git.hungrycats.org Git - xscreensaver/blob - utils/erase.c

   1 /* erase.c: Erase the screen in various more or less interesting ways.
   2  * (c) 1997 by Johannes Keukelaar <johannes@nada.kth.se>
   3  * Permission to use in any way granted. Provided "as is" without expressed
   4  * or implied warranty. NO WARRANTY, NO EXPRESSION OF SUITABILITY FOR ANY
   5  * PURPOSE. (I.e.: Use in any way, but at your own risk!)
   6  */
   7
   8 #include "utils.h"
   9 #include "yarandom.h"
  10 #include "usleep.h"
  11
  12 #define NUM_MODES 6
  13
  14 void
  15 erase_window(Display *dpy, Window window, GC gc,
  16              int width, int height, int mode, int delay)
  17 {
  18   int *clear_lines;
  19   int i, j, line, num_lines=0, granularity, max_num;
  20
  21   max_num = 2*height;
  22   if(2*width>max_num)
  23     max_num = 2*width;
  24
  25   clear_lines = (int *)calloc(max_num, sizeof(int));
  26   if(clear_lines)
  27     {
  28       if(mode<0 || mode>=NUM_MODES)
  29         mode = random()%NUM_MODES;
  30       granularity = 25;
  31       switch(mode)
  32         {
  33         case 0:
  34           for(i = 0; i < height; i++)
  35             clear_lines[i] = i;
  36           for(i = 0; i < height; i++)
  37             {
  38               int t, r;
  39               t = clear_lines[i];
  40               r = random()%height;
  41               clear_lines[i] = clear_lines[r];
  42               clear_lines[r] = t;
  43             }
  44           num_lines = height;
  45           break;
  46         case 1:
  47           for(i = 0; i < width; i++)
  48             clear_lines[i] = i+height;
  49           for(i = 0; i < width; i++)
  50             {
  51               int t, r;
  52               t = clear_lines[i];
  53               r = random()%width;
  54               clear_lines[i] = clear_lines[r];
  55               clear_lines[r] = t;
  56             }
  57           num_lines = width;
  58           break;
  59         case 2:
  60           for(i = 0; i < width/2; i++)
  61             clear_lines[i] = i*2+height;
  62           for(i = 0; i < height/2; i++)
  63             clear_lines[i+width/2] = i*2;
  64           for(i = 0; i < width/2; i++)
  65             clear_lines[i+width/2+height/2] = width-i*2-(width%2?0:1)+height;
  66           num_lines = width+height/2;
  67           granularity = 4;
  68           break;
  69         case 3:
  70           for(i = 0; i < max_num/4; i++)
  71             {
  72               clear_lines[i*4] = i*2;
  73               clear_lines[i*4+1] = height-i*2-(height%2?0:1);
  74               clear_lines[i*4+2] = height+i*2;
  75               clear_lines[i*4+3] = height+width-i*2-(width%2?0:1);
  76             }
  77           num_lines = max_num;
  78           granularity = 4;
  79           break;
  80         case 4:
  81           j = 0;
  82           for(i = 0; i < width*2; i++)
  83             {
  84               line = (i/16)*16-(i%16)*15;
  85               if(line>=0 && line<width)
  86                 {
  87                   clear_lines[j] = height+line;
  88                   j++;
  89                 }
  90             }
  91           num_lines = width;
  92           granularity = 4;
  93           break;
  94         case 5:
  95           j = 0;
  96           for(i = width*2; i >= 0; i--)
  97             {
  98               line = (i/16)*16-(i%16)*15;
  99               if(line>=0 && line<width)
 100                 {
 101                   clear_lines[j] = height+line;
 102                   j++;
 103                 }
 104             }
 105           num_lines = width;
 106           granularity = 4;
 107           break;
 108         }
 109       for (i = 0; i < num_lines; i++)
 110         {
 111           if(clear_lines[i] < height)
 112             XDrawLine (dpy, window, gc, 0, clear_lines[i], width,
 113                        clear_lines[i]);
 114           else
 115             XDrawLine (dpy, window, gc, clear_lines[i]-height, 0,
 116                        clear_lines[i]-height, height);
 117           XFlush (dpy);
 118           if ((i % granularity) == 0)
 119             {
 120               usleep (delay*granularity);
 121             }
 122         }
 123
 124       free(clear_lines);
 125     }
 126
 127   XClearWindow (dpy, window);
 128 }