android – RelativeLayout在StackLayout宽度计算

我在StackLayout嵌套的RelativeLayouts有一个奇怪的问题,似乎StackLayout计算其元素的宽度应该是使用RelativeLayout宽度,然后RelativeLayout再次重新计算它.这导致子控件是相对宽度的平方,但是下列控件被放置在相对宽度.

这是一个bug还是我做错了？

例

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage x:Class="MyClass"
             xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             >

  <StackLayout Orientation="Horizontal" BackgroundColor="Blue">
    <RelativeLayout>
      <ContentView BackgroundColor="Red"

          RelativeLayout.XConstraint=
                "{ConstraintExpression Type=RelativetoParent,Property=Width,Factor=0}"
          RelativeLayout.WidthConstraint=
                "{ConstraintExpression Type=RelativetoParent,Factor=0.707106}"
          RelativeLayout.YConstraint=
                  "{ConstraintExpression Type=RelativetoParent,Property=Height,Factor=0}"
          RelativeLayout.HeightConstraint=
                "{ConstraintExpression Type=RelativetoParent,Factor=1}">

      </ContentView>

    </RelativeLayout>
    <RelativeLayout>
      <ContentView BackgroundColor="Green"

          RelativeLayout.XConstraint=
                "{ConstraintExpression Type=RelativetoParent,Factor=0.5}"
          RelativeLayout.YConstraint=
                  "{ConstraintExpression Type=RelativetoParent,Factor=1}">

      </ContentView>

    </RelativeLayout>

  </StackLayout>
</ContentPage>

解决方法

两个RelativeLayout元素可能是一个混乱的因素,并且每个被指定为相对于父StackLayout处于X位置0的事实,这似乎是一个冲突.

从注释中可以看出,如果每个RelativeLayout预期为父StackLayout的宽度的一半,则可以通过删除RelativeLayout元素之一来简化布局.

然后可以将子条的指定宽度除以2,使得每个的宽度相对于父StackLayout是相同的,并且相对于父对象设置的X位置也是水平位置.

这是我想出来的：

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage x:Class="App1.HomePage"
         xmlns="http://xamarin.com/schemas/2014/forms"
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
>

<StackLayout Orientation="Horizontal" BackgroundColor="Blue">
  <RelativeLayout>
    <ContentView BackgroundColor="Red"
        RelativeLayout.XConstraint=
          "{ConstraintExpression Type=RelativetoParent,Factor=0}"
        RelativeLayout.WidthConstraint=
          "{ConstraintExpression Type=RelativetoParent,Factor=0.35}"
        RelativeLayout.YConstraint=
          "{ConstraintExpression Type=RelativetoParent,Factor=0}"
        RelativeLayout.HeightConstraint=
          "{ConstraintExpression Type=RelativetoParent,Factor=1}">
    </ContentView>
<!--
</RelativeLayout>
<RelativeLayout>
-->
    <ContentView BackgroundColor="Green"
        RelativeLayout.XConstraint=
          "{ConstraintExpression Type=RelativetoParent,Factor=0.5}"
        RelativeLayout.WidthConstraint=
          "{ConstraintExpression Type=RelativetoParent,Factor=0.25}"
        RelativeLayout.YConstraint=
          "{ConstraintExpression Type=RelativetoParent,Factor=1}">
      </ContentView>
    </RelativeLayout>
  </StackLayout>
</ContentPage>

这会产生更接近预期的东西吗？