Create constructor of JAudioTrack class

Bug: 70363744
Test: Built successfully (mmm libmedia -j48)
Change-Id: I51e0510039fca2e84d1ced103fea62156cd1e5c2
diff --git a/media/libmedia/JAudioTrack.cpp b/media/libmedia/JAudioTrack.cpp
new file mode 100644
index 0000000..4ba9425
--- /dev/null
+++ b/media/libmedia/JAudioTrack.cpp
@@ -0,0 +1,102 @@
+/*
+ * Copyright 2018 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.
+ */
+
+#define LOG_TAG "JAudioTrack"
+
+#include "media/JAudioAttributes.h"
+#include "media/JAudioFormat.h"
+#include "media/JAudioTrack.h"
+
+#include <android_runtime/AndroidRuntime.h>
+#include <media/AudioResamplerPublic.h>
+
+namespace android {
+
+// TODO: Add NULL && Exception checks after every JNI call.
+JAudioTrack::JAudioTrack(                             // < Usages of the arguments are below >
+        audio_stream_type_t streamType,               // AudioAudioAttributes
+        uint32_t sampleRate,                          // AudioFormat && bufferSizeInBytes
+        audio_format_t format,                        // AudioFormat && bufferSizeInBytes
+        audio_channel_mask_t channelMask,             // AudioFormat && bufferSizeInBytes
+        size_t frameCount,                            // bufferSizeInBytes
+        audio_session_t sessionId,                    // AudioTrack
+        const audio_attributes_t* pAttributes,        // AudioAttributes
+        float maxRequiredSpeed) {                     // bufferSizeInBytes
+
+    JNIEnv *env = AndroidRuntime::getJNIEnv();
+    jclass jAudioTrackCls = env->FindClass("android/media/AudioTrack");
+
+    maxRequiredSpeed = std::min(std::max(maxRequiredSpeed, 1.0f), AUDIO_TIMESTRETCH_SPEED_MAX);
+
+    int bufferSizeInBytes = 0;
+    if (sampleRate == 0 || frameCount > 0) {
+        // Manually calculate buffer size.
+        bufferSizeInBytes = audio_channel_count_from_out_mask(channelMask)
+                * audio_bytes_per_sample(format) * (frameCount > 0 ? frameCount : 1);
+    } else if (sampleRate > 0) {
+        // Call Java AudioTrack::getMinBufferSize().
+        jmethodID jGetMinBufferSize =
+                env->GetStaticMethodID(jAudioTrackCls, "getMinBufferSize", "(III)I");
+        bufferSizeInBytes = env->CallStaticIntMethod(jAudioTrackCls, jGetMinBufferSize,
+                sampleRate, outChannelMaskFromNative(channelMask), audioFormatFromNative(format));
+    }
+    bufferSizeInBytes = (int) (bufferSizeInBytes * maxRequiredSpeed);
+
+    // Create a Java AudioTrack object through its Builder.
+    jclass jBuilderCls = env->FindClass("android/media/AudioTrack$Builder");
+    jmethodID jBuilderCtor = env->GetMethodID(jBuilderCls, "<init>", "()V");
+    jobject jBuilderObj = env->NewObject(jBuilderCls, jBuilderCtor);
+
+    jmethodID jSetAudioAttributes = env->GetMethodID(jBuilderCls, "setAudioAttributes",
+            "(Landroid/media/AudioAttributes;)Landroid/media/AudioTrack$Builder;");
+    jBuilderObj = env->CallObjectMethod(jBuilderObj, jSetAudioAttributes,
+            JAudioAttributes::createAudioAttributesObj(env, pAttributes, streamType));
+
+    jmethodID jSetAudioFormat = env->GetMethodID(jBuilderCls, "setAudioFormat",
+            "(Landroid/media/AudioFormat;)Landroid/media/AudioTrack$Builder;");
+    jBuilderObj = env->CallObjectMethod(jBuilderObj, jSetAudioFormat,
+            JAudioFormat::createAudioFormatObj(env, sampleRate, format, channelMask));
+
+    jmethodID jSetBufferSizeInBytes = env->GetMethodID(jBuilderCls, "setBufferSizeInBytes",
+            "(I)Landroid/media/AudioTrack$Builder;");
+    jBuilderObj = env->CallObjectMethod(jBuilderObj, jSetBufferSizeInBytes, bufferSizeInBytes);
+
+    // We only use streaming mode of Java AudioTrack.
+    jfieldID jModeStream = env->GetStaticFieldID(jAudioTrackCls, "MODE_STREAM", "I");
+    jint transferMode = env->GetStaticIntField(jAudioTrackCls, jModeStream);
+    jmethodID jSetTransferMode = env->GetMethodID(jBuilderCls, "setTransferMode",
+            "(I)Landroid/media/AudioTrack$Builder;");
+    jBuilderObj = env->CallObjectMethod(jBuilderObj, jSetTransferMode,
+            transferMode /* Java AudioTrack::MODE_STREAM */);
+
+    if (sessionId != 0) {
+        jmethodID jSetSessionId = env->GetMethodID(jBuilderCls, "setSessionId",
+                "(I)Landroid/media/AudioTrack$Builder;");
+        jBuilderObj = env->CallObjectMethod(jBuilderObj, jSetSessionId, sessionId);
+    }
+
+    jmethodID jBuild = env->GetMethodID(jBuilderCls, "build", "()Landroid/media/AudioTrack;");
+    mAudioTrackObj = env->CallObjectMethod(jBuilderObj, jBuild);
+}
+
+void JAudioTrack::stop() {
+    JNIEnv *env = AndroidRuntime::getJNIEnv();
+    jclass jAudioTrackCls = env->FindClass("android/media/AudioTrack");
+    jmethodID jStop = env->GetMethodID(jAudioTrackCls, "stop", "()V");
+    env->CallVoidMethod(mAudioTrackObj, jStop);
+}
+
+} // namespace android