Hello programmers, today we will be learning about picasso library for image downloading developed by sqaure.
If we use the traditional method of downloading the image from a url then we need to manage a lots of thing.
And of course lines of code and development time will also increase.
But if we will use a 3rd party library like picasso then we will achieve our goal in few lines of code. So if we will not use a 3rd party library then we would need
Add the following line in the dependency block of your build.gradle file(app /module level).
I am assuming that you are using Android Studio.
After adding it just sync your project.
MainActivity.java
Thank You
- Picasso one of the most popular library for image downloading.
- It makes our wok very simple so its powerful library for image downloading.
- It uses caching technique.
- I have already published a post on Glide(similar to picasso) Image Downloading library for android.
Why Picasso library?
Its obvious that you will think why we should use picasso library.If we use the traditional method of downloading the image from a url then we need to manage a lots of thing.
And of course lines of code and development time will also increase.
But if we will use a 3rd party library like picasso then we will achieve our goal in few lines of code. So if we will not use a 3rd party library then we would need
- Very large amount of code to be written
- We have to write another logic to implement caching.
- Caching is very important to make the application faster.
- We also have to deal with memory while writing the code.
- If any error occurs we need to handle that also.
- we will not focusing more on the application feature that is going to be developed.
Adding Picasso Library to our Android Project
Adding picasso android library to your project is very easy.Add the following line in the dependency block of your build.gradle file(app /module level).
I am assuming that you are using Android Studio.
dependencies {
...
compile 'com.squareup.picasso:picasso:2.71828' //for android studio below 3.0 implementation 'com.squareup.picasso:picasso:2.71828' //above 3.0
...
}
Loading Image from URL by Using Picasso Android Library
Loading image from URL by using Picasso Android Library is very simple and easy. The first thing we would need is an ImageView.Code for Loading Image with Picasso
It is very simple. We have to use the Picasso class.
Picasso.get()
.load(IMAGE_URL)
.into(imageView);
Placeholder and Error Handling
- Because we are loading the image from internet.
- the process would take some time depending on the internet speed.
- So it would be a good idea to display a image from the device while the image from URL is getting loaded.
- One more situation could be when the image is not downloaded from the URL (when the URL given is wrong).
- In this case we should display an error image.
- Both these things can be done very easily by using picasso.
- See the following code snippet.
Picasso.get()
.load("YOUR IMAGE URL HERE")
.placeholder(Your Drawable Resource) // optional the image to display while the url image is downloading
.error(Your Drawable Resource) //this is also optional if some error has occurred in downloading the image //this image would be displayed
.into(imageView);
Re-sizing and Rotating
We can also resize and rotate the image very easily. Picasso.with(this)
.load("YOUR IMAGE URL HERE")
.placeholder(DRAWABLE RESOURCE) // optional
.error(DRAWABLE RESOURCE) // optional
.resize(width, height) // optional
.rotate(degree) // optional
.into(imageView);
Using Picasso Android Library in Our Project
Now lets try the above codes in our Android Studio Project. So I will be creating a new Android Project.- Open Android Studio and create a new project.
- I have created PicassoExample.
- First we have to add the Picasso Library.
- So open your build.gradle(app level) and add the following line inside dependency block and sync your project.
- As we will load the image from a URL so we will also need internet permission.
- So open AndroidManifest.xml and add internet permission.
<uses-permission android:name="android.permission.INTERNET"/>
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:orientation="vertical"
android:layout_height="match_parent"
tools:context=".MainActivity">
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:src="@mipmap/ic_launcher_round"
android:id="@+id/imageView"
/>
<Button
android:layout_width="match_parent"
android:id="@+id/btn"
android:layout_below="@+id/imageView"
android:layout_centerHorizontal="true"
android:text="show image"
android:layout_margin="10dp"
android:layout_height="wrap_content" />
</RelativeLayout> - Now come inside MainActivity.java and define your ImageView and a button.
MainActivity.java
package protector.video.com.picasoexample;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import com.squareup.picasso.Picasso;
public class MainActivity extends AppCompatActivity {
private ImageView imageView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btn=findViewById(R.id.btn);
imageView=findViewById(R.id.imageView); //setting click listener to the button
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Picasso.get()
.load("https://avatars0.githubusercontent.com/u/1?v=4")
.placeholder(R.drawable.ic_image_black_24dp) // optional the image to display while the url image is downloading
.error(R.drawable.ic_error_black_24dp) //this is also optional if some error has occurred in downloading the image //this image would be displayed
.into(imageView);
}
});
}
} - We need two images one for placeholder and one for error. I will be using the following images. Just save these and paste inside the drawable folder of your project.
- Now we need a URL to an ImageFile. I have this URL https://avatars0.githubusercontent.com/u/1?v=4
Finally run your application.
Picasso Android
Happy coding......
