src/Fl_visual.cxx

   1 //
   2 // "$Id: Fl_visual.cxx 7903 2010-11-28 21:06:39Z matt $"
   3 //
   4 // Visual support for the Fast Light Tool Kit (FLTK).
   5 //
   6 // Copyright 1998-2010 by Bill Spitzak and others.
   7 //
   8 // This library is free software; you can redistribute it and/or
   9 // modify it under the terms of the GNU Library General Public
  10 // License as published by the Free Software Foundation; either
  11 // version 2 of the License, or (at your option) any later version.
  12 //
  13 // This library is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16 // Library General Public License for more details.
  17 //
  18 // You should have received a copy of the GNU Library General Public
  19 // License along with this library; if not, write to the Free Software
  20 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  21 // USA.
  22 //
  23 // Please report all bugs and problems on the following page:
  24 //
  25 //     http://www.fltk.org/str.php
  26 //
  27
  28 // Set the default visual according to passed switches:
  29
  30 #include <config.h>
  31 #include <FL/Fl.H>
  32 #include <FL/x.H>
  33
  34 /** \fn  Fl::visual(int flags)
  35     Selects a visual so that your graphics are drawn correctly.  This is
  36     only allowed before you call show() on any windows.  This does nothing
  37     if the default visual satisfies the capabilities, or if no visual
  38     satisfies the capabilities, or on systems that don't have such
  39     brain-dead notions.
  40
  41     <P>Only the following combinations do anything useful:
  42
  43     <UL>
  44     <LI>Fl::visual(FL_RGB)
  45     <BR>Full/true color (if there are several depths FLTK chooses  the
  46     largest).  Do this if you use fl_draw_image
  47     for much better (non-dithered)  output.
  48     <BR>&nbsp; </LI>
  49     <LI>Fl::visual(FL_RGB8)
  50     <BR>Full color with at least 24 bits of color. FL_RGB will
  51     always  pick this if available, but if not it will happily return a
  52     less-than-24 bit deep visual.  This call fails if 24 bits are not
  53     available.
  54     <BR>&nbsp; </LI>
  55     <LI>Fl::visual(FL_DOUBLE|FL_INDEX)
  56     <BR>Hardware double buffering.  Call this if you are going to use
  57     Fl_Double_Window.
  58     <BR>&nbsp; </LI>
  59     <LI>Fl::visual(FL_DOUBLE|FL_RGB)</LI>
  60     <LI>Fl::visual(FL_DOUBLE|FL_RGB8)
  61     <BR>Hardware double buffering and full color.
  62     </UL>
  63
  64     <P>This returns true if the system has the capabilities by default or
  65     FLTK suceeded in turing them on.  Your program will still work even if
  66     this returns false (it just won't look as good).
  67 */
  68 #ifdef WIN32
  69 int Fl::visual(int flags) {
  70   fl_GetDC(0);
  71   if (flags & FL_DOUBLE) return 0;
  72   if (!(flags & FL_INDEX) &&
  73     GetDeviceCaps(fl_gc,BITSPIXEL) <= 8) return 0;
  74   if ((flags & FL_RGB8) && GetDeviceCaps(fl_gc,BITSPIXEL)<24) return 0;
  75   return 1;
  76 }
  77 #elif defined(__APPLE__)
  78
  79 // \todo Mac : need to implement Visual flags
  80 int Fl::visual(int flags) {
  81   (void)flags;
  82   return 1;
  83 }
  84
  85 #else
  86
  87 static int test_visual(XVisualInfo& v, int flags) {
  88   if (v.screen != fl_screen) return 0;
  89 #if USE_COLORMAP
  90   if (!(flags & FL_INDEX)) {
  91     if (v.c_class != StaticColor && v.c_class != TrueColor) return 0;
  92     if (v.depth <= 8) return 0; // fltk will work better in colormap mode
  93   }
  94   if (flags & FL_RGB8) {
  95     if (v.depth < 24) return 0;
  96   }
  97   // for now, fltk does not like colormaps of more than 8 bits:
  98   if ((v.c_class&1) && v.depth > 8) return 0;
  99 #else
 100   // simpler if we can't use colormapped visuals at all:
 101   if (v.c_class != StaticColor && v.c_class != TrueColor) return 0;
 102 #endif
 103   return 1;
 104 }
 105
 106 int Fl::visual(int flags) {
 107   fl_open_display();
 108   // always use default if possible:
 109   if (test_visual(*fl_visual, flags)) return 1;
 110   // get all the visuals:
 111   XVisualInfo vTemplate;
 112   int num;
 113   XVisualInfo *visualList = XGetVisualInfo(fl_display, 0, &vTemplate, &num);
 114   // find all matches, use the one with greatest depth:
 115   XVisualInfo *found = 0;
 116   for (int i=0; i<num; i++) if (test_visual(visualList[i], flags)) {
 117     if (!found || found->depth < visualList[i].depth)
 118       found = &visualList[i];
 119   }
 120   if (!found) {XFree((void*)visualList); return 0;}
 121   fl_visual = found;
 122   fl_colormap = XCreateColormap(fl_display, RootWindow(fl_display,fl_screen),
 123                                 fl_visual->visual, AllocNone);
 124   return 1;
 125 }
 126
 127 #endif
 128
 129 //
 130 // End of "$Id: Fl_visual.cxx 7903 2010-11-28 21:06:39Z matt $".
 131 //