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fg_drawarc

Usage

   #include <fg.h>
   void far fg_drawarc(fg_color_t color, int mode, int mask,
                       fg_coord_t x, fg_coord_t y, fg_coord_t radius,
                       int startangle, int endangle,
                       fg_const_pbox_t clipbox);

Description


   Draw a circular arc counter-clockwise from startangle to endangle.

   Input

   x,y         Center of circle
   radius      Radius of circle
   clipbox     Bounding box of the arc.
   startangle  Value from 0-3600 (10ths of a degree)
   endangle    Value from 0-3600 (10ths of a degree)

   To draw a complete circle, use 0, 3600 for the start and end angles. Note
   that a zero radius or zero angular distance arc will be drawn as one
   pixel. 0 degrees is to the right, such that an arc drawn from 0 to 900
   will be in the upper right quadrant of the circle described by "radius".
   Although the units for the start and end angles are in 10ths of a degree,
   there is a maximum error of about 3 degrees for some angles.

   The arc is circular in pixel units. On most displays it will appear as an
   ellipse due to the difference in dimensions in the x and y directions of

   each pixel (the aspect ratio). If a circular appearance is required use
   fg_drawellipse with the appropriate scaling for the x and y radii
   calculated with the use of fg.pixelx and fg.pixely.

Example 


   fg_drawarc(FG_WHITE, FG_MODE_XOR, ~0, fg.displaybox [FG_X2]/2,
              fg.displaybox [FG_Y2] + 10, fg.displaybox [FG_Y2]/2,
              1800, 3600, fg.displaybox);
   /*
           This will result in the lower half of a circle being
           drawn with it's center above the top of the screen
   */