我正在尝试为本地音乐会开发手电筒应用程序。这是一个更大的应用程序的一部分,因此它位于一个 fragment 中。这是代码:
首先我声明了该类及其变量:
public class ConcertFragment extends Fragment {
ToggleButton btnFlashlight;
View rootView;
private Camera cam;
private boolean hasFlash;
boolean hasCamera;
boolean isFlashOn;
Parameters params;
public ConcertFragment() {
}
接下来是 onActivityCreated
方法,它返回 getCamera 方法(在下面进一步声明):
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getCamera();
}
然后我创建用于构建布局的 onCreateView
方法:
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
rootView = inflater.inflate(R.layout.fragment_concert, container, false);
hasFlash = getActivity().getApplicationContext().getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_FLASH);
if (!hasFlash) {
// device doesn't support flash
// Show alert message and close the application
AlertDialog alert = new AlertDialog.Builder(getActivity()).create();
alert.setTitle("No Flash");
alert.setMessage("Sorry, device is not flash supported.");
alert.setButton(DialogInterface.BUTTON_POSITIVE, "OK", new android.content.DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
}
});
alert.show();
}
btnFlashlight = (ToggleButton) rootView.findViewById(R.id.toggleButton);
btnFlashlight.setOnCheckedChangeListener(new OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton buttonView,
boolean isChecked) {
if (isFlashOn) {
// turn off flash
turnOffFlash();
} else {
// turn on flash
turnOnFlash();
}
}
});
return rootView;
}
打开闪光灯的方法:
private void turnOnFlash() {
if (!isFlashOn) {
if (cam == null || params == null) {
return;
}
params = cam.getParameters();
params.setFlashMode(Parameters.FLASH_MODE_TORCH);
cam.setParameters(params);
cam.startPreview();
isFlashOn = true;
// changing button/switch image
toggleButtonImage();
}
}
关闭闪光灯的方法:
private void turnOffFlash() {
if (isFlashOn) {
if (cam == null || params == null) {
return;
}
params = cam.getParameters();
params.setFlashMode(Parameters.FLASH_MODE_OFF);
cam.setParameters(params);
cam.stopPreview();
isFlashOn = false;
// changing button/switch image
toggleButtonImage();
}
}
相机参数设置方法:
private void getCamera() {
if (cam != null) {
try {
cam = Camera.open();
params = cam.getParameters();
cam.startPreview();
hasCamera = true;
} catch (RuntimeException e) {
Log.e("Camera Error. Failed to Open. Error: ", e.getMessage());
}
}
}
private void toggleButtonImage(){
if(isFlashOn){
btnFlashlight.setBackgroundResource(R.drawable.btn_switch_on);
}else{
btnFlashlight.setBackgroundResource(R.drawable.btn_switch_off);
}
}
}
}
打开和关闭手电筒的切换按钮可以打开和关闭,但我的 Nexus 5 背面的手电筒从未打开。
我使用的相关权限如下:
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.FLASHLIGHT" />
<uses-permission android:name="android.permission.VIBRATE" />
有人可以帮忙吗?
最佳答案
我也面临着同样的问题。您需要在布局中的按钮上方添加 SurfacePreview:
<SurfaceView
android:id="@+id/PREVIEW"
android:layout_width="1dp"
android:layout_height="1dp"/>
目前我的 fragment 如下所示:
public class FlashlightFragment extends Fragment implements SurfaceHolder.Callback {
ImageButton btnSwitch;
//flag to detect flash is on or off
private boolean isLighOn = false;
private Camera camera;
Parameters params;
@Override
public void onStart() {
super.onStart();
SurfaceView preview = (SurfaceView)getView().findViewById(R.id.PREVIEW);
SurfaceHolder mHolder = preview.getHolder();
mHolder.addCallback(this);
}
@Override
public void onPause(){
super.onPause();
turnOffFlash();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.flashlight_fragment,
container, false);
// flash switch button
btnSwitch = (ImageButton) view.findViewById(R.id.flashlight_button);
// displaying button image
toggleButtonImage();
// Switch button click event to toggle flash on/off
btnSwitch.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (isLighOn) {
// turn off flash
turnOffFlash();
} else {
// turn on flash
turnOnFlash();
}
}
});
return view;
}
// Turning On flash
private void turnOnFlash() {
if (!isLighOn) {
if (camera == null || params == null) {
return;
}
params = camera.getParameters();
params.setFlashMode(Parameters.FLASH_MODE_TORCH);
camera.setParameters(params);
camera.startPreview();
isLighOn = true;
// changing button/switch image
toggleButtonImage();
}
}
// Turning Off flash
private void turnOffFlash() {
if (isLighOn) {
if (camera == null || params == null) {
return;
}
params = camera.getParameters();
params.setFlashMode(Parameters.FLASH_MODE_OFF);
camera.setParameters(params);
camera.stopPreview();
isLighOn = false;
// changing button/switch image
toggleButtonImage();
}
}
/*
* Toggle switch button images
* changing image states to on / off
* */
private void toggleButtonImage(){
if(isLighOn){
btnSwitch.setImageResource(R.drawable.icon_bulb_on);
}else{
btnSwitch.setImageResource(R.drawable.icon_bulb_off);
}
}
@Override
public void surfaceChanged(SurfaceHolder holder,int format,int width,int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
if (camera != null) {
camera.stopPreview();
camera.setPreviewCallback(null);
camera.release();
camera = null;
}
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
if (camera == null) {
camera = Camera.open();
params = camera.getParameters();
try {
camera.setPreviewDisplay(holder);
} catch (IOException e) {
camera.release();
camera = null;
}
}
}
这在我的 Nexus 5 上似乎工作正常,但在 Xperia Z 上强制关闭 camera.setPreviewDisplay(mHolder); 我还无法解决该问题。
希望这有帮助。
关于android - Android fragment 中的手电筒 - SurfaceView,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/24959664/