Make the edge where BackgroundGradientView draws a divider selectable.

chrome/browser/ui/cocoa/background_gradient_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.
 
 #include "chrome/browser/ui/cocoa/background_gradient_view.h"
 
 #import "chrome/browser/themes/theme_properties.h"
 #import "chrome/browser/themes/theme_service.h"
 #import "chrome/browser/ui/cocoa/themed_window.h"
 #include "chrome/grit/theme_resources.h"
 #import "ui/base/cocoa/nsgraphics_context_additions.h"
 #import "ui/base/cocoa/nsview_additions.h"
 #include "ui/base/material_design/material_design_controller.h"
 
-@interface BackgroundGradientView (Private)
-- (void)commonInit;
-- (NSColor*)backgroundImageColor;
-@end
-
 @implementation BackgroundGradientView
 
+@synthesize divider = divider_;
 @synthesize showsDivider = showsDivider_;
 
-- (id)initWithFrame:(NSRect)frameRect {
-  if ((self = [super initWithFrame:frameRect])) {
-    [self commonInit];
-  }
-  return self;
-}
-
-- (id)initWithCoder:(NSCoder*)decoder {
-  if ((self = [super initWithCoder:decoder])) {
-    [self commonInit];
-  }
-  return self;
-}
-
-- (void)commonInit {
-  showsDivider_ = YES;

[Nico, 2016/09/12 13:45:55]

This used to default to divider-on, now it defaults to divider-off, no?

[Sidney San Martín, 2016/09/14 17:46:59]

Fixed, thanks.

+- (void)setDivider:(BackgroundGradientViewDivider)divider {
+  if (divider_ == divider)
+    return;
+  divider_ = divider;
+  [self setNeedsDisplay:YES];
 }
 
 - (void)setShowsDivider:(BOOL)show {
   if (showsDivider_ == show)
     return;
   showsDivider_ = show;
   [self setNeedsDisplay:YES];
 }
 
 - (NSPoint)patternPhase {
@@ skipping 11 matching lines @@
     // If the background image is semi transparent then we need something
     // to blend against. Using 20% black gives us a color similar to Windows.
     [[NSColor colorWithCalibratedWhite:0.2 alpha:1.0] set];
     NSRectFill(dirtyRect);
   }
 
   [[self backgroundImageColor] set];
   NSRectFillUsingOperation(dirtyRect, NSCompositeSourceOver);
 
   if (showsDivider_) {
-    // Draw bottom stroke
-    NSRect borderRect, contentRect;
-    NSDivideRect([self bounds], &borderRect, &contentRect, [self cr_lineWidth],
-                 NSMinYEdge);
+    CGFloat lineWidth = [self cr_lineWidth];
+    NSRect borderRect = NSMakeRect(0, 0, self.bounds.size.width, lineWidth);
+
+    switch (divider_) {
+      case BackgroundGradientViewDivider::Bottom:
+        break;
+      case BackgroundGradientViewDivider::Top:
+        borderRect.origin.y = self.bounds.size.height - lineWidth;
+        break;
+    }

[Nico, 2016/09/12 13:45:55]

These 7 lines are shorter as

  if (divider_ == BackgroundGradientViewDivider::Top)
    borderRect.origin.y = NSHeight(self.bounds) - lineWidth;

But I'd probably leave the previous code and tweak it like so:

  NSDivideRect([self bounds], &borderRect, &contentRect, [self cr_lineWidth],
    divider_ == BackgroundGradientViewDivider::Top ? NSMaxYEdge : NSMinYEdge);

And if you don't make up your own enum but use NSMaxYEdge / NSMinYEdge instead,
then you don't even need the ternary.

[Sidney San Martín, 2016/09/14 17:46:59]

I think I had an incomplete understanding of NSDivideRect. I like this idea much
better.

     if (NSIntersectsRect(borderRect, dirtyRect)) {
       [[self strokeColor] set];
       NSRectFillUsingOperation(NSIntersectionRect(borderRect, dirtyRect),
                                NSCompositeSourceOver);
     }
   }
 }
 
 - (NSColor*)strokeColor {
   NSWindow* window = [self window];
@@ skipping 90 matching lines @@
 
 - (void)windowDidChangeTheme {
   [self setNeedsDisplay:YES];
 }
 
 - (void)windowDidChangeActive {
   [self setNeedsDisplay:YES];
 }
 
 @end