这个想法很简单:我的应用程序应该创建一个相机对象,显示预览并拍照(不按任何按钮),然后关闭相机。不幸的是它甚至没有拍任何照片。 (意思是:永远不会在拍摄照片后执行我的回调代码。)
我正在为android camera api使用一个小包装类。我的活动代码如下所示:
camera = new SurveillanceCamera(this, layoutForPreview);
camera.start();
camera.takePicture();
包装类:
public SurveillanceCamera(Context context, LinearLayout previewLayout) {
cameraInstance = Camera.open(findBackFacingCamera());
pictureCallback = getPictureCallback();
cameraPreview = new CameraPreview(context, cameraInstance);
this.previewLayout = previewLayout;
this.previewLayout.addView(cameraPreview);
cameraInstance.startPreview();
}
public void takePicture() {
//this code is reached
cameraInstance.takePicture(null, null, pictureCallback);
}
public void start() {
if (cameraInstance == null) {
cameraInstance = Camera.open(findBackFacingCamera());
pictureCallback = getPictureCallback();
cameraPreview.setCamera(cameraInstance);
cameraInstance.startPreview();
}
}
private PictureCallback getPictureCallback() {
PictureCallback picture = new PictureCallback() {
@Override
public void onPictureTaken(byte[] data, Camera camera) {
Log.e(TAG, "Jey picture was taken...");
// refresh camera to continue preview
cameraPreview.refreshCamera(cameraInstance);
}
};
return picture;
}
private int findBackFacingCamera() {
int cameraId = -1;
// Search for the back facing camera
// get the number of cameras
int numberOfCameras = Camera.getNumberOfCameras();
// for every camera check
for (int i = 0; i < numberOfCameras; i++) {
CameraInfo info = new CameraInfo();
Camera.getCameraInfo(i, info);
if (info.facing == CameraInfo.CAMERA_FACING_BACK) {
cameraId = i;
break;
}
}
return cameraId;
}
代码中没有抛出异常,但onPictureTaken中的Log.e()未显示。似乎显示了相机预览但没有任何反应。是否有可能在执行camera.takePicture()时预览未完全加载?有什么建议吗?
答案 0 :(得分:0)
你的怀疑很可能是合理的。我不知道何时调用setPreviewDisplay()
。但是,此调用应该完成takePicture()
才能成功。
简单地调用
是不可能的camera = new SurveillanceCamera(this, layoutForPreview);
camera.start();
camera.takePicture();
因为要完成setPreviewDisplay()
调用,您需要一个完全初始化的Holder实例,但只需在构造函数中添加表面视图。
最好注册SurfaceHolder.Callback
并从surfaceChanged()
回调中拨打takePicture()
。