UIElement.TransformToVisual(UIElement) 方法

参考

定义

命名空间:: Windows.UI.Xaml

重要

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编辑

返回一个转换对象，该对象可用于将坐标从 UIElement 转换为指定对象。

public:
 virtual GeneralTransform ^ TransformToVisual(UIElement ^ visual) = TransformToVisual;

GeneralTransform TransformToVisual(UIElement const& visual);

public GeneralTransform TransformToVisual(UIElement visual);

function transformToVisual(visual)

Public Function TransformToVisual (visual As UIElement) As GeneralTransform

参数

visual: UIElement

要与当前对象进行比较以获取转换的对象。如果此参数为 null，则使用 XAML 树的根。

GeneralTransform

作为对象的转换信息。对此对象调用方法以获取实际转换。

示例

此示例演示一个方案，用于调用 TransformToVisual 以解释不是事件发送方的元素的坐标参考框架中 PointerPoint 的坐标。在这里， queryPointer 方法首先访问与发送方相关的坐标， (这是方法) 第一行中的 GetCurrentPoint 调用，但稍后使用 TransformToVisual 将点坐标转换为布局容器的参考框架 page ，该容器实际上是 XAML 中的多个包含层。若要查看此代码 (的更多上下文，包括如何在 queryPointer UI 中显示结果以及何时) 调用它，请参阅处理指针输入主题中显示的完整代码示例。

    <Page
    x:Class="PointerInput.MainPage"
    IsTabStop="false"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:PointerInput"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Name="page">

    <Grid Background="{StaticResource ApplicationPageBackgroundThemeBrush}">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="150" />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="*" />
            <RowDefinition Height="320" />
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <Canvas Name="Container" 
                Grid.Column="0"
                Grid.Row="1"
                HorizontalAlignment="Center" 
                VerticalAlignment="Center" 
                Margin="0,0,0,0" 
                Height="320"  Width="640">
            <Rectangle Name="Target" 
                       Fill="#FF0000" 
                       Stroke="Black" 
                       StrokeThickness="0"
                       Height="320" Width="640" />
        </Canvas>
        <TextBox Name="eventLog" 
                 Grid.Column="1"
                 Grid.Row="0"
                 Grid.RowSpan="3" 
                 Background="#000000" 
                 TextWrapping="Wrap" 
                 Foreground="#FFFFFF" 
                 ScrollViewer.VerticalScrollBarVisibility="Visible" 
                 BorderThickness="0"/>
    </Grid>
</Page>

<Page
    x:Class="PointerInput.MainPage"
    IsTabStop="false"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="using:PointerInput"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    mc:Ignorable="d"
    Name="page">

    <Grid Background="{StaticResource ApplicationForegroundThemeBrush}">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="69.458" />
            <ColumnDefinition Width="80.542"/>
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="*" />
            <RowDefinition Height="320" />
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <Canvas Name="Container" 
                Grid.Column="0"
                Grid.Row="1"
                HorizontalAlignment="Center" 
                VerticalAlignment="Center" 
                Margin="245,0" 
                Height="320"  Width="640">
            <Rectangle Name="Target" 
                       Fill="#FF0000" 
                       Stroke="Black" 
                       StrokeThickness="0"
                       Height="320" Width="640" />
        </Canvas>
        <Button Name="buttonClear"
                Foreground="White"
                Width="100"
                Height="100">
            clear
        </Button>
        <TextBox Name="eventLog" 
                 Grid.Column="1"
                 Grid.Row="0"
                 Grid.RowSpan="3" 
                 Background="#000000" 
                 TextWrapping="Wrap" 
                 Foreground="#FFFFFF" 
                 ScrollViewer.VerticalScrollBarVisibility="Visible" 
                 BorderThickness="0" Grid.ColumnSpan="2"/>
    </Grid>
</Page>

