Author: Jonas Bilinkevicius
How can I control where text is dropped into a TMemo? In other words, I am in the
middle of a drag operation and want to drop selected text into a TMemo based on the
mouse position of where I drop. How can I tell the caret to go to the mouse
location prior to the drop action?
Send a EM_CHARFROMPOS message to the control, passing the mouse position (in client
1 2 procedure TForm1.Memo1MouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
3 var4 ret: Longint;
5 begin6 ret := memo1.perform(EM_CHARFROMPOS, 0, MakeLParam(X, Y));
7 label1.caption := format('row: %d, character index: %d', [HiWord(ret),
That is the first step, it gives you the mouse position in "character coordiantes".
You still need to convert that to a character index, which you assign to SelStart
to set the caret to that position.
10 with memo1 do11 selstart := perform(EM_LINEINDEX, row, 0) + col;
You can now assign the dropped text to the memos SelText property to insert it.
Note that the EM_CHARFROMPOS message can also be used with TRichedit but the