android - 如何将图片放在相机预览前

Question

我想制作一个包含 2 个 Activity 的应用。第一个是来自 api 演示的 CameraPreview，默认情况下有一个选项菜单。我向它添加了第二个按钮来启动第二个 Activity ，什么是 ImageSwitcher。我想将选定的照片以指定的宽度和高度返回到预览的前面。

此 block 适用于在普通 Activity 的 onCreate 方法中获取和显示照片，但我不知道如何使用 CameraPreview 执行此操作:

setContentView(R.layout.picturelay);                    
 int theID = getIntent().getExtras().getInt("the_image_id");
 ImageView i = (ImageView) findViewById(R.id.cameralay);
 i.setImageResource(theID);

我的开始 Activity :

    public class CameraPreview extends Activity {
        private 
        Preview mPreview;
        Camera mCamera;    
        int numberOfCameras;
        int cameraCurrentlyLocked;
        String uzenet;
        // The first rear facing camera
        int defaultCameraId;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Hide the window title.
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);                                 

        // Create a RelativeLayout container that will hold a SurfaceView,
        // and set it as the content of our activity.
        mPreview = new Preview(this);

        setContentView(mPreview);               

        try {

            int theID = getIntent().getExtras().getInt("the_image_id");
            ImageView i = (ImageView) findViewById(R.id.cameralay);
        i.setImageResource(theID);     

        } catch (Exception e){

            Toast.makeText(this, e.getMessage(), Toast.LENGTH_LONG);

        }



        // Find the total number of cameras available
        numberOfCameras = Camera.getNumberOfCameras();

        // Find the ID of the default camera
        CameraInfo cameraInfo = new CameraInfo();
            for (int i = 0; i < numberOfCameras; i++) {
                Camera.getCameraInfo(i, cameraInfo);
                if (cameraInfo.facing == CameraInfo.CAMERA_FACING_BACK) {
                    defaultCameraId = i;
                }
            }
    }




    @Override
    protected void onResume() {
        super.onResume();

        // Open the default i.e. the first rear facing camera.        
        mCamera = Camera.open();
        cameraCurrentlyLocked = defaultCameraId;
        mPreview.setCamera(mCamera);

    }

    @Override
    protected void onPause() {
        super.onPause();

        // Because the Camera object is a shared resource, it's very
        // important to release it when the activity is paused.
        if (mCamera != null) {
            mPreview.setCamera(null);
            mCamera.release();
            mCamera = null;
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate our menu which can gather user input for switching camera
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.camera_menu, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle item selection
        switch (item.getItemId()) {
        case R.id.switch_cam:
            // check for availability of multiple cameras
            if (numberOfCameras == 1) {
                AlertDialog.Builder builder = new AlertDialog.Builder(this);
                builder.setMessage(this.getString(R.string.camera_alert))
                       .setNeutralButton("Close", null);
                AlertDialog alert = builder.create();
                alert.show();
                return true;
            }


            // OK, we have multiple cameras.
            // Release this camera -> cameraCurrentlyLocked
            if (mCamera != null) {
                mCamera.stopPreview();
                mPreview.setCamera(null);
                mCamera.release();
                mCamera = null;
            }

            // Acquire the next camera and request Preview to reconfigure
            // parameters.
            mCamera = Camera
                    .open((cameraCurrentlyLocked + 1) % numberOfCameras);
            cameraCurrentlyLocked = (cameraCurrentlyLocked + 1)
                    % numberOfCameras;
            mPreview.switchCamera(mCamera);

            // Start the preview
            mCamera.startPreview();
            return true;                  

        case R.id.get_picture:

            Intent intent2 = new Intent(CameraPreview.this, ImageSwitcher1.class);
            //startActivityForResult(intent, 0);
            startActivity(intent2); 
            return true;      

        }
        return super.onOptionsItemSelected(item);
    }
    }


    class Preview extends ViewGroup implements SurfaceHolder.Callback {
        private final String TAG = "Preview";

        SurfaceView mSurfaceView;
        SurfaceHolder mHolder;
        Size mPreviewSize;
        List<Size> mSupportedPreviewSizes;
        Camera mCamera;



    Preview(Context context) {
        super(context);                

        mSurfaceView = new SurfaceView(context);
        addView(mSurfaceView);

