Ad:

Pascal and Delphi Discussion Thread
Unsolved
Views: 2907

Nov 5th, 2009

KeyPress, KeyDown not triggering event

Expand Post »

Hey All

I've recently picked up a VCL delphi project and am quite new to the language. The software so far consists of a main form, with several GroupBoxes and panels covering the entire form. I'm trying to implement some user short cuts, for example when "Ctrl+1" is pressed I want all the ComboBoxs to be set to a certain position. Correct me if I'm wrong but I have added an event that triggers when a button is pressed i.e KeyDown, KeyPress, etc.. However the event does not seem to be triggering when a keyboard button is pressed. Does anyone have an idea why this could be? My only guess is that the GroupBoxes are intefering. Any thoughts / hints would be greatly appreciated!

Cheers

Cameron

Similar Threads

Javascript event stuff in JavaScript / DHTML / AJAX
Keypress of a textbox in asp.net with c#.net in JavaScript / DHTML / AJAX
events in counting vowels in C#
backspace and delete key in Visual Basic 4 / 5 / 6
about keypress in keyascii in Visual Basic 4 / 5 / 6

CanYouHandstand

Reputation Points: 10

Solved Threads: 2

Light Poster

Offline

27 posts
since Nov 2009

Permalink

Nov 6th, 2009

Re: KeyPress, KeyDown not triggering event

You are attempting to trap the key stroke on the form instead of a
specific component.

Set the KeyPreview property to true or in the OnCreate Method as below
Add a FormKeyDown Event to process your requirements

Pascal and Delphi Syntax (Toggle Plain Text)
type
  TForm1 = class(TForm)
    GroupBox1: TGroupBox;
    Edit1: TEdit;
    procedure FormKeyDown(Sender: TObject; var Key: Word;
      Shift: TShiftState);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
 
implementation
 
{$R *.DFM}
 
procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
  if (key=ord('1')) and (ssCtrl in Shift) then
  begin
    Edit1.Text:='Pressed';
  { Add your code here }
    Key:=0;  // if required
  end;
 
end;
 
procedure TForm1.FormCreate(Sender: TObject);
begin
  KeyPreview:=True;
end;
 
end.
type
  TForm1 = class(TForm)
    GroupBox1: TGroupBox;
    Edit1: TEdit;
    procedure FormKeyDown(Sender: TObject; var Key: Word;
      Shift: TShiftState);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
  if (key=ord('1')) and (ssCtrl in Shift) then
  begin
    Edit1.Text:='Pressed';
  { Add your code here }
    Key:=0;  // if required
  end;

end;

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

end.

cao

Reputation Points: 11

Solved Threads: 5

Newbie Poster

Offline

12 posts
since Oct 2009

Permalink

Nov 6th, 2009

Re: KeyPress, KeyDown not triggering event

TRY This:

Pascal and Delphi Syntax (Toggle Plain Text)
procedure TMain.FormKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
    CASE Key OF
      Ord('1') : IF Shift = [SSCTRL] THEN
                 Edit1.Text := 'CTRL 1 - Pressed'
                 ELSE IF Shift = [SSAlt] THEN
                 Edit1.Text := 'Alt 1 - Pressed'
      End;  {CASE}
 
end;
procedure TMain.FormKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
    CASE Key OF
      Ord('1') : IF Shift = [SSCTRL] THEN
                 Edit1.Text := 'CTRL 1 - Pressed'
                 ELSE IF Shift = [SSAlt] THEN
                 Edit1.Text := 'Alt 1 - Pressed'
      End;  {CASE}

end;

Click to Expand / Collapse Quote originally posted by cao ...

You are attempting to trap the key stroke on the form instead of a
specific component.

Set the KeyPreview property to true or in the OnCreate Method as below
Add a FormKeyDown Event to process your requirements
Pascal and Delphi Syntax (Toggle Plain Text)
type
  TForm1 = class(TForm)
    GroupBox1: TGroupBox;
    Edit1: TEdit;
    procedure FormKeyDown(Sender: TObject; var Key: Word;
      Shift: TShiftState);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
 
implementation
 
{$R *.DFM}
 
procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word;
  Shift: TShiftState);
begin
  if (key=ord('1')) and (ssCtrl in Shift) then
  begin
    Edit1.Text:='Pressed';
  { Add your code here }
    Key:=0;  // if required
  end;
 
end;
 
procedure TForm1.FormCreate(Sender: TObject);
begin
  KeyPreview:=True;
end;
 
end.
type TForm1 = class(TForm) GroupBox1: TGroupBox; Edit1: TEdit; procedure FormKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState); procedure FormCreate(Sender: TObject); private { Private declarations } public { Public declarations } end; var Form1: TForm1; implementation {$R *.DFM} procedure TForm1.FormKeyDown(Sender: TObject; var Key: Word; Shift: TShiftState); begin if (key=ord('1')) and (ssCtrl in Shift) then begin Edit1.Text:='Pressed'; { Add your code here } Key:=0; // if required end; end; procedure TForm1.FormCreate(Sender: TObject); begin KeyPreview:=True; end; end.

quaifp1

Reputation Points: 11

Solved Threads: 3

Newbie Poster

Offline

10 posts
since Oct 2009

Permalink

Nov 9th, 2009

Re: KeyPress, KeyDown not triggering event

Thank you for your replies! I think what I was missing was KeyPreview := true. Your case statements saved me time as well. Thanks a lot.

CanYouHandstand

Reputation Points: 10

Solved Threads: 2

Light Poster

Offline

27 posts
since Nov 2009

This thread is more than three months old

No one has posted to this discussion for at least three months. Please let old threads die and do not reply to them unless you feel you have something new and valuable to contribute that absolutely must be added to make the discussion complete. Otherwise, please start a new thread in this forum instead.

Previous Thread in Pascal and Delphi Forum Timeline: runtime error as IOresult<>0

Next Thread in Pascal and Delphi Forum Timeline: Exporting table data to CSV.

DaniWeb Message

Cancel Changes

User Name
Password