Solved

drag button within panel

Posted on 2001-09-09
11
251 Views
Last Modified: 2010-04-06
hi! i'm creating a various number of buttons. i would like that my users can position them within a panel component where they want, by moving them with the mouse. i'm using d4 standard but a special button component which does not support dock/drag propertys.

kind regards
ItsMe
0
Comment
Question by:ItsMe
  • 4
  • 3
  • 2
  • +1
11 Comments
 
LVL 10

Expert Comment

by:Jacco
ID: 6469020
Hi ItsMe,

Here is a way you can move all TWinControls. I don't know if the TControl.WondowProc is supported under D4 but I can write a replacement function for it.

Just attach the control you want to move. And drag the control. Call detach if you want to no longer drag the control.

Regards Jacco

unit Unit1;

interface

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

type
  TMover = class
  private
    FControl: TControl;
    FOldProc: TWndMethod;
    FDragging: Boolean;
    FOfsX: Integer;
    FOfsY: Integer;
    FLeft: Integer;
    FTop: Integer;
  public
    destructor Destroy; override;
    procedure NewWndProc(var Message: TMessage);
    procedure Attach(AControl: TControl);
    procedure Detach;
  end;

  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    procedure Button2Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
  private
    { Private declarations }
    FMover: TMover;
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Button2Click(Sender: TObject);
begin
  FMover.Attach(Button1);
end;

{ TMover }

procedure TMover.Attach(AControl: TControl);
begin
  if FControl <> AControl then
  begin
    if FControl <> nil then
      Detach;
    FControl := AControl;
    if Assigned(FControl) then
    begin
      FOldProc := AControl.WindowProc;
      AControl.WindowProc := NewWndProc;
    end;
  end;
end;

destructor TMover.Destroy;
begin
  Detach;
  inherited Destroy;
end;

procedure TMover.Detach;
begin
  if Assigned(FControl) then
  begin
    FControl.WindowProc := FOldProc;
    FControl := nil;
    FOldProc := nil;
  end;
end;

procedure TMover.NewWndProc(var Message: TMessage);
var
  lbHandled: Boolean;
  liX, liY: Integer;
  lRect: TRect;
begin
  lbHandled := False;
  with Message do
  begin
    if Msg = WM_LBUTTONDOWN then
    begin
      lbHandled := True;
      FDragging := True;
      FOfsX := LParam and $FFFF;
      FOfsY := LParam shr 16;
      FLeft := FControl.Left;
      FTop := FControl.Top;
      with FControl.Parent do
      begin
        lRect.TopLeft     := Point(Left, Top);
        lRect.BottomRight := Point(Left+Width, Top+Height);
      end;
      SetCapture(TWinControl(FControl).Handle);
      ClipCursor(@lRect);
    end;
    if Msg = WM_LBUTTONDBLCLK then
      lbHandled := True;
    if Msg = WM_MOUSEMOVE then
    begin
      if FDragging then
      begin
        liX := LParam and $FFFF;
        liY := LParam shr 16;
        FControl.SetBounds(FLeft + (liX - FOfsX), FTop + (liY - FOfsY),FControl.Width, FControl.Height);
        FLeft := FControl.Left;
        FTop := FControl.Top;
        lbHandled := True;
      end;
    end;
    if Msg = WM_LBUTTONUP then
    begin
      lbHandled := True;
      FDragging := False;
      ClipCursor(nil);
      ReleaseCapture;
    end;
  end;
  if not lbHandled then
    FOldProc(Message);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  FMover := TMover.Create;
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  FMover.Free;
end;

end.
0
 
LVL 6

Accepted Solution

by:
DrDelphi earned 100 total points
ID: 6469085
MUCH less code than that would be:

procedure TForm1.Button1MouseMove(Sender: TObject; Shift: TShiftState; X,
  Y: Integer);
  const
  SC_DragMove = $F012;  { a magic number }
  begin
  ReleaseCapture;
  Button1.perform(WM_SysCommand, SC_DragMove, 0);
end;


(this is from my website: www.drdelphi.com)

-Good luck!!

0
 
LVL 6

Expert Comment

by:zebada
ID: 6469173
listening...
0
Best Practices: Disaster Recovery Testing

Besides backup, any IT division should have a disaster recovery plan. You will find a few tips below relating to the development of such a plan and to what issues one should pay special attention in the course of backup planning.

 

Author Comment

by:ItsMe
ID: 6469719
i guess i don't need to understand this ? :-)
0
 
LVL 10

Expert Comment

by:Jacco
ID: 6469871
Hi ItsMe,

Which solution do you want explanation about?

Regards Jacco
0
 

Author Comment

by:ItsMe
ID: 6470621
hi jacco! the last, short one :-)
0
 
LVL 6

Expert Comment

by:zebada
ID: 6470633
If you're referring to the "listening..." comment, that's just so I get email notification when someone adds a comment. I am also interested in how this is done.
0
 

Author Comment

by:ItsMe
ID: 6470644
hihi no, i ment the code from drdelphi. it works pretty fine but i don't know why :-)
0
 
LVL 6

Expert Comment

by:DrDelphi
ID: 6471005
Eseentially what's happening is that you are telling the form NOT to process the mouse move (ReleaseCapture), then you send the SC_Drag message to the button (or a panel, editbox, whatever). Real easy! :-)  Now, how about some points?<g>

-Dave
0
 

Author Comment

by:ItsMe
ID: 6471352
i forgot *gg*
0
 
LVL 6

Expert Comment

by:DrDelphi
ID: 6473016
thanks!
0

Featured Post

ScreenConnect 6.0 Free Trial

Want empowering updates? You're in the right place! Discover new features in ScreenConnect 6.0, based on partner feedback, to keep you business operating smoothly and optimally (the way it should be). Explore all of the extras and enhancements for yourself!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

A lot of questions regard threads in Delphi.   One of the more specific questions is how to show progress of the thread.   Updating a progressbar from inside a thread is a mistake. A solution to this would be to send a synchronized message to the…
The uses clause is one of those things that just tends to grow and grow. Most of the time this is in the main form, as it's from this form that all others are called. If you have a big application (including many forms), the uses clause in the in…
Microsoft Active Directory, the widely used IT infrastructure, is known for its high risk of credential theft. The best way to test your Active Directory’s vulnerabilities to pass-the-ticket, pass-the-hash, privilege escalation, and malware attacks …
Finds all prime numbers in a range requested and places them in a public primes() array. I've demostrated a template size of 30 (2 * 3 * 5) but larger templates can be built such 210  (2 * 3 * 5 * 7) or 2310  (2 * 3 * 5 * 7 * 11). The larger templa…

772 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question