Make new-style page scale work on Android.

cc/pinch_zoom_viewport.cc

 // Copyright 2013 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 "cc/pinch_zoom_viewport.h"
 
 #include "base/logging.h"
 
 namespace cc {
 
@@ skipping 32 matching lines @@
       max_page_scale_factor == max_page_scale_factor_)
     return false;
 
   min_page_scale_factor_ = min_page_scale_factor;
   max_page_scale_factor_ = max_page_scale_factor;
 
   page_scale_factor_ = page_scale_factor;
   return true;
 }
 
-gfx::RectF PinchZoomViewport::Bounds() const {
-  gfx::RectF bounds(gfx::PointF(), layout_viewport_size_);
-  bounds.Scale(1 / total_page_scale_factor());
-  bounds += zoomed_viewport_offset_;
-  return bounds;
+gfx::RectF PinchZoomViewport::ZoomedViewport() const {

[danakj, 2013/01/17 18:02:49]

80 cols in this file

+  gfx::SizeF dip_viewport_size = gfx::ScaleSize(device_viewport_size_, 1 / device_scale_factor_);

[danakj, 2013/01/17 18:02:49]

Can we not introduce "dip" in the compositor? I find it ambiguous. Any space
other than physical pixels is dip. I'd much prefer names like "layout viewport"
or "zoomed layout viewport" where the space is clearly defined. And if it's
relative to some space, use that space with a description of its relationship to
it please.

In this case this is the unzoomed layout viewport size right?

[aelias_OOO_until_Jul13, 2013/01/17 19:59:46]

I interpret "DIP" to specifically mean physical pixels divided by device scale
factor.  Any other space is not "DIP".  We need a word for this space and I
think "DIP" is unambiguous if the acronym ("density independent pixels") is
expanded.

Anyway, I've avoided this local variable entirely for now to avoid further
debate :).

+  gfx::SizeF layer_space_viewport_size = gfx::ScaleSize(dip_viewport_size, 1 / total_page_scale_factor());

[danakj, 2013/01/17 18:02:49]

which layer does layer_space refer to? is this the zoomed viewport size in
layout space? let's call it something like that if so.

[wjmaclean, 2013/01/17 19:45:52]

Should it perhaps be "layout_space_viewport_size"?

[aelias_OOO_until_Jul13, 2013/01/17 19:59:46]

OK, renamed to "layout_space_device_viewport_size".

+  return gfx::RectF(gfx::PointAtOffsetFromOrigin(zoomed_viewport_offset_), layer_space_viewport_size);
 }
 
 gfx::Vector2dF PinchZoomViewport::ApplyScroll(const gfx::Vector2dF delta) {
   gfx::Vector2dF overflow;
-  gfx::RectF pinched_bounds = Bounds() + delta;
+  gfx::RectF pinched_bounds = ZoomedViewport() + delta;
 
   if (pinched_bounds.x() < 0) {
     overflow.set_x(pinched_bounds.x());
     pinched_bounds.set_x(0);
   }
 
   if (pinched_bounds.y() < 0) {
     overflow.set_y(pinched_bounds.y());
     pinched_bounds.set_y(0);
   }
@@ skipping 28 matching lines @@
     gfx::Vector2dF zoomed_device_viewport_offset
       = gfx::ScaleVector2d(zoomed_viewport_offset_, device_scale_factor_);
     transform.Translate(-zoomed_device_viewport_offset.x(),
                         -zoomed_device_viewport_offset.y());
   }
 
   return transform;
 }
 
 }  // namespace cc