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Canvas Map API: Difference between revisions
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→Adding support for new Layer Types
m (prepare for changes for Hyde's 777 EFB: http://flightgear.org/forums/viewtopic.php?f=71&t=21139&p=192249#p192249) |
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Required: | Required: | ||
* callback to draw a single layer element (aircraft, waypoint, navaid, runway) | * callback to draw a single layer element (aircraft, waypoint, navaid, runway, route, fixes etc) | ||
* A new class (Nasal hash) that derives from the "Layer" class and implements its interface | * A new class (Nasal hash) that derives from the "Layer" class and implements its interface | ||
* A "data source" (provider) hash that provides the data to be rendered (i.e. populates the model) | * A "data source" (provider) hash that provides the data to be rendered (i.e. populates the model, which is just a Nasal vector of drawables) | ||
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As you can see, the draw* callback takes three arguments: | As you can see, the draw* callback takes three arguments: | ||
* the canvas group/layer to be used | * the canvas group/layer to be used as the rendering target | ||
* the layer-specific "model" information (airport/apt in this case, could also be a navaid, fix or waypoint) | * the layer-specific "model" information (airport/apt in this case, could also be a navaid, fix or waypoint) | ||
* an LOD argument (currently not yet used). | * an LOD argument (currently not yet used). | ||
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In this case, the init() method merely clears the internal vector using the "me.clear()" call, runs findNavaidsWithinRange(50); and then populates the model by appending each navaid to the MVC model in the top-level "LayerModel". Afterwards, the "notifyView" method is invoked to update the view (this will probably change pretty soon, once a real MVC controller abstraction is added). | In this case, the init() method merely clears the internal vector using the "me.clear()" call, runs findNavaidsWithinRange(50); and then populates the model by appending each navaid to the MVC model in the top-level "LayerModel". Afterwards, the "notifyView" method is invoked to update the view (this will probably change pretty soon, once a real MVC controller abstraction is added). | ||
Note that the model merely stores the data - only the draw* callback will try to access it, i.e. the lat/lon/id fields. | Note that the model merely stores the data - only the draw* callback will try to access it, i.e. the lat/lon/id fields or anything else that is model specific. | ||
Also, the LayerModel class is currently just an extremely simple wrapper, all of its fields/methods are directly available to you: | Also, the LayerModel class is currently just an extremely simple wrapper, all of its fields/methods are directly available to you: | ||