--- /dev/null
+#include "../kernel/dispatch.h"
+#include "../kernel/client.h"
+#include "../kernel/frame.h"
+#include "../kernel/stacking.h"
+#include "../kernel/screen.h"
+#include <glib.h>
+
+static int resistance = 10;
+static gboolean edge_resistance = TRUE; /* window-to-edge */
+static gboolean window_resistance = TRUE; /* window-to-window */
+
+static void resist(Client *c, int *x, int *y)
+{
+ GList *it;
+ Rect *area;
+ int l, t, r, b; /* requested edges */
+ int al, at, ar, ab; /* screen area edges */
+ int cl, ct, cr, cb; /* current edges */
+ int w, h; /* current size */
+ gboolean snapx = FALSE, snapy = FALSE;
+
+ if (!edge_resistance) return;
+
+ w = c->frame->area.width;
+ h = c->frame->area.height;
+
+ l = *x;
+ t = *y;
+ r = l + w - 1;
+ b = t + h - 1;
+
+ cl = c->frame->area.x;
+ ct = c->frame->area.y;
+ cr = cl + c->frame->area.width - 1;
+ cb = ct + c->frame->area.height - 1;
+
+ /* snap to other clients */
+ if (window_resistance)
+ for (it = stacking_list; it != NULL; it = it->next) {
+ Client *target;
+ int tl, tt, tr, tb; /* 1 past the target's edges on each side */
+
+ target = it->data;
+
+ tl = target->frame->area.x - 1;
+ tt = target->frame->area.y - 1;
+ tr = tl + target->frame->area.width + 1;
+ tb = tt + target->frame->area.height + 1;
+
+ /* snapx and snapy ensure that the window snaps to the top-most
+ window edge available, without going all the way from
+ bottom-to-top in the stacking list
+ */
+ if (!snapx && cl >= tr && l < tr && l >= tr - resistance)
+ *x = tr, snapx = TRUE;
+ else if (!snapx && cr <= tl && r > tl && r <= tl + resistance)
+ *x = tl - w + 1, snapx = TRUE;
+ else if (!snapy && ct >= tb && t < tb && t >= tb - resistance)
+ *y = tb, snapy = TRUE;
+ else if (!snapy && cb <= tt && b > tt && b <= tt + resistance)
+ *y = tt - h + 1, snapy = TRUE;
+
+ if (snapx && snapy) break;
+ }
+
+ /* get the screen boundaries */
+ area = screen_area(c->desktop);
+ al = area->x;
+ at = area->y;
+ ar = al + area->width - 1;
+ ab = at + area->height - 1;
+
+ /* snap to screen edges */
+ if (cl >= al && l < al && l >= al - resistance)
+ *x = al;
+ else if (cr <= ar && r > ar && r <= ar + resistance)
+ *x = ar - w + 1;
+ if (ct >= at && t < at && t >= at - resistance)
+ *y = at;
+ else if (cb <= ab && b > ab && b < ab + resistance)
+ *y = ab - h + 1;
+}
+
+static void event(ObEvent *e, void *foo)
+{
+ g_assert(e->type == Event_Client_Moving);
+
+ resist(e->data.c.client, &e->data.c.num[0], &e->data.c.num[1]);
+}
+
+void plugin_startup()
+{
+ dispatch_register(Event_Client_Moving, (EventHandler)event, NULL);
+}
+
+void plugin_shutdown()
+{
+ dispatch_register(0, (EventHandler)event, NULL);
+}