Bug 220546 [Decorators] performance problem with resource manager in decoaration context
20080217 I'm afraid the solution to use the IDecorationContext to provide a resource manager introduces a performance degregation. The DecoratorManager, who manages the light weight label decorations, stores decorations by context DecorationScheduler.resultCache<IDecorationContext, Map<DecorationResult>> Most label providers used the default context (DecorationContext.DEFAULT_CONTEXT). If there were several requests for the same image, all the requests were bundled and the result was only computed once before the result was broadcasted to all viewer. Now, with the new code, each label provider has its own instance of a decoration context. There will be separate computations per context. Even if two viewers want to decorate the same image, each of them will have to compute a DecorationResult The broadcast, however, still goes to all viewers.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/DecoratingLabelProvider.java
ILabelProvider, IViewerLabelProvider, IColorProvider, IFontProvider,
		ITreePathLabelProvider {
	private ILabelProvider provider;
	private ILabelDecorator decorator;
	
	private ListenerList listeners = new ListenerList();
	private WrappedDecorationContext decorationContext;
	/**
	 * The WrappedDecorationContext is a context that takes one provided outside
	 * of the receiver and creates a {@link LocalResourceManager} that can be
	 * disposed.
	 * 
	 * @since 3.4
	 * 
	 */
	private class WrappedDecorationContext implements IDecorationContext {
		private IDecorationContext context;
		private ResourceManager manager;
		private boolean isDisposed = false;
		/**
		 * Create a new instance of the receiver.
		 * 
		 * @param context
		 */
		WrappedDecorationContext(IDecorationContext context) {
			this.context = context;
		}
		/**
		 * Return the resource manager used by the receiver.