1 files changed, 107 insertions, 0 deletions
diff --git a/src/libdraw/ml-lorigin.c b/src/libdraw/ml-lorigin.c
new file mode 100644
index 00000000..0926ee8d
--- /dev/null
+++ b/src/libdraw/ml-lorigin.c
@@ -0,0 +1,107 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+#include <memdraw.h>
+#include <memlayer.h>
+
+/*
+ * Place i so i->r.min = log, i->layer->screenr.min == scr.
+*/
+int
+memlorigin(Memimage *i, Point log, Point scr)
+{
+	Memlayer *l;
+	Memscreen *s;
+	Memimage *t, *shad, *nsave;
+	Rectangle x, newr, oldr;
+	Point delta;
+	int overlap, eqlog, eqscr, wasclear;
+
+	l = i->layer;
+	s = l->screen;
+	oldr = l->screenr;
+	newr = Rect(scr.x, scr.y, scr.x+Dx(oldr), scr.y+Dy(oldr));
+	eqscr = eqpt(scr, oldr.min);
+	eqlog = eqpt(log, i->r.min);
+	if(eqscr && eqlog)
+		return 0;
+	nsave = nil;
+	if(eqlog==0 && l->save!=nil){
+		nsave = allocmemimage(Rect(log.x, log.y, log.x+Dx(oldr), log.y+Dy(oldr)), i->chan);
+		if(nsave == nil)
+			return -1;
+	}
+
+	/*
+	 * Bring it to front and move logical coordinate system.
+	 */
+	memltofront(i);
+	wasclear = l->clear;
+	if(nsave){
+		if(!wasclear)
+			memimagedraw(nsave, nsave->r, l->save, l->save->r.min, nil, Pt(0,0), S);
+		freememimage(l->save);
+		l->save = nsave;
+	}
+	delta = subpt(log, i->r.min);
+	i->r = rectaddpt(i->r, delta);
+	i->clipr = rectaddpt(i->clipr, delta);
+	l->delta = subpt(l->screenr.min, i->r.min);
+	if(eqscr)
+		return 0;
+
+	/*
+	 * To clean up old position, make a shadow window there, don't paint it,
+	 * push it behind this one, and (later) delete it.  Because the refresh function
+	 * for this fake window is a no-op, this will cause no graphics action except
+	 * to restore the background and expose the windows previously hidden.
+	 */
+	shad = memlalloc(s, oldr, memlnorefresh, nil, DNofill);
+	if(shad == nil)
+		return -1;
+	s->frontmost = i;
+	if(s->rearmost == i)
+		s->rearmost = shad;
+	else
+		l->rear->layer->front = shad;
+	shad->layer->front = i;
+	shad->layer->rear = l->rear;
+	l->rear = shad;
+	l->front = nil;
+	shad->layer->clear = 0;
+
+	/*
+	 * Shadow is now holding down the fort at the old position.
+	 * Move the window and hide things obscured by new position.
+	 */
+	for(t=l->rear->layer->rear; t!=nil; t=t->layer->rear){
+		x = newr;
+		overlap = rectclip(&x, t->layer->screenr);
+		if(overlap){
+			memlhide(t, x);
+			t->layer->clear = 0;
+		}
+	}
+	l->screenr = newr;
+	l->delta = subpt(scr, i->r.min);
+	l->clear = rectinrect(newr, l->screen->image->clipr);
+
+	/*
+	 * Everything's covered.  Copy to new position and delete shadow window.
+	 */
+	if(wasclear)
+		memdraw(s->image, newr, s->image, oldr.min, nil, Pt(0,0), S);
+	else
+		memlexpose(i, newr);
+	memldelete(shad);
+
+	return 1;
+}
+
+void
+memlnorefresh(Memimage *l, Rectangle r, void *v)
+{
+	USED(l);
+	USED(r.min.x);
+	USED(v);
+}