Difference between revisions of "key down"

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(Created page with "{{key down}} == 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 ...")
 
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== See also ==
 
== See also ==
 +
* [http://delphi.about.com/od/objectpascalide/a/keyboard_events.htm Description of keyboard events in Delphi]; should be applicable to Lazarus, as well.
 
* [[LCL Key Handling]] Detailed background on key handling in the LCL.
 
* [[LCL Key Handling]] Detailed background on key handling in the LCL.
  
 
[[Category:LCL]]
 
[[Category:LCL]]

Revision as of 09:48, 23 October 2014

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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
  ...Windows, 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