Rename VideoDecoderRenderer to VideoDecoderGLFrameRenderer

We currently have DecoderVideoRenderer and VideoDecoderRenderer, which
is very confusing! This one is package private, so we can rename it to
remove some of the confusion.

Also fix some nullness issues.

PiperOrigin-RevId: 309964088

library/core/src/main/java/com/google/android/exoplayer2/video/VideoDecoderGLFrameRenderer.java

@@ -20,16 +20,19 @@ import android.opengl.GLSurfaceView;
 import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.GlUtil;
+import java.nio.ByteBuffer;
 import java.nio.FloatBuffer;
 import java.util.concurrent.atomic.AtomicReference;
 import javax.microedition.khronos.egl.EGLConfig;
 import javax.microedition.khronos.opengles.GL10;
+import org.checkerframework.checker.nullness.compatqual.NullableType;
+import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
 
 /**
  * GLSurfaceView.Renderer implementation that can render YUV Frames returned by a video decoder
  * after decoding. It does the YUV to RGB color conversion in the Fragment Shader.
  */
-/* package */ class VideoDecoderRenderer
+/* package */ class VideoDecoderGLFrameRenderer
     implements GLSurfaceView.Renderer, VideoDecoderOutputBufferRenderer {
 
   private static final float[] kColorConversion601 = {
@@ -86,7 +89,8 @@ import javax.microedition.khronos.opengles.GL10;
       GlUtil.createBuffer(new float[] {-1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, 1.0f, -1.0f});
   private final GLSurfaceView surfaceView;
   private final int[] yuvTextures = new int[3];
-  private final AtomicReference<VideoDecoderOutputBuffer> pendingOutputBufferReference;
+  private final AtomicReference<@NullableType VideoDecoderOutputBuffer>
+      pendingOutputBufferReference;
 
   // Kept in field rather than a local variable in order not to get garbage collected before
   // glDrawArrays uses it.
@@ -98,10 +102,10 @@ import javax.microedition.khronos.opengles.GL10;
   private int[] previousWidths;
   private int[] previousStrides;
 
-  @Nullable
-  private VideoDecoderOutputBuffer renderedOutputBuffer; // Accessed only from the GL thread.
+  // Accessed only from the GL thread.
+  private @MonotonicNonNull VideoDecoderOutputBuffer renderedOutputBuffer;
 
-  public VideoDecoderRenderer(GLSurfaceView surfaceView) {
+  public VideoDecoderGLFrameRenderer(GLSurfaceView surfaceView) {
     this.surfaceView = surfaceView;
     pendingOutputBufferReference = new AtomicReference<>();
     textureCoords = new FloatBuffer[3];
@@ -119,7 +123,13 @@ import javax.microedition.khronos.opengles.GL10;
     GLES20.glUseProgram(program);
     int posLocation = GLES20.glGetAttribLocation(program, "in_pos");
     GLES20.glEnableVertexAttribArray(posLocation);
-    GLES20.glVertexAttribPointer(posLocation, 2, GLES20.GL_FLOAT, false, 0, TEXTURE_VERTICES);
+    GLES20.glVertexAttribPointer(
+        posLocation,
+        2,
+        GLES20.GL_FLOAT,
+        /* normalized= */ false,
+        /* stride= */ 0,
+        TEXTURE_VERTICES);
     texLocations[0] = GLES20.glGetAttribLocation(program, "in_tc_y");
     GLES20.glEnableVertexAttribArray(texLocations[0]);
     texLocations[1] = GLES20.glGetAttribLocation(program, "in_tc_u");
@@ -140,7 +150,9 @@ import javax.microedition.khronos.opengles.GL10;
 
   @Override
   public void onDrawFrame(GL10 unused) {
-    VideoDecoderOutputBuffer pendingOutputBuffer = pendingOutputBufferReference.getAndSet(null);
+    @Nullable
+    VideoDecoderOutputBuffer pendingOutputBuffer =
+        pendingOutputBufferReference.getAndSet(/* newValue= */ null);
     if (pendingOutputBuffer == null && renderedOutputBuffer == null) {
       // There is no output buffer to render at the moment.
       return;
@@ -151,7 +163,9 @@ import javax.microedition.khronos.opengles.GL10;
       }
       renderedOutputBuffer = pendingOutputBuffer;
     }
-    VideoDecoderOutputBuffer outputBuffer = renderedOutputBuffer;
+
+    VideoDecoderOutputBuffer outputBuffer = Assertions.checkNotNull(renderedOutputBuffer);
+
     // Set color matrix. Assume BT709 if the color space is unknown.
     float[] colorConversion = kColorConversion709;
     switch (outputBuffer.colorspace) {
@@ -163,9 +177,18 @@ import javax.microedition.khronos.opengles.GL10;
         break;
       case VideoDecoderOutputBuffer.COLORSPACE_BT709:
       default:
-        break; // Do nothing
+        // Do nothing.
+        break;
     }
-    GLES20.glUniformMatrix3fv(colorMatrixLocation, 1, false, colorConversion, 0);
+    GLES20.glUniformMatrix3fv(
+        colorMatrixLocation,
+        /* color= */ 1,
+        /* transpose= */ false,
+        colorConversion,
+        /* offset= */ 0);
+
+    int[] yuvStrides = Assertions.checkNotNull(outputBuffer.yuvStrides);
+    ByteBuffer[] yuvPlanes = Assertions.checkNotNull(outputBuffer.yuvPlanes);
 
