Merge image sizing algorithms

third_party/WebKit/Source/core/style/StyleImage.cpp

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "core/style/StyleImage.h"
+
+#include "core/svg/graphics/SVGImage.h"
+#include "core/svg/graphics/SVGImageForContainer.h"
+
+namespace blink {
+
+LayoutSize StyleImage::applyZoom(const LayoutSize& size, float multiplier)
+{
+    if (multiplier == 1.0f)
+        return size;
+
+    LayoutUnit width(size.width() * multiplier);
+    LayoutUnit height(size.height() * multiplier);
+
+    // Don't let images that have a width/height >= 1 shrink below 1 when zoomed.

[Yoav Weiss, 2016/03/07 11:16:07]

Do we have tests for this?

[davve, 2016/03/07 13:07:38]

That's a good questions. I'm assuming the reason for not wanting to zoom below
1x1 is that it would potentially change the semantics of the image. Having zero
width or height means a null image in some contexts and (I'm guessing here)
might trigger image fallback code.

I'm not aware of any explicit tests. Zooming is pretty weakly covered overall.

+    if (size.width() > LayoutUnit())
+        width = std::max(LayoutUnit(1), width);
+
+    if (size.height() > LayoutUnit())
+        height = std::max(LayoutUnit(1), height);
+
+    return LayoutSize(width, height);
+}
+
+LayoutSize StyleImage::imageSizeForSVGImage(SVGImage* svgImage, float multiplier, const LayoutSize& defaultObjectSize) const
+{
+    FloatSize unzoomedDefaultObjectSize(defaultObjectSize);
+    unzoomedDefaultObjectSize.scale(1 / multiplier);
+    return applyZoom(LayoutSize(svgImage->concreteObjectSize(svgImage->concreteObjectSize(unzoomedDefaultObjectSize))), multiplier);
+}
+
+} // namespace blink