add a jscene_owning() function to access scenes from widget scopes

include/justui/jfkeys.h

@@ -17,7 +17,7 @@
 
    * MENU KEYS are used for functions that open menus or navigate between tabs
      on a same application. The name comes from their primary usage in the
-     system apps. Navigation functions should be easilty reversible and fairly
+     system apps. Navigation functions should be easily reversible and fairly
      failproof. Menu keys are black rectangular keys with a chipped corner.
 
    * ENTRY KEYS are used for catalog entries such as the leaves of PRGM's many
@@ -29,8 +29,8 @@
 
    * SPECIAL KEYS are used for special functions, such as scrolling to the next
      set of functions keys when there are several pages, important functions
-     that should catch attention, or particulary unsafe actions. They are round
-     white keys.
+     that should catch attention, or particularly unsafe actions. They are
+     round white keys.
 
    On fx-CG 50, the keys are drawn dynamically using gint's default font, and
    specified using 6 strings that give the type and name of the keys:
@@ -40,10 +40,10 @@
    * "@NAME" for an action key;
    " "#NAME" for a special key.
 
-   The names are separated by semicolons, eg "/F1;;/F3;.F4;@F5;#F6". Several
+   The names are separated by semicolons, eg. "/F1;;/F3;.F4;@F5;#F6". Several
    sets of function keys can be defined if separated by a '|' character. For
    instance, "/F1;#F2|/F1" represents a function bar where the F2
-   function can be hidden by swithing from level 0 to level 1.
+   function can be hidden by switching from level 0 to level 1.
 
    On fx-9860G, there is not enough space to generate keys on-the-fly, so the
    full specification is just an image. The convention for the image is to be

include/justui/jscene.h

@@ -46,6 +46,11 @@ jscene *jscene_create(int x, int y, int w, int h, void *parent);
    The position is (0,0) and the size is (DWIDTH,DHEIGHT). */
 jscene *jscene_create_fullscreen(void *parent);
 
+/* jscene_owning(): Find the scene that manages a widget (if any)
+   This functions walks up the widget tree and locates the scene owning the
+   specified widget, if there is one; otherwise returns NULL. */
+jscene *jscene_owning(void *widget);
+
 /* jscene_layout(): Layout a scene
    This is automatically called by jscene_render(), but may be useful if you
    need to know the size of your widgets before rendering. The layout is

src/jscene.c

@@ -64,6 +64,17 @@ jscene *jscene_create_fullscreen(void *parent)
 	return jscene_create(0, 0, DWIDTH, DHEIGHT, parent);
 }
 
+jscene *jscene_owning(void *w0)
+{
+	J_CAST(w)
+
+	while(w) {
+		if(w->type == jscene_type_id) return (void *)w;
+		w = w->parent;
+	}
+	return NULL;
+}
+
 void jscene_render(jscene *scene)
 {
 	jwidget_layout(scene);