Get rid of the ugly gradients used with colored tabs. Draw a light outline...

Get rid of the ugly gradients used with colored tabs. Draw a light outline around the selected tab if any tab has a color. Issue 5799.

ThirdParty/PSMTabBarControl/source/PSMTabBarCell.h

@@ -66,6 +66,7 @@
 // drawing
 - (void)drawWithFrame:(NSRect)cellFrame inView:(NSView *)controlView;
+- (void)drawPostHocDecorationsOnSelectedCell;
 // drag support
 - (NSImage *)dragImage;

ThirdParty/PSMTabBarControl/source/PSMTabBarCell.m

@@ -379,6 +379,10 @@ static NSRect PSMConvertAccessibilityFrameToScreen(NSView *view, NSRect frame) {
     [[[self psmTabControlView] style] drawTabCell:self highlightAmount:[self highlightAmount]];
 }
+- (void)drawPostHocDecorationsOnSelectedCell {
+    [[[self psmTabControlView] style] drawPostHocDecorationsOnSelectedCell:self];
+}
+
 - (CGFloat)highlightAmount {
     NSTimeInterval timeSinceChange = [NSDate timeIntervalSinceReferenceDate] - _highlightChangeTime;
     CGFloat amount = self.highlighted ? 1 : 0;

ThirdParty/PSMTabBarControl/source/PSMTabStyle.h

@@ -54,6 +54,8 @@ Protocol to be observed by all style delegate objects.  These objects handle the
 // Should light-tinted controls be used?
 - (BOOL)useLightControls;
+- (void)drawPostHocDecorationsOnSelectedCell:(PSMTabBarCell *)cell;
+
 @end
 @interface PSMTabBarControl (StyleAccessors)

ThirdParty/PSMTabBarControl/source/PSMYosemiteTabStyle.m

@@ -361,7 +361,13 @@
             textColor = [NSColor whiteColor];
         }
     } else {
-        textColor = [self textColorDefaultSelected:NO];
+        if (cell.tabColor && [self tabColorBrightness:cell] > 0.5) {
+            // This is hard to read when the app is inactive and there's a dark
+            // theme and dark themes give windows dark backgrounds by default.
+            textColor = [NSColor colorWithWhite:0.4 alpha:1];
+        } else {
+            textColor = [self textColorDefaultSelected:NO];
+        }
     }
     return textColor;
 }
@@ -456,18 +462,11 @@
     if (tabColor) {
         // Alpha the non-key window's tab colors a bit to make it clearer which window is key.
-        CGFloat alpha = [_tabBar.window isKeyWindow] ? 0.8 : 0.6;
+        CGFloat alpha = [_tabBar.window isKeyWindow] ? 1.0 : 0.6;
         
         // Alpha the inactive tab's colors a bit to make it clear which tab is active.
-        if (selected) {
-            [[tabColor colorWithAlphaComponent:alpha] set];
-            NSRectFillUsingOperation(cellFrame, NSCompositeSourceOver);
-        } else {
-            NSColor *startingColor = [tabColor colorWithAlphaComponent:alpha - 0.2];
-            NSColor *endingColor = [tabColor colorWithAlphaComponent:0];
-            NSGradient *gradient = [[[NSGradient alloc] initWithStartingColor:startingColor endingColor:endingColor] autorelease];
-            [gradient drawInRect:cellFrame angle:-90];
-        }
+        [[tabColor colorWithAlphaComponent:alpha] set];
+        NSRectFillUsingOperation(cellFrame, NSCompositeSourceOver);
     }
     if (horizontal) {
@@ -531,6 +530,45 @@
     [self drawInteriorWithTabCell:cell inView:[cell controlView] highlightAmount:highlightAmount];
 }
+static CGFloat PerceivedBrightness(CGFloat r, CGFloat g, CGFloat b) {
+    static const double kRedComponentBrightness = 0.30;
+    static const double kGreenComponentBrightness = 0.59;
+    static const double kBlueComponentBrightness = 0.11;
+    return (kRedComponentBrightness * r +
+            kGreenComponentBrightness * g +
+            kBlueComponentBrightness * b);
+}
+
+- (CGFloat)tabColorBrightness:(PSMTabBarCell *)cell {
+    NSColor *tabColor = cell.tabColor ?: [self backgroundColorSelected:cell.state == NSOnState highlightAmount:0];
+    NSColor *safeColor = [tabColor colorUsingColorSpaceName:NSCalibratedRGBColorSpace];
+    CGFloat brightness = PerceivedBrightness([safeColor redComponent],
+                                             [safeColor greenComponent],
+                                             [safeColor blueComponent]);
+    return brightness;
+}
+
+- (void)drawPostHocDecorationsOnSelectedCell:(PSMTabBarCell *)cell {
+    const BOOL anyTabHasColor = [_tabBar.cells indexOfObjectPassingTest:^BOOL(PSMTabBarCell * _Nonnull cell, NSUInteger idx, BOOL * _Nonnull stop) {
+        return cell.tabColor != nil;
+    }] != NSNotFound;
+    if (anyTabHasColor) {
+        const CGFloat brightness = [self tabColorBrightness:cell];
+        [[NSColor colorWithWhite:MIN(1, brightness + 0.5) alpha:1] set];
+        NSFrameRect(cell.frame);
+        if (brightness > 0.6) {
+            NSRect rect = NSInsetRect(cell.frame, 1, 1);
+            rect.origin.x += 0.25;
+            rect.origin.y += 0.25;
+            rect.size.width -= 0.5;
+            rect.size.height -= 0.5;
+            NSBezierPath *path = [NSBezierPath bezierPathWithRect:rect];
+            [path setLineWidth:0.5];
+            [[NSColor grayColor] set];
+            [path stroke];
+        }
+    }
+}
 - (void)drawInteriorWithTabCell:(PSMTabBarCell *)cell
                          inView:(NSView*)controlView
@@ -780,6 +818,11 @@
             }
         }
     }
+    for (PSMTabBarCell *cell in [bar cells]) {
+        if (![cell isInOverflowMenu] && NSIntersectsRect([cell frame], rect) && cell.state == NSOnState) {
+            [cell drawPostHocDecorationsOnSelectedCell];
+        }
+    }
 }
 #pragma mark - Archiving