SwipeCoordinator simplifies the processs of implementing animated swipeable views. It links a view with its parent as a single behavioural unit constrained by the parent boundaries. SwipeCoordinator supports both left-to-right and top-to-bottom direction.

Add to top level gradle.build file

allprojects {
    repositories {
        maven { url "https://jitpack.io" }
    }
}

Add to app module gradle.build file

dependencies {
    compile 'com.github.VictorAlbertos:SwipeCoordinator:0.0.2'
}

Identify the swipeable view with @id/swipeable_view attribute. Thew ViewGroup containing the swipeable view can not declare any padding attribute, as such as the swipeable view can not declare any margin. Otherwise the calculations will be misleading.

<RelativeLayout
      android:id="@+id/parent_swipeable_view"
      android:layout_width="match_parent"
      android:layout_height="?attr/actionBarSize"
      android:background="@color/colorPrimary">

    <View
        android:id="@id/swipeable_view"
        android:layout_width="?attr/actionBarSize"
        android:layout_height="?attr/actionBarSize"
        android:background="@color/colorAccent"/>

</RelativeLayout>

Create an instance of SwipeCoordinator suppliyng as argument constructor the parent layout of the swipeable view, and the expected direction for the swipe gesture.

ViewGroup parentSwipeableView = (ViewGroup) findViewById(R.id.parent_swipeable_view);
    SwipeCoordinator swipeCoordinator =
        new SwipeCoordinator(parentSwipeableView, SwipeDirection.LEFT_TO_RIGHT);

ActionUpSwipeListener signals the MotionEvent ACTION_UP of the swipeable view providing a boolean as a flag to indicate if the action took place surpassing the threshold value. This callback is the place to determine if the user fulfilled the motion event.

swipeCoordinator.setOnActionUpSwipeListener(new SwipeCoordinator.ActionUpSwipeListener() {
  @Override public void onActionUp(boolean thresholdReached) {
    if (thresholdReached) Toast.makeText(this, "Approved", Toast.LENGTH_SHORT).show();
    else Toast.makeText(this, "Pending", Toast.LENGTH_SHORT).show();
  }
});

ProgressListener emits the progress of the swipeable view. From 0 to 1, this value represent in percentage the left distance to its fulfilled position. This callback is the perfect place to create animations based on the progress value.

swipeCoordinator.setProgressListener(new SwipeCoordinator.ProgressListener() {
  @Override public void onProgress(float progress) {
    tvAccepted.setScaleX(progress);
    tvAccepted.setScaleY(progress);
    tvAccepted.setAlpha(progress);
  }
});

SwipeCoordinator exposes doSwipe method. It translates the swipeable view to the fulfilled stage and calls ProgressListener::onProgress(progress) with a value of 1.0 to restore all the dependent state views (scale, alpha...).

The value in percentage of the threshold to signal it as reached when the user drops the swipeable view. From 0 to 1, being the default value 0.7.

swipeCoordinator.setThreshold(0.5f);

Increment (if number greater than 1.0) or decrement (if number less than 1.0) the duration of the rearrange animation performed when the user drops the swipeable view. Default value is 1.0.

swipeCoordinator.setVariancePercentage(0.5f);

The module test-sample contains both example and UI test driven by Espresso.

Víctor Albertos

• https://twitter.com/_victorAlbertos
• https://www.linkedin.com/in/victoralbertos
• https://github.com/VictorAlbertos

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