Re: [ft-devel] does the face cache really work ?

[Steve Hartwell]

Anstinus Anstinus wrote:

> Consider the situation: I looked up a FT_Face by myFaceID1 at first, 
> then at a later time, I want to get the same FT_Face.  Should I find 
> the myFaceID1 in my list and use it to lookup a FT_Face , or create a 
> new myFaceID2 with the same content as myFaceID1 ?

You should always pass the same FTC_FaceID (i.e. a pointer to a 
FTC_FaceIDRec_) to FTC_Manager_LookupFace(), not a (pointer to an) 
equivalent copy.  You can use an equivalent copy to compare against the 
ones you have in your list, but once you find a match, you must pass the 
one saved in your list to FTC_Manager_LookupFace() in order to get the 
same FT_Face back.

Note that FreeType does not define what a FTC_FaceIDRec_ is, only that 
it is a struct, and a FTC_FaceID is a pointer to it.  So, instead of 
having your own struct My_FaceID_Rec, you can declare in your program:

struct FTC_FaceIDRec_
{
   const char * file_path;
   int          face_index;
};

This eliminates a lot of unnecessary casting.

So to use a font face, you can write a function which takes a const char 
*file_path and an int face_index parameter and returns a FTC_FaceID.  
Use the two parameters to search your list for a match, and if found, 
return a pointer to it, else malloc a new struct FTC_FaceIDRec_, 
initialize it with a copy of the params, add it to the end of the list, 
and return a pointer to it.

Then whenever you want to access a FT_Face, you can call your function 
which maps a (file_path, face_index) to a FTC_FaceID, or use a 
FTC_FaceID that you have stored somewhere, to call 
FTC_Manager_LookupFace().

> Another question: The chars freetype rendered are all "solid". Can 
> freetype render only the outline without fill it ? I didn't find such 
> interface in documents.

Here's an example.  If it's not documented, I must have read the header 
file.

#include FT_STROKER_H

   FT_Stroker stroker;
   FT_Stroker_New(ftFace->memory, &stroker);
   FT_Stroker_Set(stroker, 32, FT_STROKER_LINECAP_ROUND, 
FT_STROKER_LINEJOIN_ROUND, 0);
   FT_Glyph_Stroke(&ftCachedGlyph, stroker, false); // false=don't 
destroy orig glyph
   FT_Stroker_Done(stroker);

HTH,

Steve Hartwell
http://stevehartwell.home.comcast.net/proj/fontinspector