1 files changed, 112 insertions, 0 deletions
diff --git a/src/libdraw/ml-layerop.c b/src/libdraw/ml-layerop.c
new file mode 100644
index 00000000..27fdcfc5
--- /dev/null
+++ b/src/libdraw/ml-layerop.c
@@ -0,0 +1,112 @@
+#include <u.h>
+#include <libc.h>
+#include <draw.h>
+#include <memdraw.h>
+#include <memlayer.h>
+
+#define	RECUR(a,b,c,d)	_layerop(fn, i, Rect(a.x, b.y, c.x, d.y), clipr, etc, front->layer->rear);
+
+static void
+_layerop(
+	void (*fn)(Memimage*, Rectangle, Rectangle, void*, int),
+	Memimage *i,
+	Rectangle r,
+	Rectangle clipr,
+	void *etc,
+	Memimage *front)
+{
+	Rectangle fr;
+
+    Top:
+	if(front == i){
+		/* no one is in front of this part of window; use the screen */
+		fn(i->layer->screen->image, r, clipr, etc, 0);
+		return;
+	}
+	fr = front->layer->screenr;
+	if(rectXrect(r, fr) == 0){
+		/* r doesn't touch this window; continue on next rearmost */
+		// assert(front && front->layer && front->layer->screen && front->layer->rear);
+		front = front->layer->rear;
+		goto Top;
+	}
+	if(fr.max.y < r.max.y){
+		RECUR(r.min, fr.max, r.max, r.max);
+		r.max.y = fr.max.y;
+	}
+	if(r.min.y < fr.min.y){
+		RECUR(r.min, r.min, r.max, fr.min);
+		r.min.y = fr.min.y;
+	}
+	if(fr.max.x < r.max.x){
+		RECUR(fr.max, r.min, r.max, r.max);
+		r.max.x = fr.max.x;
+	}
+	if(r.min.x < fr.min.x){
+		RECUR(r.min, r.min, fr.min, r.max);
+		r.min.x = fr.min.x;
+	}
+	/* r is covered by front, so put in save area */
+	(*fn)(i->layer->save, r, clipr, etc, 1);
+}
+
+/*
+ * Assumes incoming rectangle has already been clipped to i's logical r and clipr
+ */
+void
+_memlayerop(
+	void (*fn)(Memimage*, Rectangle, Rectangle, void*, int),
+	Memimage *i,
+	Rectangle screenr,	/* clipped to window boundaries */
+	Rectangle clipr,		/* clipped also to clipping rectangles of hierarchy */
+	void *etc)
+{
+	Memlayer *l;
+	Rectangle r, scr;
+
+	l = i->layer;
+	if(!rectclip(&screenr, l->screenr))
+		return;
+	if(l->clear){
+		fn(l->screen->image, screenr, clipr, etc, 0);
+		return;
+	}
+	r = screenr;
+	scr = l->screen->image->clipr;
+
+	/*
+	 * Do the piece on the screen
+	 */
+	if(rectclip(&screenr, scr))
+		_layerop(fn, i, screenr, clipr, etc, l->screen->frontmost);
+	if(rectinrect(r, scr))
+		return;
+
+	/*
+	 * Do the piece off the screen
+	*/
+	if(!rectXrect(r, scr)){
+		/* completely offscreen; easy */
+		fn(l->save, r, clipr, etc, 1);
+		return;
+	}
+	if(r.min.y < scr.min.y){
+		/* above screen */
+		fn(l->save, Rect(r.min.x, r.min.y, r.max.x, scr.min.y), clipr, etc, 1);
+		r.min.y = scr.min.y;
+	}
+	if(r.max.y > scr.max.y){
+		/* below screen */
+		fn(l->save, Rect(r.min.x, scr.max.y, r.max.x, r.max.y), clipr, etc, 1);
+		r.max.y = scr.max.y;
+	}
+	if(r.min.x < scr.min.x){
+		/* left of screen */
+		fn(l->save, Rect(r.min.x, r.min.y, scr.min.x, r.max.y), clipr, etc, 1);
+		r.min.x = scr.min.x;
+	}
+	if(r.max.x > scr.max.x){
+		/* right of screen */
+		fn(l->save, Rect(scr.max.x, r.min.y, r.max.x, r.max.y), clipr, etc, 1);
+	}
+}