Re: screen <-> printer

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Frank Kroeger

Posted: 07/23/2003 0:01:41

Hi Sergey,

I tried your suggestion but no luck. As a test I tried to draw a page on

the prncanvas and then copy this canvas to the printer.canvas. I figure this

should then print out the generated page. But this does not word. Can you

tell me what I am doing wrong here?

Here is the code I used:

procedure TForm1.test1Click(Sender: TObject);

var PrnCanvas : TCanvas;

    PrnDC : HDC;

    printerdpi, docleft, doctop, docwidth, docheight : integer;

    destrect : TRect;

begin

   PrnCanvas := TCanvas.Create;

   PrnDC := RV_GetPrinterDC;

   PrnCanvas.Handle := PrnDC;

   PrnCanvas.Font.PixelsPerInch := GetDeviceCaps(PrnDC, LOGPIXELSY);

   printerdpi := GetDeviceCaps(PrnCanvas.Handle,lOGPIXELSX);

   Try

     docleft := 0;

     doctop := 0;

     docwidth := mmToPix(167,printerdpi);

     docHeight := mmToPix(150,printerdpi);

     rvh.clear;

     If rvh.RichView.LoadRVF('d:\rabea.rvf') then

     begin

        rvh.RichView.LeftMargin := 0;

        rvh.RichView.TopMargin := 0;

        rvh.RichView.RightMargin := 0;

        rvh.RichView.BottomMargin := 0;

        rvh.Init(prncanvas,docwidth);

        While rvh.FormatNextPage(docHeight) do;

        rvh.DrawPageAt(docleft,doctop,1,PrnCanvas,false,docHeight);

        destrect.Left := 0;

        destrect.Top := 0;

        destrect.Right := getdevicecaps(prncanvas.Handle,horzres);

        destrect.Bottom := getdevicecaps(prncanvas.Handle,vertres);

        printer.BeginDoc;

        printer.canvas.CopyMode := cmSrcCopy;

        printer.canvas.CopyRect(destrect,prncanvas,destrect);

        printer.enddoc;

     end;

   finally

      PrnCanvas.Handle := 0;

      DeleteDC(PrnDC);

      PrnCanvas.Free;

   end;

end;

I created and used the prncanvas as you suggested. After drawing I simply

copy the canvas to the printer.canvas. If I am not mistaken this should also

print the generated page but all I get is a blank page.

The other method you suggested (using a dummy page and TRVPrintPreview's

OnPagePrepaint event) I believe is in my case not so easy to use. I print

several RVF-documents on one page but do not know beforehand how many pages

I need. This is calculated on the fly. To use TRVPrintPreview I would need

to know the number of pages before I start the preview.

Tia,

Frank Kroeger

"Sergey Tkachenko" <svt@trichview.com> wrote:

>Hi,

>

>If you want to create the same image on printer and paper, you need:

>1) Format reporthelper in printer resolution. You need to create

>printer-compatible canvas and use it for reporthelper.Init()

>

>Creating:

>var

>    PrnCanvas: TCanvas;

>    PrnDC: HDC;

>

>  PrnCanvas := TCanvas.Create;

>  PrnDC    := RV_GetPrinterDC; // from PtblRV unit

>  PrnCanvas.Handle := PrnDC;

>  PrnCanvas.Font.PixelsPerInch := GetDeviceCaps(PrnDC, LOGPIXELSY);

>

>Destroying (when all drawing is finished)

>

>    PrnCanvas.Handle := 0;

>    DeleteDC(PrnDC);

>    PrnCanvas.Free;

>

>2) When printing, use rvhelper.DrawPageAt(... Printer.Canvas ...), as I

>guess you currently do

>3) When drawing preview, you need to scale image.

>There is a simple method for previewing: using TRVPrintPreview showing some

>fake (empty) document. You can draw preview in OnPagePrepaint event.

>Example: http://www.trichview.com/support/files/preview.zip

>

>

>

>>

>> Hi,

>>

>> I use TRVReportHelper to print multiple records of a report on one or

more

>> pages.

>> TRVReportHelper draws the pages onto the printercanvas and as a preview

to

>> a TImage as in one of your demos. Of course it would be nice if the

>preview

>> would look like the print. But this is not the case.

>>

>> If I e.g. draw on the printercanvas in a given region of lets say 15 cm

>the

>> printer fits approx. 30 lines of text into this area. If I do the same

>with

>> the TImage it only fits 27-28 lines of text in the same region of 15 cm.

>>

>> This can leed to different number of pages send to the printer, and

>created

>> on the TImage as a preview. This can be pretty annoying.

>>

>> I calculate the width and height of my area in pixel with:

>>

>> function mmToPixel(mm:extended;dpi:integer):integer;

>> begin

>>    Result := round( (mm / 25.4) * dpi );

>> end;

>>

>> Where for the TImage dpi = GetDeviceCaps(TImage.Canvas.Handle, LOGPIXELSX)

>> and for the printer dpi = GetDeviceCaps(printer.Handle, LOGPIXELSX).

>>

>> I assume it might have something to do with the difference in resolution

>> ( 96 dpi <-> 600 dpi ) but I'm not sure.

>>

>> Furthermore in the TImage more characters can be fit in one line.

>>

>> To make it short: A page drawn to a printercanvas does not look like a

>page

>> drawn to an imagecanvas.

>>

>> Am I missing something or am I making something wrong?

>>

>> Perhaps you could enlighten me.

>>

>> Tia

>>

>> Frank Kroeger

>

>