Introduce user customization of external HighDPI mode for 4K monitor.

ash/display/display_manager.cc

Index: ash/display/display_manager.cc
diff --git a/ash/display/display_manager.cc b/ash/display/display_manager.cc
index 07d44155fa6ccdd1ad4a6e89b7d7939a69455f5e..d771657fd1fadf7de1863878de33aaa880509821 100644
--- a/ash/display/display_manager.cc
+++ b/ash/display/display_manager.cc
@@ -4,6 +4,7 @@
 
 #include "ash/display/display_manager.h"
 
+#include <algorithm>
 #include <cmath>
 #include <set>
 #include <string>
@@ -81,12 +82,6 @@ struct DisplayInfoSortFunctor {
   }
 };
 
-struct DisplayModeMatcher {
-  DisplayModeMatcher(const gfx::Size& size) : size(size) {}
-  bool operator()(const DisplayMode& mode) { return mode.size == size; }
-  gfx::Size size;
-};
-
 struct ScaleComparator {
   explicit ScaleComparator(float s) : scale(s) {}
 
@@ -429,6 +424,7 @@ void DisplayManager::SetDisplayUIScale(int64 display_id,
     return;
   }
 
+  // TODO(mukai): merge this implementation into SetDisplayMode().
   DisplayInfoList display_info_list;
   for (DisplayList::const_iterator iter = displays_.begin();
        iter != displays_.end(); ++iter) {
@@ -458,8 +454,10 @@ void DisplayManager::SetDisplayResolution(int64 display_id,
   const DisplayInfo& display_info = GetDisplayInfo(display_id);
   const std::vector<DisplayMode>& modes = display_info.display_modes();
   DCHECK_NE(0u, modes.size());
+  DisplayMode target_mode;
+  target_mode.size = resolution;
   std::vector<DisplayMode>::const_iterator iter =
-      std::find_if(modes.begin(), modes.end(), DisplayModeMatcher(resolution));
+      std::find(modes.begin(), modes.end(), target_mode);
   if (iter == modes.end()) {
     LOG(WARNING) << "Unsupported resolution was requested:"
                  << resolution.ToString();
@@ -472,6 +470,49 @@ void DisplayManager::SetDisplayResolution(int64 display_id,
 #endif
 }
 
+bool DisplayManager::SetDisplayMode(int64 display_id,
+                                    const DisplayMode& display_mode) {
+  if (IsInternalDisplayId(display_id)) {
+    SetDisplayUIScale(display_id, display_mode.ui_scale);
+    return false;
+  }
+
+  DisplayInfoList display_info_list;
+  bool display_property_changed = false;
+  bool resolution_changed = false;
+  for (DisplayList::const_iterator iter = displays_.begin();
+       iter != displays_.end(); ++iter) {
+    DisplayInfo info = GetDisplayInfo(iter->id());
+    if (info.id() == display_id) {
+      const std::vector<DisplayMode>& modes = info.display_modes();
+      std::vector<DisplayMode>::const_iterator iter =
+          std::find(modes.begin(), modes.end(), display_mode);
+      if (iter == modes.end()) {
+        LOG(WARNING) << "Unsupported resolution was requested:"
+                     << display_mode.size.ToString();
+        return false;
+      }
+      display_modes_[display_id] = *iter;
+      if (info.bounds_in_native().size() != display_mode.size)
+        resolution_changed = true;
+      if (info.device_scale_factor() != display_mode.device_scale_factor) {
+        info.set_device_scale_factor(display_mode.device_scale_factor);
+        display_property_changed = true;
+      }
+    }
+    display_info_list.push_back(info);
+  }
+  if (display_property_changed) {
+    AddMirrorDisplayInfoIfAny(&display_info_list);
+    UpdateDisplays(display_info_list);
+  }
+#if defined(OS_CHROMEOS)
+  if (resolution_changed && base::SysInfo::IsRunningOnChromeOS())
+    Shell::GetInstance()->display_configurator()->OnConfigurationChanged();
+#endif
+  return resolution_changed;
+}
+
 void DisplayManager::RegisterDisplayProperty(
     int64 display_id,
     gfx::Display::Rotation rotation,
@@ -497,6 +538,28 @@ void DisplayManager::RegisterDisplayProperty(
   }
 }
 
+DisplayMode DisplayManager::GetActiveModeForDisplayId(int64 display_id) const {
+  DisplayMode selected_mode;
+  if (GetSelectedModeForDisplayId(display_id, &selected_mode))
+    return selected_mode;
+

[oshima, 2014/07/31 02:16:52]

can you add comment that this is looking for "default" mode?

[Jun Mukai, 2014/07/31 04:57:52]

Done.

+  const DisplayInfo& info = GetDisplayInfo(display_id);
+  const std::vector<DisplayMode>& display_modes = info.display_modes();
+
+  if (IsInternalDisplayId(display_id)) {
+    for (size_t i = 0; i < display_modes.size(); ++i) {
+      if (info.configured_ui_scale() == display_modes[i].ui_scale)

[oshima, 2014/07/31 02:16:52]

I believe the ui scale should always be 1.0f in this case? If so, can you add
DCHECK? (in outs of the loop)

[Jun Mukai, 2014/07/31 04:57:52]

This case, ui scale comes from the pref store, can be different from 1.0f if the
user changes the ui-scale and reboot.

First I thought to tweak RegisterDisplayProperty() to remember restored ui scale
as a DisplayMode, but I gave up because display's original size is unknown,
which will introduce complication to GetSelectedModeForDisplayId.

[oshima, 2014/07/31 18:52:37]

Discussed offline and understood the issue. please add comment in
RegisterDisplayProperty so that we can address it correctly (if we ever want to
fix it)

[Jun Mukai, 2014/07/31 20:32:50]

Done.

+        return display_modes[i];
+    }
+  } else {
+    for (size_t i = 0; i < display_modes.size(); ++i) {
+      if (display_modes[i].native)
+        return display_modes[i];
+    }
+  }
+  return selected_mode;
+}
+
 bool DisplayManager::GetSelectedModeForDisplayId(int64 id,
                                                  DisplayMode* mode_out) const {
   std::map<int64, DisplayMode>::const_iterator iter = display_modes_.find(id);
@@ -597,15 +660,16 @@ void DisplayManager::OnNativeDisplaysChanged(
       new_display_info_list.push_back(*iter);
     }
 
-    const gfx::Size& resolution = iter->bounds_in_native().size();
+    DisplayMode new_mode;
+    new_mode.size = iter->bounds_in_native().size();
+    new_mode.device_scale_factor = iter->device_scale_factor();
+    new_mode.ui_scale = iter->configured_ui_scale();
     const std::vector<DisplayMode>& display_modes = iter->display_modes();
     // This is empty the displays are initialized from InitFromCommandLine.
     if (!display_modes.size())
       continue;
     std::vector<DisplayMode>::const_iterator display_modes_iter =
-        std::find_if(display_modes.begin(),
-                     display_modes.end(),
-                     DisplayModeMatcher(resolution));
+        std::find(display_modes.begin(), display_modes.end(), new_mode);
     // Update the actual resolution selected as the resolution request may fail.
     if (display_modes_iter == display_modes.end())
       display_modes_.erase(iter->id());