monitor_reconfig: Disable external output to avoid error.

monitor_reconfigure_main.cc

 // Copyright (c) 2010 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.
 
 #include "monitor_reconfig/monitor_reconfigure_main.h"
 
 #include <algorithm>
 #include <cstdio>
 #include <cstdlib>
 
@@ skipping 36 matching lines @@
 
   ResolutionSelector selector;
   string lcd_resolution, external_resolution, screen_resolution;
   CHECK(selector.FindBestResolutions(lcd_modes,
                                      external_modes,
                                      &lcd_resolution,
                                      &external_resolution,
                                      &screen_resolution));
 
   SetDeviceResolution(lcd_output_->name, lcd_resolution);
+
+  // If there's no external output connected, disable the device before we try
+  // to set the screen resolution; otherwise xrandr will complain if we're
+  // trying to set the screen to a smaller size than what the now-unplugged
+  // device was using.
   if (IsExternalMonitorConnected())
     SetDeviceResolution(external_output_->name, external_resolution);
+  else
+    DisableDevice(external_output_->name);
+
   SetScreenResolution(screen_resolution);
 }
 
 void MonitorReconfigureMain::DetermineOutputs() {
   CHECK(screen_info_->noutput > 1) << "Expected at least two outputs";
   XRROutputInfo* first_output =
       XRRGetOutputInfo(display_, screen_info_, screen_info_->outputs[0]);
   XRROutputInfo* second_output =
       XRRGetOutputInfo(display_, screen_info_, screen_info_->outputs[1]);
 
@@ skipping 46 matching lines @@
   return system(command.c_str()) == 0;
 }
 
 bool MonitorReconfigureMain::SetScreenResolution(
     const std::string& resolution) {
   string command = StringPrintf("xrandr --fb %s", resolution.c_str());
   LOG(INFO) << "Running " << command.c_str();
   return system(command.c_str()) == 0;
 }
 
+bool MonitorReconfigureMain::DisableDevice(const std::string& device_name) {
+  string command = StringPrintf("xrandr --output %s --off",
+                                device_name.c_str());
+  LOG(INFO) << "Running " << command.c_str();
+  return system(command.c_str()) == 0;
+}
+
 }  // end namespace monitor_reconfig
 
 int main(int argc, char** argv) {
   CommandLine::Init(argc, argv);
   logging::InitLogging(NULL,
                        logging::LOG_ONLY_TO_SYSTEM_DEBUG_LOG,
                        logging::DONT_LOCK_LOG_FILE,
                        logging::APPEND_TO_OLD_LOG_FILE);
   Display* display = XOpenDisplay(NULL);
   CHECK(display) << "Could not open display";
 
   Window window = RootWindow(display, DefaultScreen(display));
   XRRScreenResources* screen_info = XRRGetScreenResources(display, window);
   monitor_reconfig::MonitorReconfigureMain main_app(display, screen_info);
   main_app.Run();
   return 0;
 }