ImageManager could not be found in assembly reference Xamarin - xamarin

Question

Hey I am newbie in xamarin and I working on a sample that requires imaging resizing using this tutorial http://sharpmobilecode.com/android-listviews-reinvented/. However when I add ImageManager. error says It cannot find assembly reference. Its not on System.Drawing also in Android.Drawing. I tried installing in nuget but it yields an error. thanks in advance and have a nice day.

Answer 1

ImageManager is a class that the tutorial implemented as well:
https://github.com/SharpMobileCode/ListViewsReinvented/blob/master/ListViewsReinvented.Droid/ImageManager.cs
So create a class and name it ImageManager, add the code below and change namespace to match yours:
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Android.Content.Res;
using Android.Graphics;
namespace ListViewsReinvented.Droid
{
public class ImageManager : IDisposable
{
private readonly Dictionary<int, Bitmap> _imageCache = new Dictionary<int, Bitmap>();
private Resources _resources;
public ImageManager(Resources resources)
{
_resources = resources;
}
private Task<BitmapFactory.Options> GetBitmapOptionsOfImageAsync(int resourceId)
{
return Task.Run(() => GetBitmapOptionsOfImage(resourceId));
}
private BitmapFactory.Options GetBitmapOptionsOfImage(int resourceId)
{
var options = new BitmapFactory.Options
{
InJustDecodeBounds = true
};
var result = BitmapFactory.DecodeResource(_resources, resourceId, options);
return options;
}
private int CalculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight)
{
float height = options.OutHeight;
float width = options.OutWidth;
double inSampleSize = 1D;
if (height > reqHeight || width > reqWidth)
{
int halfHeight = (int)(height / 2);
int halfWidth = (int)(width / 2);
while ((halfHeight / inSampleSize) > reqHeight && (halfWidth / inSampleSize) > reqWidth)
{
inSampleSize *= 2;
}
}
return (int)inSampleSize;
}
private Task<Bitmap> LoadScaledDownBitmapForDisplayAsync(BitmapFactory.Options options, int resourceId, int reqWidth, int reqHeight)
{
return Task.Run(() => LoadScaledDownBitmapForDisplay(options, resourceId, reqWidth, reqHeight));
}
private Bitmap LoadScaledDownBitmapForDisplay(BitmapFactory.Options options, int resourceId, int reqWidth, int reqHeight)
{
options.InSampleSize = CalculateInSampleSize(options, reqWidth, reqHeight);
options.InJustDecodeBounds = false;
var bitmap = BitmapFactory.DecodeResource(_resources, resourceId, options);
return bitmap;
}
public Task<Bitmap> GetScaledDownBitmapFromResourceAsync(int resourceId, int requiredWidth, int requiredHeight)
{
return Task.Run(() => GetScaledDownBitmapFromResource(resourceId, requiredWidth, requiredHeight));
}
public Bitmap GetScaledDownBitmapFromResource(int resourceId, int requiredWidth, int requiredHeight)
{
Bitmap bitmap;
if(_imageCache.TryGetValue(resourceId, out bitmap))
{
return bitmap;
}
var options = GetBitmapOptionsOfImage(resourceId);
bitmap = LoadScaledDownBitmapForDisplay(options, resourceId, requiredWidth, requiredHeight);
_imageCache.Add(resourceId, bitmap);
return bitmap;
}
#region IDisposable implementation
public void Dispose()
{
if(_imageCache == null)
return;
foreach(var key in _imageCache.Keys)
{
Bitmap bitmap;
if(_imageCache.TryGetValue(key, out bitmap))
{
Console.WriteLine(String.Format("Recycling bitmap {0} . . .", key));
bitmap.Recycle();
}
}
_imageCache.Clear();
}
#endregion
}
}