Refactor themePatternPhase and tab_view in preparation for fixing crbug.com/176857

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/logging.h"
 #include "base/mac/sdk_forward_declarations.h"
 #include "chrome/browser/themes/theme_service.h"
 #import "chrome/browser/ui/cocoa/nsview_additions.h"
@@ skipping 283 matching lines @@
   };
 
   // Themes don't have an inactive image so only look for one if there's no
   // theme.
   bool active = [[self window] isKeyWindow] || [[self window] isMainWindow] ||
                 !themeProvider->UsingDefaultTheme();
   return themeProvider->GetNSImageColorNamed(
       bitmapResources[active][selected], true);
 }
 
+// Draws the active tab background.
+- (void)drawFillForActiveTab:(NSRect)dirtyRect {
+  NSColor* backgroundImageColor = [self backgroundColorForSelected:YES];
+  [backgroundImageColor set];
+
+  // Themes can have partially transparent images. NSRectFill() is measurably
+  // faster though, so call it for the known-safe default theme.
+  ThemeService* themeProvider =
+      static_cast<ThemeService*>([[self window] themeProvider]);
+  if (themeProvider && themeProvider->UsingDefaultTheme())
+    NSRectFill(dirtyRect);
+  else
+    NSRectFillUsingOperation(dirtyRect, NSCompositeSourceOver);
+}
+
 // Draws the tab background.
 - (void)drawFill:(NSRect)dirtyRect {
   gfx::ScopedNSGraphicsContextSaveGState scopedGState;
   NSGraphicsContext* context = [NSGraphicsContext currentContext];
   CGContextRef cgContext = static_cast<CGContextRef>([context graphicsPort]);
 
   ThemeService* themeProvider =
       static_cast<ThemeService*>([[self window] themeProvider]);
-  [context cr_setPatternPhase:[[self window] themePatternPhase] forView:self];
-
+  bool usingDefaultTheme = themeProvider && themeProvider->UsingDefaultTheme();

[Nico, 2013/07/18 19:58:30]

Why did this move up? It's not used until before where it was previously afaict.

+  NSPoint phase = [[self window]
+      themePatternPhaseForAlignment: THEME_PATTERN_ALIGN_WITH_TAB_STRIP];
+  [context cr_setPatternPhase:phase forView:self];
 
   CGImageRef mask([self tabClippingMask]);
   CGRect maskBounds = CGRectMake(0, 0, maskCacheWidth_, kMaskHeight);
   CGContextClipToMask(cgContext, maskBounds, mask);
 
-  bool selected = [self state];

[Nico, 2013/07/18 19:58:30]

nit: Keeping the bool is imo better for readability, even if it's used only
once.

+  if ([self state]) {
+    [self drawFillForActiveTab:dirtyRect];
+    return;
+  }
 
   // Background tabs should not paint over the tab strip separator, which is
   // two pixels high in both lodpi and hidpi.
-  if (!selected && dirtyRect.origin.y < 1)
+  if (dirtyRect.origin.y < 1)
     dirtyRect.origin.y = 2 * [self cr_lineWidth];
 
-  bool usingDefaultTheme = themeProvider && themeProvider->UsingDefaultTheme();
-  NSColor* backgroundImageColor = [self backgroundColorForSelected:selected];
+  // Draw the tab background.
+  NSColor* backgroundImageColor = [self backgroundColorForSelected:NO];
+  [backgroundImageColor set];
+  // Themes can have partially transparent images. NSRectFill() is measurably
+  // faster though, so call it for the known-safe default theme.
+  if (usingDefaultTheme)
+    NSRectFill(dirtyRect);
+  else
+    NSRectFillUsingOperation(dirtyRect, NSCompositeSourceOver);
 
-  // Don't draw the window/tab bar background when selected, since the tab
-  // background overlay drawn over it (see below) will be fully opaque.
-  if (!selected) {
-    [backgroundImageColor set];
-    // Themes can have partially transparent images. NSRectFill() is measurably
-    // faster though, so call it for the known-safe default theme.
-    if (usingDefaultTheme)
-      NSRectFill(dirtyRect);
-    else
-      NSRectFillUsingOperation(dirtyRect, NSCompositeSourceOver);
-  }
-
-  // Use the same overlay for the selected state and for hover and alert
-  // glows; for the selected state, it's fully opaque.
+  // Draw the glow for hover and the overlay for alerts.
   CGFloat hoverAlpha = [self hoverAlpha];
   CGFloat alertAlpha = [self alertAlpha];
-  if (selected || hoverAlpha > 0 || alertAlpha > 0) {
+  if (hoverAlpha > 0 || alertAlpha > 0) {
     gfx::ScopedNSGraphicsContextSaveGState contextSave;
+    CGContextBeginTransparencyLayer(cgContext, 0);
 