String queryPointer(PointerPoint ptrPt)
{
    String details = "";

    switch (ptrPt.PointerDevice.PointerDeviceType)
    {
        case Windows.Devices.Input.PointerDeviceType.Mouse:
            details += "\nPointer type: mouse";
            break;
        case Windows.Devices.Input.PointerDeviceType.Pen:
            details += "\nPointer type: pen";
            if (ptrPt.IsInContact)
            {
                details += "\nPressure: " + ptrPt.Properties.Pressure;
                details += "\nrotation: " + ptrPt.Properties.Orientation;
                details += "\nTilt X: " + ptrPt.Properties.XTilt;
                details += "\nTilt Y: " + ptrPt.Properties.YTilt;
                details += "\nBarrel button pressed: " + ptrPt.Properties.IsBarrelButtonPressed;
            }
            break;
        case Windows.Devices.Input.PointerDeviceType.Touch:
            details += "\nPointer type: touch";
            details += "\nrotation: " + ptrPt.Properties.Orientation;
            details += "\nTilt X: " + ptrPt.Properties.XTilt;
            details += "\nTilt Y: " + ptrPt.Properties.YTilt;
            break;
        default:
            details += "\nPointer type: n/a";
            break;
    }

    GeneralTransform gt = Target.TransformToVisual(page);
    Point screenPoint;

    screenPoint = gt.TransformPoint(new Point(ptrPt.Position.X, ptrPt.Position.Y));
    details += "\nPointer Id: " + ptrPt.PointerId.ToString() +
        "\nPointer location (parent): " + ptrPt.Position.X + ", " + ptrPt.Position.Y +
        "\nPointer location (screen): " + screenPoint.X + ", " + screenPoint.Y;
    return details;
}

String queryPointer(PointerPoint ptrPt)
{
    String details = "";

    switch (ptrPt.PointerDevice.PointerDeviceType)
    {
        case Windows.Devices.Input.PointerDeviceType.Mouse:
            details += "\nPointer type: mouse";
            break;
        case Windows.Devices.Input.PointerDeviceType.Pen:
            details += "\nPointer type: pen";
            if (ptrPt.IsInContact)
            {
                details += "\nPressure: " + ptrPt.Properties.Pressure;
                details += "\nrotation: " + ptrPt.Properties.Orientation;
                details += "\nTilt X: " + ptrPt.Properties.XTilt;
                details += "\nTilt Y: " + ptrPt.Properties.YTilt;
                details += "\nBarrel button pressed: " + ptrPt.Properties.IsBarrelButtonPressed;
            }
            break;
        case Windows.Devices.Input.PointerDeviceType.Touch:
            details += "\nPointer type: touch";
            details += "\nrotation: " + ptrPt.Properties.Orientation;
            details += "\nTilt X: " + ptrPt.Properties.XTilt;
            details += "\nTilt Y: " + ptrPt.Properties.YTilt;
            break;
        default:
            details += "\nPointer type: n/a";
            break;
    }

    GeneralTransform gt = Target.TransformToVisual(page);
    Point screenPoint;

    screenPoint = gt.TransformPoint(new Point(ptrPt.Position.X, ptrPt.Position.Y));
    details += "\nPointer Id: " + ptrPt.PointerId.ToString() +
        "\nPointer location (parent): " + ptrPt.Position.X + ", " + ptrPt.Position.Y +
        "\nPointer location (screen): " + screenPoint.X + ", " + screenPoint.Y;
    return details;
}

注解

调用 TransformToVisual 以获取 UI 中两个元素之间的坐标偏移量。要考虑的第一个元素是调用 TransformToVisual 的 UIElement，第二个元素是作为视觉参数传递的 UIElement。例如，可以使用转换来确定元素边界在相对于布局父元素（而不是应用窗口）的坐标系中的定位方式。

在应用了影响呈现和定位的所有注意事项（如 RenderTransform ）后，TransformToVisual 会提供坐标结果。如果要处理在 RenderTransform 动画或其他位置更改期间获取的点值，这非常有用。

TransformToVisual 最常见的方案是，如果要使用相对于调用它的 UIElement 的本地坐标系，并且未处理具有用于将 Point 值转换为对象的参照系的事件数据方法的实时输入事件。调用 TransformToVisual 后，可以对返回的 GeneralTransform 调用 TransformPoint。

注意

此方法返回的 GeneralTransform 对象可以强制转换为派生类型 Transform，但需要的所有方法均由 GeneralTransform 定义。无法强制转换为 TranslateTransform ，即使你可能希望转换结果为翻译。

适用于

UIElement.TransformToVisual(UIElement) 方法

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