如何使背景透明？

Question

我有一页简单的黑色背景页。我想使它透明，以便下面的一页是可见的，但模糊的。

Someone建议：

<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
         xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
         xmlns:local="clr-namespace:NameSpace"
         x:Class="NameSpace.MainPage"
         BackgroundColor="Transparent"> </ContentPage>

Another one建议：

<StackLayout VerticalOptions="End" HorizontalOptions="FillAndExpand"  BackgroundColor="#80000000" Opacity="0.5" HeightRequest="160"  Grid.Row="2" >

因此，两者都适用于平板电脑，但不适用于移动设备。有人能向我解释为什么和/或建议我如何解决它吗？提前感谢

Answer 1

您可以使用AbsoluteLayout并设置“浮点”视图的透明度。

<AbsoluteLayout>

       <!--below view-->
        <StackLayout BackgroundColor="Red" AbsoluteLayout.LayoutBounds="0,0,1,1" AbsoluteLayout.LayoutFlags="All" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand">

            <Button Text="111111" />

        </StackLayout>


        <!--float view-->
        <StackLayout BackgroundColor="Gray" Opacity="0.5" AbsoluteLayout.LayoutBounds="0.5,0,1,0.5" AbsoluteLayout.LayoutFlags="All" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand">

            

        </StackLayout>


    </AbsoluteLayout>

更新

如果使用导航，就不可能实现它。因为仅仅设置页面的backgroundColor是不够的。在ContentPage中有呈现层。

作为解决办法，我们可以模拟一个导航(打开一个新页面)。

<AbsoluteLayout>

            <!--below view-->
            <StackLayout BackgroundColor="Red" AbsoluteLayout.LayoutBounds="0,0,1,1" AbsoluteLayout.LayoutFlags="All" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand">

                <Button Text="open new page"  Clicked="Button_Clicked_1"/>

            </StackLayout>


            <!--float view-->
            <StackLayout x:Name="FloatView" BackgroundColor="Gray" Opacity="0.5" AbsoluteLayout.LayoutBounds="1,1,0.01,1" AbsoluteLayout.LayoutFlags="All" HorizontalOptions="FillAndExpand" VerticalOptions="FillAndExpand">

                <Label  Text="this is a transparent view"  HorizontalOptions="CenterAndExpand" VerticalOptions="CenterAndExpand" />

                <Button Text="Back" Clicked="Button_Clicked"/>

            </StackLayout>


        </AbsoluteLayout>

private void Button_Clicked_1(object sender, EventArgs e)
        {

            //show
            Device.BeginInvokeOnMainThread(async () =>
            {


                var xPosition = 0;
                var currentPosition = 0.9;
                while (currentPosition >xPosition)
                {
                    await Task.Delay(1);
                    currentPosition -= 0.04;

                    AbsoluteLayout.SetLayoutBounds(FloatView, new Rectangle(currentPosition,0, 1, 1));
                }

            });
        }

        private void Button_Clicked(object sender, EventArgs e)
        {
            //hide
            Device.BeginInvokeOnMainThread(async () =>
            {


                AbsoluteLayout.SetLayoutBounds(FloatView, new Rectangle(1, 0, 0.01, 0.01));


            });
        }

​

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