/**
* If this instance's image source is a <code>BufferedImage</code>, creates and returns the
* texture, otherwise creates a task in a separate thread to retrieve it from its local or remote
* location.
*
* @param dc the current draw context.
* @return the new texture, or null if the texture is not yet available.
*/
protected Texture requestTexture(DrawContext dc) {
if (this.isBufferedImageSource()) return this.makeBufferedImageTexture(dc);
if (this.getTextureData() != null && this.getTexture(dc) == null)
return this.makeTextureFromTextureData(dc);
if (WorldWind.getTaskService().isFull()) return null;
Runnable task = this.createRequestTask();
if (WorldWind.getTaskService().contains(task)) return null;
// Use either the current layer or the layer list as the listener to notify when the request
// completes. The
// latter is used when the image source is requested during ordered rendering and the current
// layer is null.
this.listener = dc.getCurrentLayer() != null ? dc.getCurrentLayer() : dc.getLayers();
WorldWind.getTaskService().addTask(task);
return null;
}