        // Install a SurfaceHolder.Callback so we get notified when the
        // underlying surface is created and destroyed.
        mHolder = mSurfaceView.getHolder();
        mHolder.addCallback(this);
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);        
    }

    public void setCamera(Camera camera) {
        mCamera = camera;
        if (mCamera != null) {
            mSupportedPreviewSizes = mCamera.getParameters().getSupportedPreviewSizes();
            requestLayout();            
        }
    }

    public void switchCamera(Camera camera) {
       setCamera(camera);
       try {
           camera.setPreviewDisplay(mHolder);
       } catch (IOException exception) {
           Log.e(TAG, "IOException caused by setPreviewDisplay()", exception);
       }
       Camera.Parameters parameters = camera.getParameters();
       parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
       requestLayout();

       camera.setParameters(parameters);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        // We purposely disregard child measurements because act as a
        // wrapper to a SurfaceView that centers the camera preview instead
        // of stretching it.
        final int width = resolveSize(getSuggestedMinimumWidth(), widthMeasureSpec);
        final int height = resolveSize(getSuggestedMinimumHeight(), heightMeasureSpec);
        setMeasuredDimension(width, height);

        if (mSupportedPreviewSizes != null) {
            mPreviewSize = getOptimalPreviewSize(mSupportedPreviewSizes, width, height);
        }        
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        if (changed && getChildCount() > 0) {
            final View child = getChildAt(0);

            final int width = r - l;
            final int height = b - t;

            int previewWidth = width;
            int previewHeight = height;
            if (mPreviewSize != null) {
                previewWidth = mPreviewSize.width;
                previewHeight = mPreviewSize.height;
            }

            // Center the child SurfaceView within the parent.
            if (width * previewHeight > height * previewWidth) {
                final int scaledChildWidth = previewWidth * height / previewHeight;
                child.layout((width - scaledChildWidth) / 2, 0,
                        (width + scaledChildWidth) / 2, height);
            } else {
                final int scaledChildHeight = previewHeight * width / previewWidth;
                child.layout(0, (height - scaledChildHeight) / 2,
                        width, (height + scaledChildHeight) / 2);
            }
        }
    }

    public void surfaceCreated(SurfaceHolder holder) {
        // The Surface has been created, acquire the camera and tell it where
        // to draw.
        try {
            if (mCamera != null) {
                mCamera.setPreviewDisplay(holder);
            }
        } catch (IOException exception) {
            Log.e(TAG, "IOException caused by setPreviewDisplay()", exception);
        }        
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // Surface will be destroyed when we return, so stop the preview.
        if (mCamera != null) {
            mCamera.stopPreview();
        }
    }


    private Size getOptimalPreviewSize(List<Size> sizes, int w, int h) {
        final double ASPECT_TOLERANCE = 0.1;
        double targetRatio = (double) w / h;
        if (sizes == null) return null;

        Size optimalSize = null;
        double minDiff = Double.MAX_VALUE;

        int targetHeight = h;

        // Try to find an size match aspect ratio and size
        for (Size size : sizes) {
            double ratio = (double) size.width / size.height;
            if (Math.abs(ratio - targetRatio) > ASPECT_TOLERANCE) continue;
            if (Math.abs(size.height - targetHeight) < minDiff) {
                optimalSize = size;
                minDiff = Math.abs(size.height - targetHeight);
            }
        }

        // Cannot find the one match the aspect ratio, ignore the requirement
        if (optimalSize == null) {
            minDiff = Double.MAX_VALUE;
            for (Size size : sizes) {
                if (Math.abs(size.height - targetHeight) < minDiff) {
                    optimalSize = size;
                    minDiff = Math.abs(size.height - targetHeight);
                }
            }
        }
        return optimalSize;
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        // Now that the size is known, set up the camera parameters and begin
        // the preview.
        Camera.Parameters parameters = mCamera.getParameters();
        parameters.setPreviewSize(mPreviewSize.width, mPreviewSize.height);
        requestLayout();        

        mCamera.setParameters(parameters);
        mCamera.startPreview();        

    }


}

第二个 Activity :

public class ImageSwitcher1 extends Activity implements
        AdapterView.OnItemSelectedListener, ViewSwitcher.ViewFactory {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);

        setContentView(R.layout.image_switcher_1);

        mSwitcher = (ImageSwitcher) findViewById(R.id.switcher);
        mSwitcher.setFactory(this);
        mSwitcher.setInAnimation(AnimationUtils.loadAnimation(this,
                android.R.anim.fade_in));
        mSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this,
                android.R.anim.fade_out));

        Gallery g = (Gallery) findViewById(R.id.gallery);
        g.setAdapter(new ImageAdapter(this));
        g.setOnItemSelectedListener(this);

        g.setOnItemClickListener(new OnItemClickListener() {
            public void onItemClick(AdapterView parent, View v, int position, long id) {


                Intent intent = new Intent(ImageSwitcher1.this, CameraPreview.class);
                intent.putExtra("the_image_id", mImageIds[position]);           

                startActivity(intent);   

                finish();
            }
        });
    }

    public void onItemSelected(AdapterView parent, View v, int position, long id) {
        mSwitcher.setImageResource(mImageIds[position]);
    }

    public void onNothingSelected(AdapterView parent) {
    }

    public View makeView() {
        ImageView i = new ImageView(this);
        i.setBackgroundColor(0xFF000000);
        i.setScaleType(ImageView.ScaleType.FIT_CENTER);
        i.setLayoutParams(new ImageSwitcher.LayoutParams(LayoutParams.MATCH_PARENT,
                LayoutParams.MATCH_PARENT));
        return i;
    }

    private ImageSwitcher mSwitcher;

    public class ImageAdapter extends BaseAdapter {
        public ImageAdapter(Context c) {
            mContext = c;
        }

        public int getCount() {
            return mThumbIds.length;
        }

        public Object getItem(int position) {
            return position;
        }

        public long getItemId(int position) {
            return position;
        }

        public View getView(int position, View convertView, ViewGroup parent) {
            ImageView i = new ImageView(mContext);

            i.setImageResource(mThumbIds[position]);
            i.setAdjustViewBounds(true);
            i.setLayoutParams(new Gallery.LayoutParams(
                    LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
            i.setBackgroundResource(R.drawable.picture_frame);
            return i;
        }

        private Context mContext;

