ChromeOS: The centered app list's top is now forced to be >= 10.

Previously, in small space environments (e.g., low resolution or big
virtual keyboard), the app list's top would disappear off screen. Now,
it is forced below the screen top (with a 10px margin), even if it means
forcing the bottom further off screen.

BUG=371681

Review URL: https://codereview.chromium.org/281523002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@270115 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 72 insertions, 8 deletions

diff --git a/ash/wm/app_list_controller.cc b/ash/wm/app_list_controller.cc
index 45915c4..6acf1ae 100644
--- a/ash/wm/app_list_controller.cc
+++ b/ash/wm/app_list_controller.cc
@@ -44,6 +44,9 @@ const int kMaxOverScrollShift = 48;
 // result of minimal bubble arrow sizes and offsets.
 const int kMinimalAnchorPositionOffset = 57;
 
+// The minimal margin (in pixels) around the app list when in centered mode.
+const int kMinimalCenteredAppListMargin = 10;
+
 ui::Layer* GetLayer(views::Widget* widget) {
   return widget->GetNativeView()->layer();
 }
@@ -115,8 +118,11 @@ gfx::Vector2d GetAnchorPositionOffsetToShelf(
 }
 
 // Gets the point at the center of the display that a particular view is on.
-// This calculation excludes the virtual keyboard area.
-gfx::Point GetCenterOfDisplayForView(const views::View* view) {
+// This calculation excludes the virtual keyboard area. If the height of the
+// display area is less than |minimum_height|, its bottom will be extended to
+// that height (so that the app list never starts above the top of the screen).
+gfx::Point GetCenterOfDisplayForView(const views::View* view,
+                                     int minimum_height) {
   gfx::Rect bounds = Shell::GetScreen()->GetDisplayNearestWindow(
       view->GetWidget()->GetNativeView()).bounds();
 
@@ -129,9 +135,18 @@ gfx::Point GetCenterOfDisplayForView(const views::View* view) {
   if (keyboard_controller && keyboard_controller->keyboard_visible())
     bounds.Subtract(keyboard_controller->current_keyboard_bounds());
 
+  // Apply the |minimum_height|.
+  if (bounds.height() < minimum_height)
+    bounds.set_height(minimum_height);
+
   return bounds.CenterPoint();
 }
 
+// Gets the minimum height of the rectangle to center the app list in.
+int GetMinimumBoundsHeightForAppList(const app_list::AppListView* app_list) {
+  return app_list->bounds().height() + 2 * kMinimalCenteredAppListMargin;
+}
+
 }  // namespace
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -189,15 +204,19 @@ void AppListController::SetVisible(bool visible, aura::Window* window) {
         Shelf::ForWindow(container)->GetAppListButtonView();
     is_centered_ = view->ShouldCenterWindow();
     if (is_centered_) {
-      // The experimental app list is centered over the display of the app list
-      // button that was pressed (if triggered via keyboard, this is the display
-      // with the currently focused window).
+      // Note: We can't center the app list until we have its dimensions, so we
+      // init at (0, 0) and then reset its anchor point.
       view->InitAsBubbleAtFixedLocation(
           container,
           pagination_model_.get(),
-          GetCenterOfDisplayForView(applist_button),
+          gfx::Point(),
           views::BubbleBorder::FLOAT,
           true /* border_accepts_events */);
+      // The experimental app list is centered over the display of the app list
+      // button that was pressed (if triggered via keyboard, this is the display
+      // with the currently focused window).
+      view->SetAnchorPoint(GetCenterOfDisplayForView(
+          applist_button, GetMinimumBoundsHeightForAppList(view)));
     } else {
       gfx::Rect applist_button_bounds = applist_button->GetBoundsInScreen();
       // We need the location of the button within the local screen.
@@ -340,7 +359,8 @@ void AppListController::UpdateBounds() {
   view_->UpdateBounds();
 
   if (is_centered_)
-    view_->SetAnchorPoint(GetCenterOfDisplayForView(view_));
+    view_->SetAnchorPoint(GetCenterOfDisplayForView(
+        view_, GetMinimumBoundsHeightForAppList(view_)));
 }
 
