NDK Samples学习 [6-1] - camera之basic

camera-basic
README
该项目演示如何使用c创建camera拍照、预览。


最低要求:

  1. Android Studio 2.3.0+ ,NDK r15+
  2. Android-24+

项目主要流程:

  1. 获取权限
  2. 初始化界面,NDKCamera、曝光度、感光度
  3. 操作相机,调整曝光度、感光度预览;拍照保存

CameraActivity.java

  1. CameraSeekBar 包装SeekBar用于调整相机预览的曝光度、感光度

void setImmersiveSticky() {} //设置全屏显示
public void RequestCamera() {} //请求权限,由c++调用
public void EnableUI(final long[] params){}//由c++调用,并传入曝光度、感光度参数
public void OnPhotoTaken(String fileName) {}//由c++调用,传入拍照图片路径
native static void notifyCameraPermission(boolean granted);//权限变化后
native static void TakePhoto();//调用c++拍照
native void OnExposureChanged(long exposure);//调用c++调整曝光度
native void OnSensitivityChanged(long sensitivity);//调用c++调整感光度
native static void notifyCameraPermission(boolean granted);//通知c++权限变化

android_main.cpp c主入口

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/*
* SampleEngine global object
*/
static CameraEngine* pEngineObj = nullptr;
/*
* 获取CameraEngine单例对象
*/
CameraEngine* GetAppEngine(void) {
ASSERT(pEngineObj, "AppEngine has not initialized");
return pEngineObj;
}

/**
* 根据收到INIT_WINDOW/TERM_WINDOW事件创建或删除camera对象,
* 使用NativeActivity的应用才会收到
*/
static void ProcessAndroidCmd(struct android_app* app, int32_t cmd) {
CameraEngine* engine = reinterpret_cast<CameraEngine*>(app->userData);
switch (cmd) {
// 窗口初始化
case APP_CMD_INIT_WINDOW:
if (engine->AndroidApp()->window != NULL) {
engine->SaveNativeWinRes(ANativeWindow_getWidth(app->window),
ANativeWindow_getHeight(app->window),
ANativeWindow_getFormat(app->window));
// 请求权限,创建camera
engine->OnAppInitWindow();
}
break;
// 窗口关闭
case APP_CMD_TERM_WINDOW:
// 删除camera
engine->OnAppTermWindow();
ANativeWindow_setBuffersGeometry(
app->window, engine->GetSavedNativeWinWidth(),
engine->GetSavedNativeWinHeight(), engine->GetSavedNativeWinFormat());
break;
// 窗口配改变
case APP_CMD_CONFIG_CHANGED:
engine->OnAppConfigChange();
break;
// 失去焦点
case APP_CMD_LOST_FOCUS:
break;
}
}

extern "C" void android_main(struct android_app* state) {
CameraEngine engine(state);
pEngineObj = &engine;

state->userData = reinterpret_cast<void*>(&engine);
state->onAppCmd = ProcessAndroidCmd;

// loop waiting for stuff to do.
while (1) {
// Read all pending events.
int events;
struct android_poll_source* source;

while (ALooper_pollAll(0, NULL, &events, (void**)&source) >= 0) {
// Process this event.
if (source != NULL) {
source->process(state, source);
}

// Check if we are exiting.
if (state->destroyRequested != 0) {
LOGI("CameraEngine thread destroy requested!");
engine.DeleteCamera();
pEngineObj = nullptr;
return;
}
}
pEngineObj->DrawFrame();
}
}

/**
* 窗口初始化时调用,请求相机相关权限,并创建camera
*/
void CameraEngine::OnAppInitWindow(void) {
if (!cameraGranted_) {
// 请求相机相关权限
RequestCameraPermission();
return;
}

// 旋转角度
rotation_ = GetDisplayRotation();

// 创建camera
CreateCamera();
ASSERT(camera_, "CameraCreation Failed");

// 启用曝光度UI
EnableUI();

// 预览
cameraReady_ = true;
camera_->StartPreview(true);
}

/**
* Handle APP_CMD_TEMR_WINDOW
*/
void CameraEngine::OnAppTermWindow(void) {
cameraReady_ = false;
// 销毁camera
DeleteCamera();
}

