Forums » Impact Engine » Bug Report: Handling "touchend" Events That Never Fire

In "input.js", there is a line that looks like this:

ig.system.canvas.addEventListener('touchend', this.keyup.bind(this), false );

Another line should be appended after it so that we have:

ig.system.canvas.addEventListener('touchend', this.keyup.bind(this), false );
ig.system.canvas.addEventListener('touchcancel', this.keyup.bind(this), false );

Why?

For example, on iOS, pressing down on a button that happens to be flush with the bottom of the screen, and then dragging up will open the Control Center. This will trigger a touchcancel event. No touchend event will ever fire for this touch.

Therefore, without adding the second line, the button will remain pressed down, even after closing the Control Center.

This should be a minor issue with vanilla Impact, because a new touchstart and touchend should clear things. Although, it is odd that technically multiple "pressed" events can fire before a "released" event.

This is a major issue for anyone supporting multi-touch, because without handling touchcancel, it's very possible to have several permanently "pressed down" and "stuck" touch events active around the canvas.

You should tweet his to Dominic Szablewski @phoboslab

This issue is now fixed in Houly's excellent multi-touch plugin.

Is this the reason also why the released never fires for mouse button if you are on a touch-pad ?

Quote from dungeonmaster
Is this the reason also why the released never fires for mouse button if you are on a touch-pad ?

Do you mean on the iPad? released should still fire there as far as I know...

Fixed in the recent dev version in the git repo. Thanks Joncom!

@Joncom: No, I mean the trackpad. In my game I check the .released for button clicks. When I use the trackpad on macbook air and tap on the trackpad, it fires the .pressed but not .released.