Mac: Optimize TabView drawing.

ui/base/cocoa/three_part_image.mm

Index: ui/base/cocoa/three_part_image.mm
diff --git a/ui/base/cocoa/three_part_image.mm b/ui/base/cocoa/three_part_image.mm
new file mode 100644
index 0000000000000000000000000000000000000000..5fb8916f9f20ba858d640eebec3b2a55a1d5b5d0
--- /dev/null
+++ b/ui/base/cocoa/three_part_image.mm
@@ -0,0 +1,82 @@
+// Copyright 2015 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 "ui/base/cocoa/three_part_image.h"
+
+#include "base/logging.h"
+#include "ui/base/resource/resource_bundle.h"
+
+namespace ui {
+
+ThreePartImage::ThreePartImage(int left_id, int middle_id, int right_id) {
+  DCHECK(left_id);
+  DCHECK(right_id);
+  ui::ResourceBundle& rb = ui::ResourceBundle::GetSharedInstance();
+  leftImage_.reset(rb.GetNativeImageNamed(left_id).CopyNSImage());
+  rightImage_.reset(rb.GetNativeImageNamed(right_id).CopyNSImage());
+  leftSize_ = [leftImage_ size];
+  rightSize_ = [rightImage_ size];
+
+  if (middle_id)
+    middleImage_.reset(rb.GetNativeImageNamed(middle_id).CopyNSImage());
+}
+
+ThreePartImage::~ThreePartImage() {
+}
+
+NSRect ThreePartImage::GetLeftRect(NSRect bounds) const {
+  NSRect left, right;
+  NSDivideRect(bounds, &left, &right, leftSize_.width, NSMinXEdge);
+  return left;
+}
+
+NSRect ThreePartImage::GetMiddleRect(NSRect bounds) const {
+  NSRect left, middle, right;
+  NSDivideRect(bounds, &left, &middle, leftSize_.width, NSMinXEdge);
+  NSDivideRect(middle, &right, &middle, rightSize_.width, NSMaxXEdge);
+  return middle;
+}
+
+NSRect ThreePartImage::GetRightRect(NSRect bounds) const {
+  NSRect left, right;
+  NSDivideRect(bounds, &right, &left, rightSize_.width, NSMaxXEdge);
+  return right;
+}
+
+void ThreePartImage::DrawInRect(NSRect rect,
+                                NSCompositingOperation op,
+                                CGFloat alpha) const {
+  rect.size.height = leftSize_.height;
+  NSDrawThreePartImage(rect, leftImage_, middleImage_, rightImage_,
+                       NO, op, alpha, NO);
+}
+
+BOOL ThreePartImage::HitTest(NSPoint point, NSRect bounds) const {
+  NSRect middleRect = GetMiddleRect(bounds);
+  if (NSPointInRect(point, middleRect))
+    return middleImage_ ? HitTestImage(point, middleImage_, middleRect) : YES;
+
+  NSRect leftRect = GetLeftRect(bounds);
+  if (NSPointInRect(point, leftRect))
+    return HitTestImage(point, leftImage_, leftRect);
+
+  NSRect rightRect = GetRightRect(bounds);
+  if (NSPointInRect(point, rightRect))
+    return HitTestImage(point, rightImage_, rightRect);
+
+  return NO;
+}
+
+BOOL ThreePartImage::HitTestImage(NSPoint point,
+                                  NSImage* image,
+                                  NSRect imageRect) const {
+  NSRect pointRect = NSMakeRect(point.x, point.y, 1, 1);
+  return [image hitTestRect:pointRect
+      withImageDestinationRect:imageRect
+                       context:nil
+                         hints:nil
+                       flipped:NO];
+}
+
+}  // namespace ui