Solved

Double-Click Without Single

Posted on 2003-11-26
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Last Modified: 2010-04-05
Probably a very easy answer to this one...

I want to do one thing if I click on my memo and another if I double click on it, so I'm using the OnClick and OnDblClick events.

But, it doesn't matter how fast I double click, it only triggers the OnClick event. Any way of stopping this happening?

TDK_Man
0
Comment
Question by:tdk_man
5 Comments
 
LVL 5

Expert Comment

by:snehanshu
ID: 9829663
Well, I thought there would be better solutions than what I could think of, but I couldn't find any in a quick search, so here goes a crude method:

Wait (Sleep) for some time in the onclick event and then see if DoubleClick was done. If not process the single click.
Code:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Memo1: TMemo;
    procedure Memo1Click(Sender: TObject);
    procedure Memo1DblClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  IsDouble: Boolean;

implementation

{$R *.dfm}

procedure TForm1.Memo1Click(Sender: TObject);
begin
 IsDouble := False;
 Sleep(100);
 Application.ProcessMessages;
 If Not ISDouble then
 begin
 //single click handling routine here
   showmessage('Single');
 End;
end;

procedure TForm1.Memo1DblClick(Sender: TObject);
begin
  showmessage('Double');
  IsDouble := True;
end;

end.


HTH,
...Shu
0
 
LVL 5

Expert Comment

by:snehanshu
ID: 9829744
Here's code that reads the doubleclick interval from the registry and sleeps for that amount of time. I am not a TRegistry expert, but this does the work for me :)

Cheers!
...Shu

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, Registry;

type
  TForm1 = class(TForm)
    Memo1: TMemo;
    procedure Memo1Click(Sender: TObject);
    procedure Memo1DblClick(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  IsDouble: Boolean;

implementation

{$R *.dfm}

procedure TForm1.Memo1Click(Sender: TObject);
Var
  MyReg: TRegistry;
  MyInterval : Integer;
begin

 try
   begin
     MyReg := TRegistry.Create(KEY_READ);
     MyReg.RootKey := HKEY_CURRENT_USER;
     MyReg.OpenKey('Control Panel\Mouse',False);
     MyInterval := StrToIntDef(MyReg.ReadString('DoubleClickSpeed'), 250);
   end
 except
   begin
     MyInterval := 250;//default mouse dblclick interval
   end
 end;
 if assigned(MyReg) then
   MyReg.Free;

 IsDouble := False;
 Sleep(MyInterval);
 Application.ProcessMessages;
 If Not ISDouble then
 begin
 //single click handling routine here
   showmessage('Single');
 End;
end;

procedure TForm1.Memo1DblClick(Sender: TObject);
begin
  showmessage('Double');
  IsDouble := True;
end;

end.
0
 
LVL 9

Accepted Solution

by:
mocarts earned 100 total points
ID: 9830447
hi, TDK_man
Shu is right about main idea, but there is a way for shorter code (and easier to support):

procedure TForm1.Memo1Click(Sender: TObject);
begin
  Memo1.Lines.Add('Click');
  // call windows api function to retrieve system setting for double click time
  // this setting depends on user preferences - by default there will be very slow response time for Click
  // but you can tune that by subtracting some variable (programm setting) value from function result
  Timer1.Interval := GetDoubleClickTime;
  Timer1.Enabled := True;
end;

procedure TForm1.Memo1DblClick(Sender: TObject);
begin
  Timer1.Enabled := False;
  Memo1.Lines.Add('DblClick');
  // your OnDblClick code here
end;

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  Timer1.Enabled := False;
  Memo1.Lines.Add('Click-Timer');
  // your OnClick code here
end;

wbr, mo.
0
 
LVL 7

Expert Comment

by:sftweng
ID: 9832708
Have you tried changing the double-click timing to a faster setting in Windows -> Control Panel -> Mouse?
0
 
LVL 1

Author Comment

by:tdk_man
ID: 9839076
Sorry for the delay in getting back - I had a power cut and my UPS failed. I ended up having to re-install Windows and all my software.

Will check out all the suggestions (thanks for them) this weekend and get back...

TDK_Man
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