1 files changed, 69 insertions, 0 deletions
diff --git a/src/libmemlayer/ltorear.c b/src/libmemlayer/ltorear.c
new file mode 100644
index 00000000..d53e8cc9
--- /dev/null
+++ b/src/libmemlayer/ltorear.c
@@ -0,0 +1,69 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+#include <memdraw.h>
+#include <memlayer.h>
+
+void
+_memltorear(Memimage *i, Memimage *rear)
+{
+	Memlayer *l;
+	Memscreen *s;
+	Memimage *f, *r, *rr;
+	Rectangle x;
+	int overlap;
+
+	l = i->layer;
+	s = l->screen;
+	while(l->rear != rear){
+		r = l->rear;
+		x = l->screenr;
+		overlap = rectclip(&x, r->layer->screenr);
+		if(overlap){
+			memlhide(i, x);
+			l->clear = 0;
+		}
+		/* swap l and r in screen's list */
+		rr = r->layer->rear;
+		f = l->front;
+		if(rr == nil)
+			s->rearmost = i;
+		else
+			rr->layer->front = i;
+		if(f == nil)
+			s->frontmost = r;
+		else
+			f->layer->rear = r;
+		l->rear = rr;
+		l->front = r;
+		r->layer->rear = i;
+		r->layer->front = f;
+		if(overlap)
+			memlexpose(r, x);
+	}
+}
+
+void
+memltorear(Memimage *i)
+{
+	_memltorear(i, nil);
+	_memlsetclear(i->layer->screen);
+}
+
+void
+memltorearn(Memimage **ip, int n)
+{
+	Memimage *i, *rear;
+	Memscreen *s;
+
+	if(n == 0)
+		return;
+	rear = nil;
+	while(--n >= 0){
+		i = *ip++;
+		_memltorear(i, rear);
+		rear = i;
+	}
+	s = rear->layer->screen;
+	_memlsetclear(s);
+}