JNI : frameworks/base/core/jni/android_hardware_camera.cpp
static JNINativeMethod camMethods[] = {
{ "getNumberOfCameras", "()I", (void *)android_hardware_Camera_getNumberOfCameras },
{ "getCameraInfo", "(ILandroid/hardware/Camera$CameraInfo;)V",
(void*)android_hardware_Camera_getCameraInfo },
{ "native_setup", "(Ljava/lang/Object;II)V", (void*)android_hardware_Camera_native_setup },
{ "native_release", "()V", (void*)android_hardware_Camera_release },
{ "setPreviewDisplay", "(Landroid/view/Surface;)V", (void *)android_hardware_Camera_setPreviewDisplay },
{ "startPreview", "()V", (void *)android_hardware_Camera_startPreview },
{ "stopPreview", "()V", (void *)android_hardware_Camera_stopPreview },
{ "previewEnabled", "()Z", (void *)android_hardware_Camera_previewEnabled },
{ "setHasPreviewCallback", "(ZZ)V", (void *)android_hardware_Camera_setHasPreviewCallback },
{ "addCallbackBuffer", "([B)V", (void *)android_hardware_Camera_addCallbackBuffer },
{ "native_autoFocus", "()V", (void *)android_hardware_Camera_autoFocus },
{ "native_encodeData", "()V", (void *)android_hardware_Camera_encodeData },
{ "native_cancelAutoFocus", "()V", (void *)android_hardware_Camera_cancelAutoFocus },
{ "native_takePicture", "()V", (void *)android_hardware_Camera_takePicture },
{ "native_setHistogramMode", "(Z)V", (void *)android_hardware_Camera_setHistogramMode },
{ "native_sendHistogramData", "()V", (void *)android_hardware_Camera_sendHistogramData },
{ "native_setFaceDetectionCb", "(Z)V", (void *)android_hardware_Camera_setFaceDetectionCb },
{ "native_sendMetaData", "()V", (void *)android_hardware_Camera_sendMetaData },
{ "native_setParameters", "(Ljava/lang/String;)V", (void *)android_hardware_Camera_setParameters },
{ "native_getParameters", "()Ljava/lang/String;", (void *)android_hardware_Camera_getParameters },
{ "reconnect", "()V", (void*)android_hardware_Camera_reconnect },
{ "lock", "()V", (void*)android_hardware_Camera_lock },
{ "unlock", "()V", (void*)android_hardware_Camera_unlock },
{ "startSmoothZoom", "(I)V", (void *)android_hardware_Camera_startSmoothZoom },
{ "stopSmoothZoom", "()V", (void *)android_hardware_Camera_stopSmoothZoom },
{ "setDisplayOrientation", "(I)V", (void *)android_hardware_Camera_setDisplayOrientation },
};
====================================================================================
static jint android_hardware_Camera_getNumberOfCameras(JNIEnv *env, jobject thiz)
{
return Camera::getNumberOfCameras();
}
此處調到/framework/base/libs/camera/camera.cpp 中。
int32_t Camera::getNumberOfCameras()
{
const sp<ICameraService>& cs = getCameraService();
if (cs == 0) return 0;
return cs->getNumberOfCameras();
}
此處調用到/framework/base/service/camera/libcameraservice/cameraservice.cpp中藉口
int32_t CameraService::getNumberOfCameras() {
return mNumberOfCameras;
}
而，此處mNumberOfCameras由cameraservice.cpp中
mNumberOfCameras = HAL_getNumberOfCameras(); 獲得。
HAL_getNumberOfCameras()函數，調用\vendor\qcom\android-open\libcamera2\QualcommCameraHardware.cpp中的接口。
extern "C" int
HAL_getNumberOfCameras()
{
QualcommCameraHardware::getCameraInfo();
