Tune time bar update based on duration

library/ui/src/main/java/com/google/android/exoplayer2/ui/DefaultTimeBar.java

@@ -205,6 +205,7 @@ public class DefaultTimeBar extends View implements TimeBar {
   private final CopyOnWriteArraySet<OnScrubListener> listeners;
   private final int[] locationOnScreen;
   private final Point touchPosition;
+  private final float density;
 
   private int keyCountIncrement;
   private long keyTimeIncrement;
@@ -242,6 +243,7 @@ public DefaultTimeBar(Context context, AttributeSet attrs) {
     // Calculate the dimensions and paints for drawn elements.
     Resources res = context.getResources();
     DisplayMetrics displayMetrics = res.getDisplayMetrics();
+    density = displayMetrics.density;
     fineScrubYThreshold = dpToPx(displayMetrics, FINE_SCRUB_Y_THRESHOLD_DP);
     int defaultBarHeight = dpToPx(displayMetrics, DEFAULT_BAR_HEIGHT_DP);
     int defaultTouchTargetHeight = dpToPx(displayMetrics, DEFAULT_TOUCH_TARGET_HEIGHT_DP);
@@ -447,6 +449,11 @@ public void setAdGroupTimesMs(@Nullable long[] adGroupTimesMs, @Nullable boolean
     update();
   }
 
+  @Override
+  public int getTimeBarWidthDp() {
+    return pxToDp(density, getWidth());
+  }
+
   // View methods.
 
   @Override
@@ -835,4 +842,8 @@ public static int getDefaultPlayedAdMarkerColor(int adMarkerColor) {
   private static int dpToPx(DisplayMetrics displayMetrics, int dps) {
     return (int) (dps * displayMetrics.density + 0.5f);
   }
+
+  private static int pxToDp(float density, int px) {
+    return (int) (px / density);
+  }
 }

library/ui/src/main/java/com/google/android/exoplayer2/ui/PlayerControlView.java

@@ -24,6 +24,7 @@
 import android.os.SystemClock;
 import android.support.annotation.Nullable;
 import android.util.AttributeSet;
+import android.util.Log;
 import android.view.KeyEvent;
 import android.view.LayoutInflater;
 import android.view.MotionEvent;
@@ -196,6 +197,9 @@ public interface VisibilityListener {
   public static final int MAX_WINDOWS_FOR_MULTI_WINDOW_TIME_BAR = 100;
 
   private static final long MAX_POSITION_FOR_SEEK_TO_PREVIOUS = 3000;
+  private static final int DEFAULT_UPDATE_DP = 5;
+  private static final long MIN_UPDATE_FREQUENCY_MS = 50;
+  private static final long MAX_UPDATE_FREQUENCY_MS = 1000;
 
   private final ComponentListener componentListener;
   private final View previousButton;
@@ -832,21 +836,10 @@ private void updateProgress() {
       long delayMs;
       if (player.getPlayWhenReady() && playbackState == Player.STATE_READY) {
         float playbackSpeed = player.getPlaybackParameters().speed;
-        if (playbackSpeed <= 0.1f) {
-          delayMs = 1000;
-        } else if (playbackSpeed <= 5f) {
-          long mediaTimeUpdatePeriodMs = 1000 / Math.max(1, Math.round(1 / playbackSpeed));
-          long mediaTimeDelayMs = mediaTimeUpdatePeriodMs - (position % mediaTimeUpdatePeriodMs);
-          if (mediaTimeDelayMs < (mediaTimeUpdatePeriodMs / 5)) {
-            mediaTimeDelayMs += mediaTimeUpdatePeriodMs;
-          }
-          delayMs =
-              playbackSpeed == 1 ? mediaTimeDelayMs : (long) (mediaTimeDelayMs / playbackSpeed);
-        } else {
-          delayMs = 200;
-        }
+        int timeBarWidth = timeBar.getTimeBarWidthDp();
+        delayMs = getTimeBarUpdateDelayMs(timeBarWidth, position, duration, playbackSpeed);
       } else {
-        delayMs = 1000;
+        delayMs = MAX_UPDATE_FREQUENCY_MS;
       }
       postDelayed(updateProgressAction, delayMs);
     }
@@ -1075,6 +1068,58 @@ private static boolean canShowMultiWindowTimeBar(Timeline timeline, Timeline.Win
     return true;
   }
 
+  /**
+   * Calculates the update delay of time bar in millis
+   *
+   * @param timeBarWidth  The width of time bar in dp
+   * @param position      The current position in millis
+   * @param duration      The duration of media in millis
+   * @param playbackSpeed The playback speed
+   * @return Update delay of time bar in millis
+   */
+  private static long getTimeBarUpdateDelayMs(int timeBarWidth, long position,
+                                              long duration, float playbackSpeed) {
+    if (timeBarWidth == 0 || duration == 0 || playbackSpeed == 0) {
+      return MAX_UPDATE_FREQUENCY_MS;
+    }
+
+    // Calculate how many updates needs to be done with DEFAULT_UPDATE_DP
+    // to fill up the time bar
+    int numberOfUpdates = timeBarWidth / DEFAULT_UPDATE_DP;
+
+    if (numberOfUpdates <= 0) {
+      return MAX_UPDATE_FREQUENCY_MS;
+    }
+
+    // Calculate the designated update interval, taking duration into consideration as well
+    long mediaTimeUpdatePeriodMs = duration / numberOfUpdates;
+
+    if (mediaTimeUpdatePeriodMs <= 0) {
+      return MAX_UPDATE_FREQUENCY_MS;
+    }
+
+    // Calculate the delay needed from the current position until the next update is due
+    long mediaTimeDelayMs = mediaTimeUpdatePeriodMs - (position % mediaTimeUpdatePeriodMs);
+
+    // If the delay would be too small, then skip the next update
+    if (mediaTimeDelayMs < (mediaTimeUpdatePeriodMs / 5)) {
+      mediaTimeDelayMs += mediaTimeUpdatePeriodMs;
+    }
+
+    // Calculate the delay until the next update (in real time), taking
+    // playbackSpeed into consideration
+    long delayMs = playbackSpeed == 1 ? mediaTimeDelayMs : (long) (mediaTimeDelayMs / playbackSpeed);
+
+    // Limit the delay if needed, to avoid too frequent / infrequent updates
+    if (delayMs < MIN_UPDATE_FREQUENCY_MS) {
+      delayMs = MIN_UPDATE_FREQUENCY_MS;
+    } else if (delayMs >= MAX_UPDATE_FREQUENCY_MS) {
+      delayMs = MAX_UPDATE_FREQUENCY_MS;
+    }
+
+    return delayMs;
+  }
+
   private final class ComponentListener
       implements Player.EventListener, TimeBar.OnScrubListener, OnClickListener {
 

library/ui/src/main/java/com/google/android/exoplayer2/ui/TimeBar.java

@@ -97,6 +97,13 @@ public interface TimeBar {
   void setAdGroupTimesMs(@Nullable long[] adGroupTimesMs, @Nullable boolean[] playedAdGroups,
       int adGroupCount);
 
+    /**
+     * Get width of time bar in dps
+     *
+     * @return Width of time bar in dps
+     */
+    int getTimeBarWidthDp();
+
   /**
    * Listener for scrubbing events.
    */