3.3.5.1.2.1.7 Construction of Cache Bitmap (Revision 3)

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The structure and fields of the Cache Bitmap (Revision 3) Secondary Drawing Order are specified in section 2.2.2.2.1.2.8. The order fields MUST be populated in accordance with this description.

The bitmaps that are cached by the Cache Bitmap (Revision 3) Secondary Drawing Order can be consumed by future MemBlt (section 3.3.5.1.1.1.9) and Mem3Blt (section 3.3.5.1.1.1.10) Primary Drawing Orders.

The cache ID and cache index to use are selected by the server based on the management policies that are implemented (for example, an LRU policy might be in effect). The server MUST create a unique 64-bit identifier and include it in the Key1 and Key2 fields of the Cache Bitmap (Revision 3) Order.

If it is the first time the server is instructing the client to cache the bitmap, and a Bitmap Cache Wait List (see section 3.3.1.3) is present, the server MUST force the bitmap into the Wait List and set the CBR3_DO_NOT_CACHE (0x10) flag in the Cache Bitmap (Revision 3) Secondary Drawing Order. The cacheId field MUST be set to the ID of the bitmap cache in which the bitmap will be stored if it is encountered again, and the cacheIndex field MUST be set to BITMAPCACHE_WAITING_LIST (32767). If the bitmap is encountered again, it MUST be removed from the Wait List and sent to the client without the CBR3_DO_NOT_CACHE flag.

The client advertises support for the Cache Bitmap (Revision 3) Order by including the ORDERFLAGS_EX_CACHE_BITMAP_REV3_SUPPORT (0x0002) flag in the orderSupportExFlags field of the Order Capability Set ([MS-RDPBCGR] section 2.2.7.1.3). If a client does not include this flag, then the Cache Bitmap (Revision 3) Order MUST NOT be sent to the client.

The Cache Bitmap (Revision 3) Order MUST NOT be sent to the client if support for bitmap caching was not specified using the Revision 2 Bitmap Cache Capability Set ([MS-RDPBCGR] section 2.2.7.1.4.2). Furthermore, if client-side support for the MemBlt (section 3.3.5.1.1.1.9) and Mem3Blt (section 3.3.5.1.1.1.10) Primary Drawing Orders (specified using the Order Capability Set specified in [MS-RDPBCGR] section 2.2.7.1.3) does not exist, the Cache Bitmap (Revision 3) Order SHOULD NOT be sent to the client.