Java Doc for IRenderer.java in  » GIS » udig-1.1 » net » refractions » udig » project » render » Java Source Code / Java DocumentationJava Source Code and Java Documentation

A renderer has the following responsibilities:

• A renderer must draw to the image provided by it RenderContext
• A renderer reprojects victim data if required
• A renderer applies styles if necessary
• A renderer is responsible for registering with its layers to obtain notifications whent the layers' styles change
• If a renderer does not extends the RendererImpl class the renderer must notify its adapters(listeners) when its rendering state changes.
• If a renderer does extend the RendererImpl class it must call the setState() method when its render state changes or it wishes to notify its listeners that it needs to be redrawn.

  The state that the renderer can use are the following:

  • RENDERING - should be called when the renderer has data that it wishes to display on the screen. May be ignored if the executor uses a timer for refreshing rather than waiting for updates from the renderers
  • DONE - Should be set when rendering is finished.
  • RENDER_REQUEST - should be called when the renderer has received events indicating that it needs to be rerendered. The event listeners should NEVER call render(), instead setState(RENDER_REQUEST) should be used and the frame work will trigger a rerender, most-likely in a seperate thread.
• If possible a renderer is responsible for registering with its data source, not layer, so it can receive notices of when the data changes. If another method of recieving update is required then the renderer is held responsible.

Render State

This implies that rendering has started and finished

IRenderer.setRenderBounds(Envelope) can be called to set the area that needs to be rendered}

Please make use of the smaller of getRenderBounds() or the viewport bounds when rendering.

The state is the current state of the

This method will block

Render State

Internal Image

 public void render( IProgressMonitor monitor ) throws RenderException {
 if( monitor == null ) monitor = NullProgressMonitor();
 Graphics2D g = getContext().getImage().createGraphics();
 render(g, monitor);
 }   
 

Updating a Portion of the Screen

Please choose the smallest of:

• getRenderBounds() - an Envelope in your CRS
• viewPortBounds()

See Also:   This method will block
See Also:   

See Also:   A value of null renders the bounds the entire viewport obtained from the
See Also:   ViewportModel.getBounds().
See Also: