Refresh output cache when setting display mode

chromeos/display/output_configurator.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 "chromeos/display/output_configurator.h"
 
 #include <X11/Xlib.h>
 #include <X11/extensions/dpms.h>
 #include <X11/extensions/Xrandr.h>
 
@@ skipping 376 matching lines @@
       output_state_ == STATE_SINGLE)
     return false;
 
   Display* display = base::MessagePumpAuraX11::GetDefaultXDisplay();
   CHECK(display != NULL);
   XGrabServer(display);
   Window window = DefaultRootWindow(display);
   XRRScreenResources* screen = XRRGetScreenResources(display, window);
   CHECK(screen != NULL);
 
+  // We are about to act on the cached output data but it could be stale so
+  // force the outputs to be recached.
+  ForceRecacheOutputs(display, screen);
   UpdateCacheAndXrandrToState(display,
                               screen,
                               window,
                               new_state);
   XRRFreeScreenResources(screen);
   XUngrabServer(display);
 
   MessageLoop::current()->PostTask(
       FROM_HERE, base::Bind(&OutputConfigurator::NotifyOnDisplayChanged,
                             base::Unretained(this)));
@@ skipping 49 matching lines @@
       outputs_did_change = (now_connected != output_cache_[i].is_connected);
       XRRFreeOutputInfo(output);
 
       if (output_cache_[i].is_connected)
         previous_connected_count += 1;
       if (now_connected)
         new_connected_count += 1;
     }
   }
 
-  if (!outputs_did_change)
-    return false;
-  // We now know that we need to recache so free and re-alloc the buffer.
+  if (outputs_did_change) {
+    // We now know that we need to recache so free and re-alloc the buffer.
+    ForceRecacheOutputs(display, screen);
+  }
+  return outputs_did_change;
+}
+
+void OutputConfigurator::ForceRecacheOutputs(Display* display,
+                                             XRRScreenResources* screen) {
   output_count_ = screen->noutput;
   if (output_count_ == 0) {
     output_cache_.reset(NULL);
   } else {
     // Ideally, this would be allocated inline in the OutputConfigurator
     // instance since we support at most 2 connected outputs but this dynamic
     // allocation was specifically requested.
     output_cache_.reset(new CachedOutputDescription[output_count_]);
   }
 
@@ skipping 84 matching lines @@
         output_cache_[secondary_output_index_].output,
         &output_cache_[primary_output_index_].mirror_mode,
         &output_cache_[secondary_output_index_].mirror_mode);
 
     RRMode primary_mode = output_cache_[primary_output_index_].mirror_mode;
     RRMode second_mode = output_cache_[secondary_output_index_].mirror_mode;
     VLOG(1) << "Mirror mode supported " << mirror_supported_
             << " primary " << primary_mode
             << " secondary " << second_mode;
   }
-  return outputs_did_change;
 }
 
 void OutputConfigurator::UpdateCacheAndXrandrToState(
     Display* display,
     XRRScreenResources* screen,
     Window window,
     OutputState new_state) {
   // Default rules:
   // - single display = rebuild framebuffer and set to ideal_mode.
   // - multi display = rebuild framebuffer and set to mirror_mode.
@@ skipping 271 matching lines @@
       &method_call,
       dbus::ObjectProxy::TIMEOUT_USE_DEFAULT,
       dbus::ObjectProxy::EmptyResponseCallback());
 }
 
 void OutputConfigurator::NotifyOnDisplayChanged() {
   FOR_EACH_OBSERVER(Observer, observers_, OnDisplayModeChanged());
 }
 
 }  // namespace chromeos