Bug 213166 [Viewers] Problems with OwnerDrawLabelProvider.setUpOwnerDraw
3.4 M4 To set up the owner draw callbacks for a viewer OwnerDrawLabelProvider.setUpOwnerDraw is offered. The problem of this is: a. there's no way to uninstall the callbacks. In our views we want to allow to enable and disable owner draw in the preferences b. from an API client perspective, it would be nicer if the label provider could install itself when installed. A good solution would be to add more life cycle to a label provider. CellLabelProvider.initialize(ColumnViewer, int column) There's already ILableProvider.dispose when a label provider is removed from a viewer.
bundles/org.eclipse.jface/src/org/eclipse/jface/viewers/SimpleStyledCellLabelProvider.java
cell.setImage(info.getImage()); 
										
		cell.setText(info.getText());
		cell.setFont(info.getDefaultFont());
		super.update(cell);
	}
	private TextLayout getSharedTextLayout(Display display) {
		if (cachedTextLayout == null) {
			cachedTextLayout = new TextLayout(display);
			cachedTextLayout.setOrientation(Window.getDefaultOrientation());
		}
		return cachedTextLayout;
	}
	private boolean useColors(Event event) {
		return (event.detail & SWT.SELECTED) == 0
				|| (this.style & COLORS_ON_SELECTION) != 0;
	}
	private boolean drawFocus(Event event) {
		return (event.detail & SWT.FOCUSED) != 0
				&& (this.style & NO_FOCUS) == 0;
	}
	/**
	 * Returns a {@link LabelPresentationInfo} instance for the given event.
	 * 
	 * @param event
	 *            the measure or paint event for which a TextLayout is needed
	 * @param element
	 *            the model element