Question

我有画布。当我点击它时，我得到鼠标的坐标（向孩子添加）有一个custum控件（带有简单圆圈的拇指）。在屏幕上，从逻辑上讲，左上角在添加时作为参考。我希望将拇指放在我点击的位置（见图片。红色星形=我点击的地方）。

要做什么，我需要获得拇指的实际宽度和高度，然后计算精确的坐标，将拇指的中心放在用户点击的位置。有没有更好的办法？在WPF中，我使用了这段代码，但它在WinRT中不起作用。

 //Circle in thumb
 Ellipse Bdr = this.GetTemplateChild("Forme") as Ellipse;
 DependencyObject dobj = VisualTreeHelper.GetParent(Bdr);
 Vector ParentPosition = VisualTreeHelper.GetOffset((Visual)VisualTreeHelper.GetParent(dobj));
 Vector BdrPosition = VisualTreeHelper.GetOffset((Visual)dobj);
 return new Point((Position.X+BdrPosition.X) + Bdr.ActualWidth /2,(Position.Y+ ParentPosition.Y) + Bdr.ActualHeight / 2);

你能帮帮我吗？谢谢！

Answer 1

ActualHeight和ActualWidth属性保持为0，直到FrameworkElement未加载。另一方面，如果您在Ellipse中调整了ControlTemplate的大小，则可以在OnApplyTemplate()上获得它的大小。您可以使用委托将高度和宽度传递给容器Page。即。

<强> ThumbControl

public class ThumbControl : Control
{
    public IThumbSize thumbSize;
    public ThumbControl()
    {
        this.DefaultStyleKey = typeof(ThumbControl);
    }

    protected override void OnApplyTemplate()
    {
        base.OnApplyTemplate();
        Ellipse child = this.GetTemplateChild("circle") as Ellipse;
        if (thumbSize != null)
            thumbSize.SizeMeasured(child.Width, child.Height);
    }
}

ThumbControl的风格

 <Style TargetType="local:ThumbControl">
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="local:ThumbControl">
                    <Ellipse x:Name="circle"
                             Fill="Blue"
                             Height="50"
                             Width="50"></Ellipse>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
  </Style>

IThumb界面

public interface IThumbSize
{
    void SizeMeasured(double width, double height);
}

<强> ContainerPage.xaml

<Grid Background="Black">
    <Canvas x:Name="rootCanvas"
            Background="Transparent"
            PointerReleased="rootCanvas_PointerReleased"></Canvas>
</Grid>

<强> ContainerPage.xaml.cs

public sealed partial class ContainerPage: Page, IThumbSize
{
    ThumbControl thumbControl = new ThumbControl();
    Point touchPoint = new Point();
    public ContainerPage()
    {
        this.InitializeComponent();
        thumbControl.thumbSize = this;
    }

    private void rootCanvas_PointerReleased(object sender, PointerRoutedEventArgs e)
    {
        PointerPoint pt = e.GetCurrentPoint(rootCanvas);
        touchPoint.X = pt.Position.X;
        touchPoint.Y = pt.Position.Y;
        if (!rootCanvas.Children.Contains(thumbControl))
            rootCanvas.Children.Add(thumbControl);
        Canvas.SetLeft(thumbControl, touchPoint.X - (thumbControl.ActualWidth / 2));
        Canvas.SetTop(thumbControl, touchPoint.Y - (thumbControl.ActualHeight / 2));
    }

    public void SizeMeasured(double width, double height)
    {
        Canvas.SetLeft(thumbControl, touchPoint.X - (width / 2));
        Canvas.SetTop(thumbControl, touchPoint.Y - (height / 2));
    }
}

希望它有所帮助。

在WinRT中获取UIElement的大小

1 个答案: