Refactor Windows DPI Point, Rect, and Size for Multiple Monitor DPI Awareness

chrome/browser/ui/views/frame/browser_desktop_window_tree_host_win.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 "chrome/browser/ui/views/frame/browser_desktop_window_tree_host_win.h"
 
 #include <dwmapi.h>
 
 #include "base/process/process_handle.h"
 #include "base/win/windows_version.h"
 #include "chrome/browser/lifetime/application_lifetime.h"
 #include "chrome/browser/themes/theme_service.h"
 #include "chrome/browser/themes/theme_service_factory.h"
 #include "chrome/browser/ui/views/frame/browser_frame.h"
 #include "chrome/browser/ui/views/frame/browser_frame_common_win.h"
 #include "chrome/browser/ui/views/frame/browser_view.h"
 #include "chrome/browser/ui/views/frame/browser_window_property_manager_win.h"
 #include "chrome/browser/ui/views/frame/system_menu_insertion_delegate_win.h"
 #include "chrome/browser/ui/views/tabs/tab_strip.h"
 #include "chrome/browser/ui/views/theme_image_mapper.h"
 #include "chrome/common/chrome_constants.h"
 #include "ui/base/theme_provider.h"
-#include "ui/gfx/win/dpi.h"
+#include "ui/gfx/screen_win.h"
 #include "ui/views/controls/menu/native_menu_win.h"
 
 #pragma comment(lib, "dwmapi.lib")
 
 namespace {
 
 const int kClientEdgeThickness = 3;
 
 // DesktopThemeProvider maps resource ids using MapThemeImage(). This is
 // necessary for BrowserDesktopWindowTreeHostWin so that it uses the windows
@@ skipping 279 matching lines @@
         margins.cxLeftWidth = kClientEdgeThickness + 1;
         margins.cxRightWidth = kClientEdgeThickness + 1;
         margins.cyBottomHeight = kClientEdgeThickness + 1;
       }
     }
     // In maximized mode, we only have a titlebar strip of glass, no side/bottom
     // borders.
     if (!browser_view_->IsFullscreen()) {
       gfx::Rect tabstrip_bounds(
           browser_frame_->GetBoundsForTabStrip(browser_view_->tabstrip()));
-      tabstrip_bounds = gfx::win::DIPToScreenRect(tabstrip_bounds);
+      tabstrip_bounds = gfx::ScreenWin::DIPToClientRect(GetHWND(),

[sky, 2015/10/29 15:51:50]

Is there a reason for changing the name of these functions? Isn't screen rect
more consistent with what the function returns and naming else where?

I also think the scale factor should be available at the widget level so that
you don't have to dig out the hwnd.

[robliao, 2015/11/07 00:56:40]

When I audited this function, I found the calculation was not performed relative
to the screen coordinate system but rather the HWND's or client's coordinate
system, hence the change. This is necessary since scaling a client means we
don't have to worry about screen origins. For rects calculated with respect to
screen origins, a transformation is possible especially if an HWND spans
multiple monitors since this implementation anchors the screen origins to handle
the multiple DPIs.

The HWND seemed to be a good lowest common denominator everyone had. My hand was
forced by TooltipWin which reasons over HWNDs and has no access to views or
widgets, so HWNDs are used for commonality. 

+                                                        tabstrip_bounds);
       margins.cyTopHeight = tabstrip_bounds.bottom();
 
       // On pre-Win 10, we need to offset the DWM frame into the toolbar so that
       // the blackness doesn't show up on our rounded toolbar corners.  In Win
       // 10 and above there are no rounded corners, so this is unnecessary.
       const int kDWMFrameTopOffset = 3;
       if (base::win::GetVersion() < base::win::VERSION_WIN10)
         margins.cyTopHeight += kDWMFrameTopOffset;
     }
   }
   return margins;
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // BrowserDesktopWindowTreeHost, public:
 
 // static
 BrowserDesktopWindowTreeHost*
     BrowserDesktopWindowTreeHost::CreateBrowserDesktopWindowTreeHost(
         views::internal::NativeWidgetDelegate* native_widget_delegate,
         views::DesktopNativeWidgetAura* desktop_native_widget_aura,
         BrowserView* browser_view,
         BrowserFrame* browser_frame) {
   return new BrowserDesktopWindowTreeHostWin(native_widget_delegate,
                                              desktop_native_widget_aura,
                                              browser_view,
                                              browser_frame);
 }