Add a Cue.Builder

I want to add fields related to vertical text support, and neither
adding another constructor nor updating all call-sites of existing
constructors seemed like attractive propositions.

PiperOrigin-RevId: 285956024

library/core/src/test/java/com/google/android/exoplayer2/text/CueTest.java

+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * 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.
+ *
+ */
+package com.google.android.exoplayer2.text;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertThrows;
+
+import android.graphics.Bitmap;
+import android.graphics.Color;
+import android.text.Layout;
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+/** Tests for {@link Cue}. */
+@RunWith(AndroidJUnit4.class)
+public class CueTest {
+
+  @Test
+  public void buildSucceeds() {
+    Cue cue =
+        new Cue.Builder()
+            .setText("text")
+            .setTextAlignment(Layout.Alignment.ALIGN_CENTER)
+            .setLine(5, Cue.LINE_TYPE_NUMBER)
+            .setLineAnchor(Cue.ANCHOR_TYPE_END)
+            .setPosition(0.4f)
+            .setPositionAnchor(Cue.ANCHOR_TYPE_MIDDLE)
+            .setTextSize(0.2f, Cue.TEXT_SIZE_TYPE_FRACTIONAL)
+            .setSize(0.8f)
+            .setWindowColor(Color.CYAN)
+            .build();
+
+    assertThat(cue.text).isEqualTo("text");
+    assertThat(cue.textAlignment).isEqualTo(Layout.Alignment.ALIGN_CENTER);
+    assertThat(cue.line).isEqualTo(5);
+    assertThat(cue.lineType).isEqualTo(Cue.LINE_TYPE_NUMBER);
+    assertThat(cue.position).isEqualTo(0.4f);
+    assertThat(cue.positionAnchor).isEqualTo(Cue.ANCHOR_TYPE_MIDDLE);
+    assertThat(cue.textSize).isEqualTo(0.2f);
+    assertThat(cue.textSizeType).isEqualTo(Cue.TEXT_SIZE_TYPE_FRACTIONAL);
+    assertThat(cue.size).isEqualTo(0.8f);
+    assertThat(cue.windowColor).isEqualTo(Color.CYAN);
+    assertThat(cue.windowColorSet).isTrue();
+  }
+
+  @Test
+  public void buildWithNoTextOrBitmapFails() {
+    assertThrows(RuntimeException.class, () -> new Cue.Builder().build());
+  }
+
+  @Test
+  public void buildWithBothTextAndBitmapFails() {
+    assertThrows(
+        RuntimeException.class,
+        () ->
+            new Cue.Builder()
+                .setText("foo")
+                .setBitmap(Bitmap.createBitmap(1, 1, Bitmap.Config.ARGB_8888))
+                .build());
+  }
+}