[Mac] Confirm-to-Quit: Wait for a KeyUp event if the user held Cmd+Q on the second tap.

chrome/browser/ui/cocoa/confirm_quit_panel_controller.mm

 // Copyright (c) 2011 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.
 
 #import <Cocoa/Cocoa.h>
 #import <QuartzCore/QuartzCore.h>
 
 #include "base/logging.h"
 #include "base/scoped_nsobject.h"
 #include "base/sys_string_conversions.h"
 #import "chrome/browser/ui/cocoa/confirm_quit_panel_controller.h"
 #include "grit/generated_resources.h"
 #include "ui/base/l10n/l10n_util_mac.h"
 
+// Constants ///////////////////////////////////////////////////////////////////
+
+// How long the user must hold down Cmd+Q to confirm the quit.
+const NSTimeInterval kTimeToConfirmQuit = 1.5;
+
+// Leeway between the |targetDate| and the current time that will confirm a
+// quit.
+const NSTimeInterval kTimeDeltaFuzzFactor = 1.0;
+
+// Duration of the window fade out animation.
+const NSTimeInterval kWindowFadeAnimationDuration = 0.2;
+
 // Custom Content View /////////////////////////////////////////////////////////
 
 // The content view of the window that draws a custom frame.
 @interface ConfirmQuitFrameView : NSView {
  @private
   NSTextField* message_;  // Weak, owned by the view hierarchy.
 }
 - (void)setMessageText:(NSString*)text;
 @end
 
@@ skipping 57 matching lines @@
   [message_ setFrame:messageFrame];
 }
 
 @end
 
 // Private Interface ///////////////////////////////////////////////////////////
 
 @interface ConfirmQuitPanelController (Private)
 - (void)animateFadeOut;
 - (NSString*)keyCommandString;
+- (NSEvent*)pumpEventQueueForKeyUp:(NSApplication*)app;
+- (void)hideAllWindowsForApplication:(NSApplication*)app
+                        withDuration:(NSTimeInterval)duration;
 @end
 
 ConfirmQuitPanelController* g_confirmQuitPanelController = nil;
 
 ////////////////////////////////////////////////////////////////////////////////
 
 @implementation ConfirmQuitPanelController
 
 + (ConfirmQuitPanelController*)sharedController {
   if (!g_confirmQuitPanelController) {
@@ skipping 24 matching lines @@
     [window setContentView:contentView_];
 
     // Set the proper string.
     NSString* message = l10n_util::GetNSStringF(IDS_CONFIRM_TO_QUIT_DESCRIPTION,
         base::SysNSStringToUTF16([self keyCommandString]));
     [contentView_ setMessageText:message];
   }
   return self;
 }
 
+- (NSApplicationTerminateReply)runModalLoopForApplication:(NSApplication*)app {
+  // If this is the second of two such attempts to quit within a certain time
+  // interval, then just quit.
+  // Time of last quit attempt, if any.
+  static NSDate* lastQuitAttempt;  // Initially nil, as it's static.
+  NSDate* timeNow = [NSDate date];
+  if (lastQuitAttempt &&
+      [timeNow timeIntervalSinceDate:lastQuitAttempt] < kTimeDeltaFuzzFactor) {
+    // The panel tells users to Hold Cmd+Q. However, we also want to have a
+    // double-tap shortcut that allows for a quick quit path. For the users who
+    // tap Cmd+Q and then hold it with the window still open, this double-tap
+    // logic will run and cause the quit to get committed. If the key
+    // combination held down, the system will start sending the Cmd+Q event to
+    // the next key application, and so on. This is bad, so instead we hide all
+    // the windows (without animation) to look like we've "quit" and then wait
+    // for the KeyUp event to commit the quit.
+    [self hideAllWindowsForApplication:app withDuration:0];
+    NSEvent* nextEvent = nil;
+    do {
+      nextEvent = [self pumpEventQueueForKeyUp:app];
+    } while (!nextEvent);

[Nico, 2011/03/07 17:40:19]

Wait, this busy-polls, right? Why not call nextEventMatchingMask just once, but
with [NSDate distantFuture] as date?

[Robert Sesek, 2011/03/07 18:07:43]

Done.

+    [app discardEventsMatchingMask:NSAnyEventMask beforeEvent:nextEvent];
+    return NSTerminateNow;
+  } else {
+    [lastQuitAttempt release];  // Harmless if already nil.
+    lastQuitAttempt = [timeNow retain];  // Record this attempt for next time.
+  }
+
+  // Show the info panel that explains what the user must to do confirm quit.
+  [self showWindow:self];
+
+  // Spin a nested run loop until the |targetDate| is reached or a KeyUp event
+  // is sent.
+  NSDate* targetDate = [NSDate dateWithTimeIntervalSinceNow:kTimeToConfirmQuit];
+  BOOL willQuit = NO;
+  NSEvent* nextEvent = nil;
+  do {
+    // Dequeue events until a key up is received.
+    nextEvent = [self pumpEventQueueForKeyUp:app];

[Nico, 2011/03/07 17:40:19]

I guess you could pass in |targetDate| to nEMM as well here?

