C++ element::is_valid方法代码示例

bool belongs_to( dom::element parent, dom::element child )
{
  if( !child.is_valid()) 
    return false;
  if( parent == child )
    return true;
  return belongs_to( parent, child.parent() );
}

    // select 
    bool select_tab( dom::element& tabs_el, dom::element& tab_el )
    {
      if(tab_el.get_state(STATE_CURRENT))
        // already selected, nothing to do...
        return true; // but we've handled it.
     
      //find currently selected element (tab and panel) and remove "selected" from them
      dom::element prev_panel_el = tabs_el.find_first(":root>[name]:expanded");
      dom::element prev_tab_el = tabs_el.find_first(":root>.strip>[panel]:current");

      // find new tab and panel       
      const wchar_t* pname = tab_el.get_attribute("panel");
      dom::element panel_el = tabs_el.find_first(":root>[name=\"%S\"]", pname);
      
      if( !panel_el.is_valid() || !tab_el.is_valid() )
      {
        assert(false); // panel="somename" without matching name="somename"
        return true;
      }

      if( prev_panel_el.is_valid() )
      {
        prev_panel_el.set_attribute("selected", 0); // remove selected attribute - just in case somone is using attribute selectors    
        prev_panel_el.set_state(STATE_COLLAPSED,0); // set collapsed in case of someone use it for styling
      }
      if( prev_tab_el.is_valid() )
      {
        prev_tab_el.set_attribute("selected", 0); // remove selected attribute
        prev_tab_el.set_state(0,STATE_CURRENT); // reset also state flag, :current
      }
      
      panel_el.set_attribute("selected", L""); // set selected attribute (empty)
      panel_el.set_state(STATE_EXPANDED,0); // expand it
      
      tab_el.set_attribute("selected", L""); // set selected attribute (empty)
      tab_el.set_state(STATE_CURRENT,0); // set also state flag, :current
                  
      // notify all parties involved
	  if (prev_tab_el.is_valid())
	  {
		  prev_tab_el.post_event(ELEMENT_COLLAPSED,0, prev_tab_el); // source here is old collapsed tab itself
	  }
      tab_el.post_event(ELEMENT_EXPANDED,0, tab_el);  // source here is new expanded tab itself
      // NOTE #1: these event will bubble from panel elements up to the root so panel itself, tabs ctl, its parent, etc.
      // will receive these notifications. Handle them if you need to change UI dependent from current tab. 
      // NOTE #2: while handling this event in:
      //        virtual BOOL on_event (HELEMENT he, HELEMENT target, BEHAVIOR_EVENTS type, UINT reason ),
      // HELEMENT target is the panel element being collapsed/expanded
      
      return true;
    }

    dom::element target_item(const dom::element& ctl, dom::element target)
    {
      if( target == ctl )
        return dom::element();

      if( !target.is_valid() )
        return target;

      dom::element target_parent = target.parent();
      if( !target_parent.is_valid() )
        return target;
      
      if( target.test("li > .caption") )
        return target_parent; // only if click on "caption" element of <li>. Returns that <li> element.

      return target_item( ctl, target.parent() );
    }

    virtual BOOL on_event (HELEMENT he, HELEMENT target, BEHAVIOR_EVENTS type, UINT_PTR reason ) 
    { 
      if( type != UI_STATE_CHANGED ) 
        return FALSE; // we handle only UI_STATE_CHANGED here.
      
      assert(objects_bar.is_valid());

      // call of getCurrentObjects method
      json::value stack = dom::element(he).xcall("getCurrentObjects"); 
      assert(stack.is_array());

      objects_bar.clear();
      int n = stack.length();
      for( int i = 0; i < n; ++i )
      {
        dom::element li = dom::element::create("li", stack.nth(i).to_string());
        objects_bar.append(li);
      }
      objects_bar.update();      
      return FALSE; /*mark it as not handled because some other behaviors in the chain may want to handle it */ 
    }

 dom::element target_row(const dom::element& table, const dom::element& target)
 {
   if( !target.is_valid() || target.parent() == table)
     return target;
   return target_row(table,target.parent());
 }

 dom::element target_header(const dom::element& header_row, const dom::element& target)
 {
   if( !target.is_valid() || target.parent() == header_row)
     return target;
   return target_header(header_row,target.parent());
 }