Delphi - Draw text multiline in the centre of a rect

Question

In Delphi i wish to draw text inside a TRect. I am hoping for the following functionality:

Draw the text centred vertically within the TRect
Draw the text centred horizontally within the TRect
If there is space for more than 1 line of text (using TRect's height), draw the text multiline
If the text does not fit in the TRect (either on a single or mult line) then append ellipsis to the text.

I can see the Windows.DrawText() function almost covers this functionality, however when writing text, multiline and vertically centred are mutually exclusive.

I was wondering if this functionality is built into windows (2000+)? If not is there a way to do this without writing my own function?

Can't you use TLabel? I think it has all the functionality required. — Andriy M
Yes it probably does, but i do not want to use a label, i have a canvas to draw on. — Simon

NGLN NGLN · Accepted Answer · 2011-08-10T11:41:33

Sorry, this is a combination of all previous answers and comments. But it seems OP needs more assistance.

function DrawTextCentered(Canvas: TCanvas; const R: TRect; S: String): Integer;
var
  DrawRect: TRect;
  DrawFlags: Cardinal;
  DrawParams: TDrawTextParams;
begin
  DrawRect := R;
  DrawFlags := DT_END_ELLIPSIS or DT_NOPREFIX or DT_WORDBREAK or
    DT_EDITCONTROL or DT_CENTER;
  DrawText(Canvas.Handle, PChar(S), -1, DrawRect, DrawFlags or DT_CALCRECT);
  DrawRect.Right := R.Right;
  if DrawRect.Bottom < R.Bottom then
    OffsetRect(DrawRect, 0, (R.Bottom - DrawRect.Bottom) div 2)
  else
    DrawRect.Bottom := R.Bottom;
  ZeroMemory(@DrawParams, SizeOf(DrawParams));
  DrawParams.cbSize := SizeOf(DrawParams);
  DrawTextEx(Canvas.Handle, PChar(S), -1, DrawRect, DrawFlags, @DrawParams);
  Result := DrawParams.uiLengthDrawn;
end;

procedure TForm1.FormPaint(Sender: TObject);
const
  S = 'This is a very long text as test case for my paint routine.';
var
  R: TRect;
begin
  SetRect(R, 100, 100, 200, 140);
  Canvas.Rectangle(R);
  InflateRect(R, -1, -1);
  Caption := Format('%d characters drawn', [DrawTextCentered(Canvas, R, S)]);
end;

Delphi - Draw text multiline in the centre of a rect

2 Answers