Alternate Secondary Drawing Orders

Alternate secondary drawing orders are used to extend the existing set of Primary and Secondary RDP drawing orders. The alternate secondary drawing orders described in this document are used to manage the Offscreen and NineGrid Bitmap Caches and to transport opaque EMF+ records that contain GDI+ 1.1 primitives (as specified in [MS-EMFPLUS] section 2.3.1).

Using these orders, a bitmap can be created in the Offscreen Bitmap Cache, and then set as the target drawing surface on the client. Alternate secondary drawing orders also enable the creation and efficient population of NineGrid bitmaps in the NineGrid bitmap cache. Besides creating and updating entries in these two caches, the alternate secondary orders also support deletion of entries.

GDI+ 1.1 remoting is enabled through the use of alternate secondary drawing orders. In this scenario, the orders are used to transport opaque GDI+ 1.1 records between endpoints, in addition to caching instructions to store GDI+ 1.1 primitives.

Other alternate secondary drawing orders added by RDP extensions are used to support remoting applications ([MS-RDPERP] section and desktop composition ([MS-RDPEDC] section 2.2).

Use of the alternate secondary orders is specified through capabilities.