 ////////////////////////////////////////////////////////////////////////////////
diff --git a/ash/wm/app_list_controller_unittest.cc b/ash/wm/app_list_controller_unittest.cc
index 7b467df..da663d6 100644
--- a/ash/wm/app_list_controller_unittest.cc
+++ b/ash/wm/app_list_controller_unittest.cc
@@ -10,12 +10,19 @@
 #include "base/command_line.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/app_list/app_list_switches.h"
+#include "ui/app_list/views/app_list_view.h"
 #include "ui/aura/test/event_generator.h"
 #include "ui/aura/test/test_windows.h"
 #include "ui/aura/window.h"
 
 namespace ash {
 
+namespace {
+
+const int kMinimalCenteredAppListMargin = 10;
+
+}
+
 // The parameter is true to test the centered app list, false for normal.
 // (The test name ends in "/0" for normal, "/1" for centered.)
 class AppListControllerTest : public test::AshTestBase,
@@ -24,6 +31,8 @@ class AppListControllerTest : public test::AshTestBase,
   AppListControllerTest();
   virtual ~AppListControllerTest();
   virtual void SetUp() OVERRIDE;
+
+  bool IsCentered() const;
 };
 
 AppListControllerTest::AppListControllerTest() {
@@ -34,12 +43,16 @@ AppListControllerTest::~AppListControllerTest() {
 
 void AppListControllerTest::SetUp() {
   AshTestBase::SetUp();
-  if (GetParam()) {
+  if (IsCentered()) {
     CommandLine* command_line = CommandLine::ForCurrentProcess();
     command_line->AppendSwitch(app_list::switches::kEnableCenteredAppList);
   }
 }
 
+bool AppListControllerTest::IsCentered() const {
+  return GetParam();
+}
+
 // Tests that app launcher hides when focus moves to a normal window.
 TEST_P(AppListControllerTest, HideOnFocusOut) {
   Shell::GetInstance()->ToggleAppList(NULL);
@@ -137,6 +150,37 @@ TEST_P(AppListControllerTest, NonPrimaryDisplay) {
   EXPECT_FALSE(Shell::GetInstance()->GetAppListTargetVisibility());
 }
 
+// Tests opening the app launcher on a tiny display that is too small to contain
+// it.
+TEST_P(AppListControllerTest, TinyDisplay) {
+  // Don't test this for the non-centered app list case; it isn't designed for
+  // small displays. The most common case of a small display --- when the
+  // virtual keyboard is open --- switches into the centered app list mode, so
+  // we just want to run this test in that case.
+  if (!IsCentered())
+    return;
+
+  // UpdateDisplay is not supported in this case, so just skip the test.
+  if (!SupportsHostWindowResize())
+    return;
+
+  // Set up a screen with a tiny display (height smaller than the app list).
+  UpdateDisplay("400x300");
+
+  Shell::GetInstance()->ToggleAppList(NULL);
+  EXPECT_TRUE(Shell::GetInstance()->GetAppListTargetVisibility());
+
+  // The top of the app list should be on-screen (even if the bottom is not).
+  // We need to manually calculate the Y coordinate of the top of the app list
+  // from the anchor (center) and height. There isn't a bounds rect that gives
+  // the actual app list position (the widget bounds include the bubble border
+  // which is much bigger than the actual app list size).
+  app_list::AppListView* app_list = Shell::GetInstance()->GetAppListView();
+  int app_list_view_top =
+      app_list->anchor_rect().y() - app_list->bounds().height() / 2;
+  EXPECT_GE(app_list_view_top, kMinimalCenteredAppListMargin);
+}
+
 INSTANTIATE_TEST_CASE_P(AppListControllerTestInstance,
                         AppListControllerTest,
                         ::testing::Bool());