Changeset 65661 in webkit

Timestamp:

Aug 19, 2010 4:00:26 AM (14 years ago)

Author:

alex

Message:

2010-08-19 Alejandro G. Castro <​alex@igalia.com>

Reviewed by Dirk Schulze.

[GTK] The size of the shadow image uses the standard deviation
size instead of the blur radius
​https://bugs.webkit.org/show_bug.cgi?id=40793

The kernelSize variable was renamed to radius and recalculated
considering the CSS3 specification
​http://www.w3.org/TR/css3-background/#the-box-shadow, and the
visual result of other browsers. The HTML5 canvas shadow standard
deviation calculation that was used, was not appropiate for the
blur distance specified in the CSS3.

• platform/graphics/GraphicsContext.h:
• platform/graphics/cairo/FontCairo.cpp: (WebCore::Font::drawGlyphs):
• platform/graphics/cairo/GraphicsContextCairo.cpp: (WebCore::GraphicsContext::calculateShadowBufferDimensions): Changed the calculation, now we use the parameter in the style directly as recomended in the CSS3 standard. (WebCore::drawPathShadow): (WebCore::drawBorderlessRectShadow): (WebCore::GraphicsContext::createPlatformShadow): We get the standard deviation from the radius using the new function and we create the filter with that deviation.
• platform/graphics/cairo/ImageCairo.cpp: (WebCore::BitmapImage::draw):
• platform/graphics/filters/FEGaussianBlur.cpp: (WebCore::FEGaussianBlur::calculateStdDeviation): Added this function that gets the standard deviation from the blur radius. Required in the CSS3 case where we have this radio and we need the deviation to initialize the algorithm.
• platform/graphics/filters/FEGaussianBlur.h:

Location:

trunk/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/graphics/GraphicsContext.h (modified) (1 diff)
• platform/graphics/cairo/FontCairo.cpp (modified) (3 diffs)
• platform/graphics/cairo/GraphicsContextCairo.cpp (modified) (8 diffs)
• platform/graphics/cairo/ImageCairo.cpp (modified) (2 diffs)
• platform/graphics/filters/FEGaussianBlur.cpp (modified) (1 diff)
• platform/graphics/filters/FEGaussianBlur.h (modified) (1 diff)

trunk/WebCore/ChangeLog

@@ +1 @@
+2010-08-19  Alejandro G. Castro  <alex@igalia.com>
+
+        Reviewed by Dirk Schulze.
+
+        [GTK] The size of the shadow image uses the standard deviation
+        size instead of the blur radius
+        https://bugs.webkit.org/show_bug.cgi?id=40793
+
+        The kernelSize variable was renamed to radius and recalculated
+        considering the CSS3 specification
+        http://www.w3.org/TR/css3-background/#the-box-shadow, and the
+        visual result of other browsers. The HTML5 canvas shadow standard
+        deviation calculation that was used, was not appropiate for the
+        blur distance specified in the CSS3.
+
+        * platform/graphics/GraphicsContext.h:
+        * platform/graphics/cairo/FontCairo.cpp:
+        (WebCore::Font::drawGlyphs):
+        * platform/graphics/cairo/GraphicsContextCairo.cpp:
+        (WebCore::GraphicsContext::calculateShadowBufferDimensions):
+        Changed the calculation, now we use the parameter in the style
+        directly as recomended in the CSS3 standard.
+        (WebCore::drawPathShadow):
+        (WebCore::drawBorderlessRectShadow):
+        (WebCore::GraphicsContext::createPlatformShadow): We get the
+        standard deviation from the radius using the new function and we
+        create the filter with that deviation.
+        * platform/graphics/cairo/ImageCairo.cpp:
+        (WebCore::BitmapImage::draw):
+        * platform/graphics/filters/FEGaussianBlur.cpp:
+        (WebCore::FEGaussianBlur::calculateStdDeviation):  Added this
+        function that gets the standard deviation from the blur
+        radius. Required in the CSS3 case where we have this radio and we
+        need the deviation to initialize the algorithm.
+        * platform/graphics/filters/FEGaussianBlur.h:
+
 2010-08-19  Andreas Kling  <andreas.kling@nokia.com>
 

trunk/WebCore/platform/graphics/GraphicsContext.h

@@ -295 +295 @@
 #if PLATFORM(CAIRO)
         float getAlpha();
-        void createPlatformShadow(PassOwnPtr<ImageBuffer> buffer, const Color& shadowColor, const FloatRect& shadowRect, float kernelSize);
-        static void calculateShadowBufferDimensions(IntSize& shadowBufferSize, FloatRect& shadowRect, float& kernelSize, const FloatRect& sourceRect, const FloatSize& shadowSize, float shadowBlur);
+        void createPlatformShadow(PassOwnPtr<ImageBuffer> buffer, const Color& shadowColor, const FloatRect& shadowRect, float radius);
+        static void calculateShadowBufferDimensions(IntSize& shadowBufferSize, FloatRect& shadowRect, float& radius, const FloatRect& sourceRect, const FloatSize& shadowSize, float shadowBlur);
 #endif
 

