DrvSaveScreenBits function (winddi.h)

Article
10/05/2021

The DrvSaveScreenBits function causes a display driver to save or restore a given rectangle of the displayed image.

Syntax

ULONG_PTR DrvSaveScreenBits(
  SURFOBJ   *pso,
  ULONG     iMode,
  ULONG_PTR ident,
  RECTL     *prcl
);

Parameters

pso

Pointer to a SURFOBJ structure that describes the surface.

iMode

Specifies the operation to perform. This parameter can be one of the following values:

SS_SAVE

The driver should save the data from the rectangle defined by prcl. The driver is responsible for managing this data in its off-screen memory. The ident parameter is ignored.

Upon success, DrvSaveScreenBits should return an identifier for the saved data. The driver can return a handle or even a pointer to its off-screen memory. This function returns zero if it fails.

SS_RESTORE

The driver should restore the data identified by ident to the rectangle prcl on the display; that is, the driver should restore the bitmap to its original position. The driver can assume that the rectangle at prcl is exactly the same size as the rectangle that was saved. The data should be discarded after this call.

DrvSaveScreenBits should return TRUE if the data has been restored to the display, or FALSE if the data cannot be restored.

SS_FREE

The data identified by ident is no longer needed and can be freed. The value of prcl is undefined and should not be used. The driver should not restore the saved rectangle to the display.

DrvSaveScreenBits should return TRUE.

ident

Pointer to a driver-defined value that was returned by a previous call to DrvSaveScreenBits if iMode is SS_RESTORE or SS_FREE. The driver should ignore this parameter when iMode is SS_SAVE.

prcl

Pointer to a RECTL structure that defines the portion of the screen to be saved or restored.

Return value

The return value is dependent on the value of the iMode parameter.

Remarks

Some display drivers might be able to move data to or from off-screen device memory much faster than the area can be redrawn. This might be useful when Window Manager must display a menu or dialog box.

DrvSaveScreenBits is optional for display drivers.

Requirements

Requirement	Value
Target Platform	Desktop
Header	winddi.h (include Winddi.h)

Share via