如何使Silverlight ScrollViewer滚动以显示具有焦点的子控件?

我用Silverlight 3测试了这个。我对SL2不太确定。

这是我的XAML:

<ScrollViewer Height="200" Width="200" KeyUp="ScrollViewer_KeyUp">
    <StackPanel>
        <Button Content="1" Height="20" />
        <Button Content="2" Height="20" />
        <Button Content="3" Height="20" />
        <Button Content="4" Height="20" />
        <Button Content="5" Height="20" />
        <Button Content="6" Height="20" />
        <Button Content="7" Height="20" />
        <Button Content="8" Height="20" />
        <Button Content="9" Height="20" />
    <Button Content="10" Height="20" />
        <Button Content="11" Height="20" />
        <Button Content="12" Height="20" />
        <Button Content="13" Height="20" />
        <Button Content="14" Height="20" />
        <Button Content="15" Height="20" />
        <Button Content="16" Height="20" />
        <Button Content="17" Height="20" />
        <Button Content="18" Height="20" />
        <Button Content="19" Height="20" />
        <Button Content="20" Height="20" />
    </StackPanel>
</ScrollViewer>

下面是代码:

private void ScrollViewer_KeyUp(object sender, KeyEventArgs e)
{
    ScrollViewer scrollViewer = sender as ScrollViewer;
    FrameworkElement focusedElement = FocusManager.GetFocusedElement() as FrameworkElement;
    GeneralTransform focusedVisualTransform = focusedElement.TransformToVisual(scrollViewer);
    Rect rectangle = focusedVisualTransform.TransformBounds(new Rect(new Point(focusedElement.Margin.Left, focusedElement.Margin.Top), focusedElement.RenderSize));
    double newOffset = scrollViewer.VerticalOffset + (rectangle.Bottom - scrollViewer.ViewportHeight);
    scrollViewer.ScrollToVerticalOffset(newOffset);
}

我所做的就是点击按钮1和标签,直到我到达按钮20。这对我很有用。试一试,让我知道它是如何为你工作的。

Silverlight工具包包含一个方法“ScrollIntoView”。

添加对system.windows.controls.toolkit.dll的引用,您应该能够使用下面的代码。

scrollViewer.ScrollIntoView(control);

只是轻微的增强。顺便说一下,对于Silverlight4仍然需要这样做。 您可以处理ScrollViewer本身的gotfocus并只实现一次,而不是对每个控件使用gotfocus。

 private void _ScrollViewer_GotFocus(object sender, RoutedEventArgs e)
        {
            FrameworkElement element = e.OriginalSource as FrameworkElement;

            if (element != null)
            {
                ScrollViewer scrollViewer = sender as ScrollViewer;
                scrollViewer.ScrollToVerticalOffset(GetVerticalOffset(element, scrollViewer));
            }

        }

        private double GetVerticalOffset(FrameworkElement child, ScrollViewer scrollViewer)
        {
            // Ensure the control is scrolled into view in the ScrollViewer. 
            GeneralTransform focusedVisualTransform = child.TransformToVisual(scrollViewer);
            Point topLeft = focusedVisualTransform.Transform(new Point(child.Margin.Left, child.Margin.Top));
            Rect rectangle = new Rect(topLeft, child.RenderSize);
            double newOffset = scrollViewer.VerticalOffset + (rectangle.Bottom - scrollViewer.ViewportHeight);
            return newOffset < 0 ? 0 : newOffset; // no use returning negative offset
        }

在上面基里尔的回答的帮助下,我把这个问题解决了。一般情况下,我的应用程序中有用户可定义的表单,并且此代码用于呈现表单上的控件。

我的一般策略是将控件添加到网格中,然后使用VisualTreeHelper查找ScrollViewer的所有子级,并向每个控件添加GotFocus事件处理程序。

当控件获得焦点时,再次使用VisualTreeHelper,我搜索可视化树以查找其父级是ScrollViewer滚动的网格的控件。然后滚动滚动滚动查看器使控件可见。

以下是代码(GridRender是添加控件的网格):

private void AfterFormRendered()
{
    var controls = VisualTreeHelperUtil.FindChildren<Control>(gridRender);
    foreach (var ctrl in controls)
    {
        ctrl.GotFocus += CtrlGotFocus;
    }
}

private void CtrlGotFocus(object sender, RoutedEventArgs e)
{
    var ctrl = sender as Control;
    var gridChildControl = VisualTreeHelperUtil.FindParentWithParent(ctrl, gridRender) as FrameworkElement;

    if (gridChildControl != null)
    {
        // Ensure the control is scrolled into view in the ScrollViewer.
        GeneralTransform focusedVisualTransform = gridChildControl.TransformToVisual(scrollViewer);
        Point topLeft = focusedVisualTransform.Transform(new Point(gridChildControl.Margin.Left, gridChildControl.Margin.Top));
        Rect rectangle = new Rect(topLeft, gridChildControl.RenderSize);
        double newOffset = scrollViewer.VerticalOffset + (rectangle.Bottom - scrollViewer.ViewportHeight);    

        scrollViewer.ScrollToVerticalOffset(newOffset);
    }
}

注意:VisualTreeHelperUtil类是我自己的类,它向VisualTreeHelper类添加了一些有用的搜索功能。