, 128);
+
+    // The type of shadow is decided by the blur radius, shadow offset, and shadow color.
+    if (!m_color.isValid() || !color.alpha()) {
+        // Can't paint the shadow with invalid or invisible color.
+        m_type = NoShadow;
+    } else if (radius > 0) {
+        // Shadow is always blurred, even the offset is zero.
+        m_type = BlurShadow;
+    } else if (!m_offset.width() && !m_offset.height()) {
+        // Without blur and zero offset means the shadow is fully hidden.
+        m_type = NoShadow;
+    } else {
+        m_type = SolidShadow;
+    }
+}
+
+void ContextShadow::clear()
+{
+    m_type = NoShadow;
+    m_color = Color();
+    m_blurDistance = 0;
+    m_offset = FloatSize();
+}
+
+bool ContextShadow::mustUseContextShadow(GraphicsContext* context)
+{
+    // We can't avoid ContextShadow, since the shadow has blur.
+    if (m_type == ContextShadow::BlurShadow)
+        return true;
+    // We can avoid ContextShadow and optimize, since we're not drawing on a
+    // canvas and box shadows are affected by the transformation matrix.
+    if (!shadowsIgnoreTransforms())
+        return false;
+    // We can avoid ContextShadow, since there are no transformations to apply to the canvas.
+    if (context->getCTM().isIdentity())
+        return false;
+    // Otherwise, no chance avoiding ContextShadow.
+    return true;
+}
+
+// Instead of integer division, we use 17.15 for fixed-point division.
+static const int BlurSumShift = 15;
+
+// Check http://www.w3.org/TR/SVG/filters.html#feGaussianBlur.
+// As noted in the SVG filter specification, running box blur 3x
+// approximates a real gaussian blur nicely.
+
+void ContextShadow::blurLayerImage(unsigned char* imageData, const IntSize& size, int rowStride)
+{
+#if CPU(BIG_ENDIAN)
+    int channels[4] = { 0, 3, 2, 0 };
+#elif CPU(MIDDLE_ENDIAN)
+    int channels[4] = { 1, 2, 3, 1 };
+#else
+    int channels[4] = { 3, 0, 1, 3 };
+#endif
+
+    int d = max(2, static_cast<int>(floorf((2 / 3.f) * m_blurDistance)));
+    int dmax = d >> 1;
+    int dmin = dmax - 1 + (d & 1);
+    if (dmin < 0)
+        dmin = 0;
+
+    // Two stages: horizontal and vertical
+    for (int k = 0; k < 2; ++k) {
+
+        unsigned char* pixels = imageData;
+        int stride = (!k) ? 4 : rowStride;
+        int delta = (!k) ? rowStride : 4;
+        int jfinal = (!k) ? size.height() : size.width();
+        int dim = (!k) ? size.width() : size.height();
+
+        for (int j = 0; j < jfinal; ++j, pixels += delta) {
+
+            // For each step, we blur the alpha in a channel and store the result
+            // in another channel for the subsequent step.
+            // We use sliding window algorithm to accumulate the alpha values.
+            // This is much more efficient than computing the sum of each pixels
+            // covered by the box kernel size for each x.
+
+            for (int step = 0; step < 3; ++step) {
+                int side1 = (!step) ? dmin : dmax;
+                int side2 = (step == 1) ? dmin : dmax;
+                int pixelCount = side1 + 1 + side2;
+                int invCount = ((1 << BlurSumShift) + pixelCount - 1) / pixelCount;
+                int ofs = 1 + side2;
+                int alpha1 = pixels[channels[step]];
+                int alpha2 = pixels[(dim - 1) * stride + channels[step]];
+                unsigned char* ptr = pixels + channels[step + 1];
+                unsigned char* prev = pixels + stride + channels[step];
+                unsigned char* next = pixels + ofs * stride + channels[step];
+
+                int i;
+                int sum = side1 * alpha1 + alpha1;
+                int limit = (dim < side2 + 1) ? dim : side2 + 1;
+                for (i = 1; i < limit; ++i, prev += stride)
+                    sum += *prev;
+                if (limit <= side2)
+                    sum += (side2 - limit + 1) * alpha2;
+
+                limit = (side1 < dim) ? side1 : dim;
+                for (i = 0; i < limit; ptr += stride, next += stride, ++i, ++ofs) {
+                    *ptr = (sum * invCount) >> BlurSumShift;
+                    sum += ((ofs < dim) ? *next : alpha2) - alpha1;
+                }
+                prev = pixels + channels[step];
+                for (; ofs < dim; ptr += stride, prev += stride, next += stride, ++i, ++ofs) {
+                    *ptr = (sum * invCount) >> BlurSumShift;
+                    sum += (*next) - (*prev);
+                }
+                for (; i < dim; ptr += stride, prev += stride, ++i) {
+                    *ptr = (sum * invCount) >> BlurSumShift;
+                    sum += alpha2 - (*prev);
+                }
+            }
+        }
+    }
+}
+
+void ContextShadow::adjustBlurDistance(GraphicsContext* context)
+{
+    const AffineTransform transform = context->getCTM();
+
+    // Adjust blur if we're scaling, since the radius must not be affected by transformations.