return HAL_numOfCameras;
}
接下來看下getCameraInfo()
void QualcommCameraHardware::getCameraInfo()
{
LOGI("getCameraInfo: IN");
mm_camera_status_t status;
#if DLOPEN_LIBMMCAMERA
void *libhandle = ::dlopen("liboemcamera.so", RTLD_NOW);
LOGI("getCameraInfo: loading libqcamera at %p", libhandle);
if (!libhandle) {
LOGE("FATAL ERROR: could not dlopen liboemcamera.so: %s", dlerror());
}
*(void **)&LINK_mm_camera_get_camera_info =
::dlsym(libhandle, "mm_camera_get_camera_info");
#endif
storeTargetType();
status = LINK_mm_camera_get_camera_info(HAL_cameraInfo, &HAL_numOfCameras);
LOGI("getCameraInfo: numOfCameras = %d", HAL_numOfCameras);
for(int i = 0; i < HAL_numOfCameras; i++) {
if((HAL_cameraInfo[i].position == BACK_CAMERA )&&
mCurrentTarget == TARGET_MSM8660){
HAL_cameraInfo[i].modes_supported |= CAMERA_ZSL_MODE;
} else{
HAL_cameraInfo[i].modes_supported |= CAMERA_NONZSL_MODE;
}
LOGI("Camera sensor %d info:", i);
LOGI("camera_id: %d", HAL_cameraInfo[i].camera_id);
LOGI("modes_supported: %x", HAL_cameraInfo[i].modes_supported);
LOGI("position: %d", HAL_cameraInfo[i].position);
LOGI("sensor_mount_angle: %d", HAL_cameraInfo[i].sensor_mount_angle);
}
#if DLOPEN_LIBMMCAMERA
if (libhandle) {
::dlclose(libhandle);
LOGV("getCameraInfo: dlclose(libqcamera)");
}
#endif
LOGI("getCameraInfo: OUT");
}
在前面有#define LINK_mm_camera_get_camera_info mm_camera_get_camera_info ，所以我們接下來到
mm_camera_get_camera_info(HAL_cameraInfo, &HAL_numOfCameras);調用到哪。
在 vendor\qcom\proprietary\mm-camera\apps\appslib\mm_camera_interface.c中有定義
mm_camera_status_t mm_camera_get_camera_info(camera_info_t* p_cam_info,
int* p_num_cameras)
{
int i = 0;
int controlfd = -1;
char device[MAX_DEV_NAME_LEN];
CDBG("%s: [S]\n", __func__);
mm_camera_status_t status = MM_CAMERA_SUCCESS;
struct msm_camera_info cameraInfo;
if (NULL == p_cam_info) {
status = MM_CAMERA_ERR_INVALID_INPUT;
goto ERROR;
}
sprintf (device, MSM_CAMERA_CONTROL, 0);
controlfd = open(device, O_RDWR);
//此處打開的是內核註冊的控制節點 "/dev/msm_camera/control%d"
// 內核一共註冊了四個節點，control、config、frame、pic 對應了四組操作函數。老一點的版本是三組節點。
if (controlfd < 0) {
CDBG_HIGH("%s: controlfd is invalid %s", __func__, strerror(errno));
status = MM_CAMERA_ERR_GENERAL;
goto ERROR;
}
if (ioctl(controlfd, MSM_CAM_IOCTL_GET_CAMERA_INFO, &cameraInfo) < 0) { //此處獲得內核註冊camera信息
CDBG_HIGH("%s: error (%s)", __func__, strerror(errno));
status = MM_CAMERA_ERR_GENERAL;
goto ERROR;
}
CDBG("%s: num %d\n", __func__, cameraInfo.num_cameras);
for (i=0; i < cameraInfo.num_cameras; i++) {
p_cam_info[i].camera_id = i;
p_cam_info[i].modes_supported =
(!cameraInfo.has_3d_support[i]) ? CAMERA_MODE_2D : //前置攝像頭只支持2D
CAMERA_MODE_2D | CAMERA_MODE_3D;
p_cam_info[i].position = //在內核前置攝像頭is_internal_cam[i]定義爲1，後置攝像頭默認爲0.
(cameraInfo.is_internal_cam[i]) ? FRONT_CAMERA : BACK_CAMERA;
//到此用戶層將前置和後置攝像頭區分開
p_cam_info[i].sensor_mount_angle = cameraInfo.s_mount_angle[i];
}
*p_num_cameras = cameraInfo.num_cameras;
ERROR:
if (controlfd > 0) {
close(controlfd);
}
CDBG("%s: %d [E]", __func__, status);
return status;
}
至此 android_hardware_Camera_getNumberOfCameras 的流程完成。