+typedef void (*Eraser) (Display *dpy, Window window, GC gc,
+ int width, int height, int delay, int granularity);
+
+
+static void
+random_lines (Display *dpy, Window window, GC gc,
+ int width, int height, int delay, int granularity)
+{
+ Bool horiz_p = (random() & 1);
+ int max = (horiz_p ? height : width);
+ int *lines = (int *) calloc(max, sizeof(*lines));
+ int i;
+
+ for (i = 0; i < max; i++)
+ lines[i] = i;
+
+ for (i = 0; i < max; i++)
+ {
+ int t, r;
+ t = lines[i];
+ r = random() % max;
+ lines[i] = lines[r];
+ lines[r] = t;
+ }
+
+ for (i = 0; i < max; i++)
+ {
+ if (horiz_p)
+ XDrawLine (dpy, window, gc, 0, lines[i], width, lines[i]);
+ else
+ XDrawLine (dpy, window, gc, lines[i], 0, lines[i], height);
+
+ XSync (dpy, False);
+ if (delay > 0 && ((i % granularity) == 0))
+ usleep (delay * granularity);
+ }
+ free(lines);
+}
+
+
+static void
+venetian (Display *dpy, Window window, GC gc,
+ int width, int height, int delay, int granularity)
+{
+ Bool horiz_p = (random() & 1);
+ Bool flip_p = (random() & 1);
+ int max = (horiz_p ? height : width);
+ int *lines = (int *) calloc(max, sizeof(*lines));
+ int i, j;
+
+ granularity /= 6;
+
+ j = 0;
+ for (i = 0; i < max*2; i++)
+ {
+ int line = ((i / 16) * 16) - ((i % 16) * 15);
+ if (line >= 0 && line < max)
+ lines[j++] = (flip_p ? max - line : line);
+ }
+
+ for (i = 0; i < max; i++)
+ {
+ if (horiz_p)
+ XDrawLine (dpy, window, gc, 0, lines[i], width, lines[i]);
+ else
+ XDrawLine (dpy, window, gc, lines[i], 0, lines[i], height);
+
+ XSync (dpy, False);
+ if (delay > 0 && ((i % granularity) == 0))
+ usleep (delay * granularity);
+ }
+ free(lines);
+}
+
+
+static void
+triple_wipe (Display *dpy, Window window, GC gc,
+ int width, int height, int delay, int granularity)
+{
+ Bool flip_x = random() & 1;
+ Bool flip_y = random() & 1;
+ int max = width + (height / 2);
+ int *lines = (int *)calloc(max, sizeof(int));
+ int i;
+
+ for(i = 0; i < width/2; i++)
+ lines[i] = i*2+height;
+ for(i = 0; i < height/2; i++)
+ lines[i+width/2] = i*2;
+ for(i = 0; i < width/2; i++)
+ lines[i+width/2+height/2] = width-i*2-(width%2?0:1)+height;
+
+ granularity /= 6;
+
+ for (i = 0; i < max; i++)
+ {
+ int x, y, x2, y2;
+ if (lines[i] < height)
+ x = 0, y = lines[i], x2 = width, y2 = y;
+ else
+ x = lines[i]-height, y = 0, x2 = x, y2 = height;
+
+ if (flip_x)
+ x = width-x, x2 = width-x2;
+ if (flip_y)
+ y = height-y, y2 = height-y2;
+
+ XDrawLine (dpy, window, gc, x, y, x2, y2);
+ XSync (dpy, False);
+ if (delay > 0 && ((i % granularity) == 0))
+ usleep (delay*granularity);
+ }
+ free(lines);
+}
+
+
+static void
+quad_wipe (Display *dpy, Window window, GC gc,
+ int width, int height, int delay, int granularity)
+{
+ Bool flip_x = random() & 1;
+ Bool flip_y = random() & 1;
