我在这里玩BarCode扫描仪的原始示例：
他们可以在相机工厂内启动AutoFocus / Flash,如下所示：
// Creates and starts the camera. Note that this uses a higher resolution in comparison
// to other detection examples to enable the barcode detector to detect small barcodes
// at long distances.
CameraSource.Builder builder = new CameraSource.Builder(getApplicationContext(),barcodeDetector)
.setFacing(CameraSource.CAMERA_FACING_BACK)
.setRequestedPreviewSize(1600,1024)
.setRequestedFps(15.0f);
// make sure that auto focus is an available option
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH) {
builder = builder.setFocusMode(
autoFocus ? Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE : null);
}
mCameraSource = builder
.setFlashMode(useFlash ? Camera.Parameters.FLASH_MODE_TORCH : null)
.build();
但是,cameraSource构建器上的此方法在当前版本中消失,因此无法访问此设置.此外,我需要在使用过程中更改FlashMode,因此这也不是这样做的方法.我发现这个丑陋的解决方案来访问相机：
public static Camera getCamera(@NonNull CameraSource cameraSource) {
Field[] declaredFields = CameraSource.class.getDeclaredFields();
for (Field field : declaredFields) {
if (field.getType() == Camera.class) {
field.setAccessible(true);
try {
Camera camera = (Camera) field.get(cameraSource);
if (camera != null) {
return camera;
}
return null;
} catch (IllegalAccessException e) {
e.printStackTrace();
}
break;
}
}
return null;
}
虽然它有效,但它没有帮助：当调用getParameters().setFocusMode()时,我收到此异常：
Attempt to invoke virtual method 'android.hardware.Camera$Parameters android.hardware.Camera.getParameters()' on a null object reference
显然我正在做的不是一种正确的方法,但似乎没有关于它的文档.
谢谢你的提示.
解决方法
只需优化您的代码如下所示,您必须在构建Camera Source类后调用此方法.
private Camera camera = null;
boolean flashmode=false;
private void flashOnButton() {
camera=getCamera(mCameraSource);
if (camera != null) {
try {
Camera.Parameters param = camera.getParameters();
param.setFlashMode(!flashmode?Camera.Parameters.FLASH_MODE_TORCH :Camera.Parameters.FLASH_MODE_OFF);
camera.setParameters(param);
flashmode = !flashmode;
if(flashmode){
showToast("Flash Switched ON");
}
else {
showToast("Flash Switched Off");
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
private static Camera getCamera(@NonNull CameraSource cameraSource) {
Field[] declaredFields = CameraSource.class.getDeclaredFields();
for (Field field : declaredFields) {
if (field.getType() == Camera.class) {
field.setAccessible(true);
try {
Camera camera = (Camera) field.get(cameraSource);
if (camera != null) {
return camera;
}
return null;
} catch (IllegalAccessException e) {
e.printStackTrace();
}
break;
}
}
return null;
}
这将有助于您使用camerasource对象在Google Vision Api中启用Flash.
