OnKeyDown (Delphi)

Description

The following code aborts a print job if you press the Esc key. Note that you should set KeyPreview to True to ensure that the OnKeyDown event handler of Form1 is called. Printer is a global Printers functions that returns a global instance of TPrinter to manage interaction with the printer.

Code

uses Printers;

procedure TForm1.Button1Click(Sender: TObject);
var
  I, X, Y: Integer;
  Memo1 : TMemo;
  r: TRect;
begin
  Memo1 := TMemo.Create(Form1);
  Memo1.Parent := Form1;
  Memo1.Visible := True;
  Memo1.Width := 700;
  if (OpenDialog1.Execute) then
  begin
    Memo1.Lines.LoadFromFile(OpenDialog1.FileName);

    Printer.BeginDoc;
    X := 200;
    Y := 200;
    for I := 0 to 140 do
      if (not Printer.Aborted) then
      begin
        Printer.Canvas.TextOut(X, Y, Memo1.Lines[I]);
        Y := Y + 80;
        if (Y > (Printer.PageHeight - 300)) then
        begin
          Y := 200;
          Printer.NewPage;
          Sleep(1000);  // to give you time to abort!
        end;
      end;
    if (not Printer.Aborted) then Printer.EndDoc;
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
   KeyPreview := True;
end;

procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState);
begin
if (Key=VK_ESCAPE) and Printer.Printing then
  begin
  Printer.Abort;
  MessageDlg('Printing aborted', mtInformation, [mbOK],0);
  end;
end;

Uses

• Vcl.Controls.TWinControl.OnKeyDown ( fr | de | ja )
• Vcl.Printers.TPrinter.Abort ( fr | de | ja )
• Vcl.Printers.Printer ( fr | de | ja )
• Vcl.Printers.TPrinter.Printing ( fr | de | ja )
• Vcl.Graphics.TCanvas.TextOut ( fr | de | ja )
• Vcl.Printers.TPrinter.PageHeight ( fr | de | ja )
• Vcl.Forms.TCustomForm.KeyPreview ( fr | de | ja )