Store a <scale, bias> tuple for textLength scale adjustment

third_party/WebKit/Source/core/layout/svg/SVGTextChunkBuilder.cpp

Index: third_party/WebKit/Source/core/layout/svg/SVGTextChunkBuilder.cpp
diff --git a/third_party/WebKit/Source/core/layout/svg/SVGTextChunkBuilder.cpp b/third_party/WebKit/Source/core/layout/svg/SVGTextChunkBuilder.cpp
index 118c035efb9ecd32872e61f5bc8d50d7feeab76f..1ab8e02f768284ec68b9f183e9d814862c98b06a 100644
--- a/third_party/WebKit/Source/core/layout/svg/SVGTextChunkBuilder.cpp
+++ b/third_party/WebKit/Source/core/layout/svg/SVGTextChunkBuilder.cpp
@@ -20,11 +20,9 @@
 #include "core/layout/svg/SVGTextChunkBuilder.h"
 
 #include "core/layout/api/LineLayoutSVGInlineText.h"
-#include "core/layout/svg/LayoutSVGInlineText.h"
 #include "core/layout/svg/line/SVGInlineTextBox.h"
 #include "core/svg/SVGLengthContext.h"
 #include "core/svg/SVGTextContentElement.h"
-#include "platform/transforms/AffineTransform.h"
 
 namespace blink {
 
@@ -172,16 +170,10 @@ void SVGTextPathChunkBuilder::handleTextChunk(BoxListConstIterator boxStart, Box
     m_totalCharacters += lengthAccumulator.numCharacters();
 }
 
-static void buildSpacingAndGlyphsTransform(bool isVerticalText, float scale, const SVGTextFragment& fragment, AffineTransform& spacingAndGlyphsTransform)
+static float computeTextLengthBias(const SVGTextFragment& fragment, float scale)
 {
-    spacingAndGlyphsTransform.translate(fragment.x, fragment.y);
-
-    if (isVerticalText)
-        spacingAndGlyphsTransform.scaleNonUniform(1, scale);
-    else
-        spacingAndGlyphsTransform.scaleNonUniform(scale, 1);
-
-    spacingAndGlyphsTransform.translate(-fragment.x, -fragment.y);
+    float initialPosition = fragment.isVertical ? fragment.y : fragment.x;
+    return initialPosition + scale * -initialPosition;
 }
 
 void SVGTextChunkBuilder::handleTextChunk(BoxListConstIterator boxStart, BoxListConstIterator boxEnd)
@@ -236,7 +228,7 @@ void SVGTextChunkBuilder::handleTextChunk(BoxListConstIterator boxStart, BoxList
         } else {
             ASSERT(lengthAdjust == SVGLengthAdjustSpacingAndGlyphs);
             float textLengthScale = desiredTextLength / chunkLength;
-            AffineTransform spacingAndGlyphsTransform;
+            float textLengthBias = 0;
 
             bool foundFirstFragment = false;
             for (auto boxIter = boxStart; boxIter != boxEnd; ++boxIter) {
@@ -247,10 +239,10 @@ void SVGTextChunkBuilder::handleTextChunk(BoxListConstIterator boxStart, BoxList
 
                 if (!foundFirstFragment) {
                     foundFirstFragment = true;
-                    buildSpacingAndGlyphsTransform(isVerticalText, textLengthScale, fragments.first(), spacingAndGlyphsTransform);
+                    textLengthBias = computeTextLengthBias(fragments.first(), textLengthScale);
                 }
 
-                applyTextLengthScaleAdjustment(spacingAndGlyphsTransform, fragments);
+                applyTextLengthScaleAdjustment(textLengthScale, textLengthBias, fragments);
             }
         }
     }
@@ -279,11 +271,12 @@ void SVGTextChunkBuilder::processTextLengthSpacingCorrection(bool isVerticalText
     }
 }
 
-void SVGTextChunkBuilder::applyTextLengthScaleAdjustment(const AffineTransform& spacingAndGlyphsTransform, Vector<SVGTextFragment>& fragments)
+void SVGTextChunkBuilder::applyTextLengthScaleAdjustment(float textLengthScale, float textLengthBias, Vector<SVGTextFragment>& fragments)
 {
     for (SVGTextFragment& fragment : fragments) {
-        ASSERT(fragment.lengthAdjustTransform.isIdentity());
-        fragment.lengthAdjustTransform = spacingAndGlyphsTransform;
+        ASSERT(fragment.lengthAdjustScale == 1);
+        fragment.lengthAdjustScale = textLengthScale;
+        fragment.lengthAdjustBias = textLengthBias;
     }
 }