Video graphic interface device and method for portrait and landscape image display modes

Abstract

A graphic interface device produces a video signal for a display such that the user may select between landscape and portrait image display modes. The graphic interface device has a pixel data memory array from which a video output signal is derived. A primary graphics engine renders graphics in a landscape orientation in conjunction with a frame buffer. The primary landscape graphics engine stores rendered graphics to the pixel data memory array and also copies selected graphics in data blocks within the frame buffer called surfaces. In order to provide other display modes to display images in different physical orientations, a mode control is provided in conjunction with a rotated pixel data array buffer to facilitate the rendering of portrait oriented graphics by the primary landscape graphics engine. In addition, to facilitate the efficiency and speed of rendering portrait oriented graphics, a secondary portrait graphics engine is provided. To enable the secondary portrait graphics engine to access the frame buffer directly, a rotated surface buffer is used by the primary landscape engine to store copies of data written to the rotated data array buffer in the frame buffer in a portrait orientation.