Patent ID: 9640148
Date: 2017-05-02
CPC Classifications: G06F,G06T,G09G

Claim:
1. A method of operating a data processing system that comprises a host processor and a graphics processor that in response to commands and data received from applications on the host processor, renders frames to be output and writes those frames to a frame buffer, the method comprising: when a new application frame to be used in a composited frame, the composited frame being composited from plural application frames, is to be generated and written to the frame buffer: determining by the host processor or the graphics processor, for a set of plural sub-regions that the new application frame has been divided into, which of those sub-regions could have changed from a previous application frame previously-used for the frame buffer; generating information indicating, for the set of plural sub-regions, which of those sub-regions should be rendered to generate the new application frame on the basis of the determination, said information comprising an indication, for each sub-region of the set of plural sub-regions, indicating whether the sub-region should be rendered or should not be rendered to generate the new application frame; and providing to the graphics processor said information indicating, for the set of plural sub-regions, which of those sub-regions should be rendered to generate the new application frame; and the graphics processor: using said information indicating, for the set of plural sub regions, which of those sub regions should be rendered to generate the new application frame to determine those sub-regions in the new application frame that the graphics processor should render; rendering those sub-regions in the new application frame that the graphics processor has determined should be rendered using said information indicating, for the set of plural sub regions, which of those sub regions should be rendered to generate the new application frame; and writing the so-rendered sub-regions of the new application frame to the frame buffer; and wherein: the graphics processor does not render one or more sub-regions in the new application frame that the graphics processor has not determined should be rendered using said information indicating, for the set of plural sub regions, which of those sub regions should be rendered to generate the new application frame; and any sub-regions in the new application frame that the graphics processor does not render are retained in or copied to the frame buffer from the previous application frame previously used for the frame buffer so as to be present in the frame buffer with the sub-regions in the new application frame that the graphics processor has rendered and written to the frame buffer; wherein each new application frame sub-region corresponds to a rendering tile that the graphics processor that is rendering the application frame produces as its rendering output; or wherein each new application frame sub-region corresponds to a set of plural rendering tiles that the graphics processor that is rendering the application frame produces as its rendering output.