textview visibility xamarin android - xamarin.android

Question

I have created an imageview and above it I created a textview. my aim is that I want to show my imageview if there's an image and if not I want to remove the imageview and display the textview that says "no image", this is my xml code:
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="10dp">
<TextView
android:textAppearance="?android:attr/textAppearanceMedium"
android:text="Item Image: "
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/textView9"
android:textColor="#android:color/holo_blue_dark"/>
<ImageView
android:src="#android:drawable/ic_menu_gallery"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:minWidth="25px"
android:minHeight="25px"
android:id="#+id/imageView1"
android:layout_toRightOf="#id/textView9"/>
<TextView
android:textAppearance="?android:attr/textAppearanceMedium"
android:text="No Image"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/textView10"
android:layout_toRightOf="#id/textView9"
/>
</RelativeLayout>
and this is my code:
ImageView imgv = view.FindViewById<ImageView>(Resource.Id.imageView1);
textview10 = view.FindViewById<TextView>(Resource.Id.textView10);
textview10.Visibility = ViewStates.Invisible;
private void Ws_getimg_clrCompleted(object sender, WSitems.getimg_clrCompletedEventArgs e)
{
Byte[] data = e.Result.datab;
if (data != null)
{
MemoryStream mem = new MemoryStream(data);
Android.Graphics.Bitmap originBitmap = BitmapFactory.DecodeStream(mem);
imgv.SetImageBitmap(originBitmap);
}
else
{
imgv.Visibility = ViewStates.Gone;
textview10.Visibility = ViewStates.Visible;
}
}
I get my image from a webservice. the problem is that only the imageview is disappearing when there's no image but the textview isn't becoming visible. why? what should I do? thanks in advance.

Answer 1

You can use FFImageLoading to replace your webservice to load Image on the intnet.
ImageView imageView1 = FindViewById<ImageView>(Resource.Id.imageView1);
TextView textView10 = FindViewById<TextView>(Resource.Id.textView10);
textView10.Visibility = ViewStates.Invisible;
// string urlToImage = "http://www.123raw.com/includes/templates/custom/images/123raw_mainpic_01.jpg";
string urlToImage = "http://www.123raw.com/includes/templates/custom/images/12311raw_mainpic_01.jpg";
var config = new FFImageLoading.Config.Configuration()
{
ExecuteCallbacksOnUIThread = true
};
ImageService.Instance.Initialize(config);
ImageService.Instance.LoadUrl(urlToImage).Error(exception =>
{
imageView1.Visibility = ViewStates.Gone;
textView10.Visibility = ViewStates.Visible;
}).Into(imageView1);
Here is running GIF, if the image cannot be loaded.

Answer 2

this is my code:
Task<Stream> GetStreamFromImageByte(CancellationToken ct)
{
//Since we need to return a Task<Stream> we will use a TaskCompletionSource>
TaskCompletionSource<Stream> tcs = new TaskCompletionSource<Stream>();
if (data != null)
{
tcs.TrySetResult(new MemoryStream(data));
}
return tcs.Task;
}
private void Ws_getimg_clrCompleted(object sender, WSitems.getimg_clrCompletedEventArgs e)
{
data = e.Result.datab;
var config = new FFImageLoading.Config.Configuration()
{
ExecuteCallbacksOnUIThread = true
};
ImageService.Instance.Initialize(config);
ImageService.Instance.LoadStream(GetStreamFromImageByte).Error(exception =>
{
imgv.Visibility = ViewStates.Gone;
textview10.Visibility = ViewStates.Visible;
}).Into(imgv);