A couple of days ago
, a friend asked this simple question in a Spanish forum. The scenario is simple, you have a map and when dragging it you would like to stop the action when the mouse goes beyond the limits of the map, really beyond the
div (or any other DOM element that) contains the map.
The first try anyone can try could be something like:
but that has no effect. (See here)
Now, remove the
mouseover listener and try again:
surprisingly, when the mouse goes out the map the dragging action continues active and once you finish dragging the
disable() method seems to take place and you can’t drag the map again. (See here).
After some time looking at Leaflet source code (we aware I have done it for Leaflet 0.7.2) I found a possible solution but, first, let me do some explanation.
L.Map class has attached hooks, like drag, or zoom actions, which provides the map with some behavior.
L.Map.Drag class is responsible to control the dragging action. It has
disable methods and, more important, it uses internally a
L.Draggable instance, which is responsible to detect and catch mouse events on the map. This way:
L.Draggablecatches mouse events on the map panel (also for mouse move),
- makes some process and triggers some new events that are catch by the
L.Map.Draginstance makes some process and triggers the know map events
In addition, invoking
L.Map.Drag.disable() implies a call to
L.Draggable.disable() too but (I don’t understand yet why), it seems not takes effect until you release the mouse button. The
L.Draggable instance continues catching mouse event and informing
All this say, a possible solution to stop the dragging action when the mouse goes out the map panel is to freeze the work of
Please, note the next code violates almost all the [SOLID](http://en.wikipedia.org/wiki/SOLID_(object-oriented_design) principles, so don’t fire me.
The code adds a new
_freeze property to the
L.Draggable class and redefines the
_updatePosition method to check the property.
Now, you can freeze the mouse dragging action as:
You can see it in action here.