DVM_UPDATE

Notifies a video capture driver to update the portion of the display associated with a VIDEO_EXTERNALOUT channel.

• Returns DV_ERR_OK if successful or an error code otherwise. The DV_ERR_NOTSUPPORTED error code indicates the message is not supported.

hWndClient

Handle to the client window in which the VIDEO_EXTERNALOUT channel is displayed.

hDC

Device context to be repainted.

This message is typically sent to an overlay device whenever its client window is moved, sized, or requires painting.

This message is sent to a driver when video overlay is enabled and the overlay key color might need updating. Painting the key color is the responsibility of the driver. An application initiates this message whenever it receives a WM_PAINT, WM_MOVE, WM_POSITIONCHANGED, or WM_SIZE message.

This message always follows DVM_SRC_RECT and DVM_DST_RECT messages for the VIDEO_EXTERNALOUT channel.

The DVM_STREAM_INIT and DVM_STREAM_FINI messages are used to enable and disable the overlay.