Uses a custom state description for the Audio Balance seek bar.

This makes the seek bar more informative for a user of a screen reader
or other accessibility service. See context in b/319575109#comment7.

Bug: 319575109
Flag: com.android.settings.accessibility.audio_balance_state_description
Test: Use TalkBack to observe the state description while moving the
      seek bar.
Test: atest BalanceSeekBarTest
Change-Id: I7be15b26116f83854efe69d6b0560edde946daf5

aconfig/accessibility/accessibility_flags.aconfig

@@ -10,6 +10,16 @@ flag {
   bug: "332974327"
 }
 
+flag {
+  name: "audio_balance_state_description"
+  namespace: "accessibility"
+  description: "Provides a more valuable state description to the audio balance slider."
+  bug: "319575109"
+  metadata {
+    purpose: PURPOSE_BUGFIX
+  }
+}
+
 flag {
   name: "edit_shortcuts_in_full_screen"
   namespace: "accessibility"

res/values/strings.xml

@@ -13451,6 +13451,10 @@
     <string name="live_caption_disabled">Off</string>
     <!-- Summary of the Live Caption enabled state. -->
     <string name="live_caption_enabled">On</string>
+    <!-- State description for the Audio Balance seek bar, with left reported before right. -->
+    <string name="audio_seek_bar_state_left_first">Audio %1$d%% left, %2$d%% right</string>
+    <!-- State description for the Audio Balance seek bar, with right reported before left. -->
+    <string name="audio_seek_bar_state_right_first">Audio %1$d%% right, %2$d%% left</string>
 
     <!--  Warning text about the visibility of device name. [CHAR LIMIT=NONE] -->
     <string name="about_phone_device_name_warning">Your device name is visible to apps you installed. It may also be seen by other people when you connect to Bluetooth devices, connect to a Wi-Fi network or set up a Wi-Fi hotspot.</string>

src/com/android/settings/accessibility/BalanceSeekBar.java

@@ -20,6 +20,7 @@ import static android.view.HapticFeedbackConstants.CLOCK_TICK;
 
 import static com.android.settings.Utils.isNightMode;
 
+import android.annotation.StringRes;
 import android.content.Context;
 import android.content.res.ColorStateList;
 import android.content.res.Resources;
@@ -86,6 +87,14 @@ public class BalanceSeekBar extends SeekBar {
                 Settings.System.putFloatForUser(mContext.getContentResolver(),
                         Settings.System.MASTER_BALANCE, balance, UserHandle.USER_CURRENT);
             }
+            final int max = getMax();
+            if (Flags.audioBalanceStateDescription() && max > 0) {
+                seekBar.setStateDescription(createStateDescription(mContext,
+                        R.string.audio_seek_bar_state_left_first,
+                        R.string.audio_seek_bar_state_right_first,
+                        progress,
+                        max));
+            }
             // If fromUser is false, the call is a set from the framework on creation or on
             // internal update. The progress may be zero, ignore (don't change system settings).
 
@@ -161,5 +170,19 @@ public class BalanceSeekBar extends SeekBar {
         canvas.restore();
         super.onDraw(canvas);
     }
+
+    private static CharSequence createStateDescription(Context context,
+            @StringRes int resIdLeftFirst, @StringRes int resIdRightFirst,
+            int progress, float max) {
+        final boolean isLayoutRtl = context.getResources().getConfiguration().getLayoutDirection()
+                == LAYOUT_DIRECTION_RTL;
+        final int rightPercent = (int) (100 * (progress / max));
+        final int leftPercent = 100 - rightPercent;
+        if (rightPercent > leftPercent || (rightPercent == leftPercent && isLayoutRtl)) {
+            return context.getString(resIdRightFirst, rightPercent, leftPercent);
+        } else {
+            return context.getString(resIdLeftFirst, leftPercent, rightPercent);
+        }
+    }
 }
 

tests/robotests/src/com/android/settings/accessibility/BalanceSeekBarTest.java

@@ -28,23 +28,32 @@ import static org.mockito.Mockito.verify;
 import static org.robolectric.Shadows.shadowOf;
 
 import android.content.Context;
+import android.platform.test.annotations.EnableFlags;
+import android.platform.test.flag.junit.SetFlagsRule;
 import android.util.AttributeSet;
 import android.widget.SeekBar;
 
