Possible new function for Preview.

[rgesswein]

I've found the following function very handy for when I need to place RTF precisely on a canvas (and I won't be letting it span pages.) The function allows me to get the print rectangle so I can, for example, put the RTF so the last line sits at the bottom of the page.

Note this was pulled mostly from the Delphi forums, probably Peter Below's source originally. Feel free to use/include as you see fit.

Code: Select all

function TPrintPreview.getRichTextRect(var Rect: TRect; RichEdit: TCustomRichEdit; pOffset: PInteger=nil): Integer;
var
  Range: TFormatRange;
  OldMap: Integer;
  SaveRect: TRect;
  SaveIndex: Integer;
begin
  Result := -1;
  FillChar(Range, SizeOf(TFormatRange), 0);
  Range.hdc := Canvas.Handle;
  Range.hdcTarget := Range.hdc;
  Range.rc.Left := ConvertUnit(Rect.Left, Units, mmTWIPS);
  Range.rc.Top := ConvertUnit(Rect.Top, Units, mmTWIPS);
  Range.rc.Right := ConvertUnit(Rect.Right, Units, mmTWIPS);
  Range.rc.Bottom := ConvertUnit(Height, Units, mmTWIPS);
  Range.rcPage := Range.rc;
  Range.chrg.cpMax := -1;
  if pOffset = nil then
    Range.chrg.cpMin := 0
  else
    Range.chrg.cpMin := pOffset^;
  SaveRect := Range.rc;
  SaveIndex := SaveDC(Range.hdc);
  OldMap := SetMapMode(Range.hdc, MM_TEXT);
  RichEdit.Perform(EM_FORMATRANGE, 0, 0);
  try
    // Measure the text to find out how high the format rectangle
    // will be. The call sets fmtrange.rc.bottom to the actual height
    // required, if all characters in the selected range will fit into
    // a smaller rectangle,
    Range.chrg.cpMin := RichEdit.Perform( EM_FORMATRANGE, 0, Integer(@Range));
    if Range.chrg.cpMin >= RichEdit.GetTextLen then
    begin
      Rect.Bottom := ConvertUnit(Range.rc.Bottom, mmTWIPS, Units);
      Result := Rect.Bottom;
    end;
  finally
    RichEdit.Perform(EM_FORMATRANGE, 0, 0);
    RestoreDC(Range.hdc, SaveIndex);
    SetMapMode(Range.hdc, OldMap);
  end;
end;

[Kambiz]

Thank you very much for the code.
In the next release I'll add it to the component's interface.

Cheers,
Kambiz