     for (int i = 0; i < 3; i++) {
       int h = (i == 0) ? outputBuffer.height : (outputBuffer.height + 1) / 2;
@@ -174,14 +197,14 @@ import javax.microedition.khronos.opengles.GL10;
       GLES20.glPixelStorei(GLES20.GL_UNPACK_ALIGNMENT, 1);
       GLES20.glTexImage2D(
           GLES20.GL_TEXTURE_2D,
-          0,
+          /* level= */ 0,
           GLES20.GL_LUMINANCE,
-          outputBuffer.yuvStrides[i],
+          yuvStrides[i],
           h,
-          0,
+          /* border= */ 0,
           GLES20.GL_LUMINANCE,
           GLES20.GL_UNSIGNED_BYTE,
-          outputBuffer.yuvPlanes[i]);
+          yuvPlanes[i]);
     }
 
     int[] widths = new int[3];
@@ -192,28 +215,34 @@ import javax.microedition.khronos.opengles.GL10;
     widths[1] = widths[2] = (widths[0] + 1) / 2;
     for (int i = 0; i < 3; i++) {
       // Set cropping of stride if either width or stride has changed.
-      if (previousWidths[i] != widths[i] || previousStrides[i] != outputBuffer.yuvStrides[i]) {
-        Assertions.checkState(outputBuffer.yuvStrides[i] != 0);
-        float widthRatio = (float) widths[i] / outputBuffer.yuvStrides[i];
+      if (previousWidths[i] != widths[i] || previousStrides[i] != yuvStrides[i]) {
+        Assertions.checkState(yuvStrides[i] != 0);
+        float widthRatio = (float) widths[i] / yuvStrides[i];
         // These buffers are consumed during each call to glDrawArrays. They need to be member
         // variables rather than local variables in order not to get garbage collected.
         textureCoords[i] =
             GlUtil.createBuffer(
                 new float[] {0.0f, 0.0f, 0.0f, 1.0f, widthRatio, 0.0f, widthRatio, 1.0f});
         GLES20.glVertexAttribPointer(
-            texLocations[i], 2, GLES20.GL_FLOAT, false, 0, textureCoords[i]);
+            texLocations[i],
+            /* size= */ 2,
+            GLES20.GL_FLOAT,
+            /* normalized= */ false,
+            /* stride= */ 0,
+            textureCoords[i]);
         previousWidths[i] = widths[i];
-        previousStrides[i] = outputBuffer.yuvStrides[i];
+        previousStrides[i] = yuvStrides[i];
       }
     }
 
     GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
-    GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, 0, 4);
+    GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, /* first= */ 0, /* count= */ 4);
     GlUtil.checkGlError();
   }
 
   @Override
   public void setOutputBuffer(VideoDecoderOutputBuffer outputBuffer) {
+    @Nullable
     VideoDecoderOutputBuffer oldPendingOutputBuffer =
         pendingOutputBufferReference.getAndSet(outputBuffer);
     if (oldPendingOutputBuffer != null) {
@@ -224,7 +253,7 @@ import javax.microedition.khronos.opengles.GL10;
   }
 
   private void setupTextures() {
-    GLES20.glGenTextures(3, yuvTextures, 0);
+    GLES20.glGenTextures(3, yuvTextures, /* offset= */ 0);
     for (int i = 0; i < 3; i++) {
       GLES20.glUniform1i(GLES20.glGetUniformLocation(program, TEXTURE_UNIFORMS[i]), i);
       GLES20.glActiveTexture(GLES20.GL_TEXTURE0 + i);

library/core/src/main/java/com/google/android/exoplayer2/video/VideoDecoderGLSurfaceView.java

@@ -30,7 +30,7 @@ import androidx.annotation.Nullable;
  */
 public class VideoDecoderGLSurfaceView extends GLSurfaceView {
 
-  private final VideoDecoderRenderer renderer;
+  private final VideoDecoderGLFrameRenderer renderer;
 
   /** @param context A {@link Context}. */
   public VideoDecoderGLSurfaceView(Context context) {
@@ -41,9 +41,14 @@ public class VideoDecoderGLSurfaceView extends GLSurfaceView {
    * @param context A {@link Context}.
    * @param attrs Custom attributes.
    */
+  @SuppressWarnings({
+    "nullness:assignment.type.incompatible",
+    "nullness:argument.type.incompatible",
+    "nullness:method.invocation.invalid"
+  })
   public VideoDecoderGLSurfaceView(Context context, @Nullable AttributeSet attrs) {
     super(context, attrs);
-    renderer = new VideoDecoderRenderer(this);
+    renderer = new VideoDecoderGLFrameRenderer(/* surfaceView= */ this);
     setPreserveEGLContextOnPause(true);
     setEGLContextClientVersion(2);
     setRenderer(renderer);

library/core/src/main/java/com/google/android/exoplayer2/video/VideoDecoderOutputBuffer.java

@@ -33,7 +33,7 @@ public class VideoDecoderOutputBuffer extends OutputBuffer {
   //     ../../../../../../../../../../extensions/vp9/src/main/jni/vpx_jni.cc
   // )
 
-  /** Decoder private data. */
+  /** Decoder private data. Used from native code. */
   public int decoderPrivate;
 
   /** Output mode. */