freetype.h

下载来的一个看图软件的源代码

  {
    FT_Pos  width;         /* glyph width  */
    FT_Pos  height;        /* glyph height */

    FT_Pos  horiBearingX;  /* left side bearing in horizontal layouts */
    FT_Pos  horiBearingY;  /* top side bearing in horizontal layouts  */
    FT_Pos  horiAdvance;   /* advance width for horizontal layout     */

    FT_Pos  vertBearingX;  /* left side bearing in vertical layouts */
    FT_Pos  vertBearingY;  /* top side bearing in vertical layouts  */
    FT_Pos  vertAdvance;   /* advance height for vertical layout    */

  } FT_Glyph_Metrics;


  /*************************************************************************/
  /*                                                                       */
  /* <Struct>                                                              */
  /*    FT_Bitmap_Size                                                     */
  /*                                                                       */
  /* <Description>                                                         */
  /*    This structure models the size of a bitmap strike (i.e., a bitmap  */
  /*    instance of the font for a given resolution) in a fixed-size font  */
  /*    face.  It is used for the `available_sizes' field of the           */
  /*    @FT_FaceRec structure.                                             */
  /*                                                                       */
  /* <Fields>                                                              */
  /*    height :: The (vertical) baseline-to-baseline distance in pixels.  */
  /*              It makes most sense to define the height of a bitmap     */
  /*              font in this way.                                        */
  /*                                                                       */
  /*    width  :: The average width of the font (in pixels).  Since the    */
  /*              algorithms to compute this value are different for the   */
  /*              various bitmap formats, it can only give an additional   */
  /*              hint if the `height' value isn't sufficient to select    */
  /*              the proper font.  For monospaced fonts the average width */
  /*              is the same as the maximum width.                        */
  /*                                                                       */
  /*    size   :: The point size in 26.6 fractional format this font shall */
  /*              represent (for a given vertical resolution).             */
  /*                                                                       */
  /*    x_ppem :: The horizontal ppem value (in 26.6 fractional format).   */
  /*                                                                       */
  /*    y_ppem :: The vertical ppem value (in 26.6 fractional format).     */
  /*                                                                       */
  /* <Note>                                                                */
  /*    The values in this structure are taken from the bitmap font.  If   */
  /*    the font doesn't provide a parameter it is set to zero to indicate */
  /*    that the information is not available.                             */
  /*                                                                       */
  /*    The following formula converts from dpi to ppem:                   */
  /*                                                                       */
  /*      ppem = size * dpi / 72                                           */
  /*                                                                       */
  /*    where `size' is in points.                                         */
  /*                                                                       */
  /*    Windows FNT:                                                       */
  /*      The `size', `x_ppem', and `y_ppem' parameters are not reliable:  */
  /*      There exist fonts (e.g. app850.fon) which have a wrong size for  */
  /*      some subfonts; since FNT files don't contain ppem but dpi values */
  /*      the computed x_ppem and y_ppem numbers are thus wrong also.      */
  /*                                                                       */
  /*    TrueType embedded bitmaps:                                         */
  /*      `size', `width', and `height' values are not contained in the    */
  /*      bitmap strike itself.  They are computed from the global font    */
  /*      parameters.                                                      */
  /*                                                                       */
  typedef struct  FT_Bitmap_Size_
  {
    FT_Short  height;
    FT_Short  width;

    FT_Pos    size;

    FT_Pos    x_ppem;
    FT_Pos    y_ppem;

  } FT_Bitmap_Size;


  /*************************************************************************/
  /*************************************************************************/
  /*                                                                       */
  /*                     O B J E C T   C L A S S E S                       */
  /*                                                                       */
  /*************************************************************************/
  /*************************************************************************/

  /*************************************************************************/
  /*                                                                       */
  /* <Type>                                                                */
  /*    FT_Library                                                         */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A handle to a FreeType library instance.  Each `library' is        */
  /*    completely independent from the others; it is the `root' of a set  */
  /*    of objects like fonts, faces, sizes, etc.                          */
  /*                                                                       */
  /*    It also embeds a memory manager (see @FT_Memory), as well as a     */
  /*    scan-line converter object (see @FT_Raster).                       */
  /*                                                                       */
  /* <Note>                                                                */
  /*    Library objects are normally created by @FT_Init_FreeType, and     */
  /*    destroyed with @FT_Done_FreeType.                                  */
  /*                                                                       */
  typedef struct FT_LibraryRec_  *FT_Library;


  /*************************************************************************/
  /*                                                                       */
  /* <Type>                                                                */
  /*    FT_Module                                                          */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A handle to a given FreeType module object.  Each module can be a  */
  /*    font driver, a renderer, or anything else that provides services   */
  /*    to the formers.                                                    */
  /*                                                                       */
  typedef struct FT_ModuleRec_*  FT_Module;


  /*************************************************************************/
  /*                                                                       */
  /* <Type>                                                                */
  /*    FT_Driver                                                          */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A handle to a given FreeType font driver object.  Each font driver */
  /*    is a special module capable of creating faces from font files.     */
  /*                                                                       */
  typedef struct FT_DriverRec_*  FT_Driver;


  /*************************************************************************/
  /*                                                                       */
  /* <Type>                                                                */
  /*    FT_Renderer                                                        */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A handle to a given FreeType renderer.  A renderer is a special    */
  /*    module in charge of converting a glyph image to a bitmap, when     */
  /*    necessary.  Each renderer supports a given glyph image format, and */
  /*    one or more target surface depths.                                 */
  /*                                                                       */
  typedef struct FT_RendererRec_*  FT_Renderer;


  /*************************************************************************/
  /*                                                                       */
  /* <Type>                                                                */
  /*    FT_Face                                                            */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A handle to a given typographic face object.  A face object models */
  /*    a given typeface, in a given style.                                */
  /*                                                                       */
  /* <Note>                                                                */
  /*    Each face object also owns a single @FT_GlyphSlot object, as well  */
  /*    as one or more @FT_Size objects.                                   */
  /*                                                                       */
  /*    Use @FT_New_Face or @FT_Open_Face to create a new face object from */
  /*    a given filepathname or a custom input stream.                     */
  /*                                                                       */
  /*    Use @FT_Done_Face to destroy it (along with its slot and sizes).   */
  /*                                                                       */
  /* <Also>                                                                */
  /*    The @FT_FaceRec details the publicly accessible fields of a given  */
  /*    face object.                                                       */
  /*                                                                       */
  typedef struct FT_FaceRec_*  FT_Face;


  /*************************************************************************/
  /*                                                                       */
  /* <Type>                                                                */
  /*    FT_Size                                                            */
  /*                                                                       */
  /* <Description>                                                         */
  /*    A handle to a given size object.  Such an object models the data   */
  /*    that depends on the current _resolution_ and _character size_ in a */
  /*    given @FT_Face.                                                    */
  /*                                                                       */
  /* <Note>                                                                */
  /*    Each face object owns one or more sizes.  There is however a       */
  /*    single _active_ size for the face at any time that will be used by */
  /*    functions like @FT_Load_Glyph, @FT_Get_Kerning, etc.               */
  /*                                                                       */
  /*    You can use the @FT_Activate_Size API to change the current        */
  /*    active size of any given face.                                     */
  /*                                                                       */
  /* <Also>                                                                */
  /*    The @FT_SizeRec structure details the publicly accessible fields   */
  /*    of a given face object.                                            */
  /*                                                                       */
  typedef struct FT_SizeRec_*  FT_Size;


  /*************************************************************************/