MacViews: Handle three-finger swipe gestures for navigation.

ui/views/cocoa/bridged_content_view.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/bridged_content_view.h"
 
 #include "base/logging.h"
 #import "base/mac/mac_util.h"
 #import "base/mac/scoped_nsobject.h"
 #import "base/mac/sdk_forward_declarations.h"
@@ skipping 782 matching lines @@
 }
 
 - (void)scrollWheel:(NSEvent*)theEvent {
   if (!hostedView_)
     return;
 
   ui::ScrollEvent event(theEvent);
   hostedView_->GetWidget()->OnScrollEvent(&event);
 }
 
+// Called when we get a three-finger swipe, and they're enabled in System

[tapted, 2017/02/13 11:26:25]

I think the pref can be set to 2-fingers or 3-fingers (or both).

[themblsha, 2017/02/15 17:35:34]

Yep. But two-finger swipes are already handled by HistoryOverlayController. By
default three-finger swipes are disabled.

[tapted, 2017/02/15 22:25:52]

ohh interesting. We'll eventually want to remove HistoryOverlayController from
the mac_views_browser build, since it's mashing native views into the hierarchy
(instead we should use gesture_nav_simple.cc). But we can worry about this later
(but there may be a large degree of "luck" that HistoryOverlayController
continues work overlaid on top of a BrowserView)

+// Preferences.
+- (void)swipeWithEvent:(NSEvent*)event {

[tapted, 2017/02/13 11:26:25]

This should bail out early when hostedView_ is null, similar to -scrollWheel:

[themblsha, 2017/02/15 17:35:34]

Done.

+  ui::GestureEventDetails swipe_details(ui::ET_GESTURE_SWIPE, [event deltaX],

[tapted, 2017/02/13 11:26:24]

EventTypeFromNative needs to be updated -- NSEventTypeSwipe doesn't currently
return ET_GESTURE_SWIPE 

[tapted, 2017/02/13 11:26:25]

swipe_details -> swipeDetails (This is between @foo/@end, so variables need to
be camelCase)

[themblsha, 2017/02/15 17:35:34]

Done.

[themblsha, 2017/02/15 17:35:34]

It's technically the same type of NSEvent that starts smooth scrolling, but
-swipeWithEvent: is only called for momentary gestures which couldn't be
tracked: you're simply notified that they happened and you handle them.

EventTypeFromNative currently returns ET_SCROLL_FLING_START for NSEventTypeSwipe
and I think this is appropriate, as the two-finger swipes are a different beast
altogether and deserve special treatment :-)

[tapted, 2017/02/15 22:25:52]

Acknowledged.

+                                        [event deltaY]);
+  swipe_details.set_device_type(ui::GestureDeviceType::DEVICE_TOUCHPAD);
+

[tapted, 2017/02/13 11:26:24]

set_touch_points?

[themblsha, 2017/02/15 17:35:34]

I don't think it's applicable to the instant three-finger swipes.

[tapted, 2017/02/15 22:25:52]

Acknowledged. (I'd also be fine with just setting it to 3, similar to how we set
`2` for trackpad scrolling in events_mac.mm)

[themblsha, 2017/02/16 15:27:49]

Ah. Okay, added setting it to `3` :-)

+  gfx::PointF location = ui::EventLocationFromNative(event);
+  ui::GestureEvent gesture_event(location.x(), location.y(),

[tapted, 2017/02/13 11:26:25]

gestureEvent, or just |event|

[themblsha, 2017/02/15 17:35:34]

Done.

+                                 [event modifierFlags],

[tapted, 2017/02/13 11:26:25]

EventFlagsFromNative - we can't pass the Cocoa flags as is

[themblsha, 2017/02/15 17:35:34]

Done.

+                                 ui::EventTimeFromNative(event), swipe_details);

[tapted, 2017/02/13 11:26:24]

-[NSEvent eventNumber] is probably an appropriate thing to pass for
unique_touch_event_id -- the comment for that arg suggests to me that it should
only be 0 in tests

[themblsha, 2017/02/15 17:35:34]

This throws an exception: Invalid message sent to event "NSEvent: type=Swipe
loc=(411.582,723.938) time=86773.1 flags=0 win=0x10031dbf0 winNum=1671 ctxt=0x0
phase: 4 axis:1 amount=0.052 velocity={-0, -0}".

And instant events cannot be tracked after all, so this doesn't seem as a
trouble spot.

[tapted, 2017/02/15 22:25:52]

Can you comment about this? (~ "Note this uses the default unique_touch_event_id
of 0 (Swipe events do not support -[NSEvent eventNumber]"). I think it will
matter if these events are ever sent on to Blink/WebContents (but currently
ui::CreateWebGestureEvent will drop them on the floor anyway)

[themblsha, 2017/02/16 15:27:49]

Done.

+
+  views::NativeWidgetMac::GetBridgeForNativeWindow([self window])
+      ->native_widget_mac()
+      ->GetWidget()

[tapted, 2017/02/13 11:26:24]

hostedView_->GetWidget()

[themblsha, 2017/02/15 17:35:34]

Done.

+      ->OnGestureEvent(&gesture_event);
+}
+
 - (void)quickLookWithEvent:(NSEvent*)theEvent {
   if (!hostedView_)
     return;
 
   const gfx::Point locationInContent =
       gfx::ToFlooredPoint(ui::EventLocationFromNative(theEvent));
   views::View* target = hostedView_->GetEventHandlerForPoint(locationInContent);
   if (!target)
     return;
 
@@ skipping 644 matching lines @@
   return [hostedView_->GetNativeViewAccessible() accessibilityHitTest:point];
 }
 
 - (id)accessibilityFocusedUIElement {
   if (!hostedView_)
     return nil;
   return [hostedView_->GetNativeViewAccessible() accessibilityFocusedUIElement];
 }
 
 @end