[cocoa] increase tab strip contrast in "Increase Contrast" mode

chrome/browser/ui/cocoa/tabs/tab_view.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/tabs/tab_view.h"
 
 #include "base/i18n/rtl.h"
 #include "base/logging.h"
 #include "base/mac/sdk_forward_declarations.h"
 #include "base/strings/sys_string_conversions.h"
@@ skipping 27 matching lines @@
 const NSTimeInterval kAlertHideDuration = 0.4;
 
 // The default time interval in seconds between glow updates (when
 // increasing/decreasing).
 const NSTimeInterval kGlowUpdateInterval = 0.025;
 
 // This is used to judge whether the mouse has moved during rapid closure; if it
 // has moved less than the threshold, we want to close the tab.
 const CGFloat kRapidCloseDist = 2.5;
 
-@interface TabView(MaterialDesign)
+// This class contains the logic for drawing Material Design tab images. The
+// |setTabEdgeStrokeColor| method is overridden by |TabHeavyImageMaker| to draw
+// high-contrast tabs.
+@interface TabImageMaker : NSObject
 + (void)drawTabLeftMaskImage;
 + (void)drawTabRightMaskImage;
 + (void)drawTabLeftEdgeImage;
 + (void)drawTabMiddleEdgeImage;
 + (void)drawTabRightEdgeImage;
++ (void)setTabEdgeStrokeColor;
+@end
+
+@interface TabHeavyImageMaker : TabImageMaker
++ (void)setTabEdgeStrokeColor;
 @end
 
 @interface TabController(Private)
 // The TabView's close button.
 - (HoverCloseButton*)closeButton;
 @end
 
+extern NSString* const _Nonnull NSWorkspaceAccessibilityDisplayOptionsDidChangeNotification;
+
 namespace {
 
-NSImage* imageForResourceID(int resource_id) {
+NSImage* imageForResourceID(int resource_id, bool heavy_stroke) {

[Nico, 2016/06/21 20:40:21]

nit: prefer enums over bool params,

imageForResourceId(IDR_FOO, NORMAL_STROKE)

reads easier than ..., false)

   if (!ui::MaterialDesignController::IsModeMaterial()) {
     ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
     return [rb.GetNativeImageNamed(resource_id).CopyNSImage() autorelease];
   }
 
   CGFloat imageWidth = resource_id == IDR_TAB_ACTIVE_CENTER ? 1 : 18;
   SEL theSelector = 0;
   switch (resource_id) {
     case IDR_TAB_ACTIVE_LEFT:
       theSelector = @selector(drawTabLeftEdgeImage);
@@ skipping 10 matching lines @@
     case IDR_TAB_ALPHA_LEFT:
       theSelector = @selector(drawTabLeftMaskImage);
       break;
 
     case IDR_TAB_ALPHA_RIGHT:
       theSelector = @selector(drawTabRightMaskImage);
       break;
   }
   DCHECK(theSelector);
 
+  Class makerClass =
+      heavy_stroke ? [TabHeavyImageMaker class] : [TabImageMaker class];
   base::scoped_nsobject<NSCustomImageRep> imageRep([[NSCustomImageRep alloc]
       initWithDrawSelector:theSelector
-                  delegate:[TabView class]]);
+                  delegate:makerClass]);
 
   NSImage* newTabButtonImage =
       [[[NSImage alloc] initWithSize:NSMakeSize(imageWidth, 29)] autorelease];
   [newTabButtonImage setCacheMode:NSImageCacheAlways];
   [newTabButtonImage addRepresentation:imageRep];
 
   return newTabButtonImage;
 }
 
 ui::ThreePartImage& GetMaskImage() {
-  CR_DEFINE_STATIC_LOCAL(ui::ThreePartImage, mask,
-      (imageForResourceID(IDR_TAB_ALPHA_LEFT), nullptr,
-          imageForResourceID(IDR_TAB_ALPHA_RIGHT)));
+  CR_DEFINE_STATIC_LOCAL(
+      ui::ThreePartImage, mask,
+      (imageForResourceID(IDR_TAB_ALPHA_LEFT, false), nullptr,
+       imageForResourceID(IDR_TAB_ALPHA_RIGHT, false)));
 
