Dji Mobile SDK 基础实现（二）

本文简要介绍如何通过调用DJI Mobile SDK，实现获取和释放无人机的控制权限、模拟遥控器按钮控制无人机的飞行、获取无人机的回传视频、获取无人机参数、实现和onboard SDK的数据透传。

下面逐个介绍以上内容，余下内容在前面文章已作介绍（文章末尾附上GitHub链接）：

• 获取无人机的回传视频
• 获取无人机参数
• 实现和onboard SDK的数据透传

获取无人机的回传视频

1、调用并实例化TextureView控件，并在调用类中实现SurfaceTextureListener接口；

2、设置回调接口并初始化回传视频：

/**
*设置回调接口
*/
protected DJICodecManager mCodecManager = null;//视频编码
private DJIFlightControllerDelegate.FlightControllerReceivedDataFromExternalDeviceCallback mRecvCallback = null;
protected CameraReceivedVideoDataCallback mReceivedVideoDataCallBack = null;
protected DJIOnReceivedVideoCallback mOnReceivedVideoCallback = null;
private DJIBaseProduct mProduct = null;//无人机实例
//设置视频的回调
        mReceivedVideoDataCallBack = new CameraReceivedVideoDataCallback() {
            @Override
            public void onResult(byte[] videoBuffer, int size) {
                count++;
                if (mCodecManager != null) {
                        mCodecManager.sendDataToDecoder(videoBuffer, size);
                } else {
                    Log.e(TAG, "mCodecManager is null");
                }
            }
        };

/**
*初始化回传视频
*/
 private void initVideo() {
        try {
            mProduct = VirtualStickApplication.getProductInstance();
        } catch (Exception exception) {
            mProduct = null;
        }

        if (null == mProduct || !mProduct.isConnected()) {
            mCamera = null;
        } else {
            if (null != mVideoSurface) {
                mVideoSurface.setSurfaceTextureListener(this);
            }

            if (!mProduct.getModel().equals(Model.UnknownAircraft)) {
                mCamera = mProduct.getCamera();
                if (mCamera != null) {
                    mCamera.setDJICameraReceivedVideoDataCallback(mReceivedVideoDataCallBack);
                }
            } else {
                if (null != mProduct.getAirLink()) {
                    if (null != mProduct.getAirLink().getLBAirLink()) {
                        // Set the callback
                        mProduct.getAirLink().getLBAirLink().setDJIOnReceivedVideoCallback(mOnReceivedVideoCallback);
                        mProduct.getAirLink().getLBAirLink().setFPVQualityLatency(DJILBAirLink.LBAirLinkFPVVideoQualityLatency.LowLatency,new DJIBaseComponent.DJICompletionCallback() {
                            @Override
                            public void onResult(DJIError djiError) {
                                if (djiError != null)
                                    VirtualStickApplication.logError("setFPVQualityLatency（）error:", djiError);
                            }
                        });
                    }
                }
            }
        }
    }

获取无人机参数

获取获取无人机的剩余电量，以百分比的形式返回

private DJIBaseProduct mProduct = null;//无人机实例
 try {
                mProduct = VirtualStickApplication.getProductInstance();
            } catch (Exception exception) {
                mProduct = null;
            }
            if(mProduct != null && mProduct.isConnected()) {
                //获取无人机的剩余电量，以百分比的形式返回
                try{
                    mProduct.getBattery().setBatteryStateUpdateCallback(new DJIBattery.DJIBatteryStateUpdateCallback() {
                        @Override
                        public void onResult(DJIBatteryState djiBatteryState) {
                            if(djiBatteryState == null){
                                VirtualStickApplication.logInfo("电量为空");
                            }else{
                                StringBuffer mBuffer = new StringBuffer();
                                mBuffer.append(djiBatteryState.getBatteryEnergyRemainingPercent());
                                tvBattery.setText(mBuffer.toString()+"%");
                                if(djiBatteryState.getBatteryEnergyRemainingPercent() != 0 && djiBatteryState.getBatteryEnergyRemainingPercent() <= 30){
                                      if(entry){
                                          AlertDialog.Builder builder =  new  AlertDialog.Builder(VirtualStickActivity.this);
                                          builder.setTitle("警告" )
                                                  .setMessage("电池电量不足！" )
                                                  .setPositiveButton("确认" ,  null )
                                                  .setNegativeButton("取消" , null)
                                                  .show();
                                          entry = false;
                                      }
                                }else{
                                    entry = true;
                                }
                            }
                        }
                    });
                }catch(Exception e){
                    Toast.makeText(VirtualStickActivity.this,"1"+e.toString(),Toast.LENGTH_LONG).show();
                    e.printStackTrace();
                }

