PreviewSeekBar

A SeekBar suited for showing a preview of something. As seen in Google Play Movies.

Google Play Movies

PreviewSeekBar's sample

Build

Add the following to your app's build.gradle:

dependencies {
    compile 'com.github.rubensousa:previewseekbar:1.0'
    
    // If you want to use this with ExoPlayer, use this one:
    compile 'com.github.rubensousa:previewseekbar-exoplayer:2.5.1'
}

How to use

Add the following XML:

<com.github.rubensousa.previewseekbar.PreviewSeekBarLayout
      android:id="@+id/previewSeekBarLayout"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:orientation="vertical">

      <FrameLayout
          android:id="@+id/previewFrameLayout"
          android:layout_width="@dimen/video_preview_width"
          android:layout_height="@dimen/video_preview_height">

          <View
              android:id="@+id/videoView"
              android:layout_width="match_parent"
              android:layout_height="match_parent"
              android:layout_gravity="start"
              android:background="@color/colorPrimary" />

      </FrameLayout>

      <com.github.rubensousa.previewseekbar.PreviewSeekBar
          android:id="@+id/previewSeekBar"
          android:layout_width="match_parent"
          android:layout_height="wrap_content"
          android:layout_below="@id/previewFrameLayout"
          android:layout_marginTop="25dp"
          android:max="800" />
          
</com.github.rubensousa.previewseekbar.PreviewSeekBarLayout>

You need to add at least one PreviewSeekBar and a FrameLayout inside PreviewSeekBarLayout, else an exception will be thrown.

PreviewSeekBarLayout extends from RelativeLayout so you can add other views or layouts there.

Create a PreviewLoader and pass it to PreviewSeekBarLayout:

// Create a class that implements this interface and implement your own preview logic there
public interface PreviewLoader {
    void loadPreview(long currentPosition, long max);
}

PreviewLoader loader = new ExoPlayerLoader();
previewSeekBarLayout.setup(loader);

How to use with ExoPlayer

Add a custom controller to your SimpleExoPlayerView

<com.google.android.exoplayer2.ui.SimpleExoPlayerView
    android:id="@+id/player_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:controller_layout_id="@layout/exoplayer_controls"/>

Here's the sample's exoplayer_controls: https://github.com/rubensousa/PreviewSeekBar/blob/master/sample/src/main/res/layout/exoplayer_controls.xml

The PreviewSeekBarLayout inside exoplayer_controls should be similar to this:

<com.github.rubensousa.previewseekbar.exoplayer.PreviewTimeBarLayout
    android:id="@+id/previewTimeBarLayout"
    android:layout_width="0dp"
    android:layout_height="wrap_content"
    android:layout_weight="1">

    <FrameLayout
        android:id="@+id/previewFrameLayout"
        android:layout_width="@dimen/video_preview_width"
        android:layout_height="@dimen/video_preview_height"
        android:background="@drawable/video_frame"
        android:padding="@dimen/video_frame_width">

        <com.google.android.exoplayer2.ui.SimpleExoPlayerView
            android:id="@+id/previewPlayerView"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:controller_layout_id="@layout/exo_simple_player_view"
            app:surface_type="texture_view"
            app:use_artwork="false"
            app:use_controller="false" />

    </FrameLayout>

    <com.github.rubensousa.previewseekbar.exoplayer.PreviewTimeBar
        android:id="@+id/exo_progress"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/previewFrameLayout"
        android:layout_marginTop="10dp"
        android:max="800" />

</com.github.rubensousa.previewseekbar.PreviewSeekBarLayout>

Use the following SimpleExoPlayerView for the preview:

<com.google.android.exoplayer2.ui.SimpleExoPlayerView
    android:id="@+id/previewPlayerView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:controller_layout_id="@layout/exo_simple_player_view"
    app:surface_type="texture_view"
    app:use_artwork="false"
    app:use_controller="false" />

We specify another controller layout because the default one includes a SeekBar with the same id as ours.

Create a player with a custom TrackSelection and LoadControl

 private SimpleExoPlayer createPreviewPlayer() {
    TrackSelection.Factory videoTrackSelectionFactory = new WorstVideoTrackSelection.Factory();
    TrackSelector trackSelector = new DefaultTrackSelector(videoTrackSelectionFactory);
    LoadControl loadControl = new PreviewLoadControl();
    SimpleExoPlayer player = ExoPlayerFactory.newSimpleInstance(
            new DefaultRenderersFactory(context), trackSelector, loadControl);
    player.setPlayWhenReady(false);
    player.setVolume(0f);
    player.prepare(mediaSourceBuilder.getMediaSource(true));
    return player;
} 

PreviewLoadControl and WorstVideoTrackSelection are already included in previewseekbar-exoplayer. Check the next section for some improvements notes.

Create your own ExoPlayerLoader that seeks the video to the current position

@Override
public void loadPreview(long currentPosition, long max) {
    previewPlayer.seekTo(currentPosition);
    previewPlayer.setPlayWhenReady(false);
}

Improvements

The sample uses some code adapted from the ExoPlayer official demo: https://github.com/google/ExoPlayer

A few improvements would be:

• Adding a stream with lower bitrate to load and display the images faster.

• Using some kind of special stream just for the thumbnails. Maybe this is how the Google Play team did it, I don't know. They load the thumbnails a lot faster than this sample.

• Caching thumbnails in disk for offline use.

Any ideas for improving this would be welcomed!

License

Copyright 2017 The Android Open Source Project
Copyright 2017 Rúben Sousa

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.