   return mask;
 }
 
-ui::ThreePartImage& GetStrokeImage(bool active) {
+ui::ThreePartImage& GetStrokeImage(bool active, bool increase_contrast) {
   if (!ui::MaterialDesignController::IsModeMaterial() && !active) {
-    CR_DEFINE_STATIC_LOCAL(
-        ui::ThreePartImage, inactiveStroke,
-            (imageForResourceID(IDR_TAB_INACTIVE_LEFT),
-             imageForResourceID(IDR_TAB_INACTIVE_CENTER),
-             imageForResourceID(IDR_TAB_INACTIVE_RIGHT)));
+    CR_DEFINE_STATIC_LOCAL(ui::ThreePartImage, inactiveStroke,
+                           (imageForResourceID(IDR_TAB_INACTIVE_LEFT, false),
+                            imageForResourceID(IDR_TAB_INACTIVE_CENTER, false),
+                            imageForResourceID(IDR_TAB_INACTIVE_RIGHT, false)));
     return inactiveStroke;
   }
-  CR_DEFINE_STATIC_LOCAL(
-      ui::ThreePartImage, stroke,
-          (imageForResourceID(IDR_TAB_ACTIVE_LEFT),
-           imageForResourceID(IDR_TAB_ACTIVE_CENTER),
-           imageForResourceID(IDR_TAB_ACTIVE_RIGHT)));
+  CR_DEFINE_STATIC_LOCAL(ui::ThreePartImage, stroke,
+                         (imageForResourceID(IDR_TAB_ACTIVE_LEFT, false),
+                          imageForResourceID(IDR_TAB_ACTIVE_CENTER, false),
+                          imageForResourceID(IDR_TAB_ACTIVE_RIGHT, false)));
+  CR_DEFINE_STATIC_LOCAL(ui::ThreePartImage, heavyStroke,
+                         (imageForResourceID(IDR_TAB_ACTIVE_LEFT, true),
+                          imageForResourceID(IDR_TAB_ACTIVE_CENTER, true),
+                          imageForResourceID(IDR_TAB_ACTIVE_RIGHT, true)));
 
-  return stroke;
+  return increase_contrast ? heavyStroke : stroke;
 }
 
 CGFloat LineWidthFromContext(CGContextRef context) {
   CGRect unitRect = CGRectMake(0.0, 0.0, 1.0, 1.0);
   CGRect deviceRect = CGContextConvertRectToDeviceSpace(context, unitRect);
   return 1.0 / deviceRect.size.height;
 }
 
 }  // namespace
 
@@ skipping 31 matching lines @@
     titleView_.reset([[NSTextField alloc] init]);
     [titleView_ setAutoresizingMask:NSViewWidthSizable];
     base::scoped_nsobject<GTMFadeTruncatingTextFieldCell> labelCell(
         [[GTMFadeTruncatingTextFieldCell alloc] initTextCell:@"Label"]);
     [labelCell setControlSize:NSSmallControlSize];
     // Font size is 12, per Material Design spec.
     CGFloat fontSize = 12;
     if (!ui::MaterialDesignController::IsModeMaterial()) {
       fontSize = [NSFont systemFontSizeForControlSize:NSSmallControlSize];
     }
-    [labelCell setFont:[NSFont systemFontOfSize:fontSize]];
     [titleView_ setCell:labelCell];
     titleViewCell_ = labelCell;
 
     [self setWantsLayer:YES];  // -drawFill: needs a layer.
+
+    if (NSWorkspaceAccessibilityDisplayOptionsDidChangeNotification) {
+      NSNotificationCenter* center =
+          [[NSWorkspace sharedWorkspace] notificationCenter];
+      [center
+          addObserver:self
+             selector:@selector(accessibilityOptionsDidChange:)
+                 name:
+                     NSWorkspaceAccessibilityDisplayOptionsDidChangeNotification

[Nico, 2016/06/21 20:40:21]