获取飞行器所在所在高度、飞行速度、无人机姿态、GPS信号 
1、获取flightController 对象；

DJIFlightController flightController;
public void setAircraft(DJIBaseProduct djiAircraft){
        if(djiAircraft==null){

            return;
        }
        flightController=((DJIAircraft)djiAircraft).getFlightController();
        if(flightController!=null) {

        }

    }

2、通过flightController对象调用方法获取飞行器所在所在高度、飞行速度、无人机姿态、GPS信号； 
所在高度

public String getHeight(){
        if(flightController != null){
            DJIFlightControllerDataType.DJIFlightControllerCurrentState currentState = flightController.getCurrentState();
            if (currentState != null) {
                return currentState.getAircraftLocation().getAltitude() + "";
            }
        }
        return null;
    }

飞行速度

//获取前后速度
    public String getX(){
        if(flightController != null){
        DJIFlightControllerDataType.DJIFlightControllerCurrentState currentState = flightController.getCurrentState();
            if (currentState != null) {
                currentState.getGpsSignalStatus();
                return currentState.getVelocityX() + "";
            }
        }

        return null;
    }

    //获取左右速度
    public String getY(){
        if(flightController != null){
            DJIFlightControllerDataType.DJIFlightControllerCurrentState currentState = flightController.getCurrentState();
            if (currentState != null) {
                return currentState.getVelocityY() + "";
            }
        }
        return null;
    }

    //获取上下速度
    public String getZ(){
        if(flightController != null){
            DJIFlightControllerDataType.DJIFlightControllerCurrentState currentState = flightController.getCurrentState();
            if (currentState != null) {
                return currentState.getVelocityZ() + "";
            }
        }
        return null;
    }

无人机姿态（roll、yaw、pitch）

public String getYaw(){
        if(flightController != null){
            DJIFlightControllerDataType.DJIFlightControllerCurrentState currentState = flightController.getCurrentState();
            if (currentState != null) {
                return "pitch:"+currentState.getAttitude().pitch+"  Yaw:"+currentState.getAttitude().yaw
                        +"  Roll:"+currentState.getAttitude().roll;
            }
        }
        return null;
    }

GPS信号

//获取GPS信号
    public String getGPS(){
        if(flightController != null){
            DJIFlightControllerDataType.DJIFlightControllerCurrentState currentState = flightController.getCurrentState();
            if (currentState != null) {
                  return currentState.getGpsSignalStatus().value()+"";
            }
        }
        return null;
    }

实现和onboard SDK的数据透传

发送数据到onboard SDK device 
1、获取flightController 对象，如上所示； 
2、通过flightController对象调用响应函数实现数据发送；

public void sendDataToOnboard(byte[] data){
            if(flightController.isOnboardSDKDeviceAvailable()){
                flightController.sendDataToOnboardSDKDevice(data, new DJIBaseComponent.DJICompletionCallback() {
                    @Override
                    public void onResult(DJIError djiError) {
                        if(djiError!=null) {
                            VirtualStickApplication.logError("SendDataToOnBoard error:", djiError);
                        }else{
                            VirtualStickApplication.logInfo("发送指令成功！");
                        }
                    }
                });
            }
        }
    }

从onboard SDK获取数据 
1、获取flightController 对象，如上所示； 
2、通过flightController对象调用响应函数实现数据回传；

/**
*设置回调接口
*/
flightController.setReceiveExternalDeviceDataCallback(flightControllerReceivedDataFromExternalDeviceCallback);
/**
*初始化并接受回传数据
*/
 flightControllerReceivedDataFromExternalDeviceCallback = new DJIFlightControllerDelegate.FlightControllerReceivedDataFromExternalDeviceCallback() {
            @Override
            public void onResult(byte[] bytes) {

            }
        };

注意事项： 
1、在向onboard SDK device发送数据时，发送的数据需要调用String.getbytes()，转换为byte[]类型的数据； 
2、在onboard device端，由于接收到的数据为int8类型的，因此需要强制转换为char类型的数据，再减去 ‘0’才可得到发送的值； 
3、接收到的数据需要进行组装才可得到大于一位的数据。

[Github链接](https://github.com/MrJoeyM/sky-app)