Update Sprite when Texture changes

Make Sprite monitor its Texture for changes and trigger an update when the sprite changes.

(cherry picked from commit a23c0877f1)

scene/2d/sprite.cpp

@@ -111,7 +111,15 @@ void Sprite::set_texture(const Ref<Texture> &p_texture) {
 
 	if (p_texture == texture)
 		return;
+
+	if (texture.is_valid())
+		texture->remove_change_receptor(this);
+
 	texture = p_texture;
+
+	if (texture.is_valid())
+		texture->add_change_receptor(this);
+
 	update();
 	emit_signal("texture_changed");
 	item_rect_changed();
@@ -346,6 +354,15 @@ void Sprite::_validate_property(PropertyInfo &property) const {
 	}
 }
 
+void Sprite::_changed_callback(Object *p_changed, const char *p_prop) {
+
+	// Changes to the texture need to trigger an update to make
+	// the editor redraw the sprite with the updated texture.
+	if (texture.is_valid() && texture.ptr() == p_changed) {
+		update();
+	}
+}
+
 void Sprite::_bind_methods() {
 
 	ClassDB::bind_method(D_METHOD("set_texture", "texture"), &Sprite::set_texture);
@@ -418,3 +435,8 @@ Sprite::Sprite() {
 	vframes = 1;
 	hframes = 1;
 }
+
+Sprite::~Sprite() {
+	if (texture.is_valid())
+		texture->remove_change_receptor(this);
+}

scene/2d/sprite.h

@@ -64,6 +64,8 @@ protected:
 
 	virtual void _validate_property(PropertyInfo &property) const;
 
+	virtual void _changed_callback(Object *p_changed, const char *p_prop);
+
 public:
 	virtual void _edit_set_pivot(const Point2 &p_pivot);
 	virtual Point2 _edit_get_pivot() const;
@@ -108,6 +110,7 @@ public:
 	int get_hframes() const;
 
 	Sprite();
+	~Sprite();
 };
 
 #endif // SPRITE_H