+import com.android.settings.R;
 import com.android.settings.testutils.shadow.ShadowSystemSettings;
 
 import org.junit.Before;
+import org.junit.Rule;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.robolectric.RobolectricTestRunner;
 import org.robolectric.RuntimeEnvironment;
 import org.robolectric.annotation.Config;
 
+import java.util.Locale;
+
 @RunWith(RobolectricTestRunner.class)
 @Config(shadows = {
         ShadowSystemSettings.class,
 })
 public class BalanceSeekBarTest {
+    @Rule
+    public final SetFlagsRule mSetFlagsRule = new SetFlagsRule();
+
     // Fix the maximum process value to 200 for testing the BalanceSeekBar.
     // It affects the SeekBar value of center(100) and snapThreshold(200 * SNAP_TO_PERCENTAGE).
     private static final int MAX_PROGRESS_VALUE = 200;
@@ -143,6 +152,58 @@ public class BalanceSeekBarTest {
         assertThat(mSeekBar.getProgress()).isEqualTo(progressWithoutThreshold);
     }
 
+    @Test
+    @EnableFlags(Flags.FLAG_AUDIO_BALANCE_STATE_DESCRIPTION)
+    public void onProgressChanged_getStateDescription_centered_leftFirst() {
+        // Seek bar centered
+        int progress = (int) (0.50f * MAX_PROGRESS_VALUE);
+        mSeekBar.setMax(MAX_PROGRESS_VALUE);
+
+        mProxySeekBarListener.onProgressChanged(mSeekBar, progress, true);
+
+        assertThat(mSeekBar.getStateDescription()).isEqualTo(
+                mContext.getString(R.string.audio_seek_bar_state_left_first, 50, 50));
+    }
+
+    @Test
+    @EnableFlags(Flags.FLAG_AUDIO_BALANCE_STATE_DESCRIPTION)
+    public void onProgressChanged_getStateDescription_centered_rtl_rightFirst() {
+        // RTL layout
+        mContext.getResources().getConfiguration().setLayoutDirection(new Locale("iw", "IL"));
+        // Seek bar centered
+        int progress = (int) (0.50f * MAX_PROGRESS_VALUE);
+        mSeekBar.setMax(MAX_PROGRESS_VALUE);
+
+        mProxySeekBarListener.onProgressChanged(mSeekBar, progress, true);
+
+        assertThat(mSeekBar.getStateDescription()).isEqualTo(
+                mContext.getString(R.string.audio_seek_bar_state_right_first, 50, 50));
+    }
+
+    @Test
+    @EnableFlags(Flags.FLAG_AUDIO_BALANCE_STATE_DESCRIPTION)
+    public void onProgressChanged_getStateDescription_25percent_leftFirst() {
+        // Seek bar 3/4th toward the left
+        int progress = (int) (0.25f * MAX_PROGRESS_VALUE);
+        mSeekBar.setMax(MAX_PROGRESS_VALUE);
+        mProxySeekBarListener.onProgressChanged(mSeekBar, progress, true);
+
+        assertThat(mSeekBar.getStateDescription()).isEqualTo(
+                mContext.getString(R.string.audio_seek_bar_state_left_first, 75, 25));
+    }
+
+    @Test
+    @EnableFlags(Flags.FLAG_AUDIO_BALANCE_STATE_DESCRIPTION)
+    public void onProgressChanged_getStateDescription_75percent_rightFirst() {
+        // Seek bar 3/4th toward the right
+        int progress = (int) (0.75f * MAX_PROGRESS_VALUE);
+        mSeekBar.setMax(MAX_PROGRESS_VALUE);
+        mProxySeekBarListener.onProgressChanged(mSeekBar, progress, true);
+
+        assertThat(mSeekBar.getStateDescription()).isEqualTo(
+                mContext.getString(R.string.audio_seek_bar_state_right_first, 75, 25));
+    }
+
     // method to get the center from BalanceSeekBar for testing setMax().
     private int getBalanceSeekBarCenter(BalanceSeekBar seekBar) {
         return seekBar.getMax() / 2;