OnKeyPress: what changed
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Title: OnKeyPress
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| 1 | + | ## Overview | |
| 2 | + | ||
| 3 | + | The [OnKeyPress](https://lazarus-ccr.sourceforge.io/docs/lcl/controls/twincontrol.onkeypress.html) event of an object allows you to check what key the user has pressed. | |
| 4 | + | ||
| 5 | + | Note that this procedure handles printable characters only. Non-printable characters (e.g. control sequences) are handled by the [[key down|OnKeyDown]] event. | |
| 6 | + | ||
| 7 | + | > **Note:** *OnKeyPress* doesn't support Unicode characters. If you need Unicode characters but no control characters, use [OnUTF8KeyPress](https://lazarus-ccr.sourceforge.io/docs/lcl/controls/twincontrol.onutf8keypress.html). | |
| 8 | + | ||
| 9 | + | ## Example | |
| 10 | + | ||
| 11 | + | ``` pascal | |
| 12 | + | uses | |
| 13 | + | ...LCLType, Dialogs, ...; | |
| 14 | + | ... | |
| 15 | + | ||
| 16 | + | procedure TMainForm.FormKeyPress(Sender: TObject; var Key: char); | |
| 17 | + | begin | |
| 18 | + | case key of | |
| 19 | + | '0': ShowMessage('"0" key pressed'); | |
| 20 | + | '1': ShowMessage('"1" key pressed'); | |
| 21 | + | '2': ShowMessage('"2" key pressed'); | |
| 22 | + | end; | |
| 23 | + | Key := #0; // Necessary for some widgetsets, e.g. Cocoa, in order to disable processing in subsequent elements. | |
| 24 | + | end; | |
| 25 | + | ``` | |
| 26 | + | ||
| 27 | + | ## See also | |
| 28 | + | ||
| 29 | + | - [[LCL Key Handling]] Detailed background on key handling in the LCL. | |
| 30 | + | - [[key down]] | |
| 31 | + | ||
| 32 | + | --- | |
| 33 | + | *From the Free Pascal wiki, page "OnKeyPress", as it stood on 2020-02-23 after a change by Trev, out of the wiki's dump of 2024-05-26. Copyright stays with the author who wrote it, according to the old wiki's [[Licensing]] page. If you have concerns about this material, [message the admin](/wiki-contact).* |