fix for 27454 - Fade out close button state on mouse exit

chrome/browser/ui/cocoa/hover_close_button.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 "chrome/browser/ui/cocoa/hover_close_button.h"
 
+#import <QuartzCore/QuartzCore.h>
+
 #include "base/memory/scoped_nsobject.h"
+#include "base/memory/scoped_ptr.h"
+#import "chrome/browser/ui/cocoa/animation_utils.h"
 #include "grit/generated_resources.h"
 #import "third_party/molokocacao/NSBezierPath+MCAdditions.h"
 #include "ui/base/l10n/l10n_util.h"
+#include "ui/gfx/scoped_ns_graphics_context_save_gstate_mac.h"
 
 namespace  {
-const CGFloat kCircleRadius = 0.415 * 16;
+const CGFloat kButtonWidth = 16;
+const CGFloat kCircleRadius = 0.415 * kButtonWidth;
 const CGFloat kCircleHoverWhite = 0.565;
 const CGFloat kCircleClickWhite = 0.396;
 const CGFloat kXShadowAlpha = 0.75;
 const CGFloat kXShadowCircleAlpha = 0.1;
+
+// Images that are used for all close buttons. Set up in +initialize.
+CGImageRef gHoverNoneImage = NULL;
+CGImageRef gHoverMouseOverImage = NULL;
+CGImageRef gHoverMouseDownImage = NULL;
+
+// Strings that are used for all close buttons. Set up in +initialize.
+NSString* gTooltip = nil;
+NSString* gDescription = nil;
 }  // namespace
 
-@interface HoverCloseButton(Private)
-- (void)updatePaths;
-- (void)setUpDrawingPaths;
+@interface HoverCloseButton ()
+// Sets up the button's tracking areas and accessibility info when instantiated
+// via initWithFrame or awakeFromNib.
+- (void)commonInit;
+
+// Draws the close button into a CGImageRef in a given state.
++ (CGImageRef)imageForBounds:(NSRect)bounds
+                       xPath:(NSBezierPath*)xPath
+                  circlePath:(NSBezierPath*)circlePath
+                  hoverState:(HoverState)hoverState;
 @end
 
 @implementation HoverCloseButton
 
++ (void)initialize {
+  if ([self class] == [HoverCloseButton class]) {
+    // Set up the paths for our images. They are centered around the origin.
+    NSRect bounds = NSMakeRect(0, 0, kButtonWidth, kButtonWidth);
+    NSBezierPath* circlePath = [NSBezierPath bezierPath];
+    [circlePath appendBezierPathWithArcWithCenter:NSZeroPoint
+                                           radius:kCircleRadius
+                                       startAngle:0.0
+                                         endAngle:365.0];
+
+    // Construct an 'x' by drawing two intersecting rectangles in the shape of a
+    // cross and then rotating the path by 45 degrees.
+    NSBezierPath* xPath = [NSBezierPath bezierPath];
+    [xPath appendBezierPathWithRect:NSMakeRect(-4.5, -1.0, 9.0, 2.0)];
+    [xPath appendBezierPathWithRect:NSMakeRect(-1.0, -4.5, 2.0, 9.0)];
+
+    NSAffineTransform* transform = [NSAffineTransform transform];
+    [transform rotateByDegrees:45.0];
+    [xPath transformUsingAffineTransform:transform];
+
+    // Move the paths into the center of the given bounds rectangle.
+    transform = [NSAffineTransform transform];
+    NSPoint xCenter = NSMakePoint(NSWidth(bounds) / 2.0,
+                                  NSHeight(bounds) / 2.0);
+    [transform translateXBy:xCenter.x yBy:xCenter.y];
+    [circlePath transformUsingAffineTransform:transform];
+    [xPath transformUsingAffineTransform:transform];
+
+    CGImageRef image = [self imageForBounds:bounds
+                                      xPath:xPath
+                                 circlePath:circlePath
+                                 hoverState:kHoverStateNone];
+    gHoverNoneImage = CGImageRetain(image);
+    image = [self imageForBounds:bounds
+                           xPath:xPath
+                      circlePath:circlePath
+                      hoverState:kHoverStateMouseOver];
+    gHoverMouseOverImage = CGImageRetain(image);
+    image = [self imageForBounds:bounds
+                           xPath:xPath
+                      circlePath:circlePath
+                      hoverState:kHoverStateMouseDown];
+    gHoverMouseDownImage = CGImageRetain(image);
+
+    // Grab some strings that are used by all close buttons.
+    gDescription = [l10n_util::GetNSStringWithFixup(IDS_ACCNAME_CLOSE) copy];
+    gTooltip = [l10n_util::GetNSStringWithFixup(IDS_TOOLTIP_CLOSE_TAB) copy];
+  }
+}
+
 - (id)initWithFrame:(NSRect)frameRect {
   if ((self = [super initWithFrame:frameRect])) {
     [self commonInit];
   }
   return self;
 }
 
