Fix folder icon animation in app list.

ui/gfx/transform_util.cc

 // Copyright (c) 2012 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 "ui/gfx/transform_util.h"
 
 #include <algorithm>
 #include <cmath>
 
 #include "base/logging.h"
@@ skipping 264 matching lines @@
 }  // namespace
 
 Transform GetScaleTransform(const Point& anchor, float scale) {
   Transform transform;
   transform.Translate(anchor.x() * (1 - scale),
                       anchor.y() * (1 - scale));
   transform.Scale(scale, scale);
   return transform;
 }
 
+Transform GetRectTransform(const gfx::Rect& from, const gfx::Rect& to) {
+  Transform transform;
+  transform.Translate(to.x(), to.y());
+  transform.Scale(static_cast<double>(to.width()) / from.width(),

[Matt Giuca, 2014/11/04 01:05:17]

Going to have infinities if from.width() or from.height() is 0. I don't know
what will happen in that case but it's probably not an intended mode of
operation (and certainly won't get the intended result).

DCHECK_NE(0, from.width());
DCHECK_NE(0, from.height());

and document that from's width and height must be non-zero.

(Also think about what happens if width and height are negative; maybe just
DCHECK that too.)

[calamity, 2014/11/04 01:40:29]

Done.

+                  static_cast<double>(to.height()) / from.height());
+  transform.Translate(-from.x(), -from.y());
+  return transform;
+}
+
 DecomposedTransform::DecomposedTransform() {
   translate[0] = translate[1] = translate[2] = 0.0;
   scale[0] = scale[1] = scale[2] = 1.0;
   skew[0] = skew[1] = skew[2] = 0.0;
   perspective[0] = perspective[1] = perspective[2] = 0.0;
   quaternion[0] = quaternion[1] = quaternion[2] = 0.0;
   perspective[3] = quaternion[3] = 1.0;
 }
 
 bool BlendDecomposedTransforms(DecomposedTransform* out,
@@ skipping 197 matching lines @@
       perspective[1],
       perspective[2],
       perspective[3],
       quaternion[0],
       quaternion[1],
       quaternion[2],
       quaternion[3]);
 }
 
 }  // namespace ui