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Text File  |  1995-07-26  |  5.8 KB  |  133 lines
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  4.      TTTTkkkk____GGGGeeeettttGGGGCCCC((((3333))))                  TTTTkkkk (((( ))))                   TTTTkkkk____GGGGeeeettttGGGGCCCC((((3333))))
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  8.      _________________________________________________________________
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  10.      NNNNAAAAMMMMEEEE
  11.           Tk_GetGC,  Tk_FreeGC  -  maintain  database   of   read-only
  12.           graphics contexts
  13.  
  14.      SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
  15.           ####iiiinnnncccclllluuuuddddeeee <<<<ttttkkkk....hhhh>>>>
  16.  
  17.           GC
  18.           TTTTkkkk____GGGGeeeettttGGGGCCCC(_t_k_w_i_n, _v_a_l_u_e_M_a_s_k, _v_a_l_u_e_P_t_r)
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  20.           TTTTkkkk____FFFFrrrreeeeeeeeGGGGCCCC((((_d_i_s_p_l_a_y, _g_c)                                        |
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  22.      AAAARRRRGGGGUUUUMMMMEEEENNNNTTTTSSSS
  23.           Tk_Window       _t_k_w_i_n       (in)      Token  for  window  in
  24.                                                 which   the   graphics
  25.                                                 context will be used.
  26.  
  27.           unsigned long   _v_a_l_u_e_M_a_s_k   (in)      Mask of bits (such  as
  28.                                                 GGGGCCCCFFFFoooorrrreeeeggggrrrroooouuuunnnndddd        or
  29.                                                 GGGGCCCCSSSSttttiiiipppppppplllleeee)  indicating
  30.                                                 which     fields    of
  31.                                                 *_v_a_l_u_e_P_t_r are valid.
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  33.           XGCValues       *_v_a_l_u_e_P_t_r   (in)      Pointer  to  structure
  34.                                                 describing the desired
  35.                                                 values     for     the
  36.                                                 graphics context.
  37.  
  38.           Display         *_d_i_s_p_l_a_y    (in)      Display for  which  _g_c
  39.                                                 was allocated.          |
  40.  
  41.           GC              _g_c          (in)      X    identifier    for
  42.                                                 graphics  context that
  43.                                                 is no  longer  needed.
  44.                                                 Must     have     been
  45.                                                 allocated by TTTTkkkk____GGGGeeeettttGGGGCCCC.
  46.      _________________________________________________________________
  47.  
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  49.      DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
  50.           TTTTkkkk____GGGGeeeettttGGGGCCCC and  TTTTkkkk____FFFFrrrreeeeeeeeGGGGCCCC  manage  a  collection  of  graphics
  51.           contexts being used by an application.  The procedures allow
  52.           graphics contexts to be shared, thereby avoiding the  server
  53.           overhead  that  would  be  incurred  if  a  separate GC were
  54.           created for each use.  TTTTkkkk____GGGGeeeettttGGGGCCCC takes  arguments  describing
  55.           the desired graphics context and returns an X identifier for
  56.           a GC that fits the description.  The graphics  context  that
  57.           is  returned  will  have default values in all of the fields
  58.           not specified explicitly by _v_a_l_u_e_M_a_s_k and _v_a_l_u_e_P_t_r.
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  63.      Page 1                                          (printed 7/23/95)
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  70.      TTTTkkkk____GGGGeeeettttGGGGCCCC((((3333))))                  TTTTkkkk (((( ))))                   TTTTkkkk____GGGGeeeettttGGGGCCCC((((3333))))
  71.  
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  73.  
  74.           TTTTkkkk____GGGGeeeettttGGGGCCCC maintains a database of all the  graphics  contexts
  75.           it  has created.  Whenever possible, a call to TTTTkkkk____GGGGeeeettttGGGGCCCC will
  76.           return an existing graphics context rather than  creating  a
  77.           new  one.   This  approach  can  substantially reduce server
  78.           overhead, so TTTTkkkk____GGGGeeeettttGGGGCCCC should generally be used in preference
  79.           to  the  Xlib  procedure  XXXXCCCCrrrreeeeaaaatttteeeeGGGGCCCC,  which  creates  a  new
  80.           graphics context on each call.
  81.  
  82.           Since the return values  of  TTTTkkkk____GGGGeeeettttGGGGCCCC  are  shared,  callers
  83.           should  never  modify  the  graphics  contexts  returned  by
  84.           TTTTkkkk____GGGGeeeettttGGGGCCCC.   If  a  graphics   context   must   be   modified
  85.           dynamically,  then it should be created by calling XXXXCCCCrrrreeeeaaaatttteeeeGGGGCCCC
  86.           instead of TTTTkkkk____GGGGeeeettttGGGGCCCC.
  87.  
  88.           When a graphics  context  is  no  longer  needed,  TTTTkkkk____FFFFrrrreeeeeeeeGGGGCCCC
  89.           should be called to release it.  There should be exactly one
  90.           call to  TTTTkkkk____FFFFrrrreeeeeeeeGGGGCCCC  for  each  call  to  TTTTkkkk____GGGGeeeettttGGGGCCCC.   When  a
  91.           graphics  context  is no longer in use anywhere (i.e. it has
  92.           been freed as many times as it has  been  gotten)  TTTTkkkk____FFFFrrrreeeeeeeeGGGGCCCC
  93.           will  release  it  to  the  X  server and delete it from the
  94.           database.
  95.  
  96.  
  97.      KKKKEEEEYYYYWWWWOOOORRRRDDDDSSSS
  98.           graphics context
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  129.      Page 2                                          (printed 7/23/95)
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