(uber nit: i'd have a local constant with a much shorter name for this one, to
make the addObserver: call look a bit less ridiculous)

+               object:nil];
+    }
   }
   return self;
 }
 
 - (void)dealloc {
   // Cancel any delayed requests that may still be pending (drags or hover).
   [NSObject cancelPreviousPerformRequestsWithTarget:self];
+  if (NSWorkspaceAccessibilityDisplayOptionsDidChangeNotification) {
+    NSNotificationCenter* center =
+        [[NSWorkspace sharedWorkspace] notificationCenter];
+    [center removeObserver:self];
+  }
   [super dealloc];
 }
 
 // Called to obtain the context menu for when the user hits the right mouse
 // button (or control-clicks). (Note that -rightMouseDown: is *not* called for
 // control-click.)
 - (NSMenu*)menu {
   if ([self isClosing])
     return nil;
 
@@ skipping 279 matching lines @@
   NSRect bounds = [self bounds];
   if (ui::MaterialDesignController::IsModeMaterial()) {
     // In Material Design the tab strip separator is always 1 pixel high -
     // add a clip rect to avoid drawing the tab edge over it.
     NSRect clipRect = bounds;
     clipRect.origin.y += [self cr_lineWidth];
     NSRectClip(clipRect);
     // In MD, the tab stroke is always opaque.
     alpha = 1;
   }
-  GetStrokeImage(state_ == NSOnState)
+  GetStrokeImage(state_ == NSOnState,
+                 [[self window] themeProvider]->ShouldIncreaseContrast())
       .DrawInRect(bounds, NSCompositeSourceOver, alpha);
 }
 
 - (void)drawRect:(NSRect)dirtyRect {
   [self drawFill:dirtyRect];
   [self drawStroke:dirtyRect];
 
   // We draw the title string directly instead of using a NSTextField subview.
   // This is so that we can get font smoothing to work on earlier OS, and even
   // when the tab background is a pattern image (when using themes).
@@ skipping 88 matching lines @@
   if (titleHidden == [titleView_ isHidden])
     return;
   [titleView_ setHidden:titleHidden];
   [self setNeedsDisplayInRect:[titleView_ frame]];
 }
 
 - (SkColor)closeButtonColor {
   return [[controller_ closeButton] iconColor];
 }
 
+- (void)accessibilityOptionsDidChange:(id)ignored {
+  [self updateLabelFont];
+  [self setNeedsDisplay:YES];
+}
+
+- (void)updateLabelFont {
+  CGFloat fontSize = [titleViewCell_ font].pointSize;
+  if ([[self window] themeProvider]->ShouldIncreaseContrast() &&
+      state_ == NSOnState) {
+    [titleViewCell_ setFont:[NSFont boldSystemFontOfSize:fontSize]];
+  } else {
+    [titleViewCell_ setFont:[NSFont systemFontOfSize:fontSize]];
+  }
+}
+
 - (void)setState:(NSCellStateValue)state {
   if (state_ == state)
     return;
   state_ = state;
+  [self updateLabelFont];
   [self setNeedsDisplay:YES];
 }
 
 - (void)setClosing:(BOOL)closing {
   closing_ = closing;  // Safe because the property is nonatomic.
   // When closing, ensure clicks to the close button go nowhere.
   if (closing) {
     [closeButton_ setTarget:nil];
     [closeButton_ setAction:nil];
   }
@@ skipping 199 matching lines @@
 
   if (nextUpdate < kNoUpdate)
     [self performSelector:_cmd withObject:nil afterDelay:nextUpdate];
 
   [self resetLastGlowUpdateTime];
   [self setNeedsDisplay:YES];
 }
 
 @end  // @implementation TabView(Private)
 
-
-@implementation TabView(MaterialDesign)
+@implementation TabImageMaker
 
 + (NSBezierPath*)tabLeftEdgeBezierPathForContext:(CGContextRef)context {
   NSBezierPath* bezierPath = [NSBezierPath bezierPath];
 
