Difference between revisions of "key down"

From Free Pascal wiki
Jump to navigationJump to search
(→‎Example: Use unit LCLType instead of Windows)
(→‎Overview: + Links to doc; Not on Unicode characters)
Line 1: Line 1:
 
{{key down}}
 
{{key down}}
 
== Overview ==
 
== Overview ==
The ''OnKeyDown'' event of an object allows you to check what key the user has pressed.
+
The {{Doc|package=LCL|unit=controls|identifier=twincontrol.onkeydown|text=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.
 
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.
 +
 +
{{Note|''OnKeyDown'' doesn't support Unicode characters. If you need Unicode characters but no control characters, use {{Doc|package=LCL|unit=controls|identifier=twincontrol.onutf8keypress|text=OnUTF8KeyPress}}.}}
  
 
== Example ==
 
== Example ==

Revision as of 21:33, 12 January 2015

Deutsch (de) English (en)

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.

Light bulb  Note: OnKeyDown doesn't support Unicode characters. If you need Unicode characters but no control characters, use OnUTF8KeyPress.

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