remoting/host/chromeos/point_transformer.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "remoting/host/chromeos/point_transformer.h"
   6
   7 #include "ash/shell.h"
   8 #include "ui/aura/window_tree_host.h"
   9 #include "ui/compositor/dip_util.h"
  10
  11 namespace remoting {
  12
  13 PointTransformer::PointTransformer() {
  14   root_window_ = ash::Shell::GetPrimaryRootWindow();
  15   root_window_->AddObserver(this);
  16 }
  17
  18 PointTransformer::~PointTransformer() {
  19   root_window_->RemoveObserver(this);
  20 }
  21
  22 void PointTransformer::OnWindowTransformed(aura::Window* window) {
  23   CHECK_EQ(window, root_window_);
  24
  25   ui::Layer* layer = root_window_->layer();
  26   float scale = ui::GetDeviceScaleFactor(layer);
  27
  28   // |layer->transform()| returns a transform comprising a rotation and a
  29   // translation, but in DIPs, so we need to switch device pixels to
  30   // DIPs, apply it, then switch from DIPs back to device pixels.
  31   gfx::Transform rotation = layer->transform();
  32   gfx::Transform inverse_rotation;
  33   gfx::Transform to_device_pixels;
  34   gfx::Transform to_dip;
  35
  36   CHECK(!rotation.GetInverse(&inverse_rotation))
  37       << "Cannot inverse the root transform." << rotation.ToString();
  38
  39   to_device_pixels.Scale(scale, scale);
  40   to_dip.Scale(1 / scale, 1 / scale);
  41
  42   // Matrix transformations are applied from right to left.  See annotations.
  43   //                (3)                (2)        (1)
  44   root_to_screen_ = to_device_pixels * rotation * to_dip;
  45   screen_to_root_ = to_device_pixels * inverse_rotation * to_dip;
  46 }
  47
  48 gfx::PointF PointTransformer::ToScreenCoordinates(
  49     const gfx::PointF& root_location) {
  50   gfx::Point3F screen_location(root_location);
  51   root_to_screen_.TransformPoint(&screen_location);
  52   return screen_location.AsPointF();
  53 }
  54
  55 gfx::PointF PointTransformer::FromScreenCoordinates(
  56     const gfx::PointF& screen_location) {
  57   gfx::Point3F root_location(screen_location);
  58   screen_to_root_.TransformPoint(&root_location);
  59   return root_location.AsPointF();
  60 }
  61
  62 }  // namespace remoting