Solved

drag button within panel

Posted on 2001-09-09
11
254 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
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 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
Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 

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

Free Tool: IP Lookup

Get more info about an IP address or domain name, such as organization, abuse contacts and geolocation.

One of a set of tools we are providing to everyone as a way of saying thank you for being a part of the community.

Question has a verified solution.

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

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…
Introduction I have seen many questions in this Delphi topic area where queries in threads are needed or suggested. I know bumped into a similar need. This article will address some of the concepts when dealing with a multithreaded delphi database…
NetCrunch network monitor is a highly extensive platform for network monitoring and alert generation. In this video you'll see a live demo of NetCrunch with most notable features explained in a walk-through manner. You'll also get to know the philos…
Michael from AdRem Software outlines event notifications and Automatic Corrective Actions in network monitoring. Automatic Corrective Actions are scripts, which can automatically run upon discovery of a certain undesirable condition in your network.…

696 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