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我明白了如何使用意图和使用意图启动相机应用捕获的图像，但是我想知道如何在下面的步骤进行：拍照不使用摄像头的应用程序 - Android电子
- 显示表面视图向用户显示相机预览
- 当用户按下捕捉时，在屏幕上向用户显示拍摄的图像并用相机预览隐藏表面视图（与Snapchat完全相同的行为）。
NP - 我不想在这个过程中的任何时候启动相机应用程序，我希望它可以在我自己的应用程序中完成。我当前的代码存在的问题是，当按下捕捉按钮时，它会启动相机应用程序。此外，它不会正确显示拍摄的照片，而是显示白色屏幕。目前，我有这个代码创建：
ANDROID活动：
public class CameraScreen extends Activity {
private Camera mCamera = null;
private SessionManager session;
private String rand_img;
private ImageView preview_pic;
private CameraPreview mCameraView = null;
static final int CAM_REQUEST = 1;
private RandomString randomString = new RandomString(10);
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_camera_screen);
session = new SessionManager(getApplicationContext());
try{
mCamera = Camera.open();//you can use open(int) to use different cameras
} catch (Exception e){
Log.d("ERROR", "Failed to get camera: " + e.getMessage());
}
if(mCamera != null) {
mCameraView = new CameraPreview(this, mCamera);//create a SurfaceView to show camera data
FrameLayout camera_view = (FrameLayout)findViewById(R.id.camera_view);
camera_view.addView(mCameraView);//add the SurfaceView to the layout
}
//btn to close the application
Button imgClose = (Button)findViewById(R.id.imgClose);
imgClose.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
System.exit(0);
}
});
//btn to logout
Button logout = (Button)findViewById(R.id.imgOpen);
logout.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
session.logOut();
Intent a = new Intent(CameraScreen.this, MainActivity.class);
startActivity(a);
finish();
}
});
//CAPTURE BUTTON
Button snap = (Button) findViewById(R.id.snap);
snap.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
Intent capture = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
capture.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(getFile()));
startActivityForResult(capture,CAM_REQUEST);
}
});
}
@Override
protected void onPause() {
super.onPause();
if (mCamera != null) {
mCamera.setPreviewCallback(null);
mCameraView.getHolder().removeCallback(mCameraView);
mCamera.release();
}
}
@Override
public void onResume() {
super.onResume();
// Get the Camera instance as the activity achieves full user focus
if (mCamera == null) {
initializeCamera(); // Local method to handle camera initialization
}
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
String path = "sdcard/city_life_pic/" + rand_img;
preview_pic = (ImageView) findViewById(R.id.picturedisplay);
FrameLayout camera_view = (FrameLayout)findViewById(R.id.camera_view);
camera_view.setVisibility(View.GONE);
preview_pic.setVisibility(View.VISIBLE);
preview_pic.setImageDrawable(Drawable.createFromPath(path));
}
protected void initializeCamera(){
// Get an instance of Camera Object
try{
mCamera = Camera.open();//you can use open(int) to use different cameras
} catch (Exception e){
Log.d("ERROR", "Failed to get camera: " + e.getMessage());
}
if(mCamera != null) {
mCameraView = new CameraPreview(this, mCamera);//create a SurfaceView to show camera data
FrameLayout camera_view = (FrameLayout)findViewById(R.id.camera_view);
camera_view.addView(mCameraView);//add the SurfaceView to the layout
}
}
private File getFile() {
File folder = new File("sdcard/city_life_pic");
if (!folder.exists()) {
folder.mkdir();
}
rand_img = randomString.nextString() + ".jpg";
File image = new File(folder,rand_img);
return image;
}
}
Camera类：
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback{
private SurfaceHolder mHolder;
private Camera mCamera;
public CameraPreview(Context context, Camera camera){
super(context);
mCamera = camera;
mCamera.setDisplayOrientation(90);
//get the holder and set this class as the callback, so we can get camera data here
mHolder = getHolder();
mHolder.addCallback(this);
mHolder.setType(SurfaceHolder.SURFACE_TYPE_NORMAL);;
}
@Override
public void surfaceCreated(SurfaceHolder surfaceHolder) {
try{
//when the surface is created, we can set the camera to draw images in this surfaceholder
mCamera.setPreviewDisplay(surfaceHolder);
mCamera.startPreview();
} catch (IOException e) {
Log.d("ERROR", "Camera error on surfaceCreated " + e.getMessage());
}
}
@Override
public void surfaceChanged(SurfaceHolder surfaceHolder, int i, int i2, int i3) {
//before changing the application orientation, you need to stop the preview, rotate and then start it again
if(mHolder.getSurface() == null)//check if the surface is ready to receive camera data
return;
try{
mCamera.stopPreview();
} catch (Exception e){
//this will happen when you are trying the camera if it's not running
}
//now, recreate the camera preview
try{
mCamera.setPreviewDisplay(mHolder);
mCamera.startPreview();
} catch (IOException e) {
Log.d("ERROR", "Camera error on surfaceChanged " + e.getMessage());
}
}
@Override
public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
//our app has only one screen, so we'll destroy the camera in the surface
//if you are unsing with more screens, please move this code your activity
mCamera.stopPreview();
mCamera.release();
}
}