3.2.5.3.2 Handling Closing Drawing Order

Upon receipt of the TS_COMPDESK_FLUSH_COMPOSEONCE message, the surface manager proxy uses the value of the hLSurface field to inform the compositor that a logical drawing operation onto a compose-once surface has been completed. The surface manager proxy MAY use the value of the hLSurface field to force the compositor to run a composition pass.

A logical drawing operation onto a surface at the server MAY be broken down into multiple primary, secondary, and alternate secondary drawing orders, as specified in [MS-RDPEGDI] section 1.3.1.2.

A surface can be created for the compose-once logical surface when the TS_COMPDESK_HLSURF_COMPOSEONCE flag is set, as specified in [MS-RDPEGDI] section 2.2.2.1. In this case, the FLUSHCOMPOSEONCE command MUST be received at the end of a logical drawing operation to cause an explicit flush.

For surfaces that are not flagged as compose once, the FLUSHCOMPOSEONCE command SHOULD NOT be received.