Allow debugPaintSizeEnabled to be toggled from the runner (#7028)

packages/flutter_tools/lib/src/hot.dart

@@ -535,8 +535,7 @@ class HotRunner extends ResidentRunner {
     );
     printStatus('The Observatory debugger and profiler is available at: http://127.0.0.1:$_observatoryPort/');
     if (details) {
-      printStatus('To dump the widget hierarchy of the app (debugDumpApp), press "w".');
-      printStatus('To dump the rendering tree of the app (debugDumpRenderTree), press "t".');
+      printHelpDetails();
       printStatus('To repeat this help message, press "h" or F1. To quit, press "q", F10, or Ctrl-C.');
     } else {
       printStatus('For a more detailed help message, press "h" or F1. To quit, press "q", F10, or Ctrl-C.');

packages/flutter_tools/lib/src/resident_runner.dart

@@ -61,17 +61,21 @@ abstract class ResidentRunner {
   Future<Null> _debugDumpApp() async {
     if (vmService != null)
       await vmService.vm.refreshViews();
-
     await currentView.uiIsolate.flutterDebugDumpApp();
   }
 
   Future<Null> _debugDumpRenderTree() async {
     if (vmService != null)
       await vmService.vm.refreshViews();
-
     await currentView.uiIsolate.flutterDebugDumpRenderTree();
   }
 
+  Future<Null> _debugToggleDebugPaintSizeEnabled() async {
+    if (vmService != null)
+      await vmService.vm.refreshViews();
+    await currentView.uiIsolate.flutterToggleDebugPaintSizeEnabled();
+  }
+
   void registerSignalHandlers() {
     ProcessSignal.SIGINT.watch().listen((ProcessSignal signal) async {
       _resetTerminal();
@@ -154,6 +158,11 @@ abstract class ResidentRunner {
         return true;
       await _debugDumpRenderTree();
       return true;
+    } else if (lower == 'p') {
+      if (!supportsServiceProtocol)
+        return true;
+      await _debugToggleDebugPaintSizeEnabled();
+      return true;
     } else if (lower == 'q' || character == AnsiTerminal.KEY_F10) {
       // F10, exit
       await stop();
@@ -225,12 +234,19 @@ abstract class ResidentRunner {
     appFinished();
   }
 
+  /// Called to print help to the terminal.
+  void printHelp({ @required bool details });
+
+  void printHelpDetails() {
+    printStatus('To dump the widget hierarchy of the app (debugDumpApp), press "w".');
+    printStatus('To dump the rendering tree of the app (debugDumpRenderTree), press "t".');
+    printStatus('To toggle the display of construction lines (debugPaintSizeEnabled), press "p".');
+  }
+
   /// Called when a signal has requested we exit.
   Future<Null> cleanupAfterSignal();
   /// Called right before we exit.
   Future<Null> cleanupAtFinish();
-  /// Called to print help to the terminal.
-  void printHelp({ @required bool details });
   /// Called when the runner should handle a terminal command.
   Future<Null> handleTerminalCommand(String code);
 }

packages/flutter_tools/lib/src/run.dart

@@ -179,10 +179,8 @@ class RunAndStayResident extends ResidentRunner {
       printStatus('The Observatory debugger and profiler is available at: http://127.0.0.1:${_result.observatoryPort}/');
     if (supportsServiceProtocol) {
       haveDetails = true;
-      if (details) {
-        printStatus('To dump the widget hierarchy of the app (debugDumpApp), press "w".');
-        printStatus('To dump the rendering tree of the app (debugDumpRenderTree), press "t".');
-      }
+      if (details)
+        printHelpDetails();
     }
     if (haveDetails && !details) {
       printStatus('For a more detailed help message, press "h" or F1. To quit, press "q", F10, or Ctrl-C.');

packages/flutter_tools/lib/src/vmservice.dart

@@ -810,6 +810,13 @@ class Isolate extends ServiceObjectOwner {
     return invokeFlutterExtensionRpcRaw('ext.flutter.debugDumpRenderTree');
   }
 
+  Future<Map<String, dynamic>> flutterToggleDebugPaintSizeEnabled() async {
+    Map<String, dynamic> state = await invokeFlutterExtensionRpcRaw('ext.flutter.debugPaint');
+    if (state != null && state.containsKey('enabled') && state['enabled'] is bool)
+      state = await invokeFlutterExtensionRpcRaw('ext.flutter.debugPaint', <String, dynamic>{ 'enabled': !state['enabled'] });
+    return state;
+  }
+
   static bool _isMethodNotFoundException(dynamic e) {
     return (e is rpc.RpcException) &&
            (e.code == rpc_error_code.METHOD_NOT_FOUND);