[improve] (render) check part pixel under cursor

src/haxe/ru/m/puzzlez/render/Render.hx

@@ -133,18 +133,32 @@ class Render extends SpriteView implements IRender {
     }
 
     private function onMouseDown(event:MouseEvent):Void {
-        if (Std.is(event.target, PartView)) {
-            var part:PartView = event.target;
+        var point:FlashPoint = new FlashPoint(event.stageX, event.stageY);
+        var objects = tableView.getObjectsUnderPoint(point);
+        objects.reverse();
+        var pointPart:PartView = null;
+        for (object in objects) {
+            if (Std.is(object, PartView)) {
+                var part:PartView = cast object;
+                var partPoint = part.globalToLocal(point);
+                var color = part.image.shadedImage.getPixel(Std.int(partPoint.x), Std.int(partPoint.y));
+                if (color > 0) {
+                    pointPart = part;
+                    break;
+                }
+            }
+        }
+        if (pointPart != null) {
             if (event.ctrlKey) {
-                save(part);
+                save(pointPart);
                 return;
             }
-            if (part.completed) {
+            if (pointPart.completed) {
                 return;
             }
-            activePart = part;
+            activePart = pointPart;
             tableView.setChildIndex(activePart, tableView.numChildren - 1);
-            activePoint = tableView.globalToLocal(new FlashPoint(event.stageX, event.stageY));
+            activePoint = tableView.globalToLocal(point);
             tableView.stage.addEventListener(MouseEvent.MOUSE_MOVE, onMouseMove);
             tableView.stage.addEventListener(MouseEvent.MOUSE_UP, onMouseUp);
             signal.emit(ACTION(PART_TAKE(activePart.id)));