When the Servo window gains focus, it should update the mouse coordinate

[paulrouget]

This is important for browserhtml. We need this to build automated tests.

in ports/glutin, the mouse coordinate is updated when receiving a glutin mousemove event.

When Servo starts, as the mouse moves, mouse_pos is updated. Then Servo loses focus. User moves the mouse. When Servo gains focus, the mouse is likely not at mouse_pos anymore. That means:

1. mouseover is not triggered and :hover styles are not applied for element below the mouse
2. if a click occurs before the mouse is moved, the clicked is triggered for the element that was under the latest known coordinate (right before losing focus)

We should update mouse_pos when gaining focus, and fire a mousemove event if it changed.

There is a Focused(bool) glutin event, but it doesn't come with new mouse coordinates.

[tschneidereit]

In addition, a mouseout event (with the current coordinates) should be fired upon losing focus, and any :hover states reset.

[paulrouget]

In addition, a mouseout event (with the current coordinates) should be fired upon losing focus, and any :hover states reset.

That will happen automatically. When I'm talking about mousemove, I'm talking about WindowEvent::MouseWindowMoveEventClass.

[paulrouget]

If someone can tell me how to get the mouse coordinates from a didBecomeKey notification, i can take care of the rest (is NSEvent::locationInWindow(nil) supposed to work?).

/cc @pcwalton

[paulrouget]

We get a NSAppKitDefined nsevent before getting the focus notification. So maybe we can use that to get a nsevent instance and do nsevent.locationInWindow().

[paulrouget]

When a Firefox window is unfocused, the chrome still get mouse events.

I think this is done with NSTrackingArea:

• http://mxr.mozilla.org/mozilla-central/source/widget/cocoa/nsCocoaWindow.mm#3086
• http://mxr.mozilla.org/mozilla-central/source/widget/cocoa/nsCocoaWindow.mm#2406
• https://developer.apple.com/library/mac/documentation/Cocoa/Reference/NSTrackingArea_class/
• https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/EventOverview/TrackingAreaObjects/TrackingAreaObjects.html

[paulrouget]

First thing first, a click should not rely on the previous mousemove coordinate, but on the actual coordinate.

In Glutin:

In src/events.rs, we need to change MouseInput(ElementState, MouseButton) to MouseInput(ElementState, MouseButton, Option<(i32, i32)>). Option<(i32, i32)> will hold the new coordinates.

In src/api/cocoa/mod.rs, MouseInput events should include the coordinates (see how we retrieve the coordinates in NSRightMouseDragged). For other platforms, we can just use None for now.

In Servo:

In ports/glutin/window.rs, for Event::MouseInput events, if coordinates are present, self.mouse_pos should be updated and a WindowEvent::MouseWindowMoveEventClass should also be fired in addition to any event handle_mouse will eventually fire.

[mrmiywj]

@paulrouget
I'll pick this up.

[metajack]

@mrmiywj Have at it!

[jdm]

@mrmiywj Have you made any progress on this?

[mrmiywj]

@jdm
Yep, I've finished my finals and will go on work on servo.

[mrmiywj]

@paulrouget
I read through all your solutions, does it mean that I need to modify glutin's source code?

[paulrouget]

@mrmiywj Yes. I think the proper way of doing it is what I described here: #11130 (comment) - that would partially address this issue.

[mrmiywj]

@paulrouget
But, will the Glutin's maintainer approve our modification of its APIs?

[paulrouget]

But, will the Glutin's maintainer approve our modification of its APIs?

This should not a be a problem.

[mrmiywj]

@paulrouget
I've pushed a PR to glutin to fix this issue. Could you review it?

[paulrouget]

@mrmiywj thanks for landing the first part. Now we need a glutin update in Servo with the changes I'm describing in the second part of #11130 (comment)