I've created a Delphi VCL app with a single TMemo control, and this is the code I have.
I use it to detect Ctrl somekey. For example, when I press Ctrl x, it pops up the alert ctrl
and the Ctrl x's effect (cut) was cancelled.
function IsKeyDown(Key: Integer): Boolean;
begin
Result := (GetAsyncKeyState(Key) and (1 shl 15) > 0);
end;
procedure TForm1.Memo1KeyPress(Sender: TObject; var Key: Char);
begin
if IsKeyDown(VK_CONTROL) then
begin
ShowMessage('ctrl');
Key := #0;
end;
end;
However, when I changed it a little bit to this:
function IsKeyDown(Key: Integer): Boolean;
begin
Result := (GetAsyncKeyState(Key) and (1 shl 15) > 0);
end;
procedure TForm1.Memo1KeyPress(Sender: TObject; var Key: Char);
begin
if IsKeyDown(VK_CONTROL) and IsKeyDown(VK_MENU) then
begin
ShowMessage('ctrl alt');
Key := #0;
end;
end;
It doesn't work anymore. What I need is to detect combinations like Ctrl Alt f. I know I can use a TActionList, but I just want to know why my code doesn't work.
CodePudding user response:
You should use OnKeyDown
instead, which provides you with both the key value and the modifier keys. I've demonstrated how to capture both one modifier key and multiple modifier keys in the code below.
uses
{ Needed for virtual key codes in recent Delphi versions. }
System.UITypes;
procedure TForm1.Memo1KeyDown(Sender: TObject; var Key: Word;
Shift: TShiftState);
begin
if (Key = vkX) and ([ssCtrl] = Shift) then
begin
Key := 0;
ShowMessage('Got Ctrl X');
end
else if (Key = vkZ) and ([ssCtrl, ssAlt] = Shift) then
begin
Key := 0;
ShowMessage('Got Ctrl Alt Z');
end;
end;