D3DKMDT_VPPR_GET_CONTENT_ROTATION function (d3dkmdt.h)

Article
04/01/2021

A helper function that extracts the combined rotation that the user sees from the default display orientation from a given value of the D3DKMDT_VIDPN_PRESENT_PATH_ROTATION enumeration. This value is effectively the sum of the offset angle and the angle that the Desktop Window Manager (DWM) has already rotated the primary clone path content. Only drivers that support path-independent rotation (DXGKDDI_INTERFACE_VERSION >= DXGKDDI_INTERFACE_VERSION_WDDM1_3_PATH_INDEPENDENT_ROTATION) should call this function.

Syntax

D3DKMDT_VIDPN_PRESENT_PATH_ROTATION D3DKMDT_VPPR_GET_CONTENT_ROTATION(
  D3DKMDT_VIDPN_PRESENT_PATH_ROTATION Rotation
);

Parameters

Rotation

On input, a value from the D3DKMDT_VIDPN_PRESENT_PATH_ROTATION enumeration.

On output, a value between 1 and 4, inclusive, that corresponds to the OFFSET portion of the D3DKMDT_VIDPN_PRESENT_PATH_ROTATION constant values. An output value of 1 (identity) represents 0 degrees of total rotation, 2 represents 90 degrees, and so on. An output value of 0 indicates that the VidPN path is not initialized.

The output value of Rotation is the sum of the output values from the D3DKMDT_VPPR_GET_CONTENT_ROTATION_PART and D3DKMDT_VPPR_GET_OFFSET_ROTATION functions minus 1.

Return value

The returned value corresponds to the rotation and offset angles as follows:

Input enumeration value	Input enumeration constant	Rotation + offset, in degrees	Output Rotation value
0	D3DKMDT_VPPR_UNINITIALIZED	-	0
1	D3DKMDT_VPPR_IDENTITY	0	1
2	D3DKMDT_VPPR_ROTATE90	90	2
3	D3DKMDT_VPPR_ROTATE180	180	3
4	D3DKMDT_VPPR_ROTATE270	270	4
5	D3DKMDT_VPPR_IDENTITY_OFFSET90	90	2
6	D3DKMDT_VPPR_ROTATE90_OFFSET90	180	3
7	D3DKMDT_VPPR_ROTATE180_OFFSET90	270	4
8	D3DKMDT_VPPR_ROTATE270_OFFSET90	0	1
9	D3DKMDT_VPPR_IDENTITY_OFFSET180	180	3
10	D3DKMDT_VPPR_ROTATE90_OFFSET180	270	4
11	D3DKMDT_VPPR_ROTATE180_OFFSET180	0	1
12	D3DKMDT_VPPR_ROTATE270_OFFSET180	90	2
13	D3DKMDT_VPPR_IDENTITY_OFFSET270	270	4
14	D3DKMDT_VPPR_ROTATE90_OFFSET270	0	1
15	D3DKMDT_VPPR_ROTATE180_OFFSET270	90	2
16	D3DKMDT_VPPR_ROTATE270_OFFSET270	180	3

Remarks

This function is declared inline in D3dkmdt.h as:

__inline
D3DKMDT_VIDPN_PRESENT_PATH_ROTATION 
    D3DKMDT_VPPR_GET_CONTENT_ROTATION(
        D3DKMDT_VIDPN_PRESENT_PATH_ROTATION Rotation)
{
    if ((Rotation >= D3DKMDT_VPPR_IDENTITY_OFFSET90) &&
        (Rotation <= D3DKMDT_VPPR_ROTATE270_OFFSET270))
    {
        D3DKMDT_VIDPN_PRESENT_PATH_ROTATION ContentPart = 
            D3DKMDT_VPPR_GET_CONTENT_ROTATION_PART(Rotation);
        D3DKMDT_VIDPN_PRESENT_PATH_ROTATION OffsetPart =
            D3DKMDT_VPPR_GET_OFFSET_ROTATION(Rotation);
        Rotation = (D3DKMDT_VIDPN_PRESENT_PATH_ROTATION)(
            (((ContentPart - 1) + (OffsetPart - 1)) % 4) + 1);
    }
    return Rotation;
}

If the content being presented has to be rotated by the driver, the output of this function represents the total rotation (the Rotate member of the DXGK_PRESENTFLAGS structure) that the driver needs to apply to the pixels provided in the DxgkDdiPresent operation. For more info, see Supporting Path-Independent Rotation.

Here's an example of how this function can provide your driver with the info it needs to properly rotate content. When a portrait-first device is connected in clone mode to a landscape-first monitor and the user changes the Orientation in the Display control panel to Portrait, this represents the default orientation of the portrait-first device. Therefore the driver should set a value of D3DKMDT_VIDPN_PRESENT_PATH_ROTATION.D3DKMDT_VPPR_ROTATE90_OFFSET270 on the path. This function will then return a Rotation value of 1 (identity) to indicate that the content displayed on the clone path is not to be rotated.

Requirements

Requirement	Value
Minimum supported client	Windows 8.1,DXGKDDI_INTERFACE_VERSION >= DXGKDDI_INTERFACE_VERSION_WDDM1_3_PATH_INDEPENDENT_ROTATION
Minimum supported server	Windows Server 2012 R2
Target Platform	Desktop
Header	d3dkmdt.h