Make SVG images for custom CSS cursors appear sharp on retina displays

Source/core/platform/Cursor.cpp

 /*
  * Copyright (C) 2010 Apple 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:
  * 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 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 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
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  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "core/platform/Cursor.h"
+#include "core/platform/graphics/ImageBuffer.h"
 
 namespace WebCore {
 
 IntPoint determineHotSpot(Image* image, const IntPoint& specifiedHotSpot)
 {
     if (image->isNull())
         return IntPoint();
 
     // Hot spot must be inside cursor rectangle.
     IntRect imageRect = image->rect();
     if (imageRect.contains(specifiedHotSpot))
         return specifiedHotSpot;
 
     // If hot spot is not specified externally, it can be extracted from some image formats (e.g. .cur).
     IntPoint intrinsicHotSpot;
     bool imageHasIntrinsicHotSpot = image->getHotSpot(intrinsicHotSpot);
     if (imageHasIntrinsicHotSpot && imageRect.contains(intrinsicHotSpot))
         return intrinsicHotSpot;
 
     return IntPoint();
 }
 
+// Similar to Image::nativeImageForCurrentFrame() but incorporates the image
+// scale factor. This ensures that SVG cursors are sharp at high DPI settings.
+Cursor rasterizeSVGCursor(const Cursor& cursor, float imageScaleFactor)
+{
+    Image* image = cursor.image();
+    if (!image || !image->isSVGImage() || imageScaleFactor == 1)
+        return cursor;
+
+    IntSize size = image->size();
+    IntPoint hotSpot = cursor.hotSpot();
+    size.scale(imageScaleFactor);
+    hotSpot.scale(imageScaleFactor, imageScaleFactor);
+
+    OwnPtr<ImageBuffer> buffer = ImageBuffer::create(size, 1);
+    if (!buffer) // failed to allocate image
+        return cursor;
+
+    buffer->context()->drawImage(image, FloatRect(IntRect(IntPoint(), size)));
+    return Cursor(buffer->copyImage(DontCopyBackingStore).get(), hotSpot, imageScaleFactor);
+}
+
 const Cursor& Cursor::fromType(Cursor::Type type)
 {
     switch (type) {
     case Cursor::Pointer:
         return pointerCursor();
     case Cursor::Cross:
         return crossCursor();
     case Cursor::Hand:
         return handCursor();
     case Cursor::IBeam:
@@ skipping 377 matching lines @@
     return c;
 }
 
 const Cursor& grabbingCursor()
 {
     DEFINE_STATIC_LOCAL(Cursor, c, (Cursor::Grabbing));
     return c;
 }
 
 } // namespace WebCore