How to remove item from array in image adapter. Xamarin gallery - xamarin.android

Question

public class ImageAdapter : BaseAdapter
{
Context context;
public ImageAdapter (Context conn)
{
context = conn;
}
public override int Count { get { return thumbIds.Length; } }
public override Java.Lang.Object GetItem (int position)
{
return null;
}
public override long GetItemId (int position)
{
return 0;
}
// create a new ImageView for each item referenced by the Adapter
public override View GetView (int position, View convertView, ViewGroup parent)
{
ImageView pic = new ImageView (context);
pic.SetImageResource (thumbIds[position]);
pic.LayoutParameters = new Gallery.LayoutParams (500, 500);
pic.SetScaleType (ImageView.ScaleType.FitXy);
return pic;
}
// references to our images
int[] thumbIds = {
Resource.Drawable.image_1,
Resource.Drawable.image_2,
Resource.Drawable.image_3,
Resource.Drawable.image_4,
Resource.Drawable.image_5,
Resource.Drawable.image_6,
Resource.Drawable.image_7
};
}
How to remove item from array
https://learn.microsoft.com/en-us/xamarin/android/user-interface/controls/gallery
Gallery

Answer 1

Do you want to achieve the result like following GIF?
I advice your to use List<int> to replace of int[], then you can add a method called removeItem in the ImageAdapter like following code.
public void removeItem(int numToRemove)
{
if (numToRemove < thumbIds.Count)
{
thumbIds.RemoveAt(numToRemove);
this.NotifyDataSetChanged();
}
}
Here is code about ImageAdapter.cs
using Android.Views;
using Android.Widget;
using Java.Lang;
using System.Collections.Generic;
using System.Linq;
namespace App25
{
internal class ImageAdapter : BaseAdapter
{
private MainActivity mainActivity;
public ImageAdapter(MainActivity mainActivity)
{
this.mainActivity = mainActivity;
}
public override int Count { get { return thumbIds.Count; } }
public override Java.Lang.Object GetItem(int position)
{
return thumbIds[position];
}
public override long GetItemId(int position)
{
return position;
}
// create a new ImageView for each item referenced by the Adapter
public override View GetView(int position, View convertView, ViewGroup parent)
{
ImageView pic = new ImageView(mainActivity);
pic.SetImageResource(thumbIds[position]);
pic.LayoutParameters = new Gallery.LayoutParams(500, 500);
pic.SetScaleType(ImageView.ScaleType.FitXy);
return pic;
}
public void removeItem(int numToRemove)
{
if (numToRemove < thumbIds.Count)
{
thumbIds.RemoveAt(numToRemove);
this.NotifyDataSetChanged();
}
}
// references to our images
List<int> thumbIds = new List<int> {
Resource.Drawable.faded_div,
Resource.Drawable.icon,
Resource.Drawable.faded_div1,
Resource.Drawable.icon1,
Resource.Drawable.faded_div,
Resource.Drawable.icon2,
Resource.Drawable.faded_div
};
}
}
Here is MainActivity.cs
[Activity(Label = "#string/app_name", Theme = "#style/AppTheme", MainLauncher = true)]
public class MainActivity : AppCompatActivity
{
ImageAdapter imageAdapter;
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);
Gallery gallery = (Gallery)FindViewById<Gallery>(Resource.Id.gallery1);
Button button1 = FindViewById<Button>(Resource.Id.button1);
imageAdapter = new ImageAdapter(this);
gallery.Adapter = imageAdapter;
button1.Click += Button1_Click;
}
int removeItem = 0;
private void Button1_Click(object sender, System.EventArgs e)
{
imageAdapter.removeItem(removeItem);
}
}
Here is my activity_main.xml.
<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">
<Button
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="remove"
android:id="#+id/button1"
/>
<Gallery
android:id="#+id/gallery1"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</LinearLayout>
=============Update==================
If you want to achieve the long click ,push alert, then delete the item, you can refer to achieve a longclick event for your gallery like following code.
gallery.ItemLongClick += Gallery_ItemLongClick;
private void Gallery_ItemLongClick(object sender, AdapterView.ItemLongClickEventArgs e)
{
// throw new System.NotImplementedException();
Android.App.AlertDialog.Builder dialog = new Android.App.AlertDialog.Builder(this);
Android.App.AlertDialog alert = dialog.Create();
alert.SetTitle("Title");
alert.SetMessage("Do you want to remove this select item");
alert.SetButton("OK", (c, ev) =>
{
// Ok button click task
imageAdapter.removeItem(e.Position);
});
alert.Show();
}
Here is my running GIF.