如果 WPF 控件从未被渲染过，它是否可能具有 ActualWidth 和 ActualHeight？

发布于 2024-09-03 07:52:51 字数 1637 浏览 2 评论 0原文

我需要一个 Viewport3D ，其唯一目的是使用 Petzold.Media3D.ViewportInfo 进行几何计算。我不想将其放置在 Window 中或以其他方式渲染它。

我尝试通过实例化 Viewport3D 并使用以下 C# 方法设置一些属性来实现此目的：

private Viewport3D CreateViewport(MainSettings settings)
{
    var cameraPosition = new Point3D(0, 0, settings.CameraHeight);
    var cameraLookDirection = new Vector3D(0, 0, -1);
    var cameraUpDirection = new Vector3D(0, 1, 0);
    var camera = new PerspectiveCamera
    {
        Position = cameraPosition,
        LookDirection = cameraLookDirection,
        UpDirection = cameraUpDirection
    };
    var viewport = new Viewport3D
    {
        Camera = camera,
        Width = settings.ViewportWidth,
        Height = settings.ViewportHeight
    };
    return viewport;
}

稍后，我尝试使用此视口将鼠标位置转换为 3D 位置方法：

public Point3D? Point2dToPoint3d(Point point)
{
    var range = new LineRange();
    var isValid = ViewportInfo.Point2DtoPoint3D(_viewport, point, out range);
    if (isValid)
        return range.PointFromZ(0);
    else
        return null;
}

不幸的是，它不起作用。我认为原因是视口的ActualWidth和ActualHeight都为零（并且这些是只读属性，因此我无法手动设置它们）。（注意：我已经使用实际渲染的 Viewport3D 测试了完全相同的方法，并且工作正常，所以我知道问题不在于我的转换器方法。）知道

如何让 WPF 进行分配基于 Width 和 Height 设置的控件的 ActualWidth 和 ActualHeight？

我尝试将 HorizontalAlignment 和 VerticalAlignment 分别设置为 Left 和 Top，而且我也弄乱了 >MinWidth 和 MinHeight，但这些属性对 ActualWidth 或 ActualHeight 没有任何影响。

原文

I need a Viewport3D for the sole purpose of doing geometric calculations using Petzold.Media3D.ViewportInfo. I would prefer not to have to place it in a Window or otherwise render it.

I'm attempting to accomplish this by instantiating a Viewport3D and setting a few properties using the following C# method:

private Viewport3D CreateViewport(MainSettings settings)
{
    var cameraPosition = new Point3D(0, 0, settings.CameraHeight);
    var cameraLookDirection = new Vector3D(0, 0, -1);
    var cameraUpDirection = new Vector3D(0, 1, 0);
    var camera = new PerspectiveCamera
    {
        Position = cameraPosition,
        LookDirection = cameraLookDirection,
        UpDirection = cameraUpDirection
    };
    var viewport = new Viewport3D
    {
        Camera = camera,
        Width = settings.ViewportWidth,
        Height = settings.ViewportHeight
    };
    return viewport;
}

Later, I'm attempting to use this viewport to convert the mouse location to a 3D location using this method:

public Point3D? Point2dToPoint3d(Point point)
{
    var range = new LineRange();
    var isValid = ViewportInfo.Point2DtoPoint3D(_viewport, point, out range);
    if (isValid)
        return range.PointFromZ(0);
    else
        return null;
}

Unfortunately, it's not working. I think the reason is that the ActualWidth and ActualHeight of the viewport are both zero (and these are read-only properties, so I can't set them manually). (Note: I have tested the exact same method with an actual rendered Viewport3D, and it worked fine, so I know the issue is not with my converter method.)

Any idea how I can get WPF to assign the ActualWidth and ActualHeight of a control based on the Width and Height settings?

I tried setting the HorizontalAlignment and VerticalAlignment to Left and Top, respectively, and I also messed with the MinWidth and MinHeight, but none of these properties had any effect on the ActualWidth or ActualHeight.