3.3.1.3 Bitmap Cache Wait List

The Bitmap Cache Wait List stores a collection of 64-bit identifiers, each of which identifies a bitmap that is a candidate for placement in the Bitmap Cache (see section 3.1.1.1.1). The usage of the Bitmap Cache Wait List is specified using the Revision 2 Bitmap Cache Capability Set (see [MS-RDPBCGR] section 2.2.7.1.4.2).

Bitmaps are placed into the Bitmap Cache Wait List the first time they are encountered in a server drawing operation. If any of the bitmaps in the wait list are encountered during a subsequent drawing operation, they MUST be removed from the wait list and placed into a Bitmap Cache.

Using a wait list in conjunction with persistent bitmap caching ensures that only bitmaps that are used more than once in rendering operations are written to persistent storage. In effect, it implies that a bitmap MUST be sent twice to the client before it is actually stored in a valid Bitmap Cache entry. (The first time it is sent to the client, it is used and not cached. The second time it is sent to the client, it is cached and then used.)