Add method to compile program from shader paths in GlUtil

This method will be useful for adding Open GL to the Transformer.

PiperOrigin-RevId: 394420744

demos/gl/src/main/java/com/google/android/exoplayer2/gldemo/BitmapOverlayVideoProcessor.java

@@ -28,9 +28,7 @@ import androidx.annotation.Nullable;
 import com.google.android.exoplayer2.C;
 import com.google.android.exoplayer2.util.Assertions;
 import com.google.android.exoplayer2.util.GlUtil;
-import com.google.android.exoplayer2.util.Util;
 import java.io.IOException;
-import java.io.InputStream;
 import java.util.Locale;
 import javax.microedition.khronos.opengles.GL10;
 
@@ -79,10 +77,15 @@ import javax.microedition.khronos.opengles.GL10;
 
   @Override
   public void initialize() {
-    String vertexShaderCode =
-        loadAssetAsString(context, "bitmap_overlay_video_processor_vertex.glsl");
-    String fragmentShaderCode =
-        loadAssetAsString(context, "bitmap_overlay_video_processor_fragment.glsl");
+    String vertexShaderCode;
+    String fragmentShaderCode;
+    try {
+      vertexShaderCode = GlUtil.loadAsset(context, "bitmap_overlay_video_processor_vertex.glsl");
+      fragmentShaderCode =
+          GlUtil.loadAsset(context, "bitmap_overlay_video_processor_fragment.glsl");
+    } catch (IOException e) {
+      throw new IllegalStateException(e);
+    }
     program = GlUtil.compileProgram(vertexShaderCode, fragmentShaderCode);
     GlUtil.Attribute[] attributes = GlUtil.getAttributes(program);
     GlUtil.Uniform[] uniforms = GlUtil.getUniforms(program);
@@ -156,16 +159,4 @@ import javax.microedition.khronos.opengles.GL10;
     GLES20.glDrawArrays(GLES20.GL_TRIANGLE_STRIP, /* first= */ 0, /* count= */ 4);
     GlUtil.checkGlError();
   }
-
-  private static String loadAssetAsString(Context context, String assetFileName) {
-    @Nullable InputStream inputStream = null;
-    try {
-      inputStream = context.getAssets().open(assetFileName);
-      return Util.fromUtf8Bytes(Util.toByteArray(inputStream));
-    } catch (IOException e) {
-      throw new IllegalStateException(e);
-    } finally {
-      Util.closeQuietly(inputStream);
-    }
-  }
 }

library/common/src/main/java/com/google/android/exoplayer2/util/GlUtil.java

@@ -31,6 +31,8 @@ import androidx.annotation.DoNotInline;
 import androidx.annotation.Nullable;
 import androidx.annotation.RequiresApi;
 import com.google.android.exoplayer2.C;
+import java.io.IOException;
+import java.io.InputStream;
 import java.nio.Buffer;
 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
@@ -436,6 +438,24 @@ public final class GlUtil {
   }
 
   /**
+   * Loads a file from the assets folder.
+   *
+   * @param context The {@link Context}.
+   * @param assetPath The path to the file to load, from the assets folder.
+   * @return The content of the file to load.
+   * @throws IOException If the file couldn't be read.
+   */
+  public static String loadAsset(Context context, String assetPath) throws IOException {
+    @Nullable InputStream inputStream = null;
+    try {
+      inputStream = context.getAssets().open(assetPath);
+      return Util.fromUtf8Bytes(Util.toByteArray(inputStream));
+    } finally {
+      Util.closeQuietly(inputStream);
+    }
+  }
+
+  /**
    * Creates a GL_TEXTURE_EXTERNAL_OES with default configuration of GL_LINEAR filtering and
    * GL_CLAMP_TO_EDGE wrapping.
    */