Print on Background of each Page

Sometimes you need a watermark, an image or just some text  on some of the pages.

Although wPDF supports the PDF watermarks it is often a good idea to paint the information on each page. To do so you can use the OnBeforePrintPage event. This event is triggered before the text of one page is exported. You can either paint to the Canvas or use DrawTGraphic to export a metafile to the PDF file.

We modified the previous example to support watermarks. It is easy to modify the example to draw different graphics or notes like 'Confidential' on each page.

uses WPDefs, WPPrint, WpWinCtr, WPRich, WPPDFR1, WPPDFWP

procedure TForm1.RTF2PDF( RTFname, PDFname : string);

var

   WPRichText: TWPRichText;

   WPPDFExport: TWPPDFExport;

  Watermark : TPicture;

begin

 WPRichText:= TWPRichText.CreateParented(Application.Handle);;

 WPPDFExport:= TWPPDFExport.Create(nil);

 Watermark := TPicture.Create;

 WPPDFExport.Tag := Integer( Watermark );

 WPPDFExport.Source := WPRichText;

WPPDFExport.OnBeforePrintPage := DoBeforePrintPage;

try

   WPRichText.LoadFromFile( RTFname );

  Watermark.LoadFromFile( watermark_graphic );

   WPPDFExport.FileName := PDFname;

   WPPDFExport.Print;

finally

   WPRichText.Free;

   WPPDFExport.Free;

end;

end;

procedure TForm1.DoBeforePrintPage(Sender: TObject; Number,

 FromPos, Length: Integer);

begin

if TWPPDFExport(Sender).Tag<>0 then

begin

    TWPPDFExport(Sender).DrawTGraphic(0,0,

         0,0,(TObject(TWPPDFExport(Sender).Tag)as TPicture).Graphic);

end;

end;

If you want to export the background color of the TWPRichText use this code:

procedure TForm1.DoBeforePrintPage(Sender: TObject; Number,

 FromPos, Length: Integer);

begin

   WPPDFExport1.Canvas.Brush.Color := WPPDFExport1.Source.Color;

   WPPDFExport1.Canvas.Brush.Style := bsSolid;

   WPPDFExport1.Canvas.Pen.Style := psClear;

   WPPDFExport1.Canvas.Rectangle(0,0,

     MulDiv(WPRichText1.Header.PageWidth,Screen.PixelsPerInch,1440),

     MulDiv(WPRichText1.Header.PageHeight,Screen.PixelsPerInch,1440)

     );

end;

If you want to export any background Image

You will need a variable

BackImageNr : Integer;

which is set to -1 before the PDF is exported. This variable is used to fist initialize the bitmap which is then only used as "clone".

The background image is expected in object 'Image2'.

procedure TForm1.DoBeforePrintPage(Sender: TObject; Number,

 FromPos, Length: Integer);

var x,y : Integer;

begin

for x:=0 to

    (MulDiv(WPRichText1.Header.PageWidth,Screen.PixelsPerInch,1440)+

       Image2.Picture.Bitmap.Width-1) div Image2.Picture.Bitmap.Width do

for y:=0 to

    (MulDiv(WPRichText1.Header.PageHeight,Screen.PixelsPerInch,1440)+

       Image2.Picture.Bitmap.Height-1) div Image2.Picture.Bitmap.Height do

begin

  if BackImageNr<=0 then

     BackImageNr := WPPDFExport1.DrawTGraphic(

       x * Image2.Picture.Bitmap.Width,

       y * Image2.Picture.Bitmap.Height,

       Image2.Picture.Bitmap.Width,

       Image2.Picture.Bitmap.Height,

       Image2.Picture.Bitmap)

  else

    WPPDFExport1.DrawBitmapClone(

       x * Image2.Picture.Bitmap.Width,

       y * Image2.Picture.Bitmap.Height,

       Image2.Picture.Bitmap.Width,

       Image2.Picture.Bitmap.Height,

       BackImageNr);

end;