MacViews: Implement capture using NSEvent local+global monitors

ui/views/cocoa/cocoa_mouse_capture_unittest.mm

+// Copyright 2014 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 "ui/views/cocoa/cocoa_mouse_capture.h"
+
+#import <Cocoa/Cocoa.h>
+
+#import "base/mac/scoped_nsobject.h"
+#import "ui/events/test/cocoa_test_event_utils.h"
+#import "ui/gfx/test/ui_cocoa_test_helper.h"
+#import "ui/views/cocoa/cocoa_mouse_capture_delegate.h"
+
+// Simple test view that counts calls to -[NSView mouseDown:].
+@interface CocoaMouseCaptureTestView : NSView {
+ @private
+  int mouseDownCount_;
+}
+@property(readonly, nonatomic) int mouseDownCount;
+@end
+
+@implementation CocoaMouseCaptureTestView
+
+@synthesize mouseDownCount = mouseDownCount_;
+
+- (void)mouseDown:(NSEvent*)theEvent {
+  ++mouseDownCount_;
+}
+
+@end
+
+namespace views {
+namespace {
+
+// Simple capture delegate that just counts events forwarded.
+class TestCaptureDelegate : public CocoaMouseCaptureDelegate {
+ public:
+  TestCaptureDelegate() : event_count_(0), capture_lost_count_(0) {}
+
+  void Acquire() { mouse_capture_.reset(new CocoaMouseCapture(this)); }
+  bool IsActive() { return mouse_capture_ && mouse_capture_->IsActive(); }
+  void SimulateDestroy() { mouse_capture_.reset(); }
+
+  int event_count() { return event_count_; }
+  int capture_lost_count() { return capture_lost_count_; }
+
+  // CocoaMouseCaptureDelegate:
+  void PostCapturedEvent(NSEvent* event) override { ++event_count_; }
+  void OnMouseCaptureLost() override { ++capture_lost_count_; }
+
+ private:
+  scoped_ptr<CocoaMouseCapture> mouse_capture_;
+  int event_count_;
+  int capture_lost_count_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestCaptureDelegate);
+};
+
+}  // namespace
+
+typedef ui::CocoaTest CocoaMouseCaptureTest;
+
+// Test that a new capture properly "steals" capture from an existing one.
+TEST_F(CocoaMouseCaptureTest, OnCaptureLost) {
+  TestCaptureDelegate capture;
+
+  capture.Acquire();
+  EXPECT_TRUE(capture.IsActive());
+  {
+    TestCaptureDelegate capture2;
+    EXPECT_EQ(0, capture.capture_lost_count());
+
+    // A second capture steals from the first.
+    capture2.Acquire();
+    EXPECT_TRUE(capture2.IsActive());
+    EXPECT_FALSE(capture.IsActive());
+    EXPECT_EQ(1, capture.capture_lost_count());
+    EXPECT_EQ(0, capture2.capture_lost_count());
+
+    // Simulate capture2 going out of scope. Inspect it.
+    capture2.SimulateDestroy();
+    EXPECT_FALSE(capture2.IsActive());
+    EXPECT_EQ(1, capture2.capture_lost_count());
+  }
+
+  // Re-acquiring is fine (not stealing).
+  EXPECT_FALSE(capture.IsActive());
+  capture.Acquire();
+  EXPECT_TRUE(capture.IsActive());
+
+  // Having no CocoaMouseCapture instance is fine.
+  capture.SimulateDestroy();
+  EXPECT_FALSE(capture.IsActive());
+  // Receives OnMouseCaptureLost again, since reacquired.
+  EXPECT_EQ(2, capture.capture_lost_count());
+}
+
+// Test event capture.
+TEST_F(CocoaMouseCaptureTest, CaptureEvents) {
+  base::scoped_nsobject<CocoaMouseCaptureTestView> view(
+      [[CocoaMouseCaptureTestView alloc] initWithFrame:NSZeroRect]);
+  [test_window() setContentView:view];
+  std::pair<NSEvent*, NSEvent*> click =
+      cocoa_test_event_utils::MouseClickInView(view, 1);
+
+  // First check that the view receives events normally.
+  EXPECT_EQ(0, [view mouseDownCount]);
+  [NSApp sendEvent:click.first];
+  EXPECT_EQ(1, [view mouseDownCount]);
+
+  {
+    TestCaptureDelegate capture;
+    capture.Acquire();
+
+    // Now check that the capture captures events.
+    EXPECT_EQ(0, capture.event_count());
+    [NSApp sendEvent:click.first];
+    EXPECT_EQ(1, [view mouseDownCount]);
+    EXPECT_EQ(1, capture.event_count());
+  }
+
+  // After the capture goes away, events should be received again.
+  [NSApp sendEvent:click.first];
+  EXPECT_EQ(2, [view mouseDownCount]);
+}
+
+}  // namespace views