Clamp dialog bounds to be fully visible on the nearest display

components/constrained_window/constrained_window_views.cc

 // Copyright (c) 2012 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 "components/constrained_window/constrained_window_views.h"
 
 #include <algorithm>
 
 #include "base/macros.h"
 #include "build/build_config.h"
 #include "components/constrained_window/constrained_window_views_client.h"
 #include "components/guest_view/browser/guest_view_base.h"
 #include "components/web_modal/web_contents_modal_dialog_host.h"
 #include "components/web_modal/web_contents_modal_dialog_manager.h"
 #include "components/web_modal/web_contents_modal_dialog_manager_delegate.h"
+#include "ui/display/display.h"
+#include "ui/display/display_finder.h"
+#include "ui/display/screen.h"
 #include "ui/views/border.h"
 #include "ui/views/widget/widget.h"
 #include "ui/views/widget/widget_observer.h"
 #include "ui/views/window/dialog_delegate.h"
 
 #if defined(OS_MACOSX)
 #import "components/constrained_window/native_web_contents_modal_dialog_manager_views_mac.h"
 #endif
 
 using web_modal::ModalDialogHost;
@@ skipping 47 matching lines @@
   }
 
  private:
   ModalDialogHost* host_;
   views::Widget* target_widget_;
   const char* const native_window_property_;
 
   DISALLOW_COPY_AND_ASSIGN(WidgetModalDialogHostObserverViews);
 };
 
+gfx::Point MoveRectToNearestHostDisplay(const gfx::Rect& screen_rect,

[msw, 2016/12/14 22:37:08]

Inline this function or rename it, since it doesn't actually move (mutate) a
rect (eg. GetOriginForRectToFitOnDisplay or similar).

+                                        const gfx::Rect& host_rect) {
+  gfx::Rect display_rect = screen_rect;
+  const display::Display* display = display::FindDisplayNearestPoint(

[msw, 2016/12/14 22:37:08]

Use Screen::GetDisplayNearestWindow(dialog_host->GetHostView()).

+      display::Screen::GetScreen()->GetAllDisplays(), host_rect.CenterPoint());
+  DCHECK(display);

[msw, 2016/12/14 22:37:08]

optional nit: DCHECK immediately before deference isn't necessary.

+  const gfx::Rect work_area = display->work_area();
+  if (!work_area.Contains(display_rect))
+    display_rect.AdjustToFit(work_area);
+  return display_rect.origin();
+}
+
 void UpdateModalDialogPosition(views::Widget* widget,
                                web_modal::ModalDialogHost* dialog_host,
                                const gfx::Size& size) {
   // Do not forcibly update the dialog widget position if it is being dragged.
   if (widget->HasCapture())
     return;
 
   views::Widget* host_widget =
       views::Widget::GetWidgetForNativeView(dialog_host->GetHostView());
 
   // If the host view is not backed by a Views::Widget, just update the widget
   // size. This can happen on MacViews under the Cocoa browser where the window
   // modal dialogs are displayed as sheets, and their position is managed by a
   // ConstrainedWindowSheetController instance.
   if (!host_widget) {
     widget->SetSize(size);
     return;
   }
 
   gfx::Point position = dialog_host->GetDialogPosition(size);
   views::Border* border = widget->non_client_view()->frame_view()->border();
   // Border may be null during widget initialization.
   if (border) {
     // Align the first row of pixels inside the border. This is the apparent
     // top of the dialog.
     position.set_y(position.y() - border->GetInsets().top());
   }
 
-  if (widget->is_top_level())
+  if (widget->is_top_level()) {
     position += host_widget->GetClientAreaBoundsInScreen().OffsetFromOrigin();
+    // If the dialog extends partially off any display, clamp its position to

[msw, 2016/12/14 22:37:08]

This should be a function comment on the helper (unless you inline it).

+    // be fully visible within that display. If the dialog doesn't intersect
+    // with any display clamp its position to be fully on the nearest display.
+    position = MoveRectToNearestHostDisplay(
+        gfx::Rect(position, size), host_widget->GetWindowBoundsInScreen());
+  }
 
   widget->SetBounds(gfx::Rect(position, size));
 }
 
 }  // namespace
 
 // static
 void SetConstrainedWindowViewsClient(
     std::unique_ptr<ConstrainedWindowViewsClient> new_client) {
   delete constrained_window_views_client;
@@ skipping 103 matching lines @@
     DCHECK_EQ(parent_view, host->GetHostView());
     ModalDialogHostObserver* dialog_host_observer =
         new WidgetModalDialogHostObserverViews(
             host, widget, kWidgetModalDialogHostObserverViewsKey);
     dialog_host_observer->OnPositionRequiresUpdate();
   }
   return widget;
 }
 
 }  // namespace constrained window