[Mac] More tweaks to the Lion gesture UI.

chrome/browser/ui/cocoa/history_overlay_controller.mm

 // Copyright (c) 2012 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 "chrome/browser/ui/cocoa/history_overlay_controller.h"
 
 #include "base/logging.h"
 #include "grit/theme_resources.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/gfx/image/image.h"
 
 #import <QuartzCore/QuartzCore.h>
 
 #include <cmath>
 
 // Constants ///////////////////////////////////////////////////////////////////
 
 // The radius of the circle drawn in the shield.
 const CGFloat kShieldRadius = 70;
 
 // The diameter of the circle and the width of its bounding box.
 const CGFloat kShieldWidth = kShieldRadius * 2;
 
 // The height of the shield.
 const CGFloat kShieldHeight = 140;
 
+// Additional height that is added to kShieldHeight when the gesture is
+// considered complete.
+const CGFloat kShieldHeightCompletionAdjust = 10;
+
 // The amount of |gestureAmount| at which AppKit considers the gesture
 // completed. This was derived more via art than science.
 const CGFloat kGestureCompleteProgress = 0.3;
 
 // HistoryOverlayView //////////////////////////////////////////////////////////
 
 // The content view that draws the semicircle and the arrow.
 @interface HistoryOverlayView : NSView {
  @private
   HistoryOverlayMode mode_;
-  CGFloat progress_;
+  CGFloat shieldAlpha_;
 }
-@property(nonatomic) CGFloat progress;
+@property(nonatomic) CGFloat shieldAlpha;
 - (id)initWithMode:(HistoryOverlayMode)mode
              image:(NSImage*)image;
 @end
 
 @implementation HistoryOverlayView
 
-@synthesize progress = progress_;
+@synthesize shieldAlpha = shieldAlpha_;
 
 - (id)initWithMode:(HistoryOverlayMode)mode
              image:(NSImage*)image {
   NSRect frame = NSMakeRect(0, 0, kShieldWidth, kShieldHeight);
   if ((self = [super initWithFrame:frame])) {
     mode_ = mode;
 
     // If going backward, the arrow needs to be in the right half of the circle,
     // so offset the X position.
     CGFloat offset = mode_ == kHistoryOverlayModeBack ? kShieldRadius : 0;
     NSRect arrowRect = NSMakeRect(offset, 0, kShieldRadius, kShieldHeight);
     arrowRect = NSInsetRect(arrowRect, 10, 0);  // Give a little padding.
 
     scoped_nsobject<NSImageView> imageView(
         [[NSImageView alloc] initWithFrame:arrowRect]);
     [imageView setImage:image];
+    [imageView setAutoresizingMask:NSViewMinYMargin | NSViewMaxYMargin];
     [self addSubview:imageView];
   }
   return self;
 }
 
 - (void)drawRect:(NSRect)dirtyRect {
-  NSRect ovalRect = NSMakeRect(0, 0, kShieldWidth, kShieldHeight);
-  NSBezierPath* path = [NSBezierPath bezierPathWithOvalInRect:ovalRect];
-  NSColor* fillColor =
-      // Clamp the minimum ligtness to be 0.666.
-      [NSColor colorWithCalibratedWhite:std::min(2.0/3.0 - progress_, 2.0/3.0)
-                                  alpha:0.85];
+  NSBezierPath* path = [NSBezierPath bezierPathWithOvalInRect:self.bounds];
+  NSColor* fillColor = [NSColor colorWithCalibratedWhite:0 alpha:shieldAlpha_];
   [fillColor set];
   [path fill];
 }
 
 @end
 
 // HistoryOverlayController ////////////////////////////////////////////////////
 
 @implementation HistoryOverlayController
 
@@ skipping 16 matching lines @@
                                          image:image.ToNSImage()]);
   self.view = contentView_;
 }
 
 - (void)setProgress:(CGFloat)gestureAmount {
   NSRect parentFrame = [parent_ frame];
   // Scale the gesture amount so that the progress is indicative of the gesture
   // being completed.
   gestureAmount = std::abs(gestureAmount) / kGestureCompleteProgress;
 
+  // When tracking the gesture, the height is constant and the alpha value
+  // changes from [0.25, 0.65].
+  CGFloat height = kShieldHeight;
+  CGFloat shieldAlpha = std::min(0.65f, std::max(gestureAmount, 0.25f));
+
+  // When the gesture is very likely to be completed (90% in this case), grow
+  // the semicircle's height and lock the alpha to 0.75.
+  if (gestureAmount > 0.9) {
+    height += kShieldHeightCompletionAdjust;
+    shieldAlpha = 0.75;
+  }
+
   // Compute the new position based on the progress.
   NSRect frame = self.view.frame;
-  frame.origin.y = (NSHeight(parentFrame) / 2) - (kShieldHeight / 2);
+  frame.size.height = height;
+  frame.origin.y = (NSHeight(parentFrame) / 2) - (height / 2);
 
   CGFloat width = std::min(kShieldRadius * gestureAmount, kShieldRadius);
   if (mode_ == kHistoryOverlayModeForward)
     frame.origin.x = NSMaxX(parentFrame) - width;
   else if (mode_ == kHistoryOverlayModeBack)
     frame.origin.x = NSMinX(parentFrame) - kShieldWidth + width;
 
   self.view.frame = frame;
-  [contentView_ setProgress:gestureAmount];
+  [contentView_ setShieldAlpha:shieldAlpha];
   [contentView_ setNeedsDisplay:YES];
 }
 
 - (void)showPanelForView:(NSView*)view {
   parent_.reset([view retain]);
   [self setProgress:0];  // Set initial view position.
   [[parent_ superview] addSubview:self.view
                        positioned:NSWindowAbove
                        relativeTo:parent_];
 }
 
 - (void)dismiss {
-  const CGFloat kFadeOutDurationSeconds = 0.2;
+  const CGFloat kFadeOutDurationSeconds = 0.4;
 
   NSView* overlay = self.view;
 
   scoped_nsobject<CAAnimation> animation(
       [[overlay animationForKey:@"alphaValue"] copy]);
   [animation setDelegate:self];
   [animation setDuration:kFadeOutDurationSeconds];
   NSMutableDictionary* dictionary =
       [NSMutableDictionary dictionaryWithCapacity:1];
   [dictionary setObject:animation forKey:@"alphaValue"];
   [overlay setAnimations:dictionary];
   [[overlay animator] setAlphaValue:0.0];
 }
 
 - (void)animationDidStop:(CAAnimation*)theAnimation finished:(BOOL)finished {
   [self.view removeFromSuperview];
 }
 
 @end