+ int max = width + height;
+ int *lines = (int *)calloc(max, sizeof(int));
+ int i;
+
+ granularity /= 3;
+
+ for (i = 0; i < max/4; i++)
+ {
+ lines[i*4] = i*2;
+ lines[i*4+1] = height-i*2-(height%2?0:1);
+ lines[i*4+2] = height+i*2;
+ lines[i*4+3] = height+width-i*2-(width%2?0:1);
+ }
+
+ for (i = 0; i < max; i++)
+ {
+ int x, y, x2, y2;
+ if (lines[i] < height)
+ x = 0, y = lines[i], x2 = width, y2 = y;
+ else
+ x = lines[i]-height, y = 0, x2 = x, y2 = height;
+
+ if (flip_x)
+ x = width-x, x2 = width-x2;
+ if (flip_y)
+ y = height-y, y2 = height-y2;
+
+ XDrawLine (dpy, window, gc, x, y, x2, y2);
+ XSync (dpy, False);
+ if (delay > 0 && ((i % granularity) == 0))
+ usleep (delay*granularity);
+ }
+ free(lines);
+}
+
+
+
+static void
+circle_wipe (Display *dpy, Window window, GC gc,
+ int width, int height, int delay, int granularity)
+{
+ int full = 360 * 64;
+ int inc = full / 64;
+ int start = random() % full;
+ int rad = (width > height ? width : height);
+ int i;
+ if (random() & 1)
+ inc = -inc;
+ for (i = (inc > 0 ? 0 : full);
+ (inc > 0 ? i < full : i > 0);
+ i += inc)
+ {
+ XFillArc(dpy, window, gc,
+ (width/2)-rad, (height/2)-rad, rad*2, rad*2,
+ (i+start) % full, inc);
+ XFlush (dpy);
+ usleep (delay*granularity);
+ }
+}
+
+
+static void
+three_circle_wipe (Display *dpy, Window window, GC gc,
+ int width, int height, int delay, int granularity)
+{
+ int i;
+ int full = 360 * 64;
+ int q = full / 6;
+ int q2 = q * 2;
+ int inc = full / 240;
+ int start = random() % q;
+ int rad = (width > height ? width : height);
+
+ for (i = 0; i < q; i += inc)
+ {
+ XFillArc(dpy, window, gc, (width/2)-rad, (height/2)-rad, rad*2, rad*2,
+ (start+i) % full, inc);
+ XFillArc(dpy, window, gc, (width/2)-rad, (height/2)-rad, rad*2, rad*2,
+ (start-i) % full, -inc);
+
+ XFillArc(dpy, window, gc, (width/2)-rad, (height/2)-rad, rad*2, rad*2,
+ (start+q2+i) % full, inc);
+ XFillArc(dpy, window, gc, (width/2)-rad, (height/2)-rad, rad*2, rad*2,
+ (start+q2-i) % full, -inc);
+
+ XFillArc(dpy, window, gc, (width/2)-rad, (height/2)-rad, rad*2, rad*2,
+ (start+q2+q2+i) % full, inc);
+ XFillArc(dpy, window, gc, (width/2)-rad, (height/2)-rad, rad*2, rad*2,
+ (start+q2+q2-i) % full, -inc);
+
+ XSync (dpy, False);
+ usleep (delay*granularity);
+ }
+}
+
+
+static void
+squaretate (Display *dpy, Window window, GC gc,
+ int width, int height, int delay, int granularity)
+{
+ int steps = (((width > height ? width : width) * 2) / granularity);
+ int i;
+ Bool flip = random() & 1;
+
+#define DRAW() \
+ if (flip) { \
+ points[0].x = width-points[0].x; \
+ points[1].x = width-points[1].x; \
+ points[2].x = width-points[2].x; } \
+ XFillPolygon (dpy, window, gc, points, 3, Convex, CoordModeOrigin)
+
+ for (i = 0; i < steps; i++)
+ {
+ XPoint points [3];
