Fix several issues with dragging tabs and quickly letting go, including crashes because we get mouseDragged "events" after mouseUp, windows that stay transucent, and windows that vanish entirely but stay in the window list.

BUG=22266, 13594, 22538
TEST=dragging tabs between windows should still work
Review URL: http://codereview.chromium.org/243080

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@27861 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 45 insertions, 15 deletions

diff --git a/chrome/browser/cocoa/tab_view.mm b/chrome/browser/cocoa/tab_view.mm
index f44a482..4d9bf82 100644
--- a/chrome/browser/cocoa/tab_view.mm
+++ b/chrome/browser/cocoa/tab_view.mm
@@ -49,6 +49,8 @@ static const NSTimeInterval kAnimationHideDuration = 0.4;
 }
 
 - (void)dealloc {
+  // Cancel any delayed requests that may still be pending (drags or hover).
+  [NSObject cancelPreviousPerformRequestsWithTarget:self];
   // [self gtm_unregisterForThemeNotifications];
   [closeButton_ removeTrackingArea:closeTrackingArea_.get()];
   [super dealloc];
@@ -164,6 +166,16 @@ static const NSTimeInterval kAnimationHideDuration = 0.4;
   return targets;
 }
 
+// Call to clear out transient weak references we hold during drags.
+- (void)resetDragControllers {
+  draggedController_ = nil;
+  dragWindow_ = nil;
+  dragOverlay_ = nil;
+  sourceController_ = nil;
+  sourceWindow_ = nil;
+  targetController_ = nil;
+}
+
 // Handle clicks and drags in this button. We get here because we have
 // overridden acceptsFirstMouse: and the click is within our bounds.
 // TODO(pinkerton/alcor): This routine needs *a lot* of work to marry Cole's
@@ -198,6 +210,8 @@ static const CGFloat kRapidCloseDist = 2.5;
     [[controller_ target] performSelector:[controller_ action]
                                withObject:self];
 
+  [self resetDragControllers];
+
   // Resolve overlay back to original window.
   sourceWindow_ = [self window];
   if ([sourceWindow_ isKindOfClass:[NSPanel class]]) {
@@ -207,10 +221,6 @@ static const CGFloat kRapidCloseDist = 2.5;
   sourceWindowFrame_ = [sourceWindow_ frame];
   sourceTabFrame_ = [self frame];
   sourceController_ = [sourceWindow_ windowController];
-  draggedController_ = nil;
-  dragWindow_ = nil;
-  dragOverlay_ = nil;
-  targetController_ = nil;
   tabWasDragged_ = NO;
   tearTime_ = 0.0;
   draggingWithinTabStrip_ = YES;
@@ -378,8 +388,18 @@ static const CGFloat kRapidCloseDist = 2.5;
     tearOrigin_ = sourceWindowFrame_.origin;
   }
 
+  DCHECK(draggedController_);
+  DCHECK(sourceController_);
+
+  // When the user first tears off the window, we want slide the window to
+  // the current mouse location (to reduce the jarring appearance). We do this
+  // by calling ourselves back with additional mouseDragged calls (not actual
+  // events). |tearProgress| is a normalized measure of how far through this
+  // tear "animation" (of length kTearDuration) we are and has values [0..1].
+  // We use sqrt() so the animation is non-linear (slow down near the end
+  // point).
   float tearProgress = [NSDate timeIntervalSinceReferenceDate] - tearTime_;
-  tearProgress /= kTearDuration;
+  tearProgress /= kTearDuration;  // Normalize.
   tearProgress = sqrtf(MAX(MIN(tearProgress, 1.0), 0.0));
 
   // Move the dragged window to the right place on the screen.
@@ -389,13 +409,16 @@ static const CGFloat kRapidCloseDist = 2.5;
 
   if (tearProgress < 1) {
     // If the tear animation is not complete, call back to ourself with the
-    // same event to animate even if the mouse isn't moving.
+    // same event to animate even if the mouse isn't moving. We need to make
+    // sure these get cancelled in mouseUp:.
     [NSObject cancelPreviousPerformRequestsWithTarget:self];
     [self performSelector:@selector(mouseDragged:)
                withObject:theEvent
                afterDelay:1.0f/30.0f];
 
-    origin.x = (1 - tearProgress) *  tearOrigin_.x + tearProgress * origin.x;
+    // Set the current window origin based on how far we've progressed through
+    // the tear animation.
+    origin.x = (1 - tearProgress) * tearOrigin_.x + tearProgress * origin.x;
     origin.y = (1 - tearProgress) * tearOrigin_.y + tearProgress * origin.y;
   }
 
@@ -443,18 +466,19 @@ static const CGFloat kRapidCloseDist = 2.5;
   BOOL chromeShouldBeVisible = targetController_ == nil;
 
   if (chromeIsVisible_ != chromeShouldBeVisible) {
+    // TODO(pinkerton): There appears to be a race-condition in CoreAnimation
+    // where if we use animators to set the alpha values, we can't guarantee
+    // that we cancel them. This has the side effect of sometimes leaving
+    // the dragged window translucent or invisible. We should re-visit this,
+    // but for now, don't animate the alpha change.
     [dragWindow_ setHasShadow:YES];
+    [[draggedController_ overlayWindow] setAlphaValue:1.0];
     if (targetController_) {
-      [NSAnimationContext beginGrouping];
-      [[NSAnimationContext currentContext] setDuration:0.00001];
-      [[dragWindow_ animator] setAlphaValue:0.0];
-      [NSAnimationContext endGrouping];
+      [dragWindow_ setAlphaValue:0.0];
       [[draggedController_ overlayWindow] setHasShadow:YES];
-      [[[draggedController_ overlayWindow] animator] setAlphaValue:1.0];
     } else {
-      [[draggedController_ overlayWindow] setAlphaValue:1.0];
+      [dragWindow_ setAlphaValue:0.5];
       [[draggedController_ overlayWindow] setHasShadow:NO];
-      [[dragWindow_ animator] setAlphaValue:0.5];
     }
     chromeIsVisible_ = chromeShouldBeVisible;
   }
@@ -468,6 +492,9 @@ static const CGFloat kRapidCloseDist = 2.5;
   if (moveWindowOnDrag_)
     return;
 
+  // Cancel any delayed -mouseDragged: requests that may still be pending.
+  [NSObject cancelPreviousPerformRequestsWithTarget:self];
+
   // We are now free to re-display the new tab button in the window we're
   // dragging. It will show when the next call to -layoutTabs (which happens
   // indrectly by several of the calls below, such as removing the placeholder).
@@ -490,7 +517,8 @@ static const CGFloat kRapidCloseDist = 2.5;
                     fromController:draggedController_];
     [targetController_ showWindow:nil];
   } else {
-    // Tab dragging did move window only.
+    // Only move the window around on screen. Make sure it's set back to
+    // normal state (fully opaque, has shadow, has key, etc).
     [draggedController_ removeOverlay];
     // Don't want to re-show the window if it was closed during the drag.
     if ([dragWindow_ isVisible]) {
@@ -504,6 +532,8 @@ static const CGFloat kRapidCloseDist = 2.5;
   }
   [sourceController_ removePlaceholder];
   chromeIsVisible_ = YES;
+
+  [self resetDragControllers];
 }
 
 - (void)otherMouseUp:(NSEvent*)theEvent {