The Microsoft Windows display grabbers provide the support that both standard- and 386 enhanced-mode Windows needs to share the display with non-Windows applications. WINOLDAP, which manages all non-Windows applications, loads the display grabbers and calls grabber functions to carry out tasks such as capturing the contents of the screen or managing output from a non-Windows application.
All display grabbers capture the contents of the screen when requested, such as when the user presses the ALT+PRNTSCRN key combination. However, the grabbers are also responsible for other kinds of support. For example, a standard-mode grabber initializes, saves, and restores the video context when switching between Windows and non-Windows applications, and a 386 enhanced-mode grabber paints the client area for non-Windows applications that run in windows.
To distinguish between standard- and 386 enhanced-mode grabbers, Windows uses the filename extensions .2GR and .3GR. For example, the grabbers that support the VGA display driver are named VGA.2GR for standard-mode Windows and VGA.3GR for 386 enhanced-mode Windows. In some cases, a single grabber may support several display drivers (for example, EGACOLOR.2GR is used for both EGA.DRV and EGAHIBW.DRV).
This chapter describes display grabbers for standard- and 386 enhanced-mode Windows.