Change DPI of lcl-pdf Unit

[Weitentaaal]

Hello,

the Unit "fpPDF" (C:\lazarus\fpc\3.2.0\source\packages\fcl-pdf\src) has a constant "cDefaultDPI" set to 72.
but when using Screen.PixelsperInch i get 96.

When Using functions like this:

Code: Pascal  [Select][+][-]

1. function PDFTomm(APixels: TPDFFloat): Single;
2. begin
3.   Result := (APixels * cInchToMM) / cDefaultDPI;
4. end;
5.  

i do not get the correct value for this:

Code: Pascal  [Select][+][-]

1.    PDFTomm(lFC.TextWidth(Tx, fFontSize))
2.  

if i use the correct DPI Value i get the correct String length, but then my other Values do not match this value.
can i somehow change it to this:

Code: Pascal  [Select][+][-]

1. function PDFTomm(APixels: TPDFFloat): Single;
2. begin
3.   Result := (APixels * cInchToMM) / Screen.PixelsPerInch;
4. end;
5.  

Example:
Code:

Code: Pascal  [Select][+][-]

1.    Pos1.Y:= Pos1.Y - fDSpace;
2.    Tx:= 'TESTING';
3.    P.WriteText(Pos1.X, Pos1.Y, Tx);
4.    //DPI 72
5.    Pos1.Y:= Pos1.Y - fDSpace;
6.    Tx:= 'TESTING';
7.    P.WriteText(Pos1.X +PDFTomm(lFC.TextWidth(Tx, fFontSize)), Pos1.Y, Tx);
8.    //DPI 96
9.    Pos1.Y:= Pos1.Y - fDSpace;
10.    Tx:= 'TESTING';
11.    P.WriteText(Pos1.X +(lFC.TextWidth(Tx, fFontSize)) * (25.4 / Screen.PixelsPerInch), Pos1.Y, Tx);
12.  

attached is what i draw whit this Code. I Added the same text 2 more times but the starting x Value adds up with the calculated Length of the String. i get the correct length with 96 dpi (Screen.PixelperInch)  but not the righ length with PDFToMM (Procedure from Unit "fpGUI", with constant 72 DPI).

Edit: noticed that my pdf "Paper" is smaller than others, but i was using:

Code: Pascal  [Select][+][-]

1.    P.PaperType:= ptA4;
2.