Patent ID: 8707191
Filing Date: 2014-04-22
Classification: G09G

Abstract:
1. An apparatus for merging display data from two different video memory logical screens onto a single physical display terminal, the apparatus comprising: a video memory comprising: a logical screen module for mapping display data of windows required to be displayed on the physical display terminal onto the first video memory logical screen and the second video memory logical screen, wherein the logical screen module maps display data corresponding to windows that correspond to at least some of the same logical coordinates on the physical display terminal onto different video memory logical screens such that, after mapping the display data of each of the windows required to be displayed, the first video memory logical screen and the second video memory logical screen each include a respective subset of different display data corresponding to the same group of pixels for an image displayed on the physical display terminal; multiple sets of window registers assigned with priority levels, which, based on their priority levels, correspond to the windows to be displayed on the physical display terminal respectively, and each set of the window registers stores location coordinates of its corresponding window and an identification of the corresponding mapped video memory logical screen; and a logical screen synthesizing module for merging the windows required to be displayed on the physical display terminal by selectively retrieving and outputting the display data which is contained in the first video memory logical screen and the second video memory logical screen, wherein the retrieved display data correspond to windows indicated by an active set among the sets of window registers, wherein the logical screen synthesizing module selects display data from only one of the first video memory logical screen or the second video memory logical screen for a currently scanned pixel on the physical display terminal based on the priority levels of the corresponding sets of window registers, and wherein the logical screen synthesizing module selects display data for a pixel corresponding to an overlapped portion of a window from one of the first video memory logical screen and the second video memory logical screen without redrawing the overlapped portion when an overlapping window is closed or when the priority level of an overlapping window changes.