“Shadow memory” does not exist (save, restore, ignore).| WORD SaveScreenBitmap(lpRect, wCommand) | |||
| LPRECT lpRect; | |||
| WORD wCommand; |
The SaveScreenBitmap function saves a single bitmap from the display or restores a single (previously stored) bitmap to the display. It is used, for example, when a menu is pulled down, to store the part of the screen that is “behind” the menu until the menu is closed.
lpRect
Points to a RECT structure containing the rectangle to use.
wCommand
Specifies the action to take. It can be one of the following values:
| Value | Meaning |
| 0 | Saves the rectangle. |
| 1 | Restores the rectangle. |
| 2 | Discards previous save, if there was one. |
The return value is AX=1 if successful. Otherwise, AX=0 for any of the following error conditions:
“Shadow memory” does not exist (save, restore, ignore).
“Shadow memory” is already in use (save).
“Shadow memory” is not in use (restore).
“Shadow memory” has been stolen or trashed (restore).
The export ordinal for this function is 92.
Because SaveScreenBitmap can save only one bitmap at a time, the device driver must maintain a record of whether or not the save area is currently in use.
The bitmap is stored in “shadow memory” (that is, memory for which the device has control of allocation). Therefore, the device can save the bitmap in whatever form is most convenient for it, without the rest of Windows worrying about where it goes.