[Robert Sesek, 2011/03/07 18:07:43]

I looked at doing this, but the FuzzFactor also must be considered. I'm going to
leave this one with untilDate:nil until I have time to explore more.

+
+    // Wait for the time expiry to happen. Once past the hold threshold,
+    // commit to quitting and hide all the open windows.
+    if (!willQuit) {
+      NSDate* now = [NSDate date];
+      NSTimeInterval difference = [targetDate timeIntervalSinceDate:now];
+      if (difference < kTimeDeltaFuzzFactor) {
+        willQuit = YES;
+
+        // At this point, the quit has been confirmed and windows should all
+        // fade out to convince the user to release the key combo to finalize
+        // the quit.
+        [self hideAllWindowsForApplication:app
+                              withDuration:kWindowFadeAnimationDuration];
+      }
+    }
+  } while (!nextEvent);
+
+  // The user has released the key combo. Discard any events (i.e. the
+  // repeated KeyDown Cmd+Q).
+  [app discardEventsMatchingMask:NSAnyEventMask beforeEvent:nextEvent];
+
+  if (willQuit) {
+    // The user held down the combination long enough that quitting should
+    // happen.
+    return NSTerminateNow;
+  } else {
+    // Slowly fade the confirm window out in case the user doesn't
+    // understand what they have to do to quit.
+    [self dismissPanel];
+    return NSTerminateCancel;
+  }
+
+  // Default case: terminate.
+  return NSTerminateNow;
+}
+
 - (void)windowWillClose:(NSNotification*)notif {
   // Release all animations because CAAnimation retains its delegate (self),
   // which will cause a retain cycle. Break it!
   [[self window] setAnimations:[NSDictionary dictionary]];
   g_confirmQuitPanelController = nil;
   [self autorelease];
 }
 
 - (void)showWindow:(id)sender {
   // If a panel that is fading out is going to be reused here, make sure it
@@ skipping 47 matching lines @@
 }
 
 // This looks at the Main Menu and determines what the user has set as the
 // key combination for quit. It then gets the modifiers and builds a string
 // to display them.
 - (NSString*)keyCommandString {
   ui::AcceleratorCocoa accelerator = [[self class] quitAccelerator];
   return [self keyCombinationForAccelerator:accelerator];
 }
 
+// Runs a nested loop that pumps the event queue until the next KeyUp event.
+- (NSEvent*)pumpEventQueueForKeyUp:(NSApplication*)app {
+  //base::mac::ScopedNSAutoreleasePool pool;  // Do we need this?

[Nico, 2011/03/07 17:40:19]

do we? my guess is 'no'.

[Robert Sesek, 2011/03/07 18:07:43]

Nope.

+  return [app nextEventMatchingMask:NSKeyUpMask
+                          untilDate:nil
+                             inMode:NSEventTrackingRunLoopMode
+                            dequeue:YES];
+}
+
+// Iterates through the list of open windows and hides them all.
+- (void)hideAllWindowsForApplication:(NSApplication*)app
+                        withDuration:(NSTimeInterval)duration {
+  [NSAnimationContext beginGrouping];
+  [[NSAnimationContext currentContext] setDuration:duration];
+  for (NSWindow* aWindow in [app windows]) {

[Nico, 2011/03/07 17:40:19]

nit: just |window|

[Robert Sesek, 2011/03/07 18:07:43]

Done.

+    // Windows that are set to animate and have a delegate do no expect to be
+    // animated by other things and could result in an invalid state. If a
+    // window is set up like so, just force the alpha value to 0. Otherwise,
+    // animate all pretty and stuff.
+    if (duration > 0 && ![[aWindow animationForKey:@"alphaValue"] delegate]) {
+      [[aWindow animator] setAlphaValue:0.0];
+    } else {
+      [aWindow setAlphaValue:0.0];
+    }
+  }
+  [NSAnimationContext endGrouping];
+}
+
 - (NSString*)keyCombinationForAccelerator:(const ui::AcceleratorCocoa&)item {
   NSMutableString* string = [NSMutableString string];
   NSUInteger modifiers = item.modifiers();
 
   if (modifiers & NSCommandKeyMask)
     [string appendString:@"\u2318"];
   if (modifiers & NSControlKeyMask)
     [string appendString:@"\u2303"];
   if (modifiers & NSAlternateKeyMask)
     [string appendString:@"\u2325"];
   if (modifiers & NSShiftKeyMask)
     [string appendString:@"\u21E7"];
 
   [string appendString:[item.characters() uppercaseString]];
   return string;
 }
 
 @end