Xamarin 窗体 DisplayAlert 按钮 TextColor

Posted 2023-02-23

【中文标题】Xamarin 窗体 DisplayAlert 按钮 TextColor

【英文标题】：Xamarin Forms DisplayAlert Button TextColor

【发布时间】：2015-09-06 21:13:15

【问题描述】：

如何更改 Xamarin Forms DisplayAlert 对话框上的按钮文本颜色？

【参考方案1】：

可以在custom renderers 的帮助下为每个平台更改颜色。 您可以在自定义渲染器中访问本机 api。 但需要确定是需要的，因为不推荐（对于 ios 肯定）。

The UIAlertView class is intended to be used as-is and does not support subclassing. The view hierarchy for this class is private and must not be modified.

iOS 相关主题here。

【讨论】：

非常有用的信息。但是，我只是看不到如何为 DisplayAlert 对话框创建自定义渲染器。我想我可以创建自己的模态对话框。

你是对的。更容易为每个平台实现自定义对话框并使用 DI 解决它们。请注意："You cannot customize the appearance of alert views."

在某些情况下，我使用 Toasts 插件代替警报对话框。它有许多可能对您有用的自定义选项。 nuget.org/packages/Toasts.Forms.Plugin

【参考方案2】：

FWIW，我选择在 XAML 中创建一个新的 ContentPage 并使用 Navigation.PushModalAsync 显示它。就我而言，这是模拟警报并保持对所有样式的控制的最简单方法。

XAML：

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="YourNamespace.AlertPage"
             BackgroundColor="DarkGray"
             Padding="40">
    <ContentPage.Content>
        <StackLayout BackgroundColor="White" Padding="10">
            <Label x:Name="lblTitle" FontAttributes="Bold" FontSize="Large" Text="Title" HorizontalOptions="Center"></Label>
            <BoxView HeightRequest="1" BackgroundColor="DarkGray"></BoxView>
            <ScrollView Orientation="Vertical" VerticalOptions="FillAndExpand">
                <Label x:Name="lblText" FontSize="Medium"></Label>
            </ScrollView>
            <BoxView HeightRequest="1" BackgroundColor="DarkGray"></BoxView>
            <StackLayout Orientation="Horizontal">
                <Button x:Name="btn1" Text="Button 1" HorizontalOptions="CenterAndExpand"></Button>
                <Button x:Name="btn2" Text="Button 2" HorizontalOptions="CenterAndExpand"></Button>
            </StackLayout>
        </StackLayout>
    </ContentPage.Content>
</ContentPage>

C#：

public partial class AlertPage : ContentPage

    public Label LblTitle
    
        get
        
            return lblTitle;
        
    

    public Label LblText
    
        get
        
            return lblText;
        
    

    public Button Button1
    
        get
        
            return btn1;
        
    

    public Button Button2
    
        get
        
            return btn2;
        
    

    public AlertPage()
    
        InitializeComponent();
    

实施：

var ap = new AlertPage();
ap.LblTitle.Text = "Instructions";
ap.LblText.Text = "The text to display!";
ap.Button1.Text = "Done";
ap.Button1.Clicked += async (s, a) =>

    await Navigation.PopModalAsync();
;
ap.Button2.IsVisible = false;
await Navigation.PushModalAsync(ap);

截图：

【讨论】：

谢谢。实现起来非常简单

【参考方案3】：

我已经创建了自定义显示警报，您可以使用任务回调 TaskCompletionSource 作为 xamarin build DisplayAlert from it

    public async Task<bool> ShowDialogAsync(string title, string message, string acceptMessage, string cancelMessage)
                
                    Grid ShowDialogMessage = null;
                    Grid CurrentPageGrid = (App.Instance.CurrentPage as ContentPage).Content as Grid;
                    TaskCompletionSource<bool> result = new TaskCompletionSource<bool>();
                    try
                    
                        ShowDialogMessage = GenericView.CustomDisplayAlert(message, CurrentPageGrid.RowDefinitions.Count, CurrentPageGrid.ColumnDefinitions.Count, () =>
                        
         //here you can add your implementation   
                            CurrentPageGrid.Children.Remove(ShowDialogMessage);

  result.SetResult(true);

