Working with events in virtual earth
The basic virtual earth map replies to several events including drag and drop, mouse clicks, different kinds of key combinations and wheel motion. Being an application developer, you are interested to influence these events for providing your own actions. In virtual earth cancelling, working and capturing with events is simple task. With the help of this article you will come to know that how can you work with events in virtual earth.
Before learning how to learn with events or how to work with shapes in virtual earth, you should get some knowledge about a basic virtual earth map. Working with events in virtual earth is classified into two the process having two steps that are given below:1) Creating a callback method for reacting to the event. Callback method must be a JavaScript function. This callback method expects a single argument and this method returns a Boolean value. The argument includes the information which is associated to the event and this return value is pointer to confirm either your callback totally processed the event. And when the event is totally handled by the callback and you don’t wish to do any further process then return true. And if you are interested to permit the default actions should be continued then return false.
2) The second step is making use of map.AttachEvent method for registering the event with your map control.
When there is occurrence of selected event you will observe that the map executes the callback function automatically. In your function when there is addition of event, object which includes a collection of properties, which are event specific. You are able to group a variety of events into 3 categories with the help of basic guidelines that are given below.
Map events: Map events are related with basic map navigation missions like, changing panning and zooming the view. You work with these events very frequently.
Mouse events: These mouse events are related with mouse driven input like mouse over, left click, and right click. By making use of these events, you are able to control the way your users are interacting with the map. Your mouse controls must be considered carefully because most of the mouse actions are with standard navigation mechanics.
Keyboard events: these keyboard events are harmonized with mouse events but these events are related with keyboard input. There are some keys, which have already mapped with standard navigation therefore, you must be careful about modifying this functionality. Now we will see the detail description of every event types.
Most of the time map events are secondary events, which take place according to user input driven or programmatic change in the map. For instance, you are able to capture events, which take place when the view, mode, and map style changed. You are also able to capture the event when error takes place while loading map. You have to note down one thing, event doesn’t include data about the recent map center point. Moreover, in order to find out that information we should access the GetCenter technique.
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