How do I determine the height of a line of text in a TMemo programmatically?

Question

I\'ve got a TMemo, and I want to always make it exactly high enough to display the number of lines it contains. Unfortunately, I don\'t quite know how to calculate that. I

Answer 1

You need to use a TCanvas for this. You can either create a TBitMap in the background and use its TCanvas (after assigning the Memo's Font property to the Bitmap.Canvas' one), or use a TCanvas from another component. Somthing like this:

BMP:=TBitMap.Create;
TRY
  BMP.Canvas.Font.Assign(Memo.Font);
  TotalHeight:=0;
  FOR LineNo:=1 TO Memo.Lines.Count DO INC(TotalHeight,BMP.Canvas.TextHeight(Memo.Lines[PRED(I)]))
FINALLY
  FreeAndNIL(BMP)
END;

Edit:

Or perhaps this one:

BMP:=TBitMap.Create;
TRY
  BMP.Canvas.Font.Assign(Memo.Font);
  LineHeight:=BMP.Canvas.TextHeight('Wq');
  TotalHeight:=Memo.Lines.Count*LineHeight
FINALLY
  FreeAndNIL(BMP)
END;