Android: Generate Java -> C++ JNI code for VideoEncoder

This is the first CL that tries generating Java -> C++ JNI code.

Bug: webrtc:8278
Change-Id: I1ff0df10db0f80a3c84a61a4e82be8f713690a69
Reviewed-on: https://webrtc-review.googlesource.com/20873
Commit-Queue: Magnus Jedvert <magjed@webrtc.org>
Reviewed-by: Sami Kalliomäki <sakal@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#20592}

sdk/android/BUILD.gn

@@ -488,6 +488,7 @@ rtc_android_library("libjingle_peerconnection_java") {
     "src/java/org/webrtc/Histogram.java",
     "src/java/org/webrtc/JniCommon.java",
     "src/java/org/webrtc/MediaCodecUtils.java",
+    "src/java/org/webrtc/NativeClassQualifiedName.java",
     "src/java/org/webrtc/NativeLibrary.java",
     "src/java/org/webrtc/NV12Buffer.java",
     "src/java/org/webrtc/NV21Buffer.java",

sdk/android/src/java/org/webrtc/NativeClassQualifiedName.java

@@ -0,0 +1,31 @@
+/*
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+package org.webrtc;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * @NativeClassQualifiedName is used by the JNI generator to create the necessary JNI
+ * bindings to call into the specified native class name.
+ */
+@Target(ElementType.METHOD)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface NativeClassQualifiedName {
+  /*
+   * Tells which native class the method is going to be bound to.
+   * The first parameter of the annotated method must be an int nativePtr pointing to
+   * an instance of this class.
+   */
+  public String value();
+}

sdk/android/src/java/org/webrtc/VideoEncoderWrapper.java

@@ -69,12 +69,13 @@ class VideoEncoderWrapper {
   @CalledByNative
   static VideoEncoder.Callback createEncoderCallback(final long nativeEncoder) {
     return (EncodedImage frame, VideoEncoder.CodecSpecificInfo info)
-               -> onEncodedFrame(nativeEncoder, frame.buffer, frame.encodedWidth,
+               -> nativeOnEncodedFrame(nativeEncoder, frame.buffer, frame.encodedWidth,
                    frame.encodedHeight, frame.captureTimeNs, frame.frameType.getNative(),
                    frame.rotation, frame.completeFrame, frame.qp);
   }
 
-  private static native void onEncodedFrame(long nativeEncoder, ByteBuffer buffer, int encodedWidth,
+  @NativeClassQualifiedName("webrtc::jni::VideoEncoderWrapper")
-      int encodedHeight, long captureTimeNs, int frameType, int rotation, boolean completeFrame,
+  private static native void nativeOnEncodedFrame(long nativeEncoder, ByteBuffer buffer,
-      Integer qp);
+      int encodedWidth, int encodedHeight, long captureTimeNs, int frameType, int rotation,
+      boolean completeFrame, Integer qp);
 }

sdk/android/src/jni/jni_generator_helper.h

@@ -19,9 +19,12 @@
 #include "sdk/android/src/jni/jni_helpers.h"
 
 #define CHECK_CLAZZ(env, jcaller, clazz, ...) RTC_DCHECK(clazz);
+#define CHECK_NATIVE_PTR(env, jcaller, native_ptr, method_name, ...) \
+  RTC_DCHECK(native_ptr) << method_name;
 
 #define BASE_EXPORT
 #define JNI_REGISTRATION_EXPORT __attribute__((visibility("default")))
+#define JNI_GENERATOR_EXPORT extern "C" JNIEXPORT JNICALL
 
 namespace jni_generator {
 inline void CheckException(JNIEnv* env) {
@@ -70,6 +73,8 @@ class JavaRef {
 // using DeleteLocalRef though.
 template <typename T>
 using ScopedJavaLocalRef = JavaRef<T>;
+template <typename T>
+using JavaParamRef = JavaRef<T>;
 
 // This function will initialize |atomic_class_id| to contain a global ref to
 // the given class, and will return that ref on subsequent calls. The caller is

sdk/android/src/jni/videoencoderwrapper.cc

@@ -192,6 +192,7 @@ const char* VideoEncoderWrapper::ImplementationName() const {
 }
 
 void VideoEncoderWrapper::OnEncodedFrame(JNIEnv* jni,
+                                         jobject j_caller,
                                          jobject j_buffer,
                                          jint encoded_width,
                                          jint encoded_height,
@@ -402,25 +403,5 @@ std::string VideoEncoderWrapper::GetImplementationName(JNIEnv* jni) const {
   return JavaToStdString(jni, jname);
 }
 
-JNI_FUNCTION_DECLARATION(void,
-                         VideoEncoderWrapper_onEncodedFrame,
-                         JNIEnv* jni,
-                         jclass,
-                         jlong j_native_encoder,
-                         jobject buffer,
-                         jint encoded_width,
-                         jint encoded_height,
-                         jlong capture_time_ns,
-                         jint frame_type,
-                         jint rotation,
-                         jboolean complete_frame,
-                         jobject qp) {
-  VideoEncoderWrapper* native_encoder =
-      reinterpret_cast<VideoEncoderWrapper*>(j_native_encoder);
-  native_encoder->OnEncodedFrame(jni, buffer, encoded_width, encoded_height,
-                                 capture_time_ns, frame_type, rotation,
-                                 complete_frame, qp);
-}
-
 }  // namespace jni
 }  // namespace webrtc

sdk/android/src/jni/videoencoderwrapper.h

@@ -55,6 +55,7 @@ class VideoEncoderWrapper : public VideoEncoder {
 
   // Should only be called by JNI.
   void OnEncodedFrame(JNIEnv* jni,
+                      jobject j_caller,
                       jobject j_buffer,
                       jint encoded_width,
                       jint encoded_height,