Full-screen Magnifier: Support warping the cursor on the edge

ui/aura/root_window.cc

Index: ui/aura/root_window.cc
diff --git a/ui/aura/root_window.cc b/ui/aura/root_window.cc
index 48a202e97188b8275a0270bdff8d2093123c916f..c1323c08c08267eaa899fa4738c8433f948af68d 100644
--- a/ui/aura/root_window.cc
+++ b/ui/aura/root_window.cc
@@ -33,6 +33,8 @@
 #include "ui/gfx/monitor.h"
 #include "ui/gfx/screen.h"
 
+#include "ui/compositor/layer_type.h"
+
 using std::vector;
 
 namespace aura {
@@ -127,6 +129,7 @@ RootWindow::RootWindow(const gfx::Rect& initial_bounds)
       defer_draw_scheduling_(false),
       mouse_move_hold_count_(0),
       should_hold_mouse_moves_(false),
+      force_hide_cursor_(false),
       compositor_lock_(NULL),
       draw_on_compositor_unlock_(false),
       draw_trace_count_(0) {
@@ -164,7 +167,15 @@ void RootWindow::Init() {
   Window::Init(ui::LAYER_NOT_DRAWN);
   last_mouse_location_ =
       ui::ConvertPointToDIP(layer(), host_->QueryMouseLocation());
-  compositor()->SetRootLayer(layer());
+
+  magnification_layer_.reset(new ui::Layer(ui::LAYER_TEXTURED));
+  magnification_layer_->SetVisible(false);
+  magnification_layer_->SetFillsBoundsOpaquely(true);
+  magnification_layer_->Add(layer());
+  magnification_layer_->SetVisible(true);
+
+  compositor()->SetRootLayer(magnification_layer_.get());
+
   SetBounds(
       ui::ConvertRectToDIP(layer(), gfx::Rect(host_->GetBounds().size())));
   Show();
@@ -211,6 +222,9 @@ void RootWindow::SetCursor(gfx::NativeCursor cursor) {
 }
 
 void RootWindow::ShowCursor(bool show) {
+  if (force_hide_cursor_ && show)
+    show = false;
+
   cursor_shown_ = show;
   host_->ShowCursor(show);
 }
@@ -309,6 +323,10 @@ bool RootWindow::DispatchScrollEvent(ScrollEvent* event) {
 
 bool RootWindow::DispatchTouchEvent(TouchEvent* event) {
   DispatchHeldMouseMove();
+
+  // Touch event should be transformed by magnifition transform matrix.
+  event->UpdateForRootTransform(magnification_layer()->transform());

[sky, 2012/05/16 15:40:48]

Why wouldn't it effect mouse or gesture events?

[yoshiki, 2012/05/17 17:19:32]

This CL magnifies the screen with |magnification_layer_|. This is because we
don't want to change the position/speed of the mouse cursor, to keep the UX of
mouse movement, even after the screen is magnified.

Once the screen is magnified by |magnification_layer_|, the hardware cursor by
the host indicated the wrong position because mouse events is not transformed.
But this is not the problem, because we hide the hardware cursor and draw a
software cursor instead. And scroll events are same.

However, touch events should be transformed by |magnification_layer_| because it
should not be misaligned. But we don't need to transform gesture events because
the events are fired from touch events and they are already transformed.

And the host size should not be transformed in OnHostResized(), because the
desktop size/shape should not be affected by magnification scale. We don't want
to make the logical desktop size smaller even after zoomed.

On 2012/05/16 15:40:48, sky wrote:

+
   if (ui::IsDIPEnabled()) {
     float scale = ui::GetDeviceScaleFactor(layer());
     ui::Transform transform = layer()->transform();