monitor_reconfigure: Try to improve resolution selection.

src/platform/monitor_reconfig/monitor_reconfigure_main.h

 // Copyright (c) 2009 The Chromium OS Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MONITOR_RECONFIGURE_MONITOR_RECONFIGURE_MAIN_H_
 #define MONITOR_RECONFIGURE_MONITOR_RECONFIGURE_MAIN_H_
 
 #include <map>
+#include <string>
+#include <vector>
 
 #include <X11/Xlib.h>
 #include <X11/extensions/Xrandr.h>
 
 namespace monitor_reconfig {
 
 // MonitorReconfigureMain is the class responsible for setting the external
 // monitor to the max resolution based on the modes supported by the native
 // monitor and the external monitor
 class MonitorReconfigureMain {
  public:
   MonitorReconfigureMain(Display* display, XRRScreenResources* screen_info);
   virtual ~MonitorReconfigureMain() {}
 
   // Main entry point
   void Run();
 
+ private:
+  // Initializes the |lcd_output_| and |external_output_| members.
+  void DetermineOutputs();
+
   // Returns whether an external monitor is connected
   bool IsExternalMonitorConnected();
 
- private:
-  // Finds the max resolution mode for the given |output|
-  XRRModeInfo* FindMaxResolution(XRROutputInfo* output);
+  // Comparator used by SortModeByResolution().
+  // Returns true if |mode_a| has more pixels than |mode_b| and false otherwise.
+  class ModeResolutionComparator {
+   public:
+    bool operator()(XRRModeInfo* mode_a, XRRModeInfo* mode_b) const {
+      return mode_a->width * mode_a->height > mode_b->width * mode_b->height;
+    }
+  };
 
-  // Finds the best matching resolution as compared to the |matching_mode|
-  XRRModeInfo* FindBestMatchingResolution(XRRModeInfo* matching_mode);
+  // Sorts |output_info|'s modes by decreasing number of pixels, storing the
+  // results in |modes_out|.
+  void SortModesByResolution(const XRROutputInfo& output_info,
+                             std::vector<XRRModeInfo*>* modes_out);
 
-  // Initializes the |notebook_output_| and |external_output_| fields
-  void DetermineOutputs();
+  // Find resolutions to use.
+  bool FindBestResolutions(
+      std::string* lcd_resolution,
+      std::string* external_resolution,
+      std::string* screen_resolution);
 
-  // Sets the resolution of the notebook's screen, the external monitor's
-  // screen, and the overall virtual screen to the given size.
-  void SetResolutions(XRRModeInfo* notebook_mode,
-                      XRRModeInfo* external_mode,
-                      XRRModeInfo* overall_screen_size);
+  // Find resolutions to use that are reasonably close together.
+  // |larger_device_modes| and |smaller_device_modes| should be sorted by
+  // descending resolution.  We choose the highest resolution from
+  // |smaller_device_modes| and the lowest resolution from |larger_device_modes|
+  // that's at least as high as the resolution from the smaller device.
+  // |screen_resolution| gets set to |smaller_resolution| to avoid clipping.
+  bool FindNearestResolutions(
+      const std::vector<XRRModeInfo*>& larger_device_modes,
+      const std::vector<XRRModeInfo*>& smaller_device_modes,
+      std::string* larger_resolution,
+      std::string* smaller_resolution,
+      std::string* screen_resolution);
 
-  // Inline helper functions for FindBestMatchingResolution
-  inline bool IsEqual(XRRModeInfo*, XRRModeInfo*);
-  inline bool IsBiggerOrEqual(XRRModeInfo*, XRRModeInfo*);
-  inline bool IsBetterMatching(XRRModeInfo* target, XRRModeInfo* to_match,
-      XRRModeInfo* previous_best);
+  // Set the resolution for a particular display or for the screen.
+  bool SetDeviceResolution(const std::string& device_name,
+                           const std::string& resolution);
+  bool SetScreenResolution(const std::string& resolution);
 
-  // Mapping between mode XID's and mode information structures
+  // Mapping between mode XIDs and mode information structures.
   std::map<int, XRRModeInfo*> mode_map_;
 
   // X Resources needed between functions
   Display* display_;
   XRRScreenResources* screen_info_;
-  XRROutputInfo* notebook_output_;
+  XRROutputInfo* lcd_output_;
   XRROutputInfo* external_output_;
 };
 
 }  // namespace monitor_reconfig
 
 #endif  // MONITOR_RECONFIGURE_MONITOR_RECONFIGURE_MAIN_H_