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How can I find the necessary height of a TLabel?

Posted on 1998-06-27
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Last Modified: 2010-08-05
I am using a TLabel component with WordWrap=True and AutoSize=False.  (Screen space is limited).  The label is Red.  Since the text in the box can be different things, the actual number of lines of text changes.  What happens now is that sometimes the box is not full and so there is a blank line of red where there could have been extra text.  What I want to be able to do is find out how much space (or how many lines) the text occupies so I can change the Label.Height property so that blank red area is hidden.

I have been looking at the StdCtrls.Pas library code file and put together some code like this:

  with Label1.Canvas do
    begin
      Font := Label1.Font;
      H := TextHeight('0');
      StrPCopy(C, Label1.Caption);
      CLen := StrLen(C);
      R := Rect(8, 0, 0, H);
      DrawText(Label1.Canvas.Handle, C, CLen, R, DT_CalcRect Or DT_WORDBREAK or DT_LEFT);
    end;

As I understand it, it is SUPPOSED to return the size of the area needed in R but I'm getting some other data.  Any ideas???

Thanks!
/MP
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Question by:mikepj
2 Comments
 
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by:
AndreasSchindler earned 200 total points
ID: 1356075
const
  Alignments: array[TAlignment] of Word = (DT_LEFT, DT_RIGHT, DT_CENTER);
  WordWraps: array[Boolean] of Word = (0, DT_WORDBREAK);

var rect:TRect;
    Text:String;
    Drawstyle:Integer;
    h:Integer;
begin
    Rect := Label1.ClientRect;
    Text:=LAbel1.Caption;
    DrawStyle := DT_EXPANDTABS or WordWraps[LAbel1.WordWrap] or Alignments[LAbel1.Alignment];
    h:=DrawText(LAbel1.Canvas.Handle, PChar(Text), Length(Text), Rect, DrawStyle or DT_CALCRECT);
    LAbel1.height:=h;
end;

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Author Comment

by:mikepj
ID: 1356076
Thank you Andreas,

After a bit of work I got the following to work...  (There was something wrong with the DrawStyle arrays and I don't need them so I took them out).

Thank you for your help; the code works great!
/MP

var
  A: array[0..100] of Char;
  rect:TRect;
  Text:String;
  Drawstyle:Integer;
  h:Integer;
begin
  Label1.Caption:=Memo1.Lines[0];
  Rect := Label1.ClientRect;
  Text:=LAbel1.Caption;
  StrPCopy(A, Text);
  DrawStyle := DT_EXPANDTABS or DT_WordBreak Or DT_Left;
  h:=DrawText(LAbel1.Canvas.Handle, A, Length(Text), Rect, DrawStyle or DT_CALCRECT);
  LAbel1.height:=h;
end;

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