                        ,
                        () =>
                        
         //here you can add your implementation      
                            CurrentPageGrid.Children.Remove(ShowDialogMessage);
                            result.SetResult(false);
                        , title, acceptMessage, cancelMessage);

                        CurrentPageGrid.Children.Add(ShowDialogMessage);
                        return await result.Task;
                    
                    catch (Exception ex)
                    
                        return await App.Current.MainPage.DisplayAlert(title, message, acceptMessage, cancelMessage);
        #if DEBUG
                        throw ex;
        #endif
                    

                

在我的方法中，我添加了实现回调的操作，方法签名您可以添加自己的设计

 public static Grid CustomDisplayAlert(string message, int rows, int columns, Action acceptAction, Action cancelAction, string title = "", string acceptMessage = "", string cancelMessage = "")
                   
             Grid overlay = new Grid
            
                BackgroundColor = Color.FromRgba(0, 0, 0, 190),
                RowDefinitions = new RowDefinitionCollection  new RowDefinition  Height = GridLength.Star , new RowDefinition  Height = GridLength.Auto , new RowDefinition  Height = GridLength.Star  
            ;

                Grid.SetRowSpan(overlay, rows);

                Grid.SetColumnSpan(overlay, columns);


            Grid bodyView = new Grid();


            StackLayout stackMainView = new StackLayout
            
                Margin = new Thickness(20)
            ;
            StackLayout stackButtonsView = new StackLayout
            
                Orientation=StackOrientation.Horizontal 
            ;
            RoundedBox bgOverlay = new RoundedBox
            
                CornerRadius = 4,
                HorizontalOptions = LayoutOptions.FillAndExpand,
                VerticalOptions = LayoutOptions.FillAndExpand,
                BackgroundColor = Color.White
            ;

            bodyView.Children.Add(bgOverlay);

            StackLayout elementsContainer = new StackLayout  Margin = new Thickness(10) ;

            IconicLabel itemDescription = new IconicLabel  MoreReadable = true, Text = message, StyleId = "Myriad-Pro-L", HorizontalTextAlignment = TextAlignment.Center, HorizontalOptions = LayoutOptions.FillAndExpand, TextColor = (Color)(App.Current.Resources["OptioDark"]), FontSize = 18, Margin = new Thickness(15) ;
            IconicLabel titleView = new IconicLabel  FontAttributes = FontAttributes.Bold, MoreReadable = true, Text = title, StyleId = "Myriad-Pro-L", HorizontalTextAlignment = TextAlignment.Center, HorizontalOptions = LayoutOptions.FillAndExpand, TextColor = (Color)(App.Current.Resources["OptioDark"]), FontSize = 22, Margin = new Thickness(15) ;

            if (titleView.Text.Length != 0)
                elementsContainer.Children.Add(titleView);
            elementsContainer.Children.Add(itemDescription);


            bodyView.Children.Add(elementsContainer);

            IconicButton acceptBtn = new IconicButton
            
                HeightRequest = 40,
                HorizontalOptions = LayoutOptions.FillAndExpand,
                VerticalOptions = LayoutOptions.FillAndExpand,
                BackgroundColor = Color.White,
                Text = acceptMessage,
                TextColor = (Color)(App.Current.Resources["OptioDark"])
            ;
            IconicButton cancelBtn = new IconicButton
            
                HeightRequest = 40,
                HorizontalOptions = LayoutOptions.FillAndExpand,
                VerticalOptions = LayoutOptions.FillAndExpand,
                BackgroundColor = Color.White,
                Text = cancelMessage,
                TextColor = (Color)(App.Current.Resources["OptioDark"])
            ;
            acceptBtn.Clicked += (sender, e) =>
            
                acceptAction?.Invoke();
            ;
            cancelBtn.Clicked += (sender, e) =>
            
                cancelAction?.Invoke();
            ;

            stackButtonsView.Children.Add(acceptBtn);
            stackButtonsView.Children.Add(cancelBtn);

            stackMainView.Children.Add(bodyView);

            stackMainView.Children.Add(stackButtonsView);
            overlay.Children.Add(stackMainView, 0, 1);
            return overlay;