Bug 606360: Don't double-count full-page-zoom factor when drawing SVG <image> element. r=longsonr a=blocking-final+

layout/reftests/svg/image/image-zoom-01-ref.svg

@@ -0,0 +1,5 @@
+<svg xmlns="http://www.w3.org/2000/svg"
+     xmlns:xlink="http://www.w3.org/1999/xlink"
+     viewBox="0 0 20 20">
+  <image width="10" height="10" xlink:href="blueRect10x10.png"/>
+</svg>

layout/reftests/svg/image/image-zoom-01a.svg

@@ -0,0 +1,8 @@
+<svg xmlns="http://www.w3.org/2000/svg"
+     xmlns:xlink="http://www.w3.org/1999/xlink"
+     viewBox="0 0 20 20"
+     reftest-zoom="1.5">
+  <title>Testcase to ensure that full-page-zoom doesn't actually zoom raster
+         images, when we have a viewBox applied.</title>
+  <image width="10" height="10" xlink:href="blueRect10x10.png"/>
+</svg>

layout/reftests/svg/image/image-zoom-01b.svg

@@ -0,0 +1,8 @@
+<svg xmlns="http://www.w3.org/2000/svg"
+     xmlns:xlink="http://www.w3.org/1999/xlink"
+     viewBox="0 0 20 20"
+     reftest-zoom="0.5">
+  <title>Testcase to ensure that full-page-zoom doesn't actually zoom raster
+         images, when we have a viewBox applied.</title>
+  <image width="10" height="10" xlink:href="blueRect10x10.png"/>
+</svg>

layout/reftests/svg/image/image-zoom-02-ref.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg"
+     xmlns:xlink="http://www.w3.org/1999/xlink">
+  <image width="15" height="15" xlink:href="blueRect10x10.png"/>
+</svg>

layout/reftests/svg/image/image-zoom-02.svg

@@ -0,0 +1,7 @@
+<svg xmlns="http://www.w3.org/2000/svg"
+     xmlns:xlink="http://www.w3.org/1999/xlink"
+     reftest-zoom="1.5">
+  <title>Testcase to ensure that full-page-zoom will zoom raster
+         images the right amount.</title>
+  <image width="10" height="10" xlink:href="blueRect10x10.png"/>
+</svg>

layout/reftests/svg/image/reftest.list

@@ -14,6 +14,9 @@
 == image-x-01.svg             image-x-01-ref.svg
 == image-xy-01.svg            image-xy-01-ref.svg
 == image-y-01.svg             image-y-01-ref.svg
+== image-zoom-01a.svg         image-zoom-01-ref.svg
+== image-zoom-01b.svg         image-zoom-01-ref.svg
+== image-zoom-02.svg          image-zoom-02-ref.svg
 
 # Tests for <image> with preserveAspectRatio
 # NOTE: The reference cases in the following tests trigger 20 assertions each

layout/svg/base/src/nsSVGImageFrame.cpp

@@ -255,10 +255,13 @@ nsSVGImageFrame::PaintSVG(nsSVGRenderState *aContext,
       nsSVGUtils::SetClipRect(ctx, GetCanvasTM(), clipRect);
     }
 
-    // NOTE: To ensure that |width| and |height| don't accidentally
-    // scale the user-unit size in SVG images, we apply those attributes
-    // via |destRect|, not via our gfxContext's transform.
-    ctx->Multiply(GetImageTransform());
+    nscoord appUnitsPerDevPx = PresContext()->AppUnitsPerDevPixel();
+    gfxFloat pageZoomFactor =
+      nsPresContext::AppUnitsToFloatCSSPixels(appUnitsPerDevPx);
+
+    // NOTE: We need to cancel out the effects of Full-Page-Zoom, or else
+    // it'll get applied an extra time by DrawSingleUnscaledImage.
+    ctx->Multiply(GetImageTransform().Scale(pageZoomFactor, pageZoomFactor));
 
     // fill-opacity doesn't affect <image>, so if we're allowed to
     // optimize group opacity, the opacity used for compositing the
@@ -274,7 +277,7 @@ nsSVGImageFrame::PaintSVG(nsSVGRenderState *aContext,
 
     nsRect dirtyRect; // only used if aDirtyRect is non-null
     if (aDirtyRect) {
-      dirtyRect = aDirtyRect->ToAppUnits(PresContext()->AppUnitsPerDevPixel());
+      dirtyRect = aDirtyRect->ToAppUnits(appUnitsPerDevPx);
       // Adjust dirtyRect to match our local coordinate system.
       dirtyRect.MoveBy(-mRect.TopLeft());
     }