Question

我正在研究RelativeLayout。我想分别为iOS和Anroid为ConstraintExpression提供X,Y, Width and Height。

如何针对以下代码做到这一点

<Picker ItemsSource="{Binding AttendanceType }"
    TitleColor="Black" Title="--Select--"   
    RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent,Property=Width,Factor=.9}"
    RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativeToParent,Property=Height,Factor=.05}"
    RelativeLayout.XConstraint="{ConstraintExpression Type=RelativeToParent,Property=Width,Factor=0,Constant=22}"
    RelativeLayout.YConstraint="{ConstraintExpression Type=RelativeToParent,Property=Height,Factor=.28}">
</Picker>

Answer 1

这应该使用xaml的“压缩” onplatform语法进行工作：

    <Picker ItemsSource="{Binding AttendanceType }"
            TitleColor="Black" Title="--Select--"   
            RelativeLayout.WidthConstraint="{ConstraintExpression Type=RelativeToParent,Property=Width,Factor={OnPlatform Android=.9, iOS=.8}}"
            RelativeLayout.HeightConstraint="{ConstraintExpression Type=RelativeToParent,Property=Height,Factor={OnPlatform Android=.05, iOS=.04}}"
            RelativeLayout.XConstraint="{ConstraintExpression Type=RelativeToParent,Property=Width,Factor={OnPlatform Android=0, iOS=1},Constant={OnPlatform Android=22, iOS=21}}"
            RelativeLayout.YConstraint="{ConstraintExpression Type=RelativeToParent,Property=Height,Factor={OnPlatform Android=.28, iOS=.27}}">
    </Picker>

有关标记扩展的更多信息，请参见： https://docs.microsoft.com/en-us/xamarin/xamarin-forms/xaml/markup-extensions/consuming#onplatform-markup-extension

如何为RelativeLayout ConstraintExpression编写OnPlatform代码

1 个答案: