Use of ViewPager in Phimpme

Previously GalleryView was used in phimpme android app but as it is now deprecated, I decided to use ViewPager instead of GalleryView.

ViewPager allows us to view data with a horizontal swipe with the help of layoutManager.

Steps to implement the viewPager:

  1. First, add the ViewPager in Activity.xml file where you want to implement the ViewPager. This can be done using the line of code below:
<android.support.v4.view.ViewPager
             android:id="@+id/view_pager"
                android:layout_width="match_parent"
               android:layout_height="match_parent">

</android.support.v4.view.ViewPager>
  1.  To display the content of viewPager we use the viewPagerAdapter. Create new java file ViewPagerAdapter and extends it to PagerAdapter.

ViewPagerAdapter.java

public class ViewPagerAdapter extends PagerAdapter {
}
  1. After extending to PagerAdaper we have to override the two basic methods of PagerAdapter.

First, implement the constructor which helps us to provide the context of activity to ViewPagerAdapter.

You can override by pressing Alt+enter combination, click on “implement methods” and then selects these two methods.

It will implement two methods  

  • getCount()
  • isViewFromObject()

getCount will return the number of items in view pager.

  1. Now we override the few methods which are required to inflate and destroy view in viewPager.

First,

Override the instantiateItem() method it creates the page for given position.

@Override

public Object instantiateItem(ViewGroup container, int position) {
 return super.instantiateItem(container, position);
}

Now we will modify this method to inflate the view for viewPager.

As we want to display imageView in viewPager first we have to inflate the imageView and set Image according to the position of ViewPager.

Next steps,

  • Implement the customView for imageView.
  • And provide the data for  ViewPager i.e Array of images.

Create new custom_layout.xml and add ImageView in it.

<ImageView

   android:layout_width="match_parent"

   android:id="@+id/image_view"

   android:layout_height="match_parent" />

And create an array for images if you want to show images from the local memory so collect path of the images which you want to show with the array name Images.

Now we will use custom_layout layout in our ViewPager instantiateItem() method.

@Override

public Object instantiateItem(ViewGroup container, int position) {

   LayoutInflater layoutInflater = (LayoutInflater)  context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

   View view=  layoutInflater.inflate(R.layout.custom_view,null);

   ImageView imageView = (ImageView)view.findViewById(R.id.image_view);

   imageView.setBackgroundResource(images[position]);

   container.addView(view,0);

   return view;

}

The above code inflates the imageView in ViewPager.

Now we have to override destroyItem() method.  This method will destroy the content of viewPager from given position.

The below code will remove the view which we added in instantiateItem() method.

@Override

public void destroyItem(ViewGroup container, int position, Object object) {
  container.removeView((View) object);
}

Now PagerAdapter is ready, we can use this in our Activity.

  1. Reference the viewPager and set the ViewPagerAdapter to ViewPager.

Activity.java

@Override

protected void onCreate(Bundle savedInstanceState) {

   super.onCreate(savedInstanceState);

   setContentView(R.layout.activity_main);

   ViewPager viewPager = (ViewPager) findViewById(R.id.view_pager);

   viewPager.setAdapter(new ViewPagerAdapter(this));

}

The above code will set the pagerAdapter to our viewPager and display the content which we defined in instantiateItem() method of pagerAdapter.

 

This is how viewPager will allow viewing images by swiping horizontally in Phimpme.

Resources:

https://developer.android.com/reference/android/support/v4/view/PagerAdapter.html

https://github.com/fossasia/phimpme-android/pull/407/files

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Set spacing in RecyclerView items by custom Item Decorator in Phimpme Android App
Spacing in RecyclerView GridLayoutManager

Set spacing in RecyclerView items by custom Item Decorator in Phimpme Android App

We have decided to shift our images Gallery code from GridView to using Grid Layout manager in RecyclerView in Phimpme Android application. RecyclerView has many advantages as compare to Grid/ List view.

  • Advantages of using layout manager either List, Grid or Staggered.
  • We can use many built in animations.
  • Item decorator for customizing the item.
  • Recycle items using the View Holder pattern

Recycler View documentation

Adding recyclerview in xml

<android.support.v7.widget.RecyclerView

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:id="@+id/rv"

    />

Setting layout manager

mLayoutManager = new GridLayoutManager(this, 3);

recyclerView.setLayoutManager(mLayoutManager);

In phimpme we have an item as an ImageView, to show into the grid. Setup the Grid using layout manager as above.

Gallery of images is set but there is no spacing in between grid items. Padding will not help in this case.

