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Smart Antialiasing

Antialiasing improves legibility for small sizes but is not that much useful for large sizes. To make a compromise between computation time, system resources and optical appearance it might be advantageous to use T1_AA_HIGH for small sizes, T1_AA_LOW for medium sizes and T1_AA_NONE for large sizes. Of course, for large sizes the non-antialiasing functions could be used which still need less resources.

In order to free the user from having to switch the antialiasing level explicitly, t1lib can be told to do this switching automatically, depending on the size requested. This is called Smart Antialiasing. It is disabled by default and can be toggled by a call to

 int T1_AASetSmartMode( int smart)

to 0pt The quantity smart should be either be T1_YES (which corresponds to 1) or T1_NO (which corresponds to 0. Notice that the current antialiasing level as set by T1_AASetLevel() is not affected by this. After having switched off smart antialiasing the former antialiasing level is restored. When smart antialiasing is active still has to take care for setting the lookup tables after a color change has happened.

The numerical limits of the requested size at which t1lib will switch between the different antialiasing levels may be specified using

 int T1_AASetSmartLimits( float limit1, float limit2)

to 0pt Here, limit1 is the value of size at which t1lib switches from T1_AA_HIGH to T1_AA_LOW and limit2 is the value of size at which t1lib switches from T1_AA_LOW to T1_AA_NONE. The default values are 20.0 for limit1 and 60.0 for limit2. This means for sizes smaller than 20.0 T1_AA_HIGH will be used and for sizes equal to or greater than 60.0 T1_AA_NONE will be used. The intermediate range is covered by T1_AA_LOW. These values are suitable for applications that display on screen when the device resolution has been left at the default value of 72 dpi.


next up previous contents index
Next: Caching of Antialiased Character Up: Antialiasing Previous: Setting Operating Parameters   Contents   Index
2005-01-12