Possible Wording Error on FreeType Tutorial 1 Page

Hi There,

Please refer to your following page: FreeType Tutorial / I<https://freetype.org/freetype2/docs/tutorial/step1.html>

Please confirm/explain if the part that I’ve highlighted in Red below, is in error?

I mean... please kindly explain what it’s trying to say? “expressed in 1/64th of a pixel”, but then specifically... for “a character size of 12 points”? What about point sizes other than 12? (Sorry if I’m missing something, but that has me quite confused 😊)

Thank you in advance, cheers, Gary.



FreeType 2 uses size objects to model all information related to a given character size for a given face. For example, a size object holds the value of certain metrics like the ascender or text height, expressed in 1/64th of a pixel, for a character size of 12 points (however, those values are rounded to integers, i.e., multiples of 64).

When the FT_New_Face function is called (or one of its siblings), it automatically creates a new size object for the returned face. This size object is directly accessible as face−>size.

NOTE: A single face object can deal with one or more size objects at a time; however, this is something that few programmers really need to do. We have thus decided to make this feature available through additional functions.

When a new face object is created, all elements are set to 0 during initialization. To populate the structure with sensible values, you should call FT_Set_Char_Size<https://freetype.org/freetype2/docs/reference/ft2-base_interface.html#ft_set_char_size>. Here is an example, setting the character size to 16pt for a 300×300dpi device:



error = FT_Set_Char_Size(

          face,    /* handle to face object           */

          0,       /* char_width in 1/64th of points  */

          16*64,   /* char_height in 1/64th of points */

          300,     /* horizontal device resolution    */

          300 );   /* vertical device resolution      */

Some notes.

  *   The character widths and heights are specified in 1/64th of points. A point is a physical distance, equaling 1/72th of an inch. Normally, it is not equivalent to a pixel.
  *   Value of 0 for the character width means ‘same as character height’, value of 0 for the character height means ‘same as character width’. Otherwise, it is possible to specify different character widths and heights.
  *   The horizontal and vertical device resolutions are expressed in dots-per-inch, or dpi. Standard values are 72 or 96 dpi for display devices like the screen. The resolution is used to compute the character pixel size from the character point size.
  *   Value of 0 for the horizontal resolution means ‘same as vertical resolution’, value of 0 for the vertical resolution means ‘same as horizontal resolution’. If both values are zero, 72 dpi is used for both dimensions.
  *   The first argument is a handle to a face object, not a size object.
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