PtValidParent()

Identify a valid parent for the specified widget

Synopsis:

PtWidget_t * PtValidParent( 
                 PtWidget_t *widget_parent, 
                 PtWidgetClassRef_t *class_ref );

Description:

This function determines the real parent widget for widgets of type class_ref, given that its parent is specified as widget_parent when created or reparented. Examples of a class_ref include PtWidget, PtBasic, PtLabel, RtMeter, and so on.

The real parent of a widget might not be the specified widget_parent in special circumstances where the specified parent widget redirects the child to an alternate parent. Some examples:

• PtScrollArea redirects all widgets created as its children or reparented to it to its virtual canvas (a container widget within the scroll area).
• PtMenuBar redirects all widgets that aren't of type PtMenuButton to the PtMenuBar's parent (i.e. PtMenuBar accepts only PtMenuButton widgets as its children).

Returns:

A pointer to the widget that will be the real parent of any widgets of type class_ref created in or reparented to widget_parent.

Examples:

PtWidget_t *
MyRedirector( PtWidget_t *widget )
{
   MyWidget_t *my = (MyWidget_t * ) widget;

   PtWidget_t *parent;
   if( ( parent = 
           PtValidParent( my->scroll_area,
                          widget->class_ref ) ) == widget )
         return PtWidgetParent( widget );

   return( parent );

  /* 
   * Returning my->scroll_area would allow the child
   * to be created as a direct child of my->scroll_area.
   * This would be undesirable because scroll_area is a 
   * compound widget, which also needs to redirect its
   * children to work correctly.
   */
}

Classification:

Photon

See also:

PtFindGuardian(), PtGetParent(), PtGetParentWidget(), PtReParentWidget(), PtSetParentWidget(), PtWidgetParent()

"Ordering widgets" in the Creating Widgets in Application Code chapter of the Photon Programmer's Guide