Initial revision
diff --git a/src/libdraw/ml-lsetrefresh.c b/src/libdraw/ml-lsetrefresh.c
new file mode 100644
index 0000000..44079be
--- /dev/null
+++ b/src/libdraw/ml-lsetrefresh.c
@@ -0,0 +1,35 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+#include <memdraw.h>
+#include <memlayer.h>
+
+int
+memlsetrefresh(Memimage *i, Refreshfn fn, void *ptr)
+{
+ Memlayer *l;
+
+ l = i->layer;
+ if(l->refreshfn!=nil && fn!=nil){ /* just change functions */
+ l->refreshfn = fn;
+ l->refreshptr = ptr;
+ return 1;
+ }
+
+ if(l->refreshfn == nil){ /* is using backup image; just free it */
+ freememimage(l->save);
+ l->save = nil;
+ l->refreshfn = fn;
+ l->refreshptr = ptr;
+ return 1;
+ }
+
+ l->save = allocmemimage(i->r, i->chan);
+ if(l->save == nil)
+ return 0;
+ /* easiest way is just to update the entire save area */
+ l->refreshfn(i, i->r, l->refreshptr);
+ l->refreshfn = nil;
+ l->refreshptr = nil;
+ return 1;
+}
