is it possible to change the background color and text color of the dropdown portion of the spinner control?

Question

i asked a previous question that worked that changed the text and background color of a spinner here:

https://forums.xamarin.com/discussion/185890/changing-the-text-color-of-all-items-in-a-spinner

but that only changes it for the selected view. i am looking to change the dropdown portion of it too to match the selected view but im having a hard time figuring it out.

what im trying to do is, when a user signs into our app, it will retrieve a color profile for them and apply it to the text and background of widgets in the app. some people on other threads mentioned creating a style xml to format it. it looks to work, but i will need to be able to change that per user. does this mean i can change this dynamically at runtime how i am changing it for the selected view?

Answer 1

Hello,​

Welcome to our Microsoft Q&A platform!

You can change the background color and text color of the dropdown portion of the spinner.

change the background color: you can use spinner.SetPopupBackgroundDrawable(Resources.GetDrawable(Resource.Color.material_blue_grey_800));

text color of the dropdown portion of the spinner: you need to create an custom adapter to achieve it.

   [Activity(Label = "@string/app_name", Theme = "@style/AppTheme", MainLauncher = true)]  
       public class MainActivity : AppCompatActivity  
       {  
           protected override void OnCreate(Bundle savedInstanceState)  
           {  
               base.OnCreate(savedInstanceState);  
               Xamarin.Essentials.Platform.Init(this, savedInstanceState);  
               // Set our view from the "main" layout resource  
               SetContentView(Resource.Layout.activity_main);  
     
               Spinner spinner = FindViewById<Spinner>(Resource.Id.spinner);  
                
               //change the background color  
               spinner.SetPopupBackgroundDrawable(Resources.GetDrawable(Resource.Color.material_blue_grey_800));  
               
               spinner.ItemSelected += new EventHandler<AdapterView.ItemSelectedEventArgs>(spinner_ItemSelected);  
               List<string> planetNames = new List<string>();  
               planetNames.Add("Mercury");  
               planetNames.Add("Venus");  
               planetNames.Add("Mars");  
               planetNames.Add("Earth");  
               planetNames.Add("Saturn");  
     
               var adapter = new MyAdapter(this, planetNames);   
                 
              
              
                 
               spinner.Adapter = adapter;  
               spinner.OnItemSelectedListener = new myItemSelectedListener();  
     
     
           }  
           private void spinner_ItemSelected(object sender, AdapterView.ItemSelectedEventArgs e)  
           {  
               //Spinner spinner = (Spinner)sender;  
                
           }  
           public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)  
           {  
               Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);  
     
               base.OnRequestPermissionsResult(requestCode, permissions, grantResults);  
           }  
       }  
     
       internal class myItemSelectedListener : Java.Lang.Object, AdapterView.IOnItemSelectedListener  
       {  
           public void OnItemSelected(AdapterView parent, View view, int position, long id)  
           {  
               ///change the select item's color  
               ((TextView)view.FindViewById<TextView>(Resource.Id.MytextView)).SetTextColor(Android.Graphics.Color.Black); //Change selected text color  
     
           }  
     
           public void OnNothingSelected(AdapterView parent)  
           {  
                
           }  
       }  
     
       internal class MyAdapter:BaseAdapter<string>  
       {  
           private MainActivity mainActivity;  
           private List<string> planetNames;  
     
           public MyAdapter(MainActivity mainActivity, List<string> planetNames)  
           {  
               this.mainActivity = mainActivity;  
               this.planetNames = planetNames;  
           }  
     
           public override string this[int position] => planetNames[position];  
     
           public override int Count => planetNames.Count;  
     
           public override long GetItemId(int position)  
           {  
               return position;  
           }  
     
           public override View GetView(int position, View convertView, ViewGroup parent)  
           {  
               var item = planetNames[position];  
               //change the item's color in popup view  
               var view = mainActivity.LayoutInflater.Inflate(Resource.Layout.layout1, null);  
               var textView=view.FindViewById<TextView>(Resource.Id.MytextView);  
               textView.SetTextColor(Android.Graphics.Color.Green);  
               textView.Text = item;  
     
               return view;  
           }  
       }  
   }  

My layout1.xml code.

   <?xml version="1.0" encoding="utf-8"?>  
   <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
       android:orientation="vertical"  
       android:layout_width="match_parent"  
       android:layout_height="wrap_content">  
       <TextView    
           android:layout_width="match_parent"   
           android:layout_height="wrap_content"  
           android:textSize="30sp"  
           android:gravity="left"  
          android:id="@+id/MytextView"  
           
            android:text="test"  
           android:padding="5dip"  
       />  
   </LinearLayout>  

And activity_main.xml

   <?xml version="1.0" encoding="utf-8"?>  
   <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
       xmlns:app="http://schemas.android.com/apk/res-auto"  
       xmlns:tools="http://schemas.android.com/tools"  
       android:orientation="vertical"  
       android:layout_width="match_parent"  
       android:layout_height="match_parent">  
     <TextView  
           android:layout_width="fill_parent"  
           android:layout_height="wrap_content"  
           android:layout_marginTop="10dip"  
           android:text="@string/planet_prompt"  
       />  
       <Spinner  
           android:id="@+id/spinner"  
           android:layout_width="fill_parent"  
           android:layout_height="wrap_content"  
           android:prompt="@string/planet_prompt"  
       />  
   </LinearLayout>  

================================
Update================================

If you get the color by RGB, you could use ColorDrawable to convert the color like following code.

   spinner.SetPopupBackgroundDrawable(new ColorDrawable(Color.Rgb(255, 0, 0)));  

Best Regards,

Leon Lu

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Answer 2

thank you this looks to work for now, question. can i use this idea to also change the background and text color of the default popups?

ie for Android.Support.V7.App.AlertDialog.Builder