1. An apparatus comprising: a shape buffer manager configured to store coverage data in a shape buffer; a screen shape converter configured to convert a shape description into screen coordinates defining a screen shape; a bounds primitive generator configured to generate a single bounds primitive from the screen shape wherein the bounds primitive bounds the screen shape; a bounds primitive rasterizer configured to rasterize the bounds primitive into a plurality of primitive pixels wherein each primitive pixel corresponds to a screen pixel; a pixel mask generator configured to decompose the screen shape into screen space primitives and to rasterize each screen space primitive into a plurality of mask pixels, wherein each mask pixel is divided into one or more pixel regions and each mask pixel corresponds to one of the primitive pixels, and wherein the pixel mask generator is also configured to classify each pixel region as a covered region or an uncovered region according to a coverage criterion and classify each mask pixel as a covered mask pixel or uncovered mask pixel according to a secondary coverage criterion, wherein the pixel mask generator generates the coverage data based on the classifications, and wherein the pixel mask generator is also configured to combine the coverage data for each successive screen space primitive with the coverage data for the previous screen space primitives to produce the coverage data for the screen shape; and a pixel screener configured to employ the coverage data from the shape buffer to screen the primitive pixels into retained pixels and discarded pixels, the retained pixels each corresponding to one of the mask pixels that the coverage data indicates is a covered pixel, and the discarded pixels each corresponding to one of the mask pixels that the coverage data indicates is an uncovered pixel, wherein at least one of the shape buffer manager, screen shape converter, bounds primitive generator, bounds primitive rasterizer, pixel mask generator, and pixel screener is implemented at least partially in hardware.