Media Data library

This library contains the implementation of the repositories defined in the media domain library, using Media3 and an internal database as data sources.

It also exposes its data sources classes so they can be used by your custom repositories.

MediaDownloadService

An implementation of Media3’s DownloadService that, in conjunction with auxiliary classes, will monitor the state and progress of media downloads, and update the information in the internal database.

Usage

1. Add your own implementation of the service, extending MediaDownloadService;

2. Add your service implementation to your app’s AndroidManifest.xml:

   <service android:name="MediaDownloadServiceImpl"
       android:exported="false">
       <intent-filter>
           <action android:name="com.google.android.exoplayer.downloadService.action.RESTART"/>
           <category android:name="android.intent.category.DEFAULT"/>
       </intent-filter>
   </service>
   

Media Toolkit implementation

DownloadManagerListener

The DownloadManagerListener is an implementation of listener for DownloadManager events which can also get notified of DownloadService creation and destruction events. This class persists information such as the id and the download status in the local database MediaDownloadLocalDataSource.

override fun onDownloadChanged(
        downloadManager: DownloadManager,
        download: Download,
        finalException: Exception?
    ) {
        coroutineScope.launch {
            val mediaId = download.request.id
            val status = MediaDownloadEntityStatusMapper.map(download.state)

            if (status == MediaDownloadEntityStatus.Downloaded) {
                mediaDownloadLocalDataSource.setDownloaded(mediaId)
            } else {
                mediaDownloadLocalDataSource.updateStatus(mediaId, status)
            }
        }

        downloadProgressMonitor.start(downloadManager)
    }

override fun onDownloadRemoved(downloadManager: DownloadManager, download: Download) {
        coroutineScope.launch {
            val mediaId = download.request.id
            mediaDownloadLocalDataSource.delete(mediaId)
        }
    }

DownloadProgressMonitor

The DownloadProgressMonitor monitors the status of the download by polling the DownloadManager and persists the progress in the local database MediaDownloadLocalDataSource.

    private fun update(downloadManager: DownloadManager) {
        coroutineScope.launch {
            val downloads = mediaDownloadLocalDataSource.getAllDownloading()

            if (downloads.isNotEmpty()) {
                for (it in downloads) {
                    downloadManager.downloadIndex.getDownload(it.mediaId)?.let { download ->
                        mediaDownloadLocalDataSource.updateProgress(
                            mediaId = download.request.id,
                            progress = download.percentDownloaded
                                .coerceAtLeast(DOWNLOAD_PROGRESS_START),
                            size = download.contentLength
                        )
                    }
                }
            } else {
                stop()
            }
        }

        if (running) {
            handler.removeCallbacksAndMessages(null)
            handler.postDelayed({ update(downloadManager) }, UPDATE_INTERVAL_MILLIS)
        }
    }

UI Implementation

The PlaylistsDownloadScreen is composed by the MediaContent and the ButtonContent. The MediaContent displays the content that is being downloaded or already downloaded. For content that is being downloaded,
we display the download progress for each track in place of the artist name in the secondaryLabel

val secondaryLabel = when (downloadMediaUiModel) {
        is DownloadMediaUiModel.Downloading -> {
            when (downloadMediaUiModel.progress) {
                is DownloadMediaUiModel.Progress.Waiting -> stringResource(
                    id = R.string.horologist_playlist_download_download_progress_waiting
                )

                is DownloadMediaUiModel.Progress.InProgress -> when (downloadMediaUiModel.size) {
                    is DownloadMediaUiModel.Size.Known -> {
                        val size = Formatter.formatShortFileSize(
                            LocalContext.current,
                            downloadMediaUiModel.size.sizeInBytes
                        )
                        stringResource(
                            id = R.string.horologist_playlist_download_download_progress_known_size,
                            downloadMediaUiModel.progress.progress,
                            size
                        )
                    }

                    DownloadMediaUiModel.Size.Unknown -> stringResource(
                        id = R.string.horologist_playlist_download_download_progress_unknown_size,
                        downloadMediaUiModel.progress.progress
                    )
                }
            }
        }

        is DownloadMediaUiModel.Downloaded -> downloadMediaUiModel.artist
        is DownloadMediaUiModel.NotDownloaded -> downloadMediaUiModel.artist
    }

The ButtonContent displays either a download chip or three buttons to delete, shuffle and play the content. While content is being downloaded, we show an animation on the first button on the left to track progress .

            if (state.downloadMediaListState == PlaylistDownloadScreenState.Loaded.DownloadMediaListState.None) {
                if (state.downloadsProgress is DownloadsProgress.InProgress) {
                    StandardChip(
                        label = stringResource(id = R.string.horologist_playlist_download_button_cancel),
                        onClick = { onCancelDownloadButtonClick(state.collectionModel) },
                        modifier = Modifier.padding(bottom = 16.dp),
                        icon = Icons.Default.Close
                    )
                } else {
                    StandardChip(
                        label = stringResource(id = R.string.horologist_playlist_download_button_download),
                        onClick = { onDownloadButtonClick(state.collectionModel) },
                        modifier = Modifier.padding(bottom = 16.dp),
                        icon = Icons.Default.Download
                    )
                }
            } else {
                Row(
                    modifier = Modifier
                        .padding(bottom = 16.dp)
                        .height(52.dp),
                    verticalAlignment = CenterVertically,
                    horizontalArrangement = Arrangement.spacedBy(6.dp, CenterHorizontally)
                ) {
                    FirstButton(
                        downloadMediaListState = state.downloadMediaListState,
                        downloadsProgress = state.downloadsProgress,
                        collectionModel = state.collectionModel,
                        onDownloadButtonClick = onDownloadButtonClick,
                        onCancelDownloadButtonClick = onCancelDownloadButtonClick,
                        onDownloadCompletedButtonClick = onDownloadCompletedButtonClick,
                        modifier = Modifier
                            .weight(weight = 0.3F, fill = false)
                    )

                    StandardButton(
                        imageVector = Icons.Default.Shuffle,
                        contentDescription = stringResource(id = R.string.horologist_playlist_download_button_shuffle_content_description),
                        onClick = { onShuffleButtonClick(state.collectionModel) },
                        modifier = Modifier
                            .weight(weight = 0.3F, fill = false)
                    )

                    StandardButton(
                        imageVector = Icons.Filled.PlayArrow,
                        contentDescription = stringResource(id = R.string.horologist_playlist_download_button_play_content_description),
                        onClick = { onPlayButtonClick(state.collectionModel) },
                        modifier = Modifier
                            .weight(weight = 0.3F, fill = false)
                    )
                }
            }

Result

Download screens: