Draws the specified page
procedure DrawPage(APageNo: Integer; ACanvas: TCanvas;
APreview: Boolean; AHeight: Integer);
APageNo – index of the page to draw. The first page has index = 1.
ACanvas – Canvas where to render the page. It's not necessary the same canvas as was used in Init, but must have the same resolution (and the same value of Font.PixelsPerInch)
The top left corner of the page is drawn at (0,0) coordinates.
APreview – should be set to True when drawing on the screen canvas, to False when drawing on printer canvas.
AHeight – height of this page; this value is used for drawing background.
This page must be formatted before drawing, see FormatNextPage.