Chrome OS: Ash support for >=3 displays.

ui/display/chromeos/display_configurator.cc

 // Copyright 2014 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 "ui/display/chromeos/display_configurator.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/logging.h"
 #include "base/strings/string_number_conversions.h"
@@ skipping 43 matching lines @@
     case MULTIPLE_DISPLAY_STATE_INVALID:
       return "INVALID";
     case MULTIPLE_DISPLAY_STATE_HEADLESS:
       return "HEADLESS";
     case MULTIPLE_DISPLAY_STATE_SINGLE:
       return "SINGLE";
     case MULTIPLE_DISPLAY_STATE_DUAL_MIRROR:
       return "DUAL_MIRROR";
     case MULTIPLE_DISPLAY_STATE_DUAL_EXTENDED:
       return "DUAL_EXTENDED";
+    case MULTIPLE_DISPLAY_STATE_MULTI_EXTENDED:
+      return "MULTI_EXTENDED";
   }
   NOTREACHED() << "Unknown state " << state;
   return "INVALID";
 }
 
 // Returns the number of displays in |displays| that should be turned on, per
 // |state|.  If |display_power| is non-NULL, it is updated to contain the
 // on/off state of each corresponding entry in |displays|.
 int GetDisplayPower(
     const std::vector<DisplayConfigurator::DisplayState>& display_states,
@@ skipping 797 matching lines @@
         return false;
       }
       size = mode_info->size();
 
       for (size_t i = 0; i < cached_displays_.size(); ++i) {
         DisplayState* state = &cached_displays_[i];
         new_mode[i] = display_power[i] ? state->mirror_mode : NULL;
       }
       break;
     }
-    case MULTIPLE_DISPLAY_STATE_DUAL_EXTENDED: {
-      if (cached_displays_.size() != 2 ||
-          (num_on_displays != 0 && num_on_displays != 2)) {
+    case MULTIPLE_DISPLAY_STATE_DUAL_EXTENDED:
+    case MULTIPLE_DISPLAY_STATE_MULTI_EXTENDED: {
+      if ((display_state == MULTIPLE_DISPLAY_STATE_DUAL_EXTENDED &&
+           cached_displays_.size() != 2) ||
+          (display_state == MULTIPLE_DISPLAY_STATE_MULTI_EXTENDED &&
+           cached_displays_.size() <= 2) ||
+          (num_on_displays != 0 &&
+           num_on_displays != static_cast<int>(cached_displays_.size()))) {
         LOG(WARNING) << "Ignoring request to enter extended mode with "
                      << cached_displays_.size() << " connected display(s) and "
                      << num_on_displays << " turned on";
         return false;
       }
 
       for (size_t i = 0; i < cached_displays_.size(); ++i) {
         DisplayState* state = &cached_displays_[i];
         new_origins[i].set_y(size.height() ? size.height() + kVerticalGap : 0);
         new_mode[i] = display_power[i] ? state->selected_mode : NULL;
@@ skipping 98 matching lines @@
           return MULTIPLE_DISPLAY_STATE_DUAL_EXTENDED;
         // With either both displays on or both displays off, use one of the
         // dual modes.
         std::vector<int64_t> display_ids;
         for (size_t i = 0; i < cached_displays_.size(); ++i)
           display_ids.push_back(cached_displays_[i].display->display_id());
 
         return state_controller_->GetStateForDisplayIds(display_ids);
       }
     }
-    default:
-      NOTREACHED();
+    default: {

[oshima, 2014/12/05 22:18:15]

add comment that this is for >3 case. 

[hshi1, 2014/12/05 23:25:12]

Acknowledged.

+      if (num_on_displays == 1)
+        return MULTIPLE_DISPLAY_STATE_SINGLE;

[oshima, 2014/12/05 22:18:15]

don't you have to handle == 2 case?

[hshi1, 2014/12/05 23:25:13]

I think it is actually better to just handle the cases based on number of on
displays.

+      else
+        return MULTIPLE_DISPLAY_STATE_MULTI_EXTENDED;
+    }
   }
   return MULTIPLE_DISPLAY_STATE_INVALID;
 }
 
 }  // namespace ui