trunk/WebCore/platform/graphics/cairo/FontCairo.cpp

@@ -95 +95 @@
         IntSize shadowBufferSize;
         FloatRect shadowRect;
-        float kernelSize = 0.f;
-        GraphicsContext::calculateShadowBufferDimensions(shadowBufferSize, shadowRect, kernelSize, rect, shadowSize, shadowBlur);
+        float radius = 0;
+        context->calculateShadowBufferDimensions(shadowBufferSize, shadowRect, radius, rect, shadowSize, shadowBlur);
 
         // Draw shadow into a new ImageBuffer
@@ -103 +103 @@
         cairo_t* shadowCr = shadowContext->platformContext();
 
-        cairo_translate(shadowCr, kernelSize, extents.height + kernelSize);
+        cairo_translate(shadowCr, radius, extents.height + radius);
 
         cairo_set_scaled_font(shadowCr, font->platformData().scaledFont());
@@ -114 +114 @@
         }
         cairo_translate(cr, 0.0, -extents.height);
-        context->createPlatformShadow(shadowBuffer.release(), shadowColor, shadowRect, kernelSize);
+        context->createPlatformShadow(shadowBuffer.release(), shadowColor, shadowRect, radius);
 #else
         cairo_translate(cr, shadowSize.width(), shadowSize.height());

trunk/WebCore/platform/graphics/cairo/GraphicsContextCairo.cpp

@@ -62 +62 @@
 #include "GraphicsContextPrivate.h"
 
+using namespace std;
+
 #ifndef M_PI
 #define M_PI 3.14159265358979323846
@@ -174 +176 @@
 }
 
-void GraphicsContext::calculateShadowBufferDimensions(IntSize& shadowBufferSize, FloatRect& shadowRect, float& kernelSize, const FloatRect& sourceRect, const FloatSize& shadowSize, float shadowBlur)
+void GraphicsContext::calculateShadowBufferDimensions(IntSize& shadowBufferSize, FloatRect& shadowRect, float& radius, const FloatRect& sourceRect, const FloatSize& shadowSize, float shadowBlur)
 {
 #if ENABLE(FILTERS)
-    // calculate the kernel size according to the HTML5 canvas shadow specification
-    kernelSize = (shadowBlur < 8 ? shadowBlur / 2.f : sqrt(shadowBlur * 2.f));
-    int blurRadius = ceil(kernelSize);
-
-    shadowBufferSize = IntSize(sourceRect.width() + blurRadius * 2, sourceRect.height() + blurRadius * 2);
+    // limit radius to 128
+    radius = min(128.f, max(shadowBlur, 0.f));
+
+    shadowBufferSize = IntSize(sourceRect.width() + radius * 2, sourceRect.height() + radius * 2);
 
     // determine dimensions of shadow rect
     shadowRect = FloatRect(sourceRect.location(), shadowBufferSize);
-    shadowRect.move(shadowSize.width() - kernelSize, shadowSize.height() - kernelSize);
+    shadowRect.move(shadowSize.width() - radius, shadowSize.height() - radius);
 #endif
 }
@@ -210 +211 @@
     IntSize shadowBufferSize;
     FloatRect shadowRect;
-    float kernelSize = 0;
-    GraphicsContext::calculateShadowBufferDimensions(shadowBufferSize, shadowRect, kernelSize, rect, shadowSize, shadowBlur);
+    float radius = 0;
+    GraphicsContext::calculateShadowBufferDimensions(shadowBufferSize, shadowRect, radius, rect, shadowSize, shadowBlur);
 
     // Create suitably-sized ImageBuffer to hold the shadow.
@@ -219 +220 @@
     cairo_t* shadowContext = shadowBuffer->context()->platformContext();
     copyContextProperties(cr, shadowContext);
-    cairo_translate(shadowContext, -rect.x() + kernelSize, -rect.y() + kernelSize);
+    cairo_translate(shadowContext, -rect.x() + radius, -rect.y() + radius);
     cairo_new_path(shadowContext);
     cairo_append_path(shadowContext, path);
@@ -228 +229 @@
         setPlatformStroke(context, shadowContext, gcp);
 