    }

    private Integer[] mThumbIds = {
            R.drawable.1, R.drawable.2,
            R.drawable.3, R.drawable.4,
            R.drawable.5, R.drawable.6,
            R.drawable.7, R.drawable.8,
            R.drawable.9
            };

    private Integer[] mImageIds = {
        R.drawable.1, R.drawable.2,
            R.drawable.3, R.drawable.4,
            R.drawable.5, R.drawable.6,
            R.drawable.7, R.drawable.8,
            R.drawable.9
            };

}

感谢您的回复!

Answer 1

我有一个具有不同预览 Activity 的解决方案。所以我可以在相机预览前看到选定的图像。这是使用的预览 Activity :

public class PreviewDemo extends Activity {
  private SurfaceView preview=null;
  private SurfaceHolder previewHolder=null;
  private Camera camera=null;
  private boolean inPreview=false;
  private boolean cameraConfigured=false;
  private Context context;

  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.main);

    preview=(SurfaceView)findViewById(R.id.preview);
    previewHolder=preview.getHolder();
    previewHolder.addCallback(surfaceCallback);
    previewHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);             

    try {   
        int theID = getIntent().getExtras().getInt("the_image_id");
        ImageView i = (ImageView) findViewById(R.id.cameralay);
        i.setImageResource(theID);     

    } catch (Exception e){  

    Toast.makeText(this, e.getMessage(), Toast.LENGTH_LONG);

    }

  }

  @Override
  public void onResume() {
    super.onResume();

    camera=Camera.open();
    startPreview();
  }

  @Override
  public void onPause() {
    if (inPreview) {
      camera.stopPreview();
    }

    camera.release();
    camera=null;
    inPreview=false;

    super.onPause();
  }

  private Camera.Size getBestPreviewSize(int width, int height,
                                         Camera.Parameters parameters) {
    Camera.Size result=null;

    for (Camera.Size size : parameters.getSupportedPreviewSizes()) {
      if (size.width<=width && size.height<=height) {
        if (result==null) {
          result=size;
        }
        else {
          int resultArea=result.width*result.height;
          int newArea=size.width*size.height;

          if (newArea>resultArea) {
            result=size;
          }
        }
      }
    }

    return(result);
  }

  private void initPreview(int width, int height) {
    if (camera!=null && previewHolder.getSurface()!=null) {
      try {
        camera.setPreviewDisplay(previewHolder);
      }
      catch (Throwable t) {
        Log.e("PreviewDemo-surfaceCallback",
              "Exception in setPreviewDisplay()", t);
        Toast
          .makeText(PreviewDemo.this, t.getMessage(), Toast.LENGTH_LONG)
          .show();
      }

      if (!cameraConfigured) {
        Camera.Parameters parameters=camera.getParameters();
        Camera.Size size=getBestPreviewSize(width, height,
                                            parameters);

        if (size!=null) {
          parameters.setPreviewSize(size.width, size.height);
          camera.setParameters(parameters);
          cameraConfigured=true;
        }
      }
    }
  }

  private void startPreview() {
    if (cameraConfigured && camera!=null) {
      camera.startPreview();
      inPreview=true;
    }
  }

  SurfaceHolder.Callback surfaceCallback=new SurfaceHolder.Callback() {
    public void surfaceCreated(SurfaceHolder holder) {
      // no-op -- wait until surfaceChanged()
    }

    public void surfaceChanged(SurfaceHolder holder,
                               int format, int width,
                               int height) {
      initPreview(width, height);
      startPreview();
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
      // no-op
    }
  };

  public boolean onCreateOptionsMenu(Menu menu) {

      // Inflate our menu which can gather user input for switching camera
      MenuInflater inflater = getMenuInflater();
      inflater.inflate(R.menu.camera_menu2, menu);
      return true;
  }

  @Override
  public boolean onOptionsItemSelected(MenuItem item) {
      // Handle item selection
      switch (item.getItemId()) {

      case R.id.take_photo:
          //code of taking a photo will be here...

        return true;

      }
      return super.onOptionsItemSelected(item);
  }
}

我的布局文件包含表面 View 和 ImageView :

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

<android.view.SurfaceView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/preview"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
</android.view.SurfaceView>        
<ImageView
        android:id="@+id/cameralay"
        android:layout_width="150dp"
        android:layout_height="150dp"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:contentDescription="@+id/app_name"> 
</ImageView>
</RelativeLayout>