Windows phone 7列表框ArrangeOverride无法工作？

Question

我重写了列表框的ArrangeOverride方法，希望像这样显示itemSource：(我在PrepareContainerForItemOverride方法上整理DependencyObject )

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.

......100

但是当我滚动滚动条时，数组的变化是这样的：

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protected override Size ArrangeOverride(Size finalSize)
    {
        if (this._ItemsDictionary.Count <= 0)
        {
            return base.ArrangeOverride(finalSize);
        }
        base.ArrangeOverride(finalSize);
        finalSize = this.MeasureOverride(_availableSize);

        double xMemory = 0;
        double yMemory = 0;
        double maxBoderWidth = 0;
        double maxHeight = 0;

        foreach (FrameworkElement element in _ItemsDictionary.Values)
        {
            if (xMemory + element.DesiredSize.Width <= finalSize.Width)
            {
                element.Arrange(new Rect(xMemory, yMemory, element.DesiredSize.Width, element.DesiredSize.Height));
                xMemory += element.DesiredSize.Width;
                maxHeight = Math.Max(element.DesiredSize.Height, maxHeight);
            }
            else
            {
                yMemory += maxHeight;
                maxBoderWidth = Math.Max(maxBoderWidth, xMemory);
                xMemory = 0;
                maxHeight = 0;

                element.Arrange(new Rect(xMemory, yMemory, element.DesiredSize.Width, element.DesiredSize.Height));
                xMemory += element.DesiredSize.Width;
                maxHeight = Math.Max(element.DesiredSize.Height, maxHeight);
            }
        }
        return finalSize;
    }

    protected override void PrepareContainerForItemOverride(DependencyObject element, object item)
    {
        base.PrepareContainerForItemOverride(element, item);
        FrameworkElement fElement = element as FrameworkElement;
        if (!_ItemsDictionary.ContainsKey(item))
        {
            _ItemsDictionary.Add(item, fElement);
        }
    }

Answer 1

我可能错了。但是您的基类似乎是ItemsPresenter (或从它继承的东西，如ListBox)。这不是一个好的idia。因为每个ItemsPresenter都有自己的ItemsPanel！和Silverlight使用此面板对项目进行布局。因此ItemsPresenter不能直接布局它自己的项目，只能使用ItemsPanel面板。

1)我推荐你使用WrapPanel (它是Silverlight SDK的一部分)，这样你就可以免费使用它了，我想这就是你想要的。只需用WrapPanel替换ListBox.ItemsPanel属性，您就会得到想要的结果

2)如果你想创建你自己的面板，你最好创建新的类并从Panel继承它

public class SomeNewPanel: Panel
{
    protected override System.Windows.Size MeasureOverride(System.Windows.Size availableSize)
    {
        //you can add here your custom measure logic
        return base.MeasureOverride(availableSize);
    }

    protected override System.Windows.Size ArrangeOverride(System.Windows.Size finalSize)
    {
        //you can add here your custom arrange logic
        return base.ArrangeOverride(finalSize);
    }
}

然后像这样在ListBox中使用它。

<Page x:Class="SilverlightApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    <!--Don't forget to add namespace of your newly created panel-->
    xmlns:local="clr-namespace:SilverlightApplication1"
    Title="MainWindow" Height="350" Width="525">
<Grid>
    <ListBox x:Name="listBox1" ItemsSource="{Binding SomeItemSource}">
        <!--ItemPanel property set or get Panel that-->
        <!--will be used for layouting items-->
        <ListBox.ItemsPanel>

            <!--Here you and your newly created panle-->
            <local:SomeNewPanel/>

        </ListBox.ItemsPanel>
    </ListBox>
</Grid>
</Page>