/**
* Handle APP_CMD_CONFIG_CHANGED
* 获取旋转角度
* 旋转角度有变化,销毁camera,再重新创建camera
*/
void CameraEngine::OnAppConfigChange(void) {
int newRotation = GetDisplayRotation();

if (newRotation != rotation_) {
OnAppTermWindow();

rotation_ = newRotation;
OnAppInitWindow();
}
}

camera_engine.cpp

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/**
* 构造函数,初始camera资源
* @param app native_app_glue environment
*/
CameraEngine::CameraEngine(android_app* app)

/**
* 析构造函数,释放camera资源
*/
CameraEngine::~CameraEngine() {
cameraReady_ = false;
DeleteCamera();
}

/**
* 创建后台camera
*/
void CameraEngine::CreateCamera(void) {
// 没有权限直接返回
if (!cameraGranted_ || !app_->window) {
LOGW("Camera Sample requires Full Camera access");
return;
}

int32_t displayRotation = GetDisplayRotation();
rotation_ = displayRotation;

// 创建NDKCamera
camera_ = new NDKCamera();
ASSERT(camera_, "Failed to Create CameraObject");

// 旋转角度
int32_t facing = 0, angle = 0, imageRotation = 0;
if (camera_->GetSensorOrientation(&facing, &angle)) {
if (facing == ACAMERA_LENS_FACING_FRONT) {
imageRotation = (angle + rotation_) % 360;
imageRotation = (360 - imageRotation) % 360;
} else {
imageRotation = (angle - rotation_ + 360) % 360;
}
}
LOGI("Phone Rotation: %d, Present Rotation Angle: %d", rotation_,
imageRotation);
ImageFormat view{0, 0, 0}, capture{0, 0, 0};
camera_->MatchCaptureSizeRequest(app_->window, &view, &capture);

ASSERT(view.width && view.height, "Could not find supportable resolution");

// Request the necessary nativeWindow to OS
bool portraitNativeWindow =
(savedNativeWinRes_.width < savedNativeWinRes_.height);
ANativeWindow_setBuffersGeometry(
app_->window, portraitNativeWindow ? view.height : view.width,
portraitNativeWindow ? view.width : view.height, WINDOW_FORMAT_RGBA_8888);

yuvReader_ = new ImageReader(&view, AIMAGE_FORMAT_YUV_420_888);
yuvReader_->SetPresentRotation(imageRotation);
jpgReader_ = new ImageReader(&capture, AIMAGE_FORMAT_JPEG);
jpgReader_->SetPresentRotation(imageRotation);
jpgReader_->RegisterCallback(this, [this](void* ctx, const char* str) -> void {
reinterpret_cast<CameraEngine* >(ctx)->OnPhotoTaken(str);
});

// now we could create session
camera_->CreateSession(yuvReader_->GetNativeWindow(),
jpgReader_->GetNativeWindow(), imageRotation);
}

// 释放camera
void CameraEngine::DeleteCamera(void) {
cameraReady_ = false;
if (camera_) {
delete camera_;
camera_ = nullptr;
}
if (yuvReader_) {
delete yuvReader_;
yuvReader_ = nullptr;
}
if (jpgReader_) {
delete jpgReader_;
jpgReader_ = nullptr;
}
}

/**
* 请求camera相关权限
* 通过调用CameraActivity.notifyCameraPermission,
* 授权结果,调用native notifyCameraPermission()
*/
void CameraEngine::RequestCameraPermission() {
if (!app_) return;

JNIEnv* env;
ANativeActivity* activity = app_->activity;
activity->vm->GetEnv((void**)&env, JNI_VERSION_1_6);

activity->vm->AttachCurrentThread(&env, NULL);

jobject activityObj = env->NewGlobalRef(activity->clazz);
jclass clz = env->GetObjectClass(activityObj);
env->CallVoidMethod(activityObj,
env->GetMethodID(clz, "RequestCamera", "()V"));
env->DeleteGlobalRef(activityObj);

activity->vm->DetachCurrentThread();
}
/**
* 调整曝光度、感光度
*/
void CameraEngine::OnCameraParameterChanged(int32_t code, int64_t val) {
camera_->UpdateCameraRequestParameter(code, val);
}

