key down

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Overview

The OnKeyDown event of an object allows you to check what key the user has pressed.

Note that the procedure keeps track of shift/alt/ctrl etc keys separately (in Shift) from the "regular" keys (in Key) - see the procedure signature in the example.

Example

uses
  ...LCLType, Dialogs, ...;
  ...  
procedure TForm1.Edit1KeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
  // Example: checking for simple keys:
  if (Key = VK_DOWN) or
     (Key = VK_UP) then
    ShowMessage('Pressed arrow up or down key');
  // Check for Alt-F2
  if (Key = VK_F2) and (ssAlt in Shift) then
    ShowMessage('Alt F2 was pressed')
end;

See also

• Description of keyboard events in Delphi; should be applicable to Lazarus, as well.
• LCL Key Handling Detailed background on key handling in the LCL.