(svn r16140) -Codechange: Call a function while contructing a widget tree.

src/widget.cpp

@@ -1400,13 +1400,15 @@ bool CompareWidgetArrays(const Widget *orig, const Widget *gen, bool report)
  * @param parts Array with parts of the nested widget.
  * @param count Length of the \a parts array.
  * @param dest  Address of pointer to use for returning the composed widget.
+ * @param fill_dest Fill the composed widget with child widgets.
  * @return Number of widget part elements used to compose the widget.
  */
-static int MakeNWidget(const NWidgetPart *parts, int count, NWidgetBase **dest)
+static int MakeNWidget(const NWidgetPart *parts, int count, NWidgetBase **dest, bool *fill_dest)
 {
 	int num_used = 0;
 
 	*dest = NULL;
+	*fill_dest = false;
 
 	while (count > num_used) {
 		switch (parts->type) {
@@ -1418,11 +1420,13 @@ static int MakeNWidget(const NWidgetPart *parts, int count, NWidgetBase **dest)
 			case NWID_HORIZONTAL:
 				if (*dest != NULL) return num_used;
 				*dest = new NWidgetHorizontal();
+				*fill_dest = true;
 				break;
 
 			case NWID_HORIZONTAL_LTR:
 				if (*dest != NULL) return num_used;
 				*dest = new NWidgetHorizontalLTR();
+				*fill_dest = true;
 				break;
 
 			case WWT_PANEL:
@@ -1430,11 +1434,19 @@ static int MakeNWidget(const NWidgetPart *parts, int count, NWidgetBase **dest)
 			case WWT_FRAME:
 				if (*dest != NULL) return num_used;
 				*dest = new NWidgetBackground(parts->type, parts->u.widget.colour, parts->u.widget.index);
+				*fill_dest = true;
 				break;
 
 			case NWID_VERTICAL:
 				if (*dest != NULL) return num_used;
 				*dest = new NWidgetVertical();
+				*fill_dest = true;
+				break;
+
+			case WPT_FUNCTION:
+				if (*dest != NULL) return num_used;
+				*dest = parts->u.func_ptr();
+				*fill_dest = false;
 				break;
 
 			case WPT_RESIZE: {
@@ -1550,7 +1562,8 @@ static int MakeWidgetTree(const NWidgetPart *parts, int count, NWidgetBase *pare
 	int total_used = 0;
 	while (true) {
 		NWidgetBase *sub_widget = NULL;
-		int num_used = MakeNWidget(parts, count - total_used, &sub_widget);
+		bool fill_sub = false;
+		int num_used = MakeNWidget(parts, count - total_used, &sub_widget, &fill_sub);
 		parts += num_used;
 		total_used += num_used;
 
@@ -1563,7 +1576,7 @@ static int MakeWidgetTree(const NWidgetPart *parts, int count, NWidgetBase *pare
 
 		/* If sub-widget is a container, recursively fill that container. */
 		WidgetType tp = sub_widget->type;
-		if (tp == NWID_HORIZONTAL || tp == NWID_HORIZONTAL_LTR || tp == NWID_VERTICAL || tp == WWT_PANEL || tp == WWT_FRAME || tp == WWT_INSET) {
+		if (fill_sub && (tp == NWID_HORIZONTAL || tp == NWID_HORIZONTAL_LTR || tp == NWID_VERTICAL || tp == WWT_PANEL || tp == WWT_FRAME || tp == WWT_INSET)) {
 			int num_used = MakeWidgetTree(parts, count - total_used, sub_widget);
 			parts += num_used;
 			total_used += num_used;

src/widget_type.h

@@ -112,6 +112,7 @@ enum WidgetType {
 	WPT_PADDING,      ///< Widget part for specifying a padding.
 	WPT_PIPSPACE,     ///< Widget part for specifying pre/inter/post space for containers.
 	WPT_ENDCONTAINER, ///< Widget part to denote end of a container.
+	WPT_FUNCTION,     ///< Widget part for calling a user function.
 
 	/* Pushable window widget types. */
 	WWT_MASK = 0x7F,
@@ -312,6 +313,9 @@ struct NWidgetPartPIP {
 	uint8 pre, inter, post; ///< Amount of space before/between/after child widgets.
 };
 
+/** Pointer to function returning a nested widget. */
+typedef NWidgetBase *NWidgetFunctionType();
+
 /** Partial widget specification to allow NWidgets to be written nested. */
 struct NWidgetPart {
 	WidgetType type;                         ///< Type of the part. @see NWidgetPartType.
@@ -323,6 +327,7 @@ struct NWidgetPart {
 		NWidgetPartWidget widget;        ///< Part with a start of a widget.
 		NWidgetPartPaddings padding;     ///< Part with paddings.
 		NWidgetPartPIP pip;              ///< Part with pre/inter/post spaces.
+		NWidgetFunctionType *func_ptr;   ///< Part with a function call.
 	} u;
 };
 
@@ -523,6 +528,16 @@ static inline NWidgetPart NWidget(WidgetType tp)
 	return part;
 }
 
+static inline NWidgetPart NWidgetFunction(NWidgetFunctionType *func_ptr)
+{
+	NWidgetPart part;
+
+	part.type = WPT_FUNCTION;
+	part.u.func_ptr = func_ptr;
+
+	return part;
+}
+
 NWidgetContainer *MakeNWidgets(const NWidgetPart *parts, int count);
 
 #endif /* WIDGET_TYPE_H */