CheckTransparentWindow procedure
Checks whether the handle for a windowed control (or a parent control) is transparent.
Declaration
procedure CheckTransparentWindow(var Handle: TLCLHandle;
var AWinControl: TWinControl)Arguments
Handle | Handle for the control (or parent) found for the specified windowed control. |
AWinControl | Handle for the windowed control examined in the routine. |
Description
CheckTransparentWindow is procedure used to check whether the
handle for a windowed control (or a parent control) is transparent.
CheckTransparentWindow uses the current mouse position to locate controls or
forms under the mouse pointer. The LM_NCHITTEST message is performed for
AWinControl to determine if the handle is drawn transparently. Additional
Forms in the Z-Order are visited until an opaque windowed control is located.
Parent controls are searched too (when needed).
CheckTransparentWindow updates the values in Handle and AWinControl to reflect the results from the search. When an overlayed control is not located, the value in Handle is set to 0, and AWinControl is set to Nil.
Modified in LCL version 4.0 to use the TLCLHandle type instead of the deprecated THandle type for the Handle argument.
See also
An experiment, built from development snapshots. Not the official Free Pascal or Lazarus documentation.