Scale x/y coordinate of svg path separately for hit-test

Source/platform/graphics/skia/SkiaUtils.cpp

 /*
  * Copyright (c) 2006,2007,2008, 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
@@ skipping 170 matching lines @@
     // to include them.
     SkScalar fX = SkFloatToScalar(point.x());
     SkScalar fY = SkFloatToScalar(point.y());
     if (fX < bounds.fLeft || fX > bounds.fRight || fY < bounds.fTop || fY > bounds.fBottom)
         return false;
 
     // Scale the path to a large size before hit testing for two reasons:
     // 1) Skia has trouble with coordinates close to the max signed 16-bit values, so we scale larger paths down.
     //    TODO: when Skia is patched to work properly with large values, this will not be necessary.
     // 2) Skia does not support analytic hit testing, so we scale paths up to do raster hit testing with subpixel accuracy.
-    SkScalar biggestCoord = std::max(std::max(std::max(bounds.fRight, bounds.fBottom), -bounds.fLeft), -bounds.fTop);
-    if (SkScalarNearlyZero(biggestCoord))
+    // 3) Scale the x/y axis separately so an extreme large/small scale factor on one axis won't
+    //    ruin the resolution of the other axis.
+    SkScalar biggestCoordX = std::max(bounds.fRight, -bounds.fLeft);
+    SkScalar biggestCoordY = std::max(bounds.fBottom, -bounds.fTop);
+    if (SkScalarNearlyZero(biggestCoordX) || SkScalarNearlyZero(biggestCoordY))
         return false;
-    biggestCoord = std::max(std::max(biggestCoord, fX + 1), fY + 1);
+
+    biggestCoordX = std::max(biggestCoordX, fX + 1);

[f(malita), 2015/08/20 09:29:06]

Not new to this CL, but are we missing a fabs(fX) here?

[Yufeng Shen (Slow to review), 2015/08/24 20:13:07]

right, also it makes the code easier to follow.

+    biggestCoordY = std::max(biggestCoordY, fY + 1);

[f(malita), 2015/08/20 09:29:06]

Ditto for fY.

[Yufeng Shen (Slow to review), 2015/08/24 20:13:07]

Done.

 
     const SkScalar kMaxCoordinate = SkIntToScalar(1 << 15);
-    SkScalar scale = kMaxCoordinate / biggestCoord;
+    SkScalar scaleX = kMaxCoordinate / biggestCoordX;
+    SkScalar scaleY = kMaxCoordinate / biggestCoordY;
 
     SkRegion rgn;
     SkRegion clip;
     SkMatrix m;
     SkPath scaledPath(originalPath);
 
     scaledPath.setFillType(ft);
-    m.setScale(scale, scale);
+    m.setScale(scaleX, scaleY);
     scaledPath.transform(m, 0);
 
-    int x = static_cast<int>(floorf(0.5f + point.x() * scale));
-    int y = static_cast<int>(floorf(0.5f + point.y() * scale));
+    int x = static_cast<int>(floorf(0.5f + point.x() * scaleX));
+    int y = static_cast<int>(floorf(0.5f + point.y() * scaleY));
     clip.setRect(x - 1, y - 1, x + 1, y + 1);
 
     return rgn.setPath(scaledPath, clip);
 }
 
 SkMatrix affineTransformToSkMatrix(const AffineTransform& source)
 {
     SkMatrix result;
 
     result.setScaleX(WebCoreDoubleToSkScalar(source.a()));
@@ skipping 171 matching lines @@
     paint.setAlpha(128);
     paint.setStrokeWidth(paint.getStrokeWidth() * 0.5f);
     drawFocusRingPrimitive(primitive, canvas, paint, cornerRadius);
 #endif
 }
 
 template void PLATFORM_EXPORT drawPlatformFocusRing<SkRect>(const SkRect&, SkCanvas*, SkColor, int width);
 template void PLATFORM_EXPORT drawPlatformFocusRing<SkPath>(const SkPath&, SkCanvas*, SkColor, int width);
 
 }  // namespace blink