如何制作可更改的 Xamarin.Form Xaml 页面？

Question

我想在 Xamarin.Form 中实现一个 Xaml 页面，可以通过用户输入进行修改。例如，如果用户单击一个按钮，应用程序将显示一个日期选择器，如果用户单击另一个按钮，应用程序将删除日期选择器并在完全相同的位置显示一个文本条目。 我尝试使用“IsVisible”属性，但它没有按预期工作（xaml 对象仍然存在但只是不可见，所以我无法替换它）。

有什么建议吗？

Answer 1

您可以移除一个孩子。

像这样：

Children.Remove 或 Children.RemoveAt

参考：

https://docs.microsoft.com/en-us/dotnet/api/xamarin.forms.layout-1.children?view=xamarin-forms

Answer 2

如果您想让您的 xaml 页面像警报一样显示，您可以使用来自 nuget 的插件 Rg.Plugins.Popup。

用法

<?xml version="1.0" encoding="utf-8" ?>
<pages:PopupPage 
    xmlns="http://xamarin.com/schemas/2014/forms"
    xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
    xmlns:pages="clr-namespace:Rg.Plugins.Popup.Pages;assembly=Rg.Plugins.Popup"
    xmlns:animations="clr-namespace:Rg.Plugins.Popup.Animations;assembly=Rg.Plugins.Popup"
    x:Class="MyProject.MyPopupPage">
    <!--You can set an animation in the xaml file or in the csharp code behind-->
    <pages:PopupPage.Animation>
        <animations:ScaleAnimation 
            PositionIn="Center"
            PositionOut="Center"
            ScaleIn="1.2"
            ScaleOut="0.8"
            DurationIn="400"
            DurationOut="300"
            EasingIn="SinOut"
            EasingOut="SinIn"
            HasBackgroundAnimation="True"/>
    </pages:PopupPage.Animation>

    <!--You can use any elements here which are extended from Xamarin.Forms.View-->
    <StackLayout 
        VerticalOptions="Center" 
        HorizontalOptions="Center" 
        Padding="20, 20, 20, 20">
        <Label
            Text="Test"/>
    </StackLayout>
</pages:PopupPage>

public partial class MyPopupPage : Rg.Plugins.Popup.Pages.PopupPage
    {
        public MyPopupPage()
        {
            InitializeComponent();
        }

        protected override void OnAppearing()
        {
            base.OnAppearing();
        }

        protected override void OnDisappearing()
        {
            base.OnDisappearing();
        }

        // ### Methods for supporting animations in your popup page ###

        // Invoked before an animation appearing
        protected override void OnAppearingAnimationBegin()
        {
            base.OnAppearingAnimationBegin();
        }

        // Invoked after an animation appearing
        protected override void OnAppearingAnimationEnd()
        {
            base.OnAppearingAnimationEnd();
        }

        // Invoked before an animation disappearing
        protected override void OnDisappearingAnimationBegin()
        {
            base.OnDisappearingAnimationBegin();
        }

        // Invoked after an animation disappearing
        protected override void OnDisappearingAnimationEnd()
        {
            base.OnDisappearingAnimationEnd();
        }

        protected override Task OnAppearingAnimationBeginAsync()
        {
            return base.OnAppearingAnimationBeginAsync();
        }

        protected override Task OnAppearingAnimationEndAsync()
        {
            return base.OnAppearingAnimationEndAsync();
        }

        protected override Task OnDisappearingAnimationBeginAsync()
        {
            return base.OnDisappearingAnimationBeginAsync();
        }

        protected override Task OnDisappearingAnimationEndAsync()
        {
            return base.OnDisappearingAnimationEndAsync();
        }

        // ### Overrided methods which can prevent closing a popup page ###

        // Invoked when a hardware back button is pressed
        protected override bool OnBackButtonPressed()
        {
            // Return true if you don't want to close this popup page when a back button is pressed
            return base.OnBackButtonPressed();
        }

        // Invoked when background is clicked
        protected override bool OnBackgroundClicked()
        {
            // Return false if you don't want to close this popup page when a background of the popup page is clicked
            return base.OnBackgroundClicked();
        }
    }

该插件具有默认动画，您可以非常简单地使用它们。更多详情可以查看https://github.com/rotorgames/Rg.Plugins.Popup/wiki/PopupPage。