how to change background colors of a Display Alert

Question

How can I change the screen background and button of a DisplayAlert popup, to get good colors on dark and normal screen

Answer 1

Hello @Bruno Silva ,

Please define the styles for the dialog under dark and light themes. You can open styles.xaml in the Resources/values folder in your Android project, then define the styles.

<style name="MyDialogLightStyle" parent="android:Theme.Material.Dialog.NoActionBar">  
<!--Dialog Background Color-->  
<item name="android:colorBackground">#FF0000</item>  
</style>  
<style name="MyDialogDarkStyle" parent="android:Theme.Material.Dialog.NoActionBar">  
<!--Dialog Background Color-->  
<item name="android:colorBackground">#FFF</item>  
</style>  

Then you can use DependencyService to call the native Android code. And you can try to obtain theme information by Xamarin.Essentials: App Theme, then set different style for the AlertDialog.

    public class DeviceOpenAlertService : IAlertService  
    {  
    public void DisplayAlert()  
    {  
    Xamarin.Essentials.AppTheme theme = AppInfo.RequestedTheme;// get the theme  
    AlertDialog alert;  
switch (theme){  
    case Xamarin.Essentials.AppTheme.Dark:// for dark theme  
     alert = new AlertDialog  
.Builder(MainActivity.Instance, Resource.Style.MyDialogDarkStyle)  
.SetTitle("Alert Title")  
.SetMessage("Do you want to close this application")  
.SetPositiveButton("Yes", (c, ev) =>{// Ok button click task})  
.SetNegativeButton("No", (c, ev) =>{...})  
.Create();  
    break;  
...//for light theme  
    }  
}  

After that , you can call it in forms : DependencyService.Get<IAlertService>().DisplayAlert();

Best Regards,
Wenyan Zhang

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