-    // Draw the selected background / glow overlay.
-    CGContextBeginTransparencyLayer(cgContext, 0);
-    if (!selected) {
-      // The alert glow overlay is like the selected state but at most at most
-      // 80% opaque. The hover glow brings up the overlay's opacity at most
-      // 50%.
-      CGFloat backgroundAlpha = 0.8 * alertAlpha;
-      backgroundAlpha += (1 - backgroundAlpha) * 0.5 * hoverAlpha;
-      CGContextSetAlpha(cgContext, backgroundAlpha);
-    }
+    // The alert glow overlay is like the selected state but at most at most 80%
+    // opaque. The hover glow brings up the overlay's opacity at most 50%.
+    CGFloat backgroundAlpha = 0.8 * alertAlpha;
+    backgroundAlpha += (1 - backgroundAlpha) * 0.5 * hoverAlpha;
+    CGContextSetAlpha(cgContext, backgroundAlpha);
 
-    // For background tabs, this branch is taken to draw a highlight. The
-    // highlight is drawn using the foreground tab bitmap.

[pkotwicz, 2013/07/17 21:24:01]

[self drawFillForActiveTab:dirtyRect] is used to draw the highlight.

The main reason I decided to do this refactoring is that 
https://codereview.chromium.org/19115003/ splits IDR_THEME_TAB_BACKGROUND into
two images IDR_THEME_TAB_BACKGROUND and IDR_THEME_TAB_BACKGROUND_OVERLAY. That
changes makes drawFill deal with two "overlay" images. (So I felt compelled to
try to make things hopefully a bit more straightforward)

-    if (!selected && themeProvider)
-      backgroundImageColor = [self backgroundColorForSelected:YES];
-
-    [backgroundImageColor set];
-    // Themes can have partially transparent images. NSRectFill() is measurably
-    // faster though, so call it for the known-safe default theme.
-    if (usingDefaultTheme)
-      NSRectFill(dirtyRect);
-    else
-      NSRectFillUsingOperation(dirtyRect, NSCompositeSourceOver);
+    [self drawFillForActiveTab:dirtyRect];
 
     // ui::ThemeProvider::HasCustomImage is true only if the theme provides the
     // image. However, even if the theme doesn't provide a tab background, the
     // theme machinery will make one if given a frame image. See
     // BrowserThemePack::GenerateTabBackgroundImages for details.
     BOOL hasCustomTheme = themeProvider &&
         (themeProvider->HasCustomImage(IDR_THEME_TAB_BACKGROUND) ||
          themeProvider->HasCustomImage(IDR_THEME_FRAME));
     // Draw a mouse hover gradient for the default themes.
-    if (!selected && hoverAlpha > 0) {
+    if (hoverAlpha > 0) {
       if (themeProvider && !hasCustomTheme) {
         base::scoped_nsobject<NSGradient> glow([NSGradient alloc]);
         [glow initWithStartingColor:[NSColor colorWithCalibratedWhite:1.0
                                         alpha:1.0 * hoverAlpha]
                         endingColor:[NSColor colorWithCalibratedWhite:1.0
                                                                 alpha:0.0]];
         NSRect rect = [self bounds];
         NSPoint point = hoverPoint_;
         point.y = NSHeight(rect);
         [glow drawFromCenter:point
@@ skipping 314 matching lines @@
   CGFloat middleWidth = tabWidth - leftWidth - rightWidth;
   NSRect middleRect = NSMakeRect(leftWidth, 0, middleWidth, kFillHeight);
   [[NSColor whiteColor] setFill];
   NSRectFill(middleRect);
 
   maskCache_.reset(CGBitmapContextCreateImage(maskContext));
   return maskCache_;
 }
 
 @end  // @implementation TabView(Private)