Saturday, July 13, 2013

Bing Maps Module: InfoboxAutoPan

I've just created a very, very simple Bing Maps module. I'll jump ahead to the demo before any explanation.

Demo:  http://psousa.net/demos/bingmaps/infoBoxAutoPanModule/simpleExample.html

Basically there are two maps, both with a pushpin near the edge and a click handler to display an infobox.


After clicking the pushpins this is the end-result:



The first one shows the default behavior: the infobox is displayed, although outside the map boundaries.
The second one, using my module, pans the map so that the infobox is fully visible.

Usage:
Using this module is incredibly simple. Just load it as usual and run the InitInfoboxAutoPanModule command:
MM.registerModule("InfoboxAutoPanModule", "js/InfoboxAutoPanModule.js");
MM.loadModule("InfoboxAutoPanModule", { callback: function () {
    InitInfoboxAutoPanModule(map);

    //Rest of the code
}); 

Then, just create an infobox, using the typical infobox.setOptions({visible: true}) to display it.

Now, here's the detail: I've created an additional parameter called "autoPan". Just add it to the previous command and the map should automatically pan if required:
infobox.setOptions({visible: true, autoPan: true});

And that's mostly it :)

I've also added an optional argument to the module initialization which allows the margin to the edge to be configured (default: 5x5). Thus, if for instance the module would be initialized as:
InitInfoboxAutoPanModule(map,{horizontalPadding:50, verticalPadding:20});

The end-result after panning would be:


 Implementation:

The implementation is also simple. I just copy the original setOptions function to a new field inside the infobox and redefine setOptions to include some extra code. Basically it's just an hook on the existing function:
this._oldSetOptions(arguments);

if(arguments.autoPan == true && arguments.visible == true) {

    var infobox = this;
    var mapWidth = _map.getWidth();
    var mapHeight = _map.getHeight();
    var point = _map.tryLocationToPixel(infobox.getLocation());
    var remainderX = (mapWidth / 2) - point.x;
    var remainderY = (mapHeight / 2) + point.y;

    //Empirical values based on the current infobox implementation
    var xExtraOffset = 33;
    var yExtraOffset = 37;

    var pixelsOutsideX = infobox.getWidth() + 
                         infobox.getOffset().x - remainderX - xExtraOffset + 
                         _options.horizontalPadding;
    
    var pixelsOutsideY = infobox.getHeight() + 
                         infobox.getOffset().y + yExtraOffset - remainderY + 
                         _options.verticalPadding;

    var newPoint = new Microsoft.Maps.Point(0, 0);

    if (pixelsOutsideX > 0) {
        newPoint.x += pixelsOutsideX;
    }

    if (pixelsOutsideY > 0) {
        newPoint.y -= pixelsOutsideY;
    }

    var newLocation = _map.tryPixelToLocation(newPoint);

    _map.setView({
        center: new MM.Location(newLocation.latitude, newLocation.longitude)
    });
}

Enjoy.

4 comments:

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  3. Pedro I have a question on this - I am confused as to where to place the code for the autopan? Can you email me? Or can I email you my code? Sorry to bother you but I am new to JS. Thank you.

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    Replies
    1. Hi,

      Just check my example above. It's quite simple: http://psousa.net/demos/bingmaps/infoBoxAutoPanModule/simpleExample.html

      Delete