cocoa: draw new tab button with heavier stroke in high contrast

chrome/browser/ui/cocoa/new_tab_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/new_tab_button.h"
 
 #include "base/mac/foundation_util.h"
 #include "base/mac/sdk_forward_declarations.h"
 #import "chrome/browser/ui/cocoa/image_button_cell.h"
 #include "chrome/browser/ui/cocoa/l10n_util.h"
 #include "chrome/browser/ui/cocoa/tabs/tab_view.h"
 #include "chrome/grit/theme_resources.h"
 #include "ui/base/cocoa/nsgraphics_context_additions.h"
 #include "ui/base/material_design/material_design_controller.h"
 #include "ui/base/resource/resource_bundle.h"
 #include "ui/base/theme_provider.h"
 
 @class NewTabButtonCell;
 
 namespace {
 
 enum class OverlayOption {
   NONE,
   LIGHTEN,
   DARKEN,
 };
 
-  const NSSize newTabButtonImageSize = { 34, 18 };
-
-const CGFloat k7PercentAlpha = 0.07;
-const CGFloat k8PercentAlpha = 0.08;
-const CGFloat k10PercentAlpha = 0.1;
-const CGFloat k20PercentAlpha = 0.2;
-const CGFloat k25PercentAlpha = 0.25;
+const NSSize newTabButtonImageSize = {34, 18};
 
 NSImage* GetMaskImageFromCell(NewTabButtonCell* aCell) {
   return [aCell imageForState:image_button_cell::kDefaultState view:nil];
 }
 
 // Creates an NSImage with size |size| and bitmap image representations for both
 // 1x and 2x scale factors. |drawingHandler| is called once for every scale
 // factor.  This is similar to -[NSImage imageWithSize:flipped:drawingHandler:],
 // but this function always evaluates drawingHandler eagerly, and it works on
 // 10.6 and 10.7.
@@ skipping 133 matching lines @@
 
 // Returns a new tab button image appropriate for the specified button state
 // (e.g. hover) and theme. In Material Design, the theme color affects the
 // button color.
 - (NSImage*)imageForState:(image_button_cell::ButtonState)state
                     theme:(const ui::ThemeProvider*)theme;
 
 // Returns a new tab button image bezier path with the specified line width.
 + (NSBezierPath*)newTabButtonBezierPathWithLineWidth:(CGFloat)lineWidth;
 
-// NSCustomImageRep custom drawing method that renders the new tab button image.
-+ (void)drawNewTabButtonImage:(NewTabButtonCustomImageRep*)imageRep;
+// Draws the new tab button image to |imageRep|, with either a normal stroke or
+// a heavy stroke for increased visibility.
++ (void)drawNewTabButtonImage:(NewTabButtonCustomImageRep*)imageRep
+              withHeavyStroke:(BOOL)heavyStroke;
+
+// NSCustomImageRep custom drawing method shims for normal and heavy strokes
+// respectively.
++ (void)drawNewTabButtonImageWithNormalStroke:
+    (NewTabButtonCustomImageRep*)imageRep;
++ (void)drawNewTabButtonImageWithHeavyStroke:
+    (NewTabButtonCustomImageRep*)imageRep;
 
 // Returns a new tab button image filled with |fillColor|.
 - (NSImage*)imageWithFillColor:(NSColor*)fillColor;
 
 @end
 
 @implementation NewTabButton
 
 + (Class)cellClass {
   return [NewTabButtonCell class];
@@ skipping 111 matching lines @@
       fillColor =
           theme->GetNSImageColorNamed(IDR_THEME_TAB_BACKGROUND_INACTIVE);
       break;
 
     default:
       fillColor = [NSColor redColor];
       // All states should be accounted for above.
       NOTREACHED();
   }
 
+  SEL drawSelector = @selector(drawNewTabButtonImageWithNormalStroke:);
+  if (theme && theme->ShouldIncreaseContrast())
+    drawSelector = @selector(drawNewTabButtonImageWithHeavyStroke:);
+
   base::scoped_nsobject<NewTabButtonCustomImageRep> imageRep(
       [[NewTabButtonCustomImageRep alloc]
-          initWithDrawSelector:@selector(drawNewTabButtonImage:)
+          initWithDrawSelector:drawSelector
                       delegate:[NewTabButton class]]);
   [imageRep setDestView:self];
   [imageRep setFillColor:fillColor];
   [imageRep setPatternPhasePosition:
       [[self window]
           themeImagePositionForAlignment:THEME_IMAGE_ALIGN_WITH_TAB_STRIP]];
   [imageRep setOverlayOption:overlayOption];
 
   NSImage* newTabButtonImage =
       [[[NSImage alloc] initWithSize:newTabButtonImageSize] autorelease];
@@ skipping 57 matching lines @@
   // Adjust by half the line width to get crisp lines.
   NSAffineTransform* transform = [NSAffineTransform transform];
   [transform translateXBy:lineWidth / 2 yBy:lineWidth / 2];
   [bezierPath transformUsingAffineTransform:transform];
 
   [bezierPath setLineWidth:lineWidth];
 
   return bezierPath;
 }
 
-+ (void)drawNewTabButtonImage:(NewTabButtonCustomImageRep*)imageRep {
++ (void)drawNewTabButtonImage:(NewTabButtonCustomImageRep*)imageRep
+              withHeavyStroke:(BOOL)heavyStroke {
   [[NSGraphicsContext currentContext]
       cr_setPatternPhase:[imageRep patternPhasePosition]
       forView:[imageRep destView]];
 
