我发现了几个问题,但没有答案,因此希望有人对此有所了解。当我尝试交换相机时,我会调用下面的swapCamera函数。但是,摄像机预览只会卡住(该应用程序不会卡住,而只是实时摄像机预览)。
当我第一次打开该应用程序时,一切正常。但是我注意到了一些有趣的事情。当我注销_surfaceHolder对象(即我的SurfaceHolder对象)的内存地址时,它为我提供了一个值,但是每当我在应用程序完成启动并且所有操作完成后查询该值时,该内存地址就会更改。
更进一步,当我swapCamera时,它给我的错误非常令人困惑。我先注销_surfaceHolder,然后再将其传递给_camera.setPreviewDisplay(_surfaceHolder);
到相机
并且在传递之前不为null。
任何帮助是极大的赞赏。
我注意到一些有趣的行为
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback
{
private SurfaceHolder _surfaceHolder;
private Camera _camera;
boolean _isBackFacing;
public CameraPreview(Context context, Camera camera) {
super(context);
_camera = camera;
_isBackFacing = true;
// Install a SurfaceHolder.Callback so we get notified when the
// underlying surface is created and destroyed.
_surfaceHolder = getHolder();
_surfaceHolder.addCallback(this);
}
void refreshCamera()
{
try {
_camera.setPreviewDisplay(_surfaceHolder);
_camera.startPreview();
} catch (IOException e) {
Log.d("iCamera", "Error setting camera preview: " + e.getMessage());
}
}
public void surfaceCreated(SurfaceHolder holder)
{
// The Surface has been created, now tell the camera where to draw the preview.
refreshCamera();
}
public void surfaceDestroyed(SurfaceHolder holder)
{
// empty. Take care of releasing the Camera preview in your activity.
_surfaceHolder.removeCallback(this);
}
public void surfaceChanged(SurfaceHolder holder, int format, int w, int h)
{
// If your preview can change or rotate, take care of those events here.
// Make sure to stop the preview before resizing or reformatting it.
if (_surfaceHolder.getSurface() == null){
// preview surface does not exist
return;
}
try {
_camera.stopPreview();
} catch (Exception e) {
// ignore: tried to stop a non-existent preview
}
// set preview size and make any resize, rotate or
// reformatting changes her
_camera.setDisplayOrientation(90);
// _startPoint preview with new settings
refreshCamera();
}
public void swapCamera()
{
Camera cam = null;
int cameraCount = Camera.getNumberOfCameras();
Camera.CameraInfo cameraInfo = new Camera.CameraInfo();
_camera.stopPreview();
_camera.release();
for (int i = 0; i < cameraCount; i++)
{
Camera.getCameraInfo(i,cameraInfo);
if(cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_FRONT && _isBackFacing == true)
{
try
{
_camera = Camera.open(i);
}catch (RuntimeException e)
{
Log.e("Error","Camera failed to open: " + e.getLocalizedMessage());
}
}
if(cameraInfo.facing == Camera.CameraInfo.CAMERA_FACING_BACK && _isBackFacing == false)
{
try
{
_camera = Camera.open(i);
}catch (RuntimeException e)
{
Log.e("Error","Camera failed to open: " + e.getLocalizedMessage());
}
}
}
_isBackFacing = !_isBackFacing;
refreshCamera();
}
}
最佳答案
因此,经过大量调试和挖掘后,发现问题的根源是onResume函数。
在其中,我正在“刷新”相机变量,以防在上下文切换之间丢失。
public void onResume()
{
super.onResume();
_cameraPreview = new CameraPreview(getActivity());
}
这导致重新创建了surfaceHolder。我不确定为什么会导致null,但是我想是因为我创建了SurfaceHolder的新实例,所以内部的Android代码会保留对旧(现在为null)SurfaceHolder的引用。通过从onResume删除我的“刷新”(即重新实例化)调用,此问题已解决。
这个错误是令人误解的,我认为是因为它说了传递了一个空表面,但是那是因为我认为即使您创建了一个新的表面并传递了它,它也保持了对一个空surfaceHolder的引用(无论如何,现在似乎都使用了OLD空) 。因此,如果收到此错误,请检查是否没有重新创建surfaceHolder并将其传递。