feat: seekbar preview for downloaded videos

app/src/main/java/com/github/libretube/ui/activities/OfflinePlayerActivity.kt

@@ -33,7 +33,10 @@ import com.github.libretube.helpers.PlayerHelper
 import com.github.libretube.helpers.PlayerHelper.loadPlaybackParams
 import com.github.libretube.helpers.WindowHelper
 import com.github.libretube.ui.base.BaseActivity
+import com.github.libretube.ui.interfaces.TimeFrameReceiver
+import com.github.libretube.ui.listeners.SeekbarPreviewListener
 import com.github.libretube.ui.models.PlayerViewModel
+import com.github.libretube.util.OfflineTimeFrameReceiver
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
@@ -45,6 +48,7 @@ class OfflinePlayerActivity : BaseActivity() {
     private lateinit var player: ExoPlayer
     private lateinit var playerView: PlayerView
     private lateinit var trackSelector: DefaultTrackSelector
+    private var timeFrameReceiver: TimeFrameReceiver? = null
 
     private lateinit var playerBinding: ExoStyledPlayerControlViewBinding
     private val playerViewModel: PlayerViewModel by viewModels()
@@ -89,6 +93,20 @@ class OfflinePlayerActivity : BaseActivity() {
                             player.duration / 1000
                         )
                     }
+
+                    override fun onPlaybackStateChanged(playbackState: Int) {
+                        super.onPlaybackStateChanged(playbackState)
+                        // setup seekbar preview
+                        if (playbackState == Player.STATE_READY) {
+                            binding.player.binding.exoProgress.addListener(
+                                SeekbarPreviewListener(
+                                    timeFrameReceiver ?: return,
+                                    binding.player.binding,
+                                    player.duration
+                                )
+                            )
+                        }
+                    }
                 })
             }
             .loadPlaybackParams()
@@ -134,6 +152,10 @@ class OfflinePlayerActivity : BaseActivity() {
                 setPreferredTextLanguage("en")
             }
 
+            timeFrameReceiver = video?.path?.let {
+                OfflineTimeFrameReceiver(this@OfflinePlayerActivity, it)
+            }
+
             player.prepare()
             player.play()
         }

app/src/main/java/com/github/libretube/ui/listeners/SeekbarPreviewListener.kt

@@ -1,6 +1,7 @@
 package com.github.libretube.ui.listeners
 
 import android.text.format.DateUtils
+import android.util.Log
 import android.view.View
 import android.view.ViewGroup.MarginLayoutParams
 import androidx.core.view.isVisible
@@ -13,16 +14,18 @@ import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 import kotlinx.coroutines.withContext
+import kotlin.math.absoluteValue
 
 @UnstableApi
 class SeekbarPreviewListener(
     private val timeFrameReceiver: TimeFrameReceiver,
     private val playerBinding: ExoStyledPlayerControlViewBinding,
     private val duration: Long,
-    private val onScrub: (position: Long) -> Unit,
-    private val onScrubEnd: (position: Long) -> Unit
+    private val onScrub: (position: Long) -> Unit = {},
+    private val onScrubEnd: (position: Long) -> Unit = {}
 ) : TimeBar.OnScrubListener {
     private var scrubInProgress = false
+    private var lastPreviewPosition = Long.MAX_VALUE
 
     override fun onScrubStart(timeBar: TimeBar, position: Long) {
         scrubInProgress = true
@@ -39,6 +42,13 @@ class SeekbarPreviewListener(
         scrubInProgress = true
 
         playerBinding.seekbarPreviewPosition.text = DateUtils.formatElapsedTime(position / 1000)
+
+        // minimum of five seconds of additional seeking in order to show a preview
+        if ((lastPreviewPosition - position).absoluteValue < 5000) {
+            updatePreviewX(position)
+            return
+        }
+
         CoroutineScope(Dispatchers.IO).launch {
             processPreview(position)
         }
@@ -72,10 +82,7 @@ class SeekbarPreviewListener(
      * Make a request to get the image frame and update its position
      */
     private suspend fun processPreview(position: Long) {
-        // update the offset of the preview image view
-        withContext(Dispatchers.Main) {
-            updatePreviewX(position)
-        }
+        lastPreviewPosition = position
 
         val frame = timeFrameReceiver.getFrameAtTime(position)
         if (!scrubInProgress) return
@@ -83,6 +90,7 @@ class SeekbarPreviewListener(
         withContext(Dispatchers.Main) {
             playerBinding.seekbarPreviewImage.setImageBitmap(frame)
             playerBinding.seekbarPreview.isVisible = true
+            updatePreviewX(position)
         }
     }
 

app/src/main/java/com/github/libretube/util/OfflineTimeFrameReceiver.kt

@@ -0,0 +1,20 @@
+package com.github.libretube.util
+
+import android.content.Context
+import android.graphics.Bitmap
+import android.media.MediaMetadataRetriever
+import com.github.libretube.extensions.toAndroidUri
+import com.github.libretube.ui.interfaces.TimeFrameReceiver
+import java.nio.file.Path
+
+class OfflineTimeFrameReceiver(
+    private val context: Context,
+    private val videoSource: Path
+): TimeFrameReceiver() {
+    private val metadataRetriever = MediaMetadataRetriever().apply {
+        setDataSource(context, videoSource.toAndroidUri())
+    }
+    override suspend fun getFrameAtTime(position: Long): Bitmap? {
+        return metadataRetriever.getFrameAtTime(position * 1000)
+    }
+}

app/src/main/java/com/github/libretube/util/OnlineTimeFrameReceiver.kt

@@ -5,7 +5,6 @@ import android.graphics.Bitmap
 import androidx.core.graphics.drawable.toBitmap
 import com.github.libretube.api.obj.PreviewFrames
 import com.github.libretube.helpers.ImageHelper
-import com.github.libretube.helpers.PlayerHelper
 import com.github.libretube.obj.PreviewFrame
 import com.github.libretube.ui.interfaces.TimeFrameReceiver