Asynchronously convert byte array into bitmap in Xamarin.Android

Question

I am retrieving a set of images of a server and the images are stored in string form. How I'm doing this is:

String imageString = jObject.GetString("Image");
byte[] imageAsBytes = Base64.Decode(imageString, Base64Flags.Default);
Bitmap bitmap = BitmapFactory.DecodeByteArray(imageAsBytes, 0, 
imageAsBytes.Length);
ProcImage.SetImageBitmap(bitmap);
bitmap = null;

This is apparently very slow. The screens that have a lot of images needing to be retrieved have an 8 second load time.

As a result, I was wondering if I could do the "DecodeByteArray()" asynchronously somehow, as this is what takes the most time.

I know it is possible, but I am unsure of how to approach this as I am fairly new to Android and Xamarin

Jordy Dieltjens · Accepted Answer · 2017-06-30 09:21:03Z

1

So if I understand you correctly you want to do the decoding in the background? If so you can start a background task with:

     Task.Run(() =>
        {
          //Code here
        });

edit It seems you more interested in making the image load faster in your application. I would suggest taking a look at: https://forums.xamarin.com/discussion/58341/ffimageloading-plugin-fast-and-memory-friendly-image-loader-ios-android-forms-windows

edited Jun 30, 2017 at 9:21

answered Jun 30, 2017 at 8:47

Jordy Dieltjens

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8 Comments

VCS User Over a year ago

This displays the image like I need it to, but do you think that loading the images in the background will improve my load time at all?

Jordy Dieltjens Over a year ago

It will improve the load time of your next page, but your images won't be decoded faster. I use this task to upload my pictures to my servers since I do want the user to wait till the end

VCS User Over a year ago

The reason I ask is, the process of retrieving the images from the server is taking almost 8 seconds on the device I'm testing it on. I was just trying to do anything to make that number lower ~

Jordy Dieltjens Over a year ago

I'm confused why you asked for a async solution than, if I understand you correctly you want a faster way of getting the images from you server and converting them? A background task is no option since the user needs to see the images instantly?

VCS User Over a year ago

the only issue is that this plugin helps make instant loading faster when it is from a stream, a url, or a file.I am retrieving a string and have to decode it that way

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