Android Build Tools

Android/android-ndk-r27d/sources/android/ndk_helper/JNIHelper.h

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+/*
+ * Copyright 2013 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.
+ */
+
+#pragma once
+
+#include <jni.h>
+#include <vector>
+#include <string>
+
+#include <android/log.h>
+#include <android_native_app_glue.h>
+
+#define LOGI(...) ((void)__android_log_print(ANDROID_LOG_INFO, ndk_helper::JNIHelper::GetInstance()->GetAppName(), __VA_ARGS__))
+#define LOGW(...) ((void)__android_log_print(ANDROID_LOG_WARN, ndk_helper::JNIHelper::GetInstance()->GetAppName(), __VA_ARGS__))
+#define LOGE(...) ((void)__android_log_print(ANDROID_LOG_ERROR, ndk_helper::JNIHelper::GetInstance()->GetAppName(), __VA_ARGS__))
+
+namespace ndk_helper
+{
+
+/******************************************************************
+ * Helper functions for JNI calls
+ * This class wraps JNI calls and provides handy interface calling commonly used features
+ * in Java SDK.
+ * Such as
+ * - loading graphics files (e.g. PNG, JPG)
+ * - character code conversion
+ * - retrieving system properties which only supported in Java SDK
+ *
+ * NOTE: To use this class, add NDKHelper.java as a corresponding helpers in Java code
+ */
+class JNIHelper
+{
+private:
+    std::string app_name_;
+
+    ANativeActivity* activity_;
+    jobject jni_helper_java_ref_;
+    jclass jni_helper_java_class_;
+
+    //mutex for synchronization
+    //This class uses singleton pattern and can be invoked from multiple threads,
+    //each methods locks the mutex for a thread safety
+    mutable pthread_mutex_t mutex_;
+
+    jstring GetExternalFilesDirJString( JNIEnv *env );
+    jclass RetrieveClass( JNIEnv *jni,
+            const char* class_name );
+
+    JNIHelper();
+    ~JNIHelper();
+    JNIHelper( const JNIHelper& rhs );
+    JNIHelper& operator=( const JNIHelper& rhs );
+
+public:
+    /*
+     * To load your own Java classes, JNIHelper requires to be initialized with a ANativeActivity handle.
+     * This methods need to be called before any call to the helper class.
+     * Static member of the class
+     *
+     * arguments:
+     * in: activity, pointer to ANativeActivity. Used internally to set up JNI environment
+     * in: helper_class_name, pointer to Java side helper class name. (e.g. "com/sample/helper/NDKHelper" in samples )
+     */
+    static void Init( ANativeActivity* activity,
+            const char* helper_class_name );
+
+    /*
+     * Retrieve the singleton object of the helper.
+     * Static member of the class
+
+     * Methods in the class are designed as thread safe.
+     */
+    static JNIHelper* GetInstance();
+
+    /*
+     * Read a file from a strorage.
+     * First, the method tries to read the file from an external storage.
+     * If it fails to read, it falls back to use assset manager and try to read the file from APK asset.
+     *
+     * arguments:
+     * in: file_name, file name to read
+     * out: buffer_ref, pointer to a vector buffer to read a file.
+     *      when the call succeeded, the buffer includes contents of specified file
+     *      when the call failed, contents of the buffer remains same
+     * return:
+     * true when file read succeeded
+     * false when it failed to read the file
+     */
+    bool ReadFile( const char* file_name,
+            std::vector<uint8_t>* buffer_ref );
+
+    /*
+     * Load and create OpenGL texture from given file name.
+     * The method invokes BitmapFactory in Java so it can read jpeg/png formatted files
+     *
+     * The methods creates mip-map and set texture parameters like this,
+     * glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_NEAREST );
+     * glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
+     * glGenerateMipmap( GL_TEXTURE_2D );
+     *
+     * arguments:
+     * in: file_name, file name to read, PNG&JPG is supported
+     * return:
+     * OpenGL texture name when the call succeeded
+     * When it failed to load the texture, it returns -1
+     */
+    uint32_t LoadTexture( const char* file_name );
+
+    /*
+     * Convert string from character code other than UTF-8
+     *
+     * arguments:
+     *  in: str, pointer to a string which is encoded other than UTF-8
+     *  in: encoding, pointer to a character encoding string.
+     *  The encoding string can be any valid java.nio.charset.Charset name
+     *  e.g. "UTF-16", "Shift_JIS"
+     * return: converted input string as an UTF-8 std::string
+     */
+    std::string ConvertString( const char* str,
+            const char* encode );
+    /*
+     * Retrieve external file directory through JNI call
+     *
+     * return: std::string containing external file diretory
+     */
+    std::string GetExternalFilesDir();
+
+    /*
+     * Audio helper
+     * Retrieves native audio buffer size which is required to achieve low latency audio
+     *
+     * return: Native audio buffer size which is a hint to achieve low latency audio
+     * If the API is not supported (API level < 17), it returns 0
+     */
+    int32_t GetNativeAudioBufferSize();
+
+    /*
+     * Audio helper
+     * Retrieves native audio sample rate which is required to achieve low latency audio
+     *
+     * return: Native audio sample rate which is a hint to achieve low latency audio
+     */
+    int32_t GetNativeAudioSampleRate();
+
+    /*
+     * Retrieves application bundle name
+     *
+     * return: pointer to an app name string
+     *
+     */
+    const char* GetAppName()
+    {
+        return app_name_.c_str();
+    }
+
+};
+
+} //namespace ndkHelper