/**
* The main function rendering a frame. In our case, it is yuv to RGBA8888
* converter
*/
void CameraEngine::DrawFrame(void) {
if (!cameraReady_ || !yuvReader_) return;
AImage* image = yuvReader_->GetNextImage();
if (!image) {
return;
}

ANativeWindow_acquire(app_->window);
ANativeWindow_Buffer buf;
if (ANativeWindow_lock(app_->window, &buf, nullptr) < 0) {
yuvReader_->DeleteImage(image);
return;
}

yuvReader_->DisplayImage(&buf, image);
ANativeWindow_unlockAndPost(app_->window);
ANativeWindow_release(app_->window);
}

camera_ui.cpp

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/**
* 获取旋转角度Retrieve current rotation from Java side
* 调用CameraActivity.getRotationDegree
*/
int CameraEngine::GetDisplayRotation() {
...
}

/**
* 设置曝光度、感光度
*/
void CameraEngine::EnableUI(void) {
// 1. 获取曝光度,感光度NDKCamera::GetExposureRange\NDKCamera::GetSensitivityRange
// 2. 调用CameraActivity.EnableUI设置
}

/**
* 拍照
*/
void CameraEngine::OnTakePhoto() {
if (camera_) {
camera_->TakePhoto();
}
}

/**
* 回传照片文件路径,CameraActivity.OnPhotoTaken
*/
void CameraEngine::OnPhotoTaken(const char* fileName) {
...
}
/**
* camera和文件写入权限回调
*/
void CameraEngine::OnCameraPermission(jboolean granted) {
//有权限则调用OnAppInitWindow初始化
}

/**
* native响应权限变化
*/
extern "C" JNIEXPORT void JNICALL
Java_com_sample_camera_basic_CameraActivity_notifyCameraPermission(
JNIEnv *env, jclass type, jboolean permission) {
//CameraEngine::OnCameraPermission权限变化
}

/**
* native拍照
*/
extern "C" JNIEXPORT void JNICALL
Java_com_sample_camera_basic_CameraActivity_TakePhoto(JNIEnv *env,
jclass type) {
//CameraEngine::OnTakePhoto
}

/**
* native曝光度变化,调整预览
*/
extern "C" JNIEXPORT void JNICALL
Java_com_sample_camera_basic_CameraActivity_OnExposureChanged(
JNIEnv *env, jobject instance, jlong exposurePercent) {
//GetAppEngine()::OnCameraParameterChanged
}

/**
* native感光度变化,调整预览
*/
extern "C" JNIEXPORT void JNICALL
Java_com_sample_camera_basic_CameraActivity_OnSensitivityChanged(
JNIEnv *env, jobject instance, jlong sensitivity) {
//GetAppEngine()::OnCameraParameterChanged
}

camera_manager.cpp

  1. 初始化camera
  2. 更新属性
  3. 拍照

image_reader.cpp 图片转换相关
camera_listeners.cpp camera manager相关Listener


项目功能为:

  1. native监听窗口变化判断调用java请求camera相关权限
  2. native创建NDKCamera,并获取曝光度、感光度属性回调到Java并展示
  3. native预览
  4. java调用native调整预览曝光度、感光度
  5. java调用native拍照并回调java提示图片文件路径

android-ndk-samples学习目录

部份引用其他大牛的项目

  1. hello-jni by 七零八落问号
    演示如何从Java层调用C层代码。

  2. hello-jniCallback by 七零八落问
    演示如何在C层回调Java层方法。

  3. hello-libs by 七零八落问
    演示如何在Android Studio上使用第三方的C / C++库。

  4. audio echo by hunter800421
    演示如何如何使用OpenSL ES创建播放器和录音。

  5. bitmap-plasma by hunter800421
    演示如何使用c代码在bitmap上绘制细胞质效果。

6.1. camera-basic by Tu
演示如何使用c创建camera拍照、预览。

参考

NatvieActivity事件

转载请标明出处:
http://2tu.github.io/
本文出自Tu’s blog