Question:
How can I tell if the PrintScreen key has been pressed?
Answer:
The PrintScreen system key is not processed during the TForm
keydown event. The following example tests if the PrintScreen key has
been pressed by calling the Windows API function GetAsyncKeyState()
during the Application.OnIdle event.
Example:
type
TForm1 = class(TForm)
Button1: TButton;
procedure FormCreate(Sender: TObject);
private
{ Private declarations }
procedure AppIdle(Sender: TObject; var Done: Boolean);
public
{ Public declarations }
end;
var
Form1: TForm1;
implementation
{$R *.DFM}
procedure TForm1.FormCreate(Sender: TObject);
begin
Application.OnIdle := AppIdle;
end;
procedure TForm1.AppIdle(Sender: TObject; var Done: Boolean);
begin
if GetAsyncKeyState(VK_SNAPSHOT) <> 0 then
Form1.Caption := 'SnapShot';
Done := True;
end;