Scale ImageView to fit screen width/height while maintaining aspect ratio

Question

I'm developing a mobile app on Xamarin.

In the app, there's an ImageView displaying an image that is too small to fit the width of the screen.

I want to scale the image to fit the width of the screen while maintaining the aspect ratio.

My axml

<LinearLayout
    android:id="@+id/overlayImageContainer"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content">
    <ImageView
        android:id="@+id/overlayImageView"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:adjustViewBounds="true"
        android:scaleType="fitCenter"/>
</LinearLayout>

The result

Two ImageViews displaying a) a picture that is wider than the width of the screen and b) a picture that is narrower than the width of the screen

I've tried various combinations of android:scaleType and android:adjustViewBounds="true" without success.

Answer 1

It turned out to be a bit hard, and not possible out of the box. Many have similar problems.

I ended up porting @patrick-boos solution to .Net like so:

Extended ImageView Class

using Android.Content;
using Android.Util;
using Android.Widget;

namespace Nsa.BigBrotherUtility.Helpers
{
    /// <summary>
    /// DynamicImageView is a helper extension that overrides OnMeasure in order to scale the said image
    /// to fit the entire width/or height of the parent container. 
    /// </summary>
    public class DynamicImageView : ImageView
    {
        public DynamicImageView(Context context, IAttributeSet attributeSet) : base(context, attributeSet)
        {

        }

        protected override void OnMeasure(int widthMeasureSpec, int heightMeasureSpec)
        {
            int width = MeasureSpec.GetSize(widthMeasureSpec);
            int height = width * Drawable.IntrinsicHeight / Drawable.IntrinsicWidth;
            SetMeasuredDimension(width, height);
        }

    }
}

My axml

<Nsa.BigBrotherUtility.Helpers.DynamicImageView
  android:id="@+id/overlayImageView"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:layout_gravity="center_vertical"
/>

The result

The 600x600 image now stretches to fill width of screen while maintaining aspect ratio