How To Calculate the Point Font Size (264243)

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• Retrieve the notional-to-device transform (XFORMOBJ *pxo) for the specified font (FONTOBJ *pfo), as follows:

  	XFORMOBJ FONTOBJ_pxoGetXform(
  	    IN FONTOBJ  *pfo
  	    );
  
  					

• Download the associated xform transform (XFORML xform), as follows:

  	ULONG XFORMOBJ_iGetXform(
    	   IN XFORMOBJ  *pxo,
    	   OUT XFORML  *pxform
    	   );
  
  					

• Compute the the X and Y scale for the general case, as follows:

  	eXScale = sqrt(xform.eM11 * xform.eM11 + xform.eM12 * xform.eM12);
  	eYScale = sqrt(xform.eM22 * xform.eM22 + xform.eM21 * xform.eM21);
  					

• Find fwdUnitsPerEm (the em-height of the font) from the IFIMETRICS structure, by calling:

  	PIFIMETRICS DrvQueryFont(
  	   IN DHPDEV  dhpdev,
  	   IN ULONG_PTR  iFile,
  	   IN ULONG  iFace,
  	   IN ULONG  *pid
  	   );
  					

• Find sizLogResPpi, (the resolution of the device for which this font is realized) from the structure FONTOBJ *pfo (iFile and iFace are from the same FONTOBJ structure).
• Compute the point size by using the following formula:

  	iTmp = (int)(0.5 + eYScale * fwdUnitsPerEm * 72) / sizLogResPpi;