Found a way to set offset by creating a Custom item decoration class. Add a constructor with parameter as a dimension resource.

 

public class ItemOffsetDecoration extends RecyclerView.ItemDecoration {

   private int mItemOffset;

   public ItemOffsetDecoration(int itemOffset) {

       mItemOffset = itemOffset;

   }



   public ItemOffsetDecoration(@NonNull Context context, @DimenRes int itemOffsetId) {

       this(context.getResources().getDimensionPixelSize(itemOffsetId));

   }

   @Override

   public void getItemOffsets(Rect outRect, View view, RecyclerView parent,

           RecyclerView.State state) {

       super.getItemOffsets(outRect, view, parent, state);

       outRect.set(mItemOffset, mItemOffset, mItemOffset, mItemOffset);

   }

}

Author: gist.github.com/yqritc/ccca77dc42f2364777e1

Usage:

ItemOffsetDecoration itemDecoration = new ItemOffsetDecoration(context, R.dimen.item_offset);

mRecyclerView.addItemDecoration(itemDecoration)

Pass the item_offset value in the function. Go through the material design guidelines for a clear understanding of dimensions in item offset.

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UI Testing in Phimpme Android

Espresso is an Android Testing tool which helps developers to write UI based tests. After writing tests, developers can make use of Android studio to run the tests or can implement a method in various Continuous integration sites like Travis CI to run the tests on a new push or a pull request. I implemented Espresso tests in the Phimpme Android project of FOSSASIA to test the basic UI elements of the home screen, camera view and the settings activity.

Steps to Add the UI tests :

    1. The first step is to import the packages related to the instrumentation tests and configure the build.gradle file of the application to add certain dependencies. This can be done using the line of code below:
      dependencies {
      androidTestCompile 'com.android.support.test.espresso:espresso-core:2.2.2'
      }
      
    2. To ensure best test results make sure that you turn off the device animations. For this go to developer options and disable the:
      • Window animation scale
      • Transition animation scale
      • Animator duration scale

      After doing the above, your developer options screen should look like the screenshot below with all the animation scale disabled.

    3. Create the java class for the android test with the name of the activity you want to test followed by the word Test. Suppose you want to create a test for your MainActivity. Make a test class with the name MainActivityTest.
    4. Define your tests with annotations @LargeTest @RunWith(AndroidJUnit4.class) and define the MainActivity Test.
    5. Define the Test activity rule with the annotation @Rule and mention the java class which you want to test. I’ll be explaining the codes exactly as I used to add espresso test in Phimpme Android application below. In this for testing the PhimpMe.class, I used the following codes
      
      @Rule
      public ActivityTestRule<PhimpMe> mActivityTestRule = new ActivityTestRule<>(PhimpMe.class);

      The codes from defining the tests to defining the rules are given below:

      @LargeTest
      @RunWith(AndroidJUnit4.class)
          public class MainActivityTest {
             @Rule
             public ActivityTestRule<PhimpMe> mActivityTestRule = new ActivityTestRule<>(PhimpMe.class);
      
    6. After this, start writing the tests with the @Test annotations, the code as I used to test the Load more photos button in the MainActivity of the Phimpme Application is shown below:
      
      @Test
      ViewInteraction imageView = onView(
                      allOf(withId(R.id.btnLoadMoreLocalPhotos),
                              childAtPosition(
                                      allOf(withId(R.id.titlebarLocalPhotos),
                                              childAtPosition(
                                                      IsInstanceOf.instanceOf(android.widget.LinearLayout.class),
                                                      0)),
                                      1),
                              isDisplayed()));
      imageView.check(matches(isDisplayed()));
      

 

The above code checks whether the plus button in the top right corner is visible in the UI.

For the complete code, please refer to the Phimpme Android Repository of FOSSASIA or refer to this pull request in which I added tests for all the Activities and Fragments of the Phimpme Android Application. Since we are rebuilding the application by modifying the whole view of the application, the tests are currently removed. As soon as the application becomes fairly stable, I will be adding the Tests in this in the same way.

For complete tutorial on setting up the test using the Android Studio Inbuilt functionality. Refer to :

https://developer.android.com/studio/test/espresso-test-recorder.html#run-an-espresso-test-with-firebase-test-lab

That’s it for now. Thanks!

Resources :

https://developer.android.com/training/testing/ui-testing/espresso-testing.html

https://github.com/fossasia/phimpme-android/pull/85/files

https://developer.android.com/studio/test/espresso-test-recorder.html#run-an-espresso-test-with-firebase-test-lab

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