 - (void)awakeFromNib {
   [super awakeFromNib];
   [self commonInit];
 }
 
-- (void)drawRect:(NSRect)rect {
-  if (!circlePath_.get() || !xPath_.get())
-    [self setUpDrawingPaths];
+- (void)setHoverState:(HoverState)state {
+  [super setHoverState:state];
 
-  // Only call updatePaths if the size changed.
-  if (!NSEqualSizes(oldSize_, [self bounds].size))
-    [self updatePaths];
+  // Only animate the HoverStateNone case.
+  scoped_ptr<ScopedCAActionDisabler> disabler;
+  if (state != kHoverStateNone) {
+    disabler.reset(new ScopedCAActionDisabler);
+  }
+  [hoverNoneLayer_ setHidden:state != kHoverStateNone];
+  [hoverMouseDownLayer_ setHidden:state != kHoverStateMouseDown];
+  [hoverMouseOverLayer_ setHidden:state != kHoverStateMouseOver];
+}
+
+- (void)commonInit {
+  // Set accessibility description.
+  NSCell* cell = [self cell];
+  [cell accessibilitySetOverrideValue:gDescription
+                         forAttribute:NSAccessibilityDescriptionAttribute];
+
+  // Add a tooltip.
+  [self setToolTip:gTooltip];
+
+  // Set up layers
+  CALayer* viewLayer = [self layer];
+
+  // Layers will be contrained to be 0 pixels from left edge horizontally,
+  // and centered vertically.
+  viewLayer.layoutManager = [CAConstraintLayoutManager layoutManager];
+  CAConstraint* xConstraint =
+      [CAConstraint constraintWithAttribute:kCAConstraintMinX
+                                 relativeTo:@"superlayer"
+                                  attribute:kCAConstraintMinX
+                                     offset:0];
+  CAConstraint* yConstraint =
+      [CAConstraint constraintWithAttribute:kCAConstraintMidY
+                                 relativeTo:@"superlayer"
+                                  attribute:kCAConstraintMidY];
+
+  hoverNoneLayer_.reset([[CALayer alloc] init]);
+  [hoverNoneLayer_ setDelegate:self];
+
+  // .get() is being used here (and below) because if it isn't used, the
+  // compiler doesn't realize that the call to setFrame: is being performed
+  // on a CALayer, and assumes that the call is being performed on a NSView.
+  // setFrame: on NSView takes an NSRect, setFrame: on CALayer takes a CGRect.
+  // The difference in arguments causes a compile error.
+  [hoverNoneLayer_.get() setFrame:viewLayer.frame];
+  [viewLayer addSublayer:hoverNoneLayer_];
+  [hoverNoneLayer_ addConstraint:xConstraint];
+  [hoverNoneLayer_ addConstraint:yConstraint];
+  [hoverNoneLayer_ setContents:reinterpret_cast<id>(gHoverNoneImage)];
+  [hoverNoneLayer_ setHidden:NO];
+
+  hoverMouseOverLayer_.reset([[CALayer alloc] init]);
+  [hoverMouseOverLayer_.get() setFrame:viewLayer.frame];
+  [viewLayer addSublayer:hoverMouseOverLayer_];
+  [hoverMouseOverLayer_ addConstraint:xConstraint];
+  [hoverMouseOverLayer_ addConstraint:yConstraint];
+  [hoverMouseOverLayer_ setContents:reinterpret_cast<id>(gHoverMouseOverImage)];
+  [hoverMouseOverLayer_ setHidden:YES];
+
+  hoverMouseDownLayer_.reset([[CALayer alloc] init]);
+  [hoverMouseDownLayer_.get() setFrame:viewLayer.frame];
+  [viewLayer addSublayer:hoverMouseDownLayer_];
+  [hoverMouseDownLayer_ addConstraint:xConstraint];
+  [hoverMouseDownLayer_ addConstraint:yConstraint];
+  [hoverMouseDownLayer_ setContents:reinterpret_cast<id>(gHoverMouseDownImage)];
+  [hoverMouseDownLayer_ setHidden:YES];
+}
+
++ (CGImageRef)imageForBounds:(NSRect)bounds
+                       xPath:(NSBezierPath*)xPath
+                  circlePath:(NSBezierPath*)circlePath
+                  hoverState:(HoverState)hoverState {
+  gfx::ScopedNSGraphicsContextSaveGState graphicsStateSaver;
+
+  scoped_nsobject<NSBitmapImageRep> imageRep(
+      [[NSBitmapImageRep alloc]
+        initWithBitmapDataPlanes:NULL
+                      pixelsWide:NSWidth(bounds)
+                      pixelsHigh:NSHeight(bounds)
+                   bitsPerSample:8
+                 samplesPerPixel:4
+                        hasAlpha:YES
+                        isPlanar:NO
+                  colorSpaceName:NSCalibratedRGBColorSpace
+                    bitmapFormat:0
+                     bytesPerRow:kButtonWidth * 4
+                    bitsPerPixel:32]);
+  NSGraphicsContext* gc =
+      [NSGraphicsContext graphicsContextWithBitmapImageRep:imageRep];
+  [NSGraphicsContext setCurrentContext:gc];
+
+  [[NSColor clearColor] set];
+  NSRectFill(bounds);
 
