Changeset 123419 in webkit

Timestamp:

Jul 23, 2012 7:44:29 PM (12 years ago)

Author:

mikelawther@chromium.org

Message:

CSS3 calc: optimise blending expression
​https://bugs.webkit.org/show_bug.cgi?id=90037

Reviewed by Tony Chang.

Introduce a new calc expression node - a BlendLength node. Given two Lengths and a progress
this blends them together when evaluated.

An alternative and more general approach of being able to blend two CalcExpressionNodes was
tested, but involves more memory allocations, was measurably slower, and nothing currently
would make use of the generality.

No functional change. Covered by existing tests.

• platform/CalculationValue.h:

(CalcExpressionBlendLength):
(WebCore::CalcExpressionBlendLength::CalcExpressionBlendLength):
(WebCore::CalcExpressionBlendLength::operator==):
(WebCore::CalcExpressionBlendLength::evaluate):
(WebCore):

• platform/Length.cpp:

(WebCore::Length::blendCalculation):

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• platform/CalculationValue.h (modified) (2 diffs)
• platform/Length.cpp (modified) (1 diff)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2012-07-23  Mike Lawther  <mikelawther@chromium.org>
+
+        CSS3 calc: optimise blending expression
+        https://bugs.webkit.org/show_bug.cgi?id=90037
+
+        Reviewed by Tony Chang.
+
+        Introduce a new calc expression node - a BlendLength node. Given two Lengths and a progress
+        this blends them together when evaluated.
+
+        An alternative and more general approach of being able to blend two CalcExpressionNodes was
+        tested, but involves more memory allocations, was measurably slower, and nothing currently
+        would make use of the generality. 
+
+        No functional change. Covered by existing tests.
+
+        * platform/CalculationValue.h:
+        (CalcExpressionBlendLength):
+        (WebCore::CalcExpressionBlendLength::CalcExpressionBlendLength):
+        (WebCore::CalcExpressionBlendLength::operator==):
+        (WebCore::CalcExpressionBlendLength::evaluate):
+        (WebCore):
+        * platform/Length.cpp:
+        (WebCore::Length::blendCalculation):
+
 2012-07-23  Nico Weber  <thakis@chromium.org>
 

trunk/Source/WebCore/platform/CalculationValue.h

@@ -57 +57 @@
     CalcExpressionNodeNumber,
     CalcExpressionNodeLength,
-    CalcExpressionNodeBinaryOperation
+    CalcExpressionNodeBinaryOperation,
+    CalcExpressionNodeBlendLength,
 };
         
@@ -184 +185 @@
 };
 
+class CalcExpressionBlendLength : public CalcExpressionNode {
+public:
+    CalcExpressionBlendLength(Length from, Length to, float progress)
+        : m_from(from)
+        , m_to(to)
+        , m_progress(progress)
+    {
+        m_type = CalcExpressionNodeBlendLength;
+    }
+    
+    bool operator==(const CalcExpressionBlendLength& o) const
+    {
+        return m_progress == o.m_progress && m_from == o.m_from && m_to == o.m_to;
+    }
+    
+    virtual bool operator==(const CalcExpressionNode& o) const
+    {
+        return type() == o.type() && *this == static_cast<const CalcExpressionBlendLength&>(o);
+    }
+    
+    virtual float evaluate(float maxValue) const
+    {
+        return (1.0f - m_progress) * floatValueForLength(m_from, maxValue) + m_progress * floatValueForLength(m_to, maxValue);
+    }
+    
+private:  
+    Length m_from;
+    Length m_to;
+    float m_progress;
+};
+    
 } // namespace WebCore
 

trunk/Source/WebCore/platform/Length.cpp

@@ -211 +211 @@
         return *this;
         
-    // FIXME: https://webkit.org/b/90037 - some of these allocations can be eliminated
-    OwnPtr<CalcExpressionNode> startScale = adoptPtr(new CalcExpressionNumber(1.0 - progress));
-    OwnPtr<CalcExpressionNode> startLength = adoptPtr(new CalcExpressionLength(from));
-    OwnPtr<CalcExpressionNode> startNode = adoptPtr(new CalcExpressionBinaryOperation(startScale.release(), startLength.release(), CalcMultiply));
-    
-    OwnPtr<CalcExpressionNode> endScale = adoptPtr(new CalcExpressionNumber(progress));
-    OwnPtr<CalcExpressionNode> endLength = adoptPtr(new CalcExpressionLength(*this));
-    OwnPtr<CalcExpressionNode> endNode = adoptPtr(new CalcExpressionBinaryOperation(endScale.release(), endLength.release(), CalcMultiply));
-    
-    OwnPtr<CalcExpressionNode> blend = adoptPtr(new CalcExpressionBinaryOperation(startNode.release(), endNode.release(), CalcAdd));
-        
+    OwnPtr<CalcExpressionNode> blend = adoptPtr(new CalcExpressionBlendLength(from, *this, progress));
     return Length(CalculationValue::create(blend.release(), CalculationRangeAll));
 }