DragLinearLayout

An Android LinearLayout that supports draggable and swappable child Views.

Why?

Why bother doing drag & swap in a LinearLayout when there are so many solutions for ListView?

1. Simplicity - no need for ListAdapters. By default, works like a LinearLayout.
2. Flexibility - supports heterogeneous, selectively draggable (or not draggable), children.
3. Portability - can be used in any layout, e.g. as a child in a ScrollView container.

Usage

Add it to your project using Gradle:

compile 'com.jmedeisis:draglinearlayout:1.1.0'

The DragLinearLayout can be used in place of any LinearLayout. However, by default, children will not be draggable. To set an existing View as draggable, use DragLinearLayout#setViewDraggable(View, View), passing in the child View and a (non-null!) View that will act as the handle for dragging it (this can be the View itself).

XML layout file:

<com.jmedeisis.draglinearlayout.DragLinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/container"
  android:layout_width="match_parent"
  android:layout_height="match_parent" >

<TextView

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:text="@string/text" />

<ImageView

android:layout_width="match_parent"

android:layout_height="120dp"

android:scaleType="centerCrop"

android:src="@drawable/image"/>

<Button

android:id="@+id/button"

android:layout_width="match_parent"

android:layout_height="wrap_content"

android:text="@string/button_text"/>

 </com.jmedeisis.draglinearlayout.DragLinearLayout>

Enabling drag & swap for all child views:

DragLinearLayout dragLinearLayout = (DragLinearLayout) findViewById(R.id.container);
 for(int i = 0; i < dragLinearLayout.getChildCount();
 i++){

  View child = dragLinearLayout.getChildAt(i);

  // the child will act as its own drag handle
  dragLinearLayout.setViewDraggable(child, child);
 
}

Use #addDragView(View, View), #addDragView(View, View, int) and #removeDragView(View) to manage draggable children dynamically:

final View view = View.inflate(context, R.layout.view_layout, null);
 dragLinearLayout.addDragView(view, view.findViewById(R.id.view_drag_handle));
  // ..  dragLinearLayout.removeDragView(view);

Attach an OnViewSwapListener with #setOnViewSwapListener(OnViewSwapListener) to detect changes to the ordering of child Views:

dragLinearLayout.setOnViewSwapListener(new DragLinearLayout.OnViewSwapListener() {

  @Override
  public void onSwap(View firstView, int firstPosition,

 View secondView, int secondPosition) {

// update data, etc..
  
}
 
}
);

When placing the DragLinearLayout inside a ScrollView, call #setContainerScrollView(ScrollView) to enable the user to scroll while dragging a child view.

For best visual results, use children that have opaque backgrounds. Furthermore, do not use horizontal padding for the DragLinearLayout; instead, let children apply their own horizontal padding.

Refer to the included sample activity project for a demonstration of the above usage techniques and more.

Limitations

• Supports only the LinearLayout#VERTICAL orientation.

License

This project is licensed under the terms of the MIT license. You may find a copy of the license in the included LICENSE file.