Add support for constrained windows on os x, based on Avi's GTMWindowSheetController.

chrome/browser/cocoa/tab_view.mm

 // Copyright (c) 2009 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 "chrome/browser/cocoa/nsimage_cache.h"
 #include "chrome/browser/cocoa/tab_controller.h"
 #include "chrome/browser/cocoa/tab_view.h"
 #include "chrome/browser/cocoa/tab_window_controller.h"
 
 
@@ skipping 68 matching lines @@
   // corners of the tab inset by height*2/3, so we inset by half of
   // that here.  This doesn't completely eliminate the overlap, but it
   // works well enough.
   NSRect hitRect = NSInsetRect(frame, frame.size.height / 3.0f, 0);
   if (![closeButton_ isHidden])
     if (NSPointInRect(viewPoint, [closeButton_ frame])) return closeButton_;
   if (NSPointInRect(aPoint, hitRect)) return self;
   return nil;
 }
 
+// Returns |YES| if this tab can be torn away into a new window.
+- (BOOL)canBeDragged {
+  NSWindowController *controller = [sourceWindow_ windowController];
+  if ([controller isKindOfClass:[TabWindowController class]]) {
+    TabWindowController* realController =
+        static_cast<TabWindowController*>(controller);
+    return [realController isTabDraggable:self];
+  }
+  return YES;
+}
+
 // 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
 // ideas of dragging cocoa views between windows and how the Browser and
 // TabStrip models want to manage tabs.
 
 static const CGFloat kTearDistance = 36.0;
 static const NSTimeInterval kTearDuration = 0.333;
 static const double kDragStartDistance = 3.0;
 
@@ skipping 18 matching lines @@
   targetController_ = nil;
   tabWasDragged_ = NO;
   tearTime_ = 0.0;
   draggingWithinTabStrip_ = YES;
 
   // We don't want to "tear off" a tab if there's only one in the window. Treat
   // it like we're dragging around a tab we've already detached. Note that
   // unit tests might have |-numberOfTabs| reporting zero since the model
   // won't be fully hooked up. We need to be prepared for that and not send
   // them into the "magnetic" codepath.
-  isTheOnlyTab_ = [sourceController_ numberOfTabs] <= 1;
+  moveWindowOnDrag_ =
+      [sourceController_ numberOfTabs] <= 1 || ![self canBeDragged];
 
   dragOrigin_ = [NSEvent mouseLocation];
 
   // Because we move views between windows, we need to handle the event loop
   // ourselves. Ideally we should use the standard event loop.
   while (1) {
     theEvent =
     [NSApp nextEventMatchingMask:NSLeftMouseUpMask | NSLeftMouseDraggedMask
                        untilDate:[NSDate distantFuture]
                           inMode:NSDefaultRunLoopMode dequeue:YES];
     NSPoint thisPoint = [NSEvent mouseLocation];
 
     NSEventType type = [theEvent type];
     if (type == NSLeftMouseDragged) {
       [self mouseDragged:theEvent];
     } else { // Mouse Up
       [self mouseUp:theEvent];
       break;
     }
   }
 }
 
 - (void)mouseDragged:(NSEvent *)theEvent {
+  // Special-case this to keep the logic below simpler.
+  if (moveWindowOnDrag_) {
+    NSPoint thisPoint = [NSEvent mouseLocation];
+    NSPoint origin = sourceWindowFrame_.origin;
+    origin.x += (thisPoint.x - dragOrigin_.x);
+    origin.y += (thisPoint.y - dragOrigin_.y);
+    [sourceWindow_ setFrameOrigin:NSMakePoint(origin.x, origin.y)];
+    return;
+  }
+
   // First, go through the magnetic drag cycle. We break out of this if
-  // "stretchiness" ever exceeds the a set amount.
+  // "stretchiness" ever exceeds a set amount.
   tabWasDragged_ = YES;
 
-  if (isTheOnlyTab_) draggingWithinTabStrip_ = NO;
   if (draggingWithinTabStrip_) {
     NSRect frame = [self frame];
     NSPoint thisPoint = [NSEvent mouseLocation];
     CGFloat stretchiness = thisPoint.y - dragOrigin_.y;
     stretchiness = copysign(sqrtf(fabs(stretchiness))/sqrtf(kTearDistance),
                             stretchiness) / 2.0;
     CGFloat offset = thisPoint.x - dragOrigin_.x;
     if (fabsf(offset) > 100) stretchiness = 0;
     [sourceController_ insertPlaceholderForTab:self
                                          frame:NSOffsetRect(sourceTabFrame_,
@@ skipping 17 matching lines @@
   // moving more than 3 pixels.
   NSDate* targetDwellDate = nil; // The date this target was first chosen
   NSMutableArray* targets = [NSMutableArray array];
 
   NSPoint thisPoint = [NSEvent mouseLocation];
 
