Fix code around display overscan settings.

ash/display/multi_display_manager.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 "ash/display/multi_display_manager.h"
 
 #include <string>
 #include <vector>
 
 #include "ash/display/display_controller.h"
@@ skipping 130 matching lines @@
        iter != displays_.end(); ++iter) {
     const gfx::Display& display = *iter;
     if (display.bounds().Contains(point_in_screen))
       return display;
   }
   return GetInvalidDisplay();
 }
 
 void MultiDisplayManager::SetOverscanInsets(int64 display_id,
                                             const gfx::Insets& insets_in_dip) {
+  std::map<int64, gfx::Insets>::const_iterator old_overscan =
+      overscan_mapping_.find(display_id);
+  if (old_overscan != overscan_mapping_.end()) {
+    gfx::Insets old_insets = old_overscan->second;
+    for (DisplayList::iterator iter = displays_.begin();

[oshima, 2012/10/16 23:54:17]

FindDisplayForId

[Jun Mukai, 2012/10/17 00:07:49]

Thanks.  But as far as I see, it returns a const reference, so the code to
reimburse the existing insets could be awkward -- I want to edit an existing
display in the list.  Also it raises DLOG(FATAL) in case no displays are found,
but it wouldn't be exceptional here.

By the way, I found GetDisplayForId() too, and both are almost identical.  Why
do we have both?

[oshima, 2012/10/17 01:09:40]

FindDisplayId returns non const reference. GetDisplayId is const versino of it.
I think it's just mistake that const/non const versions have different name and
one of them should be renamed. (it'd be outside of this scope)

[Jun Mukai, 2012/10/17 15:45:46]

Done.

+         iter != displays_.end(); ++iter) {
+      if (iter->id() == display_id) {
+        // Reimburse the existing insets before applying the new insets.
+        gfx::Rect bounds = iter->bounds_in_pixel();
+        gfx::Insets negated_insets = old_insets.Scale(-1);
+        bounds.Inset(negated_insets.Scale(iter->device_scale_factor()));

[oshima, 2012/10/16 23:54:17]

Scale(- iter->device_scale_factor()); (or -1 *)

[Jun Mukai, 2012/10/17 00:07:49]

Done.

+        iter->SetScaleAndBounds(iter->device_scale_factor(), bounds);
+        break;
+      }
+    }
+  }
   overscan_mapping_[display_id] = insets_in_dip;
   OnNativeDisplaysChanged(displays_);
 }
 
 void MultiDisplayManager::OnNativeDisplaysChanged(
     const std::vector<gfx::Display>& updated_displays) {
   if (updated_displays.empty()) {
     // Don't update the displays when all displays are disconnected.
     // This happens when:
     // - the device is idle and powerd requested to turn off all displays.
@@ skipping 310 matching lines @@
   DisplayList::iterator iter_to_update = to_update->begin();
   DisplayList::const_iterator iter = displays_.begin();
   for (; iter != displays_.end() && iter_to_update != to_update->end();
        ++iter, ++iter_to_update) {
     (*iter_to_update).set_id((*iter).id());
   }
 }
 
 }  // namespace internal
 }  // namespace ash