How to detect end of Right drag of TControl?

Question

edit: VCL has no problem around right dragging and the sample program below works perfect. A mouse gesture utility causes the problem. (Perhaps it hooks & intercept WM_RBUTTONUP event...)

I want to detect end of right-dragging on the control.

For left-dragging, I can use MouseUp event, but it doesn't occur after right dragging.

On the test program below(put a memo on the right side of the form and drag form), I want to reset mouse cursor after right dragging.

How can I achieve this ? (WM_RBUTTONUP doesn't come.)

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Memo1: TMemo;
    procedure FormMouseDown(Sender: TObject; Button: TMouseButton; Shift:
        TShiftState; X, Y: Integer);
    procedure FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y: Integer);
    procedure FormMouseUp(Sender: TObject; Button: TMouseButton; Shift:
        TShiftState; X, Y: Integer);
    procedure WMRButtonUp(var Message: TWMRButtonUp); message WM_RBUTTONUP;
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

function ShiftStateToStr(Shift: TShiftState): string;
begin
  if ssShift in Shift then
    Result := Result + 'S-';
  if ssCtrl in Shift then
    Result := Result + 'C-';
  if ssAlt in Shift then
    Result := Result + 'A-';
  if ssDouble in Shift then
    Result := Result + 'D-';
  if ssLeft in Shift then
    Result := Result + 'L';
  if ssRight in Shift then
    Result := Result + 'R';
  if ssMiddle in Shift then
    Result := Result + 'M';
end;

function MouseButtonToStr(Btn: TMouseButton): string;
begin
  if Btn = mbLeft then
    Result := 'Left'
  else if Btn = mbRight then
    Result := 'Right'
  else if Btn = mbMiddle then
    Result := 'Middle';
end;


procedure TForm1.FormMouseDown(Sender: TObject; Button: TMouseButton; Shift:
    TShiftState; X, Y: Integer);
begin
  SetCapture(Handle);
  Memo1.Lines.Add(Format('Down(Btn=%s, Shift=[%s])', [MouseButtonToStr(Button), ShiftStateToStr(Shift)]));

  if Button = mbLeft then
    Screen.Cursor := crDrag
  else if Button = mbRight then
    Screen.Cursor := crSize;
end;

procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X, Y:
    Integer);
begin
  Memo1.Lines.Add(Format('Move(Shift=[%s])', [ShiftStateToStr(Shift)]));
end;

procedure TForm1.FormMouseUp(Sender: TObject; Button: TMouseButton; Shift:
    TShiftState; X, Y: Integer);
begin
  ReleaseCapture;
  Memo1.Lines.Add(Format('Up(Btn=%s, Shift=[%s])', [MouseButtonToStr(Button), ShiftStateToStr(Shift)]));

  Screen.Cursor := crDefault;
end;

procedure TForm1.WMRButtonUp(var Message: TWMRButtonUp);
begin
  Memo1.Lines.Add('WMRbuttonUp');
  inherited;
end;

end.

Why aren't you using the OnDrag... events of the control/form? — Marjan Venema
In the real situation, I want to rotate & translate 3D space's viewpoint. It's just a simplified sample. — benok

bepe4711 bepe4711 · Accepted Answer · 2010-06-24T07:32:42

I tried your test program with D2007. Everything works like expected. The FormMouseUp and WMRButtonUp get triggerd when i release the right mouse button.

Can you test it on another machine? I guess you have installed something "bad" in Delphi or you have some kind of hook on your system. But your source is correct and should work.

How to detect end of Right drag of TControl?

2 Answers