Xamarin.forms中的垂直滑块? [英] Vertical slider in Xamarin.forms?

问题描述

我正在尝试在Xamarin.forms中实现垂直"滑块.我知道我需要分别在ios和android中创建渲染类.对于ios，我的渲染器工作正常.对于Android，我正在点击链接 https://forums.xamarin.com/discussion/69933/vertical-slider .但是，上面链接中提供的解决方案给我留下了一个没有拇指的滑块.有什么方法可以在Xamarin.forms中为Android实现垂直滑块吗?

I am trying to implement Vertical slider in Xamarin.forms. I know for that I need to create render classes in ios and android respectively. For ios, my renderer seems to be working fine. For android I am following the link https://forums.xamarin.com/discussion/69933/vertical-slider. However the solution provided in above link left me with a slider with no thumb. Is there any way to implement vertical slider for android in Xamarin.forms?

推荐答案

我遇到了同样的问题，并花了一些时间进行搜索.与其他评论者一样，我的解决方案是旋转滑块.事实证明，在Forms中要做的事情相当棘手.旋转围绕中心点进行，并在任何定位之后应用，这就是为什么事物最终会偏离目标(或离开屏幕)的原因.我最终使用了RelativeLayout来应用正确的大小和位置，并将其包装在ContentView中以使其易于使用.

I had the same issue, and spent some time searching. My solution, as other commenters, was to rotate the slider. As it turns out that is quite the finicky thing to do in Forms. The rotation is around the center point and is applied after any positioning, which is why things tend to end up off target (or off screen..). I ended up using a RelativeLayout to apply the correct size and position and wrapped it up in a ContentView to make it nice and easy to use.

像这样使用:

... 
xmlns:components="clr-namespace:YourNamespace.Components" 
...
<components:VerticalContentView>
    <Slider />
</components:VerticalContentView>

VerticalContentView可以像其他任何ContentView一样使用.添加到该视图的任何视图都将旋转-90度.可以使用ContentRotation属性自定义旋转.

The VerticalContentView can be used like any other ContentView. Any view added to it will be rotated by -90 degrees. The rotation can be customized by using the ContentRotation property.

请注意，任何视图都可以旋转，而不仅仅是滑块.

Note that any view can be rotated, not just a slider.

这是课程.

[ContentProperty("VerticalContent")]
public class VerticalContentView : ContentView
{
    public View VerticalContent 
    { 
        get => (View)GetValue(ContentProperty); 
        set => SetValue(ContentProperty, Verticalize(value)); 
    }

    public double ContentRotation { get; set; } = -90;

    private View Verticalize(View toBeRotated)
    {
        if (toBeRotated == null)
            return null;

        toBeRotated.Rotation = ContentRotation;
        var result = new RelativeLayout();

        result.Children.Add(toBeRotated,
        xConstraint: Constraint.RelativeToParent((parent) =>
        {
            return parent.X - ((parent.Height - parent.Width) / 2);
        }),
        yConstraint: Constraint.RelativeToParent((parent) =>
        {
            return (parent.Height / 2) - (parent.Width / 2);
        }),
        widthConstraint: Constraint.RelativeToParent((parent) =>
        {
            return parent.Height;
        }),
        heightConstraint: Constraint.RelativeToParent((parent) =>
        {
            return parent.Width;
        }));

        return result;
    }
}

它在C#中，因为我找不到在XAML中基于父级尺寸进行算术的方法.

It's in C# as I found no way of doing arithmetic based on parent dimensions in XAML.

对于Xamarin(和XAML而言)，我还很陌生，因此以这种方式进行操作可能会产生一些我不知道的负面影响.欢迎任何批评.

I'm pretty new to Xamarin (and XAML in general), so there might be negative effects of doing it this way that I am not aware of. Any criticisms are welcome.

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