Patent ID: 7545390

Claim:
A computer program product for compositing graphics elements having a compositing order, the computer program product being tangibly embodied in a computer-readable storage device and comprising computer executable instructions operable to cause a programmable processor to perform operations comprising: initializing an accumulation buffer and one or more backdrop buffers and then processing the graphics elements taken in the compositing order through a compositing loop of actions, the actions comprising processing each graphics element in order by: determining whether the graphics element is a backdrop update element; if the graphics element is a backdrop update element, identifying one or more backdrop buffers associated with the graphics element and updating each of the one or more backdrop buffers using the current accumulation buffer contents; and if the graphics element is not a backdrop update element, identifying a source buffer, the source buffer being the accumulation buffer or a backdrop buffer; copying the source buffer to a working buffer; using the element to modify the working buffer; determining a shape mask for the graphics element; and crossfading content of the accumulation buffer with content of the working buffer using the shape mask, leaving the result in the accumulation buffer.