Xamarin forms: Image Cache

Question

Hi I am trying to build an app using xamarin forms PCL. I am implementing image gallery in which I have used a default image. All the images are on blob. I want to download image and cache that Image in device and as soon as download is complete I need to replace my default image with it. And on loading app next time download image only if it is not present in cache. I dont get any plugin for image caching and loading image from cache. I have seen a plugin named FFPLUGIN but it didnt work. Any idea how I can implement this? IMAGE CACHING

Justifier

Are your images named dynamically or do they have a static url such as mywebsite.com/myimage.png? – Ransom

@user1 dynamically named – Justifier

web images are cached by default for 24 hours with Xamarin.Forms.Image. You can increase that by changing CacheValidity – Livonia

Answer 1

You could use the built in ImageCaching in Xamarin Forms shown here:

https://developer.xamarin.com/guides/xamarin-forms/working-with/images/#Downloaded_Image_Caching

Downloaded Image Caching

UriImageSource also supports caching of downloaded images, configured through the following properties:

CachingEnabled - Whether caching is enabled ( true by default).

CacheValidity - A TimeSpan that defines how long the image will be stored locally. Caching is enabled by default and will store the image locally for 24 hours. To disable caching for a particular image, instantiate the image source like this:

Image.Source = new UriImageSource {CachingEnabled = false,
Uri="http://server.com/image"}; To set a specific cache period (for
example, 5 days) instantiate the image source like this:


webImage.Source = new UriImageSource {
Uri = new Uri("https://xamarin.com/content/images/pages/forms/example-app.png"),
CachingEnabled = true,
CacheValidity = new TimeSpan(5,0,0,0) };

Built-in caching makes it very easy to support scenarios like scrolling lists of images, where you can set (or bind) an image in each cell and let the built-in cache take care of re-loading the image when the cell is scrolled back into view.

Ransom

But how will I check it if it is in cache or not – Justifier

I want my images to download only if they are not in app cache – Justifier

Xamarin Forms Image will do that check for you, and if not redownload the image – Ransom

My app can run in offline mode also that is why I am looking for image cache. Will it make any difference if no internet is there? – Justifier

If the application cannot download the image to the cache then no image will be displayed. Once the image is in the cache I suggest setting the CacheValidity to Timspan.MaxValue then the image will be cached forever – Ransom

Then how my default image will come up then? I first need to set my local default image and then URI Image source? – Justifier

Is there any callback function that I can use for getting the image download complete event? I need to catch image download event? – Justifier