Feathers（基于Starling的Adobe AIR库）列表控件在第二次实例化时不起作用

Question

I'm having a problem with a Feathers List control. It works the first time I enter the screen that contains the list, but the second time I enter that screen in the same app execution, the scrolling list doesn't scroll at all plus texts don't appear. No error appears in the console.

I've tried lots of stuff, but I still have the same problem: It only works the first time it's instantiated. If I exit the screen and come back, it doesn't work at all!

When exiting the screen it's disposed and when coming back to that screen it's a new instance of List. Why does it work only the first time?

Also, I tried not using a custom ItemRenderer at all, so only the images appear, no text, and still the same happens. The list doesn't respond to scroll events the SECOND time is instantiated. So it's not a problem with the ItemRenderer.

Ok, here's some code:

        typeList = new List();
        typeList.x = Settings.appResolution[0] - Settings.menuTypeColumnWidth;
        typeList.y = Settings.topBarHeight;
        typeList.width = Settings.menuTypeColumnWidth;
        typeList.height = Settings.appResolution[1] - Settings.topBarHeight;
        typeList.dataProvider = new ListCollection(listContents);
        typeList.itemRendererProperties['labelField'] = 'text';
        typeList.itemRendererProperties['accessoryLabelField'] = 'articles';
        typeList.itemRendererProperties['iconSourceField'] = 'thumbnail';
        var listLayout:VerticalLayout = new VerticalLayout();
        listLayout.gap = Settings.menuTypeItemGap;
        typeList.layout = listLayout;
        typeList.addEventListener(Event.CHANGE, onListChange);
        typeList.itemRendererType = MenuTypeItemRenderer;

As you can see it's nothing out of the ordinary.

Thanks for your help.

Answer 1

确定执行第二次实例化时，列表使用的ListCollection是否仍然可用？

_list.dataProvider = new ListCollection(items);

Answer 2

Here's a sample of code I've used. See if it offers any clues. I call the clearList function before the class is removed from the stage.

private function onAddedToStage(e:starling.events.Event):void {

removeEventListener(starling.events.Event.ADDED_TO_STAGE, onAddedToStage);
addEventListener(starling.events.Event.REMOVED_FROM_STAGE, onRemovedFromStage);


//only do this if a list does not already exist.
if(!_list){

items = new <ListItem>[];
for(var i:int = 0; i < 20; i++) {
items.push(new ListItem("Item text"));
}

_list = new List();
_list.itemRendererFactory = function():IListItemRenderer {
renderer = new ListItemRenderer();  
// pass your skins in here
renderer.defaultSkin = new Image(AssetManager.getAtlas().getTexture("listItemClear_normal"));
renderer.defaultSelectedSkin = new Image(AssetManager.getAtlas().getTexture("listItemClear_selected"));
return renderer;
};

vl = new VerticalLayout();  
vl.hasVariableItemDimensions = false;
_list.layout = vl;                      
_list.scrollerProperties.snapScrollPositionsToPixels = true;
_list.scrollerProperties.verticalScrollPolicy = Scroller.SCROLL_POLICY_AUTO;
_list.scrollerProperties.horizontalScrollPolicy = Scroller.SCROLL_POLICY_OFF;
_list.scrollerProperties.scrollBarDisplayMode = Scroller.SCROLL_BAR_DISPLAY_MODE_FLOAT;

//need to use a factory as we are not using a theme
_list.scrollerProperties.verticalScrollBarFactory = myScrollBarFactoryFunction;

_list.isSelectable = false;
_list.scrollerProperties.hasElasticEdges = true;
_list.itemRendererProperties.height = 60r;

_list.addEventListener(starling.events.Event.CHANGE, list_changeHandler);
_list.width = 320;
_list.height = StartUp._stageHeight;

addChild(_list);

_list.dataProvider = new ListCollection(items);
}
}



public function myScrollBarFactoryFunction():IScrollBar {

scrollBar = new SimpleScrollBar();
scrollBar.direction = SimpleScrollBar.DIRECTION_VERTICAL;
scrollBar.thumbProperties.defaultSkin = new Scale3Image(new Scale3Textures(AssetManager.getAtlas().getTexture("vertical-scroll-bar-thumb-skin"), 5, 14, Scale3Textures.DIRECTION_VERTICAL));      
scrollBar.thumbProperties.width = 4;
scrollBar.thumbProperties.minHeight = 20;
scrollBar.width = 4;
return scrollBar;

}


public function clearList():void {

if (_list) {
scrollBar = null;           
renderer = null;
vl = null;
removeChild(_list);     
_list = null;   

items.length = 0;
items = null;
}
}