+    if (transform.isIdentity())
+        return;
+
+    // Calculate transformed unit vectors.
+    const FloatQuad unitQuad(FloatPoint(0, 0), FloatPoint(1, 0),
+                             FloatPoint(0, 1), FloatPoint(1, 1));
+    const FloatQuad transformedUnitQuad = transform.mapQuad(unitQuad);
+
+    // Calculate X axis scale factor.
+    const FloatSize xUnitChange = transformedUnitQuad.p2() - transformedUnitQuad.p1();
+    const float xAxisScale = sqrtf(xUnitChange.width() * xUnitChange.width()
+                                   + xUnitChange.height() * xUnitChange.height());
+
+    // Calculate Y axis scale factor.
+    const FloatSize yUnitChange = transformedUnitQuad.p3() - transformedUnitQuad.p1();
+    const float yAxisScale = sqrtf(yUnitChange.width() * yUnitChange.width()
+                                   + yUnitChange.height() * yUnitChange.height());
+
+    // blurLayerImage() does not support per-axis blurring, so calculate a balanced scaling.
+    const float scale = sqrtf(xAxisScale * yAxisScale);
+    m_blurDistance = roundf(static_cast<float>(m_blurDistance) / scale);
+}
+
+IntRect ContextShadow::calculateLayerBoundingRect(GraphicsContext* context, const FloatRect& layerArea, const IntRect& clipRect)
+{
+    // Calculate the destination of the blurred and/or transformed layer.
+    FloatRect layerFloatRect;
+    float inflation = 0;
+
+    const AffineTransform transform = context->getCTM();
+    if (m_shadowsIgnoreTransforms && !transform.isIdentity()) {
+        FloatQuad transformedPolygon = transform.mapQuad(FloatQuad(layerArea));
+        transformedPolygon.move(m_offset);
+        layerFloatRect = transform.inverse().mapQuad(transformedPolygon).boundingBox();
+    } else {
+        layerFloatRect = layerArea;
+        layerFloatRect.move(m_offset);
+    }
+
+    // We expand the area by the blur radius to give extra space for the blur transition.
+    if (m_type == BlurShadow) {
+        layerFloatRect.inflate(m_blurDistance);
+        inflation += m_blurDistance;
+    }
+
+    FloatRect unclippedLayerRect = layerFloatRect;
+
+    if (!clipRect.contains(enclosingIntRect(layerFloatRect))) {
+        // No need to have the buffer larger than the clip.
+        layerFloatRect.intersect(clipRect);
+
+        // If we are totally outside the clip region, we aren't painting at all.
+        if (layerFloatRect.isEmpty())
+            return IntRect(0, 0, 0, 0);
+
+        // We adjust again because the pixels at the borders are still
+        // potentially affected by the pixels outside the buffer.
+        if (m_type == BlurShadow) {
+            layerFloatRect.inflate(m_blurDistance);
+            unclippedLayerRect.inflate(m_blurDistance);
+            inflation += m_blurDistance;
+        }
+    }
+
+    const int frameSize = inflation * 2;
+    m_sourceRect = IntRect(0, 0, layerArea.width() + frameSize, layerArea.height() + frameSize);
+    m_layerOrigin = FloatPoint(layerFloatRect.x(), layerFloatRect.y());
+
+    const FloatPoint m_unclippedLayerOrigin = FloatPoint(unclippedLayerRect.x(), unclippedLayerRect.y());
+    const FloatSize clippedOut = m_unclippedLayerOrigin - m_layerOrigin;
+
+    // Set the origin as the top left corner of the scratch image, or, in case there's a clipped
+    // out region, set the origin accordingly to the full bounding rect's top-left corner.
+    const float translationX = -layerArea.x() + inflation - fabsf(clippedOut.width());
+    const float translationY = -layerArea.y() + inflation - fabsf(clippedOut.height());
+    m_layerContextTranslation = FloatPoint(translationX, translationY);
+
+    return enclosingIntRect(layerFloatRect);
+}
+
+} // namespace WebCore