   [bezierPath moveToPoint:NSMakePoint(-2, 0)];
   [bezierPath curveToPoint:NSMakePoint(2.5, 2)
              controlPoint1:NSMakePoint(1.805, -0.38)
              controlPoint2:NSMakePoint(2.17, 1.415)];
 
   [bezierPath lineToPoint:NSMakePoint(14, 27)];
@@ skipping 31 matching lines @@
 + (void)setTabEdgeStrokeColor {
   static NSColor* strokeColor =
       [skia::SkColorToSRGBNSColor(SkColorSetARGB(76, 0, 0, 0)) retain];
   [strokeColor set];
 }
 
 + (void)drawTabLeftEdgeImage {
   CGContextRef context = static_cast<CGContextRef>(
       [[NSGraphicsContext currentContext] graphicsPort]);
 
-  [TabView setTabEdgeStrokeColor];
+  [self setTabEdgeStrokeColor];
   [[self tabLeftEdgeBezierPathForContext:context] stroke];
 }
 
 + (void)drawTabMiddleEdgeImage {
   NSBezierPath* middleEdgePath = [NSBezierPath bezierPath];
   [middleEdgePath moveToPoint:NSMakePoint(0, 29)];
   [middleEdgePath lineToPoint:NSMakePoint(1, 29)];
   [middleEdgePath setLineCapStyle:NSSquareLineCapStyle];
 
   CGContextRef context = static_cast<CGContextRef>(
       [[NSGraphicsContext currentContext] graphicsPort]);
   CGFloat lineWidth = LineWidthFromContext(context);
 
   // Line width is always 1px.
   [middleEdgePath setLineWidth:lineWidth];
 
   // Align to device pixels.
   NSAffineTransform* translationTransform = [NSAffineTransform transform];
   [translationTransform translateXBy:0 yBy:-1 + lineWidth / 2.];
   [middleEdgePath transformUsingAffineTransform:translationTransform];
 
-  [TabView setTabEdgeStrokeColor];
+  [self setTabEdgeStrokeColor];
   [middleEdgePath stroke];
 }
 
 + (void)drawTabRightEdgeImage {
   CGContextRef context = static_cast<CGContextRef>(
       [[NSGraphicsContext currentContext] graphicsPort]);
 
   NSBezierPath* leftEdgePath = [self tabLeftEdgeBezierPathForContext:context];
 
   // Draw the right edge path by flipping the left edge path vertically.
   NSAffineTransform* transform = [NSAffineTransform transform];
   [transform scaleXBy:-1 yBy:1];
   [transform translateXBy:-18 yBy:0];
   [leftEdgePath transformUsingAffineTransform:transform];
 
-  [TabView setTabEdgeStrokeColor];
+  [self setTabEdgeStrokeColor];
   [leftEdgePath stroke];
 }
 
 + (NSBezierPath*)tabLeftMaskBezierPath {
   NSBezierPath* bezierPath = [self tabLeftEdgeBezierPathForContext:nullptr];
 
   // Box in the open edges.
   [bezierPath lineToPoint:NSMakePoint(18, 0)];
   [bezierPath lineToPoint:NSMakePoint(0, 0)];
 
@@ skipping 18 matching lines @@
   NSBezierPath* bezierPath = [self tabLeftMaskBezierPath];
   NSAffineTransform* transform = [NSAffineTransform transform];
   [transform scaleXBy:-1 yBy:1];
   [transform translateXBy:-17.5 yBy:-0.25];
   [bezierPath transformUsingAffineTransform:transform];
 
   [[NSColor whiteColor] set];
   [bezierPath fill];
 }
 
-@end  // @implementation TabView(MaterialDesign)
+@end
+
+@implementation TabHeavyImageMaker
+
+// For "Increase Contrast" mode, use flat black instead of semitransparent black
+// for the tab edge stroke.
++ (void)setTabEdgeStrokeColor {

[Nico, 2016/06/21 20:40:21]

overriding static methods is a bit clever, maybe this could be an instance
method and a real object now. but up to you.

+  static NSColor* heavyStrokeColor =
+      [skia::SkColorToSRGBNSColor(SK_ColorBLACK) retain];
+  [heavyStrokeColor set];
+}
+
+@end