This section applies only to Windows 7 and later, and Windows Server 2008 R2 and later versions of Windows operating system.
The Overlay DDI is an extension to the Direct3D version 9 DDI to verify overlay support. The Overlay DDI consists of the following entry points:
The D3DDDICAPS_CHECKOVERLAYSUPPORT value from the D3DDDICAPS_TYPE enumeration is used by the Direct3D runtime to verify whether the display device supports a particular overlay. The runtime sets D3DDDICAPS_CHECKOVERLAYSUPPORT in the Type member of the D3DDDIARG_GETCAPS structure that the pData parameter of the driver's GetCaps function points to when the runtime calls GetCaps. The runtime also sets the pInfo member of D3DDDIARG_GETCAPS to a pointer to a DDICHECKOVERLAYSUPPORTINPUT structure that describes the overlay. If the driver supports the overlay, the driver sets the members of a D3DOVERLAYCAPS structure and returns a pointer to this structure in the pData member of D3DDDIARG_GETCAPS. Otherwise, if the driver does not support the overlay, the driver fails the call to its GetCaps function with either D3DDDIERR_UNSUPPORTEDOVERLAYFORMAT or D3DDDIERR_UNSUPPORTEDOVERLAY depending on whether the lack of support was based on the overlay format. D3DOVERLAYCAPS is described in the DirectX SDK documentation.
The driver sets the MaxOverlayDisplayWidth and MaxOverlayDisplayHeight members of D3DOVERLAYCAPS to indicate any restrictions that the driver and hardware might have, which involve the final overlay size (after stretching the overlay data).
The driver sets the D3DOVERLAYCAPS_STRETCHX (0x00000040) and D3DOVERLAYCAPS_STRETCHY (0x00000080) capability bits in the Caps member of D3DOVERLAYCAPS to indicate that the overlay hardware is capable of arbitrarily stretching and shrinking the overlay data. Drivers should not attempt to emulate overlay stretching through the GPU and should only set these caps if the overlay hardware supports stretching. Less overhead is typically required for the application to perform GPU stretching as a part of the video processing and composition phase than for the driver to perform a separate pass at the very end to emulate overlay stretching.
The driver should handle the following new bit-field flags from the D3DDDI_OVERLAYINFOFLAGS structure. A D3DDDI_OVERLAYINFOFLAGS structure identifies the type of overlay operation to perform. A D3DDDI_OVERLAYINFOFLAGS structure is specified in the Flags member of the D3DDDI_OVERLAYINFO structure in a call to either the driver's CreateOverlay or UpdateOverlay function.
The overlay is limited range RGB rather than full range RGB. In limited range RGB, the RGB range is compressed such that 16:16:16 is black and 235:235:235 is white.
The overlay is BT.709, which indicates high-definition TV (HDTV), rather than BT.601.
The overlay is extended YCbCr (xvYCC) rather than conventional YCbCr.
When the display format is 64 bits rather than 32 bits (for example, when the Desktop Windows Manager (DWM) uses D3DFMT_A16B16G16R16F for the display mode), the runtime places the lower 32 bits of the overlay colorkey in the DstColorKeyLow member of the D3DDDI_OVERLAYINFO structure and the upper 32 bits in the DstColorKeyHigh member of D3DDDI_OVERLAYINFO.
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