Develop Reference

Scale an image in Kotlin Android Studio

I'm new to Kotlin and Java and don't know how to scale an image in an image view.
I want something like this: MyImageView.setHeight(300)
I don't want to distort the image.
Thanks in advance!

This solution might be overkill for your current question, but if you have to show images in your app, I recommend using an image handling library such as Picasso or Glide.
If you are to use Picasso, add it to your dependencies by adding the following line to your gradle files :
dependencies {
implementation 'com.squareup.picasso:picasso:2.71828'
}
Then in your Kotlin file, when you are about to load the picture onto an ImageView,
do it using Picasso using the following lines :
Picasso
.get()
.load(imageUrl)
.fit()
.centerInside()
.into(imageView)

Yes, I agree with rgv. Use an image handling library, preferably Picasso. It can reduce a lot of hardwork and also, the result is better than what you would have got by scaling image manually.

Firebase Images are not properly scaling up

I am working on an application which uses Google Firebase and RecyclerView. While retrieving the images from Firebease, images are not properly scaling up. When scrolling the recyclerview, sometimes images are showing as smaller ones and sometimes bigger. They are not scalling properly. I am using Glide to load the images. Please help me .
Also, is it a good idea to use Recuyclerview to use in complex application since OnbindViewHolder being called multiple times causing performance issues. Is there any alternative for that.

Please use this code:
Glide.with(profilePhotoImageView.getContext())
.load(profilePhotoUrl).centerCrop()
.transform(new CircleTransform(profilePhotoImageView.getContext()))
.override(40,40)
.into(profilePhotoImageView);
This means that you are setting a fixed width and height. In which profilePhotoUrl is the url of your image and profilePhotoImageView is the ImageView in which you want to display the image.
And don't forget to add the latest version of Glide in your build.gradle file.
'com.github.bumptech.glide:glide:4.0.0-RC1'
Hope it helps.

Download image as thumbnail in listview adapter android

I have a decent android app which is using two fragments one of them is Listfragment. And my question is, can I use Asynctask to download the image and compress it to a thumbnail and then assign it to an imageview ? (Imagine there are like 100 items in ListView). Or is this even possible to call the asynctask each time ?

You don't need to reinvent the wheel. There are libraries which already can download, cache and resize image for you. For instance Picasso:
Picasso
.with(context)
.load(url)
.resizeDimen(width, height)
.centerCrop()
.error(R.drawable.error_img);
.into(placeholder);

For this task, I would strongly recommend the use of an external library.
There are many to choose from that can be used to download, display and cache images from an online source. As many of these libraries have been developed for many years, they are usually going to be better than any bespoke code you write.

Display large images without lags

I have 4 images set as a background of screens in my application and displaying them cause lags in application. They have 1280x768px and about 70kb. How can I display them without loosing performance?

To use Picasso, simply add this to your gradle:
compile 'com.squareup.picasso:picasso:2.5.2'
And then, in case you have this image on our project folder:
Picasso.with(context).load(R.drawable.landing_screen).into(imageView1);
Instead, if you're downloading the image:
Picasso.with(context).load("http://i.imgur.com/DvpvklR.png").into(imageView);
Source: http://square.github.io/picasso/

Check google's sample project here: http://developer.android.com/training/displaying-bitmaps/load-bitmap.html

Grid View image load on scroll and image cache

I want to load the Async image loading for grid view. The image loading should be Async and should only when grid view scrolled. And when scroll up the image should be loaded from cache. Simply i need a loading style just like fb,pinterest.

Use Jake Wharton's Picasso Library. (A Perfect ImageLoading Library form the developer of ActionBarSherlock)
A powerful image downloading and caching library for Android.
Images add much-needed context and visual flair to Android applications. Picasso allows for hassle-free image loading in your application—often in one line of code!
Picasso.with(context).load("http://i.imgur.com/DvpvklR.png").into(imageView);
Many common pitfalls of image loading on Android are handled automatically by Picasso:
Handling ImageView recycling and download cancelation in an adapter. Complex image transformations with minimal memory use. Automatic memory and disk caching.
Picasso Jake Wharton's Library

Your exact requirement in serviced by Android Universal Image Loader Library. Check out the github repository here
There is a sample code given here which shows the working of the loader for a grid layout.
Hopefully this will serve your need.