1 files changed, 35 insertions, 0 deletions
diff --git a/src/libdraw/ml-lsetrefresh.c b/src/libdraw/ml-lsetrefresh.c
new file mode 100644
index 00000000..44079be2
--- /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;
+}