   // Find all the windows that could be a target. It has to be of the
   // appropriate class, and visible (obviously).
   if (![targets count]) {
     for (NSWindow* window in [NSApp windows]) {
-      if (window == sourceWindow_ && isTheOnlyTab_) continue;
       if (window == dragWindow_) continue;
       if (![window isVisible]) continue;
       NSWindowController *controller = [window windowController];
       if ([controller isKindOfClass:[TabWindowController class]]) {
         TabWindowController* realController =
             static_cast<TabWindowController*>(controller);
         if ([realController canReceiveFrom:sourceController_]) {
           [targets addObject:controller];
         }
       }
@@ skipping 24 matching lines @@
     [targetController_ removePlaceholder];
     targetController_ = newTarget;
     if (!newTarget) {
       tearTime_ = [NSDate timeIntervalSinceReferenceDate];
       tearOrigin_ = [dragWindow_ frame].origin;
     }
   }
 
   // Create or identify the dragged controller.
   if (!draggedController_) {
-    if (isTheOnlyTab_) {
-      draggedController_ = sourceController_;
-      dragWindow_ = [draggedController_ window];
-    } else {
-      // Detach from the current window and put it in a new window.
-      draggedController_ = [sourceController_ detachTabToNewWindow:self];
-      dragWindow_ = [draggedController_ window];
-      [dragWindow_ setAlphaValue:0.0];
-    }
+    // Detach from the current window and put it in a new window.
+    draggedController_ = [sourceController_ detachTabToNewWindow:self];
+    dragWindow_ = [draggedController_ window];
+    [dragWindow_ setAlphaValue:0.0];
 
+    // If dragging the tab only moves the current window, do not show overlay
+    // so that sheets stay on top of the window.
     // Bring the target window to the front and make sure it has a border.
     [dragWindow_ setLevel:NSFloatingWindowLevel];
     [dragWindow_ orderFront:nil];
     [dragWindow_ makeMainWindow];
     [draggedController_ showOverlay];
     dragOverlay_ = [draggedController_ overlayWindow];
     // Force the new tab button to be hidden. We'll reset it on mouse up.
     [draggedController_ showNewTabButton:NO];
     //if (![targets count])
     //  [dragOverlay_ setHasShadow:NO];
-    if (!isTheOnlyTab_) {
-      tearTime_ = [NSDate timeIntervalSinceReferenceDate];
-      tearOrigin_ = sourceWindowFrame_.origin;
-    }
+    tearTime_ = [NSDate timeIntervalSinceReferenceDate];
+    tearOrigin_ = sourceWindowFrame_.origin;
   }
 
   float tearProgress = [NSDate timeIntervalSinceReferenceDate] - tearTime_;
   tearProgress /= kTearDuration;
   tearProgress = sqrtf(MAX(MIN(tearProgress, 1.0), 0.0));
 
   // Move the dragged window to the right place on the screen.
   NSPoint origin = sourceWindowFrame_.origin;
   origin.x += (thisPoint.x - dragOrigin_.x);
   origin.y += (thisPoint.y - dragOrigin_.y);
@@ skipping 69 matching lines @@
       [[dragWindow_ animator] setAlphaValue:0.5];
     }
     chromeIsVisible_ = chromeShouldBeVisible;
   }
 }
 
 - (void)mouseUp:(NSEvent *)theEvent {
   // The drag/click is done. If the user dragged the mouse, finalize the drag
   // and clean up.
 
+  // Special-case this to keep the logic below simpler.
+  if (moveWindowOnDrag_)
+    return;
+
   // 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).
   [draggedController_ showNewTabButton:YES];
 
   if (draggingWithinTabStrip_) {
     if (tabWasDragged_) {
       // Move tab to new location.
       TabWindowController* dropController = sourceController_;
       [dropController moveTabView:[dropController selectedTabView]
                    fromController:nil];
     }
   } else if (targetController_) {
     // Move between windows. If |targetController_| is nil, we're not dropping
     // into any existing window.
     NSView* draggedTabView = [draggedController_ selectedTabView];
     [draggedController_ removeOverlay];
     [targetController_ moveTabView:draggedTabView
                     fromController:draggedController_];
     [targetController_ showWindow:nil];
   } else {
+    // Tab dragging did move window only.
     [dragWindow_ setAlphaValue:1.0];
     [dragOverlay_ setHasShadow:NO];
     [dragWindow_ setHasShadow:YES];
     [draggedController_ removeOverlay];
     [dragWindow_ makeKeyAndOrderFront:nil];
 
     [[draggedController_ window] setLevel:NSNormalWindowLevel];
     [draggedController_ removePlaceholder];
   }
   [sourceController_ removePlaceholder];
@@ skipping 122 matching lines @@
   [[NSGraphicsContext currentContext] restoreGraphicsState];
 }
 
 // Called when the user hits the right mouse button (or control-clicks) to
 // show a context menu.
 - (void)rightMouseDown:(NSEvent*)theEvent {
   [NSMenu popUpContextMenu:[self menu] withEvent:theEvent forView:self];
 }
 
 @end