android: add AudioManager

meson.build

@@ -290,6 +290,7 @@ if not is_android
 else
   sources += [
     'src/android/Context.cxx',
+    'src/android/AudioManager.cxx',
     'src/android/Environment.cxx',
     'src/android/LogListener.cxx',
   ]

src/android/AudioManager.cxx

@@ -0,0 +1,56 @@
+/*
+ * Copyright 2003-2020 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "AudioManager.hxx"
+#include "java/Class.hxx"
+#include "java/Exception.hxx"
+#include "java/File.hxx"
+
+#define STREAM_MUSIC 3
+
+AudioManager::AudioManager(JNIEnv *env, jobject obj) noexcept
+	: Java::GlobalObject(env, obj)
+{
+	Java::Class cls(env, env->GetObjectClass(Get()));
+	jmethodID method = env->GetMethodID(cls, "getStreamMaxVolume", "(I)I");
+	assert(method);
+	maxVolume = env->CallIntMethod(Get(), method, STREAM_MUSIC);
+
+	getStreamVolumeMethod = env->GetMethodID(cls, "getStreamVolume", "(I)I");
+	assert(getStreamVolumeMethod);
+
+	setStreamVolumeMethod = env->GetMethodID(cls, "setStreamVolume", "(III)V");
+	assert(setStreamVolumeMethod);
+}
+
+int
+AudioManager::GetVolume(JNIEnv *env)
+{
+	if (maxVolume == 0)
+		return 0;
+	return env->CallIntMethod(Get(), getStreamVolumeMethod, STREAM_MUSIC);
+}
+
+void
+AudioManager::SetVolume(JNIEnv *env, int volume)
+{
+	if (maxVolume == 0)
+		return;
+	env->CallVoidMethod(Get(), setStreamVolumeMethod, STREAM_MUSIC, volume, 0);
+}

src/android/AudioManager.hxx

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2003-2020 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_ANDROID_AUDIO_MANAGER_HXX
+#define MPD_ANDROID_AUDIO_MANAGER_HXX
+
+#include "java/Object.hxx"
+
+class AudioManager : public Java::GlobalObject {
+	int maxVolume;
+	jmethodID getStreamVolumeMethod;
+	jmethodID setStreamVolumeMethod;
+
+public:
+	AudioManager(JNIEnv *env, jobject obj) noexcept;
+
+	AudioManager(std::nullptr_t) noexcept { maxVolume = 0; }
+
+	~AudioManager() noexcept {}
+
+	int GetMaxVolume() { return maxVolume; }
+	int GetVolume(JNIEnv *env);
+	void SetVolume(JNIEnv *env, int);
+};
+
+#endif