-    context->createPlatformShadow(shadowBuffer.release(), shadowColor, shadowRect, kernelSize);
+    context->createPlatformShadow(shadowBuffer.release(), shadowColor, shadowRect, radius);
 #endif
 }
@@ -632 +633 @@
     IntSize shadowBufferSize;
     FloatRect shadowRect;
-    float kernelSize = 0;
-    GraphicsContext::calculateShadowBufferDimensions(shadowBufferSize, shadowRect, kernelSize, rect, shadowSize, shadowBlur);
+    float radius = 0;
+    GraphicsContext::calculateShadowBufferDimensions(shadowBufferSize, shadowRect, radius, rect, shadowSize, shadowBlur);
 
     // Draw shadow into a new ImageBuffer
     OwnPtr<ImageBuffer> shadowBuffer = ImageBuffer::create(shadowBufferSize);
     GraphicsContext* shadowContext = shadowBuffer->context();
-    shadowContext->fillRect(FloatRect(FloatPoint(kernelSize, kernelSize), rect.size()), rectColor, DeviceColorSpace);
-
-    context->createPlatformShadow(shadowBuffer.release(), shadowColor, shadowRect, kernelSize);
+    shadowContext->fillRect(FloatRect(FloatPoint(radius, radius), rect.size()), rectColor, DeviceColorSpace);
+
+    context->createPlatformShadow(shadowBuffer.release(), shadowColor, shadowRect, radius);
 #endif
 }
@@ -921 +922 @@
 }
 
-void GraphicsContext::createPlatformShadow(PassOwnPtr<ImageBuffer> buffer, const Color& shadowColor, const FloatRect& shadowRect, float kernelSize)
+void GraphicsContext::createPlatformShadow(PassOwnPtr<ImageBuffer> buffer, const Color& shadowColor, const FloatRect& shadowRect, float radius)
 {
 #if ENABLE(FILTERS)
     cairo_t* cr = m_data->cr;
 
-    // draw the shadow without blurring, if kernelSize is zero
-    if (!kernelSize) {
+    // calculate the standard deviation
+    float sd = FEGaussianBlur::calculateStdDeviation(radius);
+
+    // draw the shadow without blurring, if radius is zero
+    if (!radius || !sd) {
         setColor(cr, shadowColor);
         cairo_mask_surface(cr, buffer->m_data.m_surface, shadowRect.x(), shadowRect.y());
         return;
     }
-
-    // limit kernel size to 1000, this is what CG is doing.
-    kernelSize = std::min(1000.f, kernelSize);
 
     // create filter
@@ -942 +943 @@
     source->setScaledSubRegion(FloatRect(FloatPoint(), shadowRect.size()));
     source->setIsAlphaImage(true);
-    RefPtr<FilterEffect> blur = FEGaussianBlur::create(source.get(), kernelSize, kernelSize);
+    RefPtr<FilterEffect> blur = FEGaussianBlur::create(source.get(), sd, sd);
     blur->setScaledSubRegion(FloatRect(FloatPoint(), shadowRect.size()));
     blur->apply(filter.get());

trunk/WebCore/platform/graphics/cairo/ImageCairo.cpp

@@ -142 +142 @@
         IntSize shadowBufferSize;
         FloatRect shadowRect;
-        float kernelSize (0.0);
-        GraphicsContext::calculateShadowBufferDimensions(shadowBufferSize, shadowRect, kernelSize, dstRect, shadowSize, shadowBlur);
+        float radius = 0;
+        context->calculateShadowBufferDimensions(shadowBufferSize, shadowRect, radius, dstRect, shadowSize, shadowBlur);
         shadowColor = colorWithOverrideAlpha(shadowColor.rgb(), (shadowColor.alpha() *  context->getAlpha()) / 255.f);
 
@@ -154 +154 @@
         cairo_fill(shadowContext);
 
-        context->createPlatformShadow(shadowBuffer.release(), shadowColor, shadowRect, kernelSize);
+        context->createPlatformShadow(shadowBuffer.release(), shadowColor, shadowRect, radius);
     }
 #endif

trunk/WebCore/platform/graphics/filters/FEGaussianBlur.cpp

@@ -201 +201 @@
 }
 
+float FEGaussianBlur::calculateStdDeviation(float radius)
+{
+    // Blur radius represents 2/3 times the kernel size, the dest pixel is half of the radius applied 3 times
+    return max((radius * 2 / 3.f - 0.5f) / gGaussianKernelFactor, 0.f);
+}
+
 } // namespace WebCore
 

trunk/WebCore/platform/graphics/filters/FEGaussianBlur.h

@@ -44 +44 @@
     TextStream& externalRepresentation(TextStream&, int indent) const;
 
+    static float calculateStdDeviation(float);
+
 private:
     FEGaussianBlur(FilterEffect*, const float&, const float&);