GetDisplayNearestPoint returns the nearest display when point is outside of any display.

BUG=146893
TEST=ash_unittests --gtest_filter=DisplayControllerTest.FindNearestDisplay

Review URL: https://codereview.chromium.org/99163006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@243273 0039d316-1c4b-4281-b951-d872f2087c98

3 files changed, 67 insertions, 9 deletions

diff --git a/ash/display/display_controller.cc b/ash/display/display_controller.cc
index 09927b3..d66af7d 100644
--- a/ash/display/display_controller.cc
+++ b/ash/display/display_controller.cc
@@ -567,11 +567,27 @@ const gfx::Display& DisplayController::GetDisplayNearestWindow(
 
 const gfx::Display& DisplayController::GetDisplayNearestPoint(
     const gfx::Point& point) const {
-  // Fallback to the primary display if there is no root display containing
-  // the |point|.
   const gfx::Display& display =
       GetDisplayManager()->FindDisplayContainingPoint(point);
-  return display.is_valid() ? display : GetPrimaryDisplay();
+  if (display.is_valid())
+    return display;
+
+  // Fallback to the display that has the shortest Manhattan distance from
+  // the |point|. This is correct in the only areas that matter, namely in the
+  // corners between the physical screens.
+  int min_distance = INT_MAX;
+  const gfx::Display* nearest_display = NULL;
+  for (size_t i = 0; i < GetDisplayManager()->GetNumDisplays(); ++i) {
+    const gfx::Display& display = GetDisplayManager()->GetDisplayAt(i);
+    int distance = display.bounds().ManhattanDistanceToPoint(point);
+    if (distance < min_distance) {
+      min_distance = distance;
+      nearest_display = &display;
+    }
+  }
+  // There should always be at least one display that is less than INT_MAX away.
+  DCHECK(nearest_display);
+  return *nearest_display;
 }
 
 const gfx::Display& DisplayController::GetDisplayMatching(
@@ -707,8 +723,7 @@ void DisplayController::PreDisplayConfigurationChange(bool clear_focus) {
   focus_activation_store_->Store(clear_focus);
 
   gfx::Point point_in_screen = Shell::GetScreen()->GetCursorScreenPoint();
-  gfx::Display display =
-      Shell::GetScreen()->GetDisplayNearestPoint(point_in_screen);
+  gfx::Display display = GetDisplayNearestPoint(point_in_screen);
   aura::Window* root_window = GetRootWindowForDisplayId(display.id());
 
   aura::client::ScreenPositionClient* client =
diff --git a/ash/display/display_controller_unittest.cc b/ash/display/display_controller_unittest.cc
index 98f9304..ffcd6b0 100644
--- a/ash/display/display_controller_unittest.cc
+++ b/ash/display/display_controller_unittest.cc
@@ -641,7 +641,7 @@ TEST_F(DisplayControllerTest, SwapPrimary) {
   EXPECT_EQ(secondary_display.id(),
             Shell::GetScreen()->GetPrimaryDisplay().id());
   EXPECT_EQ(primary_display.id(), ScreenAsh::GetSecondaryDisplay().id());
-  EXPECT_EQ(secondary_display.id(),
+  EXPECT_EQ(primary_display.id(),
             Shell::GetScreen()->GetDisplayNearestPoint(
                 gfx::Point(-100, -100)).id());
   EXPECT_EQ(secondary_display.id(),
@@ -684,6 +684,49 @@ TEST_F(DisplayControllerTest, SwapPrimary) {
   EXPECT_TRUE(primary_root->Contains(shelf_window));
 }
 
+TEST_F(DisplayControllerTest, FindNearestDisplay) {
+  if (!SupportsMultipleDisplays())
+    return;
+
+  DisplayController* display_controller =
+      Shell::GetInstance()->display_controller();
+  internal::DisplayManager* display_manager =
+      Shell::GetInstance()->display_manager();
+
+  UpdateDisplay("200x200,300x300");
+  DisplayLayout display_layout(DisplayLayout::RIGHT, 50);
+  display_manager->SetLayoutForCurrentDisplays(display_layout);
+
+  gfx::Display primary_display = Shell::GetScreen()->GetPrimaryDisplay();
+  gfx::Display secondary_display = ScreenAsh::GetSecondaryDisplay();
+  EXPECT_NE(primary_display.id(), secondary_display.id());
+  aura::Window* primary_root =
+      display_controller->GetRootWindowForDisplayId(primary_display.id());
+  aura::Window* secondary_root =
+      display_controller->GetRootWindowForDisplayId(secondary_display.id());
+  EXPECT_NE(primary_root, secondary_root);
+
+  // Test that points outside of any display return the nearest display.
+  EXPECT_EQ(primary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
+      gfx::Point(-100, 0)).id());
+  EXPECT_EQ(primary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
+      gfx::Point(0, -100)).id());
+  EXPECT_EQ(primary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
+      gfx::Point(100, 100)).id());
+  EXPECT_EQ(primary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
+      gfx::Point(224, 25)).id());
+  EXPECT_EQ(secondary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
+      gfx::Point(226, 25)).id());
+  EXPECT_EQ(secondary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
+      gfx::Point(600, 100)).id());
+  EXPECT_EQ(primary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
+      gfx::Point(174, 225)).id());
+  EXPECT_EQ(secondary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
+      gfx::Point(176, 225)).id());
+  EXPECT_EQ(secondary_display.id(), Shell::GetScreen()->GetDisplayNearestPoint(
+      gfx::Point(300, 400)).id());
+}
+
 TEST_F(DisplayControllerTest, SwapPrimaryForLegacyShelfLayout) {
   if (!SupportsMultipleDisplays())
     return;
@@ -735,7 +778,7 @@ TEST_F(DisplayControllerTest, SwapPrimaryForLegacyShelfLayout) {
   EXPECT_EQ(secondary_display.id(),
             Shell::GetScreen()->GetPrimaryDisplay().id());
   EXPECT_EQ(primary_display.id(), ScreenAsh::GetSecondaryDisplay().id());
-  EXPECT_EQ(secondary_display.id(),
+  EXPECT_EQ(primary_display.id(),
             Shell::GetScreen()->GetDisplayNearestPoint(
                 gfx::Point(-100, -100)).id());
   EXPECT_EQ(secondary_display.id(),
diff --git a/ash/extended_desktop_unittest.cc b/ash/extended_desktop_unittest.cc
index 225deca..1ba8297 100644
--- a/ash/extended_desktop_unittest.cc
+++ b/ash/extended_desktop_unittest.cc
@@ -351,8 +351,8 @@ TEST_F(ExtendedDesktopTest, GetRootWindowAt) {
   // Zero origin.
   EXPECT_EQ(root_windows[0], wm::GetRootWindowAt(gfx::Point(0, 0)));
 
-  // Out of range point should return the primary root window
-  EXPECT_EQ(root_windows[0], wm::GetRootWindowAt(gfx::Point(-600, 0)));
+  // Out of range point should return the nearest root window
+  EXPECT_EQ(root_windows[1], wm::GetRootWindowAt(gfx::Point(-600, 0)));
   EXPECT_EQ(root_windows[0], wm::GetRootWindowAt(gfx::Point(701, 100)));
 }