Controlling The Preview

This article shows how to alter the properties of the preview window AFTER it is created and displayed.

Sample code:

Controlling a preview using a timer.
====================================

This code snippet shows how the preview form may be controlled
using a timer to to fire API calls that can re-size, or minimise and
maximise a showing preview.
The zoom state and other properties may also be set

The app has 2 forms, Mainform and RepForm
which has a quickrep called QuickRep1.

The code is rather bare - but the principles are illustrated.
The most amazing thing is that this -

repform.QuickRep1.QRPrinter.Client.Parent.Handle

is the handle of the preview window.

{-----------------------------------------------------
  This button on the main form kicks-off the preview
  and sets the timer on mainform.
  Set the interval of the timer to 50000 in design mode.
-----------------------------------------------------}
procedure TMainform.SpeedButton1Click(Sender: TObject);
begin
     timer1.enabled := false;
     repform.Table1.open;
     // this can be as small as you like - provided the
     // tick routine checks that the preview is showing
     timer1.Interval := 3000; // millisecs
     timer1.enabled := true;
     repform.QuickRep1.Preview;
     repform.Table1.close;
end;

{---------------------------------------------------
 Reposition and/or resize the window. See WinAPI help
 for the possibilities of the SetWindowPlacement call.
----------------------------------------------------}
procedure Tmainform.Timer1Timer(Sender: TObject);
var
   pStru : WINDOWPLACEMENT;
begin
     // here we should check if the preview is showing
     // and exit if not. A delay of 1 or 2 seconds is
     // enough usually to allow this.
     // This test might fail - but it hasn't yet
     if not assigned(repform.QuickRep1.QRPrinter) then exit;

     timer1.enabled := false; // we've finished with the timer.

     // Doing it the easy way. Resetting the WindowState may not be
     // necessary.
     TForm( repform.QuickRep1.QRPrinter.Client.parent).WindowState := wsNormal;
     repform.QuickRep1.QRPrinter.Client.parent.width := 800;
     repform.QuickRep1.QRPrinter.Client.parent.height := 600;
     repform.QuickRep1.QRPrinter.Client.parent.top := 50;
     repform.QuickRep1.QRPrinter.Client.parent.left := 50;
     exit;

     // How to do it with API calls. This way is smoother.
     // set the Window position structure
     pstru.length := sizeof( WINDOWPLACEMENT);// mandatory
     pstru.showCmd := SW_RESTORE; // could be SW_SHOWMAXIMIZED etc.
     pstru.flags := WPF_SETMINPOSITION;
     // set the rect in screen pixels for a move/resize
     pstru.rcNormalPosition := rect( 100, 100, 850, 700 );
     SetWindowPlacement( repform.QuickRep1.QRPrinter.Client.parent.Handle, @pstru );
end;


Setting the toolbar buttons
---------------------------
Use a longer time delay to do this - because the buttons
are reset in the QR code when the report is done.

// add some vars in the proc above
var
   prevFrm : TForm;
   tBar, tBut, tPrev : TComponent;
..
..
     // this code goes into the proc above
     // find the buttons and set them
     prevfrm := TForm( repform.QuickRep1.QRPrinter.Client.parent);
     for j := 0 to prevfrm.controlcount-1 do
     begin
         tBar := prevfrm.controls[ j ];
         if tBar is TToolbar then
         begin
             // Vanish the toolbar !!
             // TToolbar(tBar).visible := false;
             // break; // if vanishing
             for k := 0 to TToolbar(tBar).controlcount-1 do
             begin
                tBut := TToolbar(tBar).controls[ k ];
                if tBut is TToolbutton then  // could test the name here
                    TToolbutton(tBut).enabled := false;
             end;
         end;
     end;



Setting the preview component properties.
----------------------------------------
     // insert into the procedure above

     // set preview component
     tPrev := repform.QuickRep1.QRPrinter.Client;
     TQRPreview(tPrev).ZoomToWidth;
     TQRPreview(tPrev).Zoom := 80;
     TQRPreview(tPrev).color := clRed;