   // If the user is hovering over the button, a light/dark gray circle is drawn
   // behind the 'x'.
-  if (hoverState_ != kHoverStateNone) {
+  if (hoverState != kHoverStateNone) {
     // Adjust the darkness of the circle depending on whether it is being
     // clicked.
-    CGFloat white = (hoverState_ == kHoverStateMouseOver) ?
+    CGFloat white = (hoverState == kHoverStateMouseOver) ?
         kCircleHoverWhite : kCircleClickWhite;
     [[NSColor colorWithCalibratedWhite:white alpha:1.0] set];
-    [circlePath_ fill];
+    [circlePath fill];
   }
 
   [[NSColor whiteColor] set];
-  [xPath_ fill];
+  [xPath fill];
 
   // Give the 'x' an inner shadow for depth. If the button is in a hover state
   // (circle behind it), then adjust the shadow accordingly (not as harsh).
   NSShadow* shadow = [[[NSShadow alloc] init] autorelease];
-  CGFloat alpha = (hoverState_ != kHoverStateNone) ?
+  CGFloat alpha = (hoverState != kHoverStateNone) ?
       kXShadowCircleAlpha : kXShadowAlpha;
-  [shadow setShadowColor:[NSColor colorWithCalibratedWhite:0.15
-                                                     alpha:alpha]];
+  [shadow setShadowColor:[NSColor colorWithCalibratedWhite:0.15 alpha:alpha]];
   [shadow setShadowOffset:NSMakeSize(0.0, 0.0)];
   [shadow setShadowBlurRadius:2.5];
-  [xPath_ fillWithInnerShadow:shadow];
-}
+  [xPath fillWithInnerShadow:shadow];
 
-- (void)commonInit {
-  // Set accessibility description.
-  NSString* description = l10n_util::GetNSStringWithFixup(IDS_ACCNAME_CLOSE);
-  [[self cell]
-      accessibilitySetOverrideValue:description
-                       forAttribute:NSAccessibilityDescriptionAttribute];
-
-  // Add a tooltip.
-  [self setToolTip:l10n_util::GetNSStringWithFixup(IDS_TOOLTIP_CLOSE_TAB)];
-}
-
-- (void)setUpDrawingPaths {
-  // Keep the paths centered around the origin in this function. It is then
-  // translated in -updatePaths.
-  NSPoint xCenter = NSZeroPoint;
-
-  circlePath_.reset([[NSBezierPath bezierPath] retain]);
-  [circlePath_ moveToPoint:xCenter];
-  CGFloat radius = kCircleRadius;
-  [circlePath_ appendBezierPathWithArcWithCenter:xCenter
-                                          radius:radius
-                                      startAngle:0.0
-                                        endAngle:365.0];
-
-  // Construct an 'x' by drawing two intersecting rectangles in the shape of a
-  // cross and then rotating the path by 45 degrees.
-  xPath_.reset([[NSBezierPath bezierPath] retain]);
-  [xPath_ appendBezierPathWithRect:NSMakeRect(3.5, 7.0, 9.0, 2.0)];
-  [xPath_ appendBezierPathWithRect:NSMakeRect(7.0, 3.5, 2.0, 9.0)];
-
-  NSRect pathBounds = [xPath_ bounds];
-  NSPoint pathCenter = NSMakePoint(NSMidX(pathBounds), NSMidY(pathBounds));
-
-  NSAffineTransform* transform = [NSAffineTransform transform];
-  [transform translateXBy:xCenter.x yBy:xCenter.y];
-  [transform rotateByDegrees:45.0];
-  [transform translateXBy:-pathCenter.x yBy:-pathCenter.y];
-
-  [xPath_ transformUsingAffineTransform:transform];
-}
-
-- (void)updatePaths {
-  oldSize_ = [self bounds].size;
-
-  // Revert the current transform for the two points.
-  if (transform_.get()) {
-    [transform_.get() invert];
-    [circlePath_.get() transformUsingAffineTransform:transform_.get()];
-    [xPath_.get() transformUsingAffineTransform:transform_.get()];
-  }
-
-  // Create the new transform. [self bounds] is prefered in case aRect wasn't
-  // literally taken as bounds (e.g. cropped).
-  NSPoint xCenter = NSMakePoint(8, oldSize_.height / 2.0f);
-
-  // Retain here, as scoped_* don't retain.
-  transform_.reset([[NSAffineTransform transform] retain]);
-  [transform_.get() translateXBy:xCenter.x yBy:xCenter.y];
-  [circlePath_.get() transformUsingAffineTransform:transform_.get()];
-  [xPath_.get() transformUsingAffineTransform:transform_.get()];
+  // CGImage returns an autoreleased CGImageRef.
+  return [imageRep CGImage];
 }
 
 @end