   CGContextRef context = static_cast<CGContextRef>(
       [[NSGraphicsContext currentContext] graphicsPort]);
   CGFloat lineWidth = LineWidthFromContext(context);
   NSBezierPath* bezierPath =
       [self newTabButtonBezierPathWithLineWidth:lineWidth];
 
   if ([imageRep fillColor]) {
     [[imageRep fillColor] set];
     [bezierPath fill];
   }
 
+  CGFloat alpha = heavyStroke ? 1.0 : 0.25;
   static NSColor* strokeColor =
-      [[NSColor colorWithCalibratedWhite:0 alpha:k25PercentAlpha] retain];
+      [[NSColor colorWithCalibratedWhite:0 alpha:alpha] retain];
   [strokeColor set];
   [bezierPath stroke];
 
   // Bottom edge.
   const CGFloat kBottomEdgeX = 9;
   const CGFloat kBottomEdgeY = 1.2825;
   const CGFloat kBottomEdgeWidth = 22;
   NSPoint bottomEdgeStart = NSMakePoint(kBottomEdgeX, kBottomEdgeY);
   NSPoint bottomEdgeEnd = NSMakePoint(kBottomEdgeX + kBottomEdgeWidth,
                                       kBottomEdgeY);
   NSBezierPath* bottomEdgePath = [NSBezierPath bezierPath];
   [bottomEdgePath moveToPoint:bottomEdgeStart];
   [bottomEdgePath lineToPoint:bottomEdgeEnd];
   static NSColor* bottomEdgeColor =
-      [[NSColor colorWithCalibratedWhite:0 alpha:k7PercentAlpha] retain];
+      [[NSColor colorWithCalibratedWhite:0 alpha:0.07] retain];
   [bottomEdgeColor set];
   [bottomEdgePath setLineWidth:lineWidth];
   [bottomEdgePath setLineCapStyle:NSRoundLineCapStyle];
   [bottomEdgePath stroke];
 
   CGPoint shadowStart = NSZeroPoint;
   CGPoint shadowEnd = NSZeroPoint;
   NSColor* overlayColor = nil;
   const CGFloat kBottomShadowX = 8;
   const CGFloat kBottomShadowY = kBottomEdgeY - lineWidth;
   const CGFloat kTopShadowX = 1;
   const CGFloat kTopShadowY = kBottomShadowY + 15;
   const CGFloat kShadowWidth = 24;
   static NSColor* lightOverlayColor =
-      [[NSColor colorWithCalibratedWhite:1 alpha:k20PercentAlpha] retain];
+      [[NSColor colorWithCalibratedWhite:1 alpha:0.20] retain];
   static NSColor* darkOverlayColor =
-      [[NSColor colorWithCalibratedWhite:0 alpha:k8PercentAlpha] retain];
+      [[NSColor colorWithCalibratedWhite:0 alpha:0.08] retain];
 
   switch ([imageRep overlayOption]) {
     case OverlayOption::LIGHTEN:
       overlayColor = lightOverlayColor;
       break;
 
     case OverlayOption::DARKEN:
       overlayColor = darkOverlayColor;
       shadowStart = NSMakePoint(kTopShadowX, kTopShadowY);
       shadowEnd = NSMakePoint(kTopShadowX + kShadowWidth, kTopShadowY);
       break;
 
     case OverlayOption::NONE:
       shadowStart = NSMakePoint(kBottomShadowX, kBottomShadowY);
       shadowEnd = NSMakePoint(kBottomShadowX + kShadowWidth, kBottomShadowY);
       break;
   }
 
   // Shadow beneath the bottom or top edge.
   if (!NSEqualPoints(shadowStart, NSZeroPoint)) {
     NSBezierPath* shadowPath = [NSBezierPath bezierPath];
     [shadowPath moveToPoint:shadowStart];
     [shadowPath lineToPoint:shadowEnd];
     [shadowPath setLineWidth:lineWidth];
     [shadowPath setLineCapStyle:NSRoundLineCapStyle];
     static NSColor* shadowColor =
-      [[NSColor colorWithCalibratedWhite:0 alpha:k10PercentAlpha] retain];
+        [[NSColor colorWithCalibratedWhite:0 alpha:0.10] retain];
     [shadowColor set];
     [shadowPath stroke];
   }
 
   if (overlayColor) {
     [overlayColor set];
     [[self newTabButtonBezierPathWithLineWidth:lineWidth] fill];
   }
 }
 
++ (void)drawNewTabButtonImageWithNormalStroke:
+    (NewTabButtonCustomImageRep*)image {
+  [self drawNewTabButtonImage:image withHeavyStroke:NO];
+}
+
++ (void)drawNewTabButtonImageWithHeavyStroke:
+    (NewTabButtonCustomImageRep*)image {
+  [self drawNewTabButtonImage:image withHeavyStroke:YES];
+}
+
 - (NSImage*)imageWithFillColor:(NSColor*)fillColor {
   NSImage* image =
       [[[NSImage alloc] initWithSize:newTabButtonImageSize] autorelease];
 
   [image lockFocus];
   [fillColor set];
   CGContextRef context = static_cast<CGContextRef>(
       [[NSGraphicsContext currentContext] graphicsPort]);
   CGFloat lineWidth = LineWidthFromContext(context);
   [[NewTabButton newTabButtonBezierPathWithLineWidth:lineWidth] fill];
   [image unlockFocus];
   return image;
 }
 
 @end