+ points[0].x = 0;
+ points[0].y = 0;
+ points[1].x = width;
+ points[1].y = 0;
+ points[2].x = 0;
+ points[2].y = points[0].y + ((i * height) / steps);
+ DRAW();
+
+ points[0].x = 0;
+ points[0].y = 0;
+ points[1].x = 0;
+ points[1].y = height;
+ points[2].x = ((i * width) / steps);
+ points[2].y = height;
+ DRAW();
+
+ points[0].x = width;
+ points[0].y = height;
+ points[1].x = 0;
+ points[1].y = height;
+ points[2].x = width;
+ points[2].y = height - ((i * height) / steps);
+ DRAW();
+
+ points[0].x = width;
+ points[0].y = height;
+ points[1].x = width;
+ points[1].y = 0;
+ points[2].x = width - ((i * width) / steps);
+ points[2].y = 0;
+ DRAW();
+
+ XSync (dpy, True);
+ if (delay > 0)
+ usleep (delay * granularity);
+ }
+#undef DRAW
+}
+
+
+/* from Frederick Roeber <roeber@netscape.com> */
+static void
+fizzle (Display *dpy, Window window, GC gc,
+ int width, int height, int delay, int granularity)
+{
+ /* These dimensions must be prime numbers. They should be roughly the
+ square root of the width and height. */
+# define BX 31
+# define BY 31
+# define SIZE (BX*BY)
+
+ int array[SIZE];
+ int i, j;
+ XPoint *skews;
+ int nx, ny;
+
+ /* Distribute the numbers [0,SIZE) randomly in the array */
+ {
+ int indices[SIZE];
+
+ for( i = 0; i < SIZE; i++ ) {
+ array[i] = -1;
+ indices[i] = i;
+ }
+
+ for( i = 0; i < SIZE; i++ ) {
+ j = random()%(SIZE-i);
+ array[indices[j]] = i;
+ indices[j] = indices[SIZE-i-1];
+ }
+ }
+
+ /* nx, ny are the number of cells across and down, rounded up */
+ nx = width / BX + (0 == (width %BX) ? 0 : 1);
+ ny = height / BY + (0 == (height%BY) ? 0 : 1);
+ skews = (XPoint *)malloc(sizeof(XPoint) * (nx*ny));
+ if( (XPoint *)0 != skews ) {
+ for( i = 0; i < nx; i++ ) {
+ for( j = 0; j < ny; j++ ) {
+ skews[j * nx + i].x = random()%BX;
+ skews[j * nx + i].y = random()%BY;
+ }
+ }
+ }
+
+# define SKEWX(cx, cy) (((XPoint *)0 == skews)?0:skews[cy*nx + cx].x)
+# define SKEWY(cx, cy) (((XPoint *)0 == skews)?0:skews[cy*nx + cx].y)
+
+ for( i = 0; i < SIZE; i++ ) {
+ int x = array[i] % BX;
+ int y = array[i] / BX;
+
+ {
+ int iy, cy;
+ for( iy = 0, cy = 0; iy < height; iy += BY, cy++ ) {
+ int ix, cx;
+ for( ix = 0, cx = 0; ix < width; ix += BX, cx++ ) {
+ int xx = ix + (SKEWX(cx, cy) + x*((cx%(BX-1))+1))%BX;
+ int yy = iy + (SKEWY(cx, cy) + y*((cy%(BY-1))+1))%BY;
+ XDrawPoint(dpy, window, gc, xx, yy);
+ }
+ }
+ }
+
+ if( (BX-1) == (i%BX) ) {
+ XSync (dpy, False);
+ usleep (delay*granularity);
+ }
+ }
+
+# undef SKEWX
+# undef SKEWY
+
+ if( (XPoint *)0 != skews ) {
+ free(skews);
+ }
+
+# undef BX
+# undef BY
+# undef SIZE
+}
+
+
+/* from Rick Campbell <rick@campbellcentral.org> */
+static void
+spiral (Display *display, Window window, GC context,
+ int width, int height, int delay, int granularity)