core/jni/android_window_WindowInfosListener.cpp

/*
 * Copyright 2021 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 "WindowInfosListener"

#include <android_runtime/AndroidRuntime.h>
#include <android_runtime/Log.h>
#include <gui/SurfaceComposerClient.h>
#include <nativehelper/JNIHelp.h>
#include <utils/Log.h>

#include "android_hardware_input_InputWindowHandle.h"
#include "core_jni_helpers.h"

namespace android {

using gui::WindowInfo;

namespace {

static struct {
    jclass clazz;
    jmethodID onWindowInfosChanged;
} gListenerClassInfo;

static jclass gInputWindowHandleClass;

struct WindowInfosListener : public gui::WindowInfosListener {
    WindowInfosListener(JNIEnv* env, jobject listener)
          : mListener(env->NewWeakGlobalRef(listener)) {}

    void onWindowInfosChanged(const std::vector<WindowInfo>& windowInfos) override {
        JNIEnv* env = AndroidRuntime::getJNIEnv();
        LOG_ALWAYS_FATAL_IF(env == nullptr, "Unable to retrieve JNIEnv in onWindowInfoChanged.");

        jobject listener = env->NewGlobalRef(mListener);
        if (listener == nullptr) {
            // Weak reference went out of scope
            return;
        }

        jobjectArray jWindowHandlesArray =
                env->NewObjectArray(windowInfos.size(), gInputWindowHandleClass, nullptr);
        for (int i = 0; i < windowInfos.size(); i++) {
            ScopedLocalRef<jobject>
                    jWindowHandle(env,
                                  android_view_InputWindowHandle_fromWindowInfo(env,
                                                                                windowInfos[i]));
            env->SetObjectArrayElement(jWindowHandlesArray, i, jWindowHandle.get());
        }

        env->CallVoidMethod(listener, gListenerClassInfo.onWindowInfosChanged, jWindowHandlesArray);
        env->DeleteGlobalRef(listener);

        if (env->ExceptionCheck()) {
            ALOGE("WindowInfosListener.onWindowInfosChanged() failed.");
            LOGE_EX(env);
            env->ExceptionClear();
        }
    }

    ~WindowInfosListener() override {
        JNIEnv* env = AndroidRuntime::getJNIEnv();
        env->DeleteWeakGlobalRef(mListener);
    }

private:
    jweak mListener;
};

jlong nativeCreate(JNIEnv* env, jclass clazz, jobject obj) {
    WindowInfosListener* listener = new WindowInfosListener(env, obj);
    listener->incStrong((void*)nativeCreate);
    return reinterpret_cast<jlong>(listener);
}

void destroyNativeService(void* ptr) {
    WindowInfosListener* listener = reinterpret_cast<WindowInfosListener*>(ptr);
    listener->decStrong((void*)nativeCreate);
}

void nativeRegister(JNIEnv* env, jclass clazz, jlong ptr) {
    sp<WindowInfosListener> listener = reinterpret_cast<WindowInfosListener*>(ptr);
    SurfaceComposerClient::getDefault()->addWindowInfosListener(listener);
}

void nativeUnregister(JNIEnv* env, jclass clazz, jlong ptr) {
    sp<WindowInfosListener> listener = reinterpret_cast<WindowInfosListener*>(ptr);
    SurfaceComposerClient::getDefault()->removeWindowInfosListener(listener);
}

static jlong nativeGetFinalizer(JNIEnv* /* env */, jclass /* clazz */) {
    return static_cast<jlong>(reinterpret_cast<uintptr_t>(&destroyNativeService));
}

const JNINativeMethod gMethods[] = {
        /* name, signature, funcPtr */
        {"nativeCreate", "(Landroid/window/WindowInfosListener;)J", (void*)nativeCreate},
        {"nativeRegister", "(J)V", (void*)nativeRegister},
        {"nativeUnregister", "(J)V", (void*)nativeUnregister},
        {"nativeGetFinalizer", "()J", (void*)nativeGetFinalizer}};

} // namespace

int register_android_window_WindowInfosListener(JNIEnv* env) {
    int res = jniRegisterNativeMethods(env, "android/window/WindowInfosListener", gMethods,
                                       NELEM(gMethods));
    LOG_ALWAYS_FATAL_IF(res < 0, "Unable to register native methods.");

    jclass clazz = env->FindClass("android/window/WindowInfosListener");
    gListenerClassInfo.clazz = MakeGlobalRefOrDie(env, clazz);
    gListenerClassInfo.onWindowInfosChanged =
            env->GetMethodID(gListenerClassInfo.clazz, "onWindowInfosChanged",
                             "([Landroid/view/InputWindowHandle;)V");

    clazz = env->FindClass("android/view/InputWindowHandle");
    gInputWindowHandleClass = MakeGlobalRefOrDie(env, clazz);
    return 0;
}

} // namespace android