/*
The following example is taken from the docking demo. It
shows how the OnUnDock event handler of the conjoinment
docking site re-enables docking in the control that is
undocked (if it is a dockable form). In addition, when the
next to last docked control is undocked, the conjoinment
docking site sends itself a close message so that the last
docked control is undocked to its old position and size.
*/
void __fastcall TConjoinDockHost::FormUnDock(TObject *Sender, TControl *Client,
      TWinControl *NewTarget, bool &Allow)
{
  // Only 2 dock clients means the host must be destroyed and
  // the remaining window undocked to its old position and size.
  // Recall that OnUnDock gets called before the undocking
  // actually occurs.
  if (Client->ClassNameIs("TDockableForm"))
    dynamic_cast<TDockableForm *>(Client)->DockSite = True;
  if ((DockClientCount == 2) && (NewTarget != this))        // Self?
    PostMessage(dynamic_cast<TConjoinDockHost *>(this)->Handle, WM_CLOSE, 0, 0);
  UpdateCaption(Client);
}

/*
The following example is taken from the docking demo. It
shows how set permissions to dock dockable objects onto a
docking site.
*/

void __fastcall TMainForm::LeftDockPanelDockDrop(TObject *Sender,
      TDragDockObject *Source, int X, int Y)
{
  //OnDockDrop gets called AFTER the client has actually docked,
  //so we check for DockClientCount = 1 before making the dock panel visible.
  TPanel *panel = dynamic_cast<TPanel *>(Sender);
  if (panel->DockClientCount == 1)
    ShowDockPanel(panel, True, NULL);
  panel->DockManager->ResetBounds(True);
  //Make DockManager repaints it's clients.
}

void __fastcall TMainForm::LeftDockPanelDockOver(TObject *Sender,
      TDragDockObject *Source, int X, int Y, TDragState State, bool &Accept)
{
  Accept = (dynamic_cast<TDockableForm*>(Source->Control) != NULL);
  if (Accept)
  {
    // Modify the DockRect to preview dock area.
    Types::TPoint TopLeft = LeftDockPanel->ClientToScreen(Point(0, 0));
    Types::TPoint BottomRight = LeftDockPanel->ClientToScreen(
      Point(this->ClientWidth/3, LeftDockPanel->Height));
    Source->DockRect = Types::TRect(TopLeft, BottomRight);
  }
}

void __fastcall TMainForm::LeftDockPanelUnDock(TObject *Sender,
      TControl *Client, TWinControl *NewTarget, bool &Allow)
{
  //OnUnDock gets called BEFORE the client is undocked, in order to optionally
  //disallow the undock. DockClientCount is never 0 when called from this event.
  TPanel *panel = dynamic_cast<TPanel *>(Sender);
  if (panel->DockClientCount == 1)
    ShowDockPanel(panel, False, NULL);
}

void __fastcall TMainForm::LeftDockPanelGetSiteInfo(TObject *Sender,
      TControl *DockClient, TRect &InfluenceRect, TPoint &MousePos,
      bool &CanDock)
{
  //if CanDock is true, the panel will not automatically draw the preview rect.
  CanDock = DockClient->ClassNameIs("TDockableForm");
  if (!CanDock)
  {
     ShowMessage("GetSiteInfo CanDock went bad!");
  }
}

{
The following example is taken from the docking demo. It
shows how the OnUnDock event handler of the conjoinment
docking site re-enables docking in the control that is
undocked (if it is a dockable form). In addition, when the
next to last docked control is undocked, the conjoinment
docking site sends itself a close message so that the last
docked control is undocked to its old position and size.
} 
procedure TConjoinDockHost.FormUnDock(Sender: TObject; Client: TControl;
  NewTarget: TWinControl; var Allow: Boolean);
begin
  // Only 2 dock clients means the host must be destroyed and
  // the remaining window undocked to its old position and size.
  // Recall that OnUnDock gets called before the undocking
  // actually occurs.
  if Client is TDockableForm then
    TDockableForm(Client).DockSite := True;
  if (DockClientCount = 2) and (NewTarget <> Self) then
    PostMessage(Self.Handle, WM_CLOSE, 0, 0);
  UpdateCaption(Client);
end;

{
The following example is taken from the docking demo. It
shows how set permissions to dock dockable objects onto a
docking site.
}

procedure TMainForm.LeftDockPanelDockDrop(Sender: TObject;
  Source: TDragDockObject; X, Y: Integer);
begin
  //OnDockDrop gets called AFTER the client has actually docked,
  //so we check for DockClientCount = 1 before making the dock panel visible.
  if (Sender as TPanel).DockClientCount = 1 then
    ShowDockPanel(Sender as TPanel, True, nil);
  (Sender as TPanel).DockManager.ResetBounds(True);
  //Make DockManager repaints it's clients.
end;

procedure TMainForm.LeftDockPanelDockOver(Sender: TObject;
  Source: TDragDockObject; X, Y: Integer; State: TDragState;
  var Accept: Boolean);
var
  ARect: TRect;
begin
  Accept := Source.Control is TDockableForm;
  if Accept then
  begin
    //Modify the DockRect to preview dock area.
    ARect.TopLeft := LeftDockPanel.ClientToScreen(Point(0, 0));
    ARect.BottomRight := LeftDockPanel.ClientToScreen(
      Point(Self.ClientWidth div 3, LeftDockPanel.Height));
    Source.DockRect := ARect;
  end;
end;

procedure TMainForm.LeftDockPanelUnDock(Sender: TObject; Client: TControl;
  NewTarget: TWinControl; var Allow: Boolean);
begin
  //OnUnDock gets called BEFORE the client is undocked, in order to optionally
  //disallow the undock. DockClientCount is never 0 when called from this event.
  if (Sender as TPanel).DockClientCount = 1 then
    ShowDockPanel(Sender as TPanel, False, nil);
end;

procedure TMainForm.LeftDockPanelGetSiteInfo(Sender: TObject;
  DockClient: TControl; var InfluenceRect: TRect; MousePos: TPoint;
  var CanDock: Boolean);
begin
  //if CanDock is true, the panel will not automatically draw the preview rect.
  CanDock := DockClient is TDockableForm;
end;