content: package com.myapps.documentscanner.uicamera;
  
  import android.Manifest;
  import android.content.Context;
  import android.content.res.Configuration;
  import android.support.annotation.RequiresPermission;
  import android.util.AttributeSet;
  import android.util.Log;
  import android.view.SurfaceHolder;
  import android.view.SurfaceView;
  import android.view.ViewGroup;
  
  import com.google.android.gms.common.images.Size;
  
  import java.io.IOException;
  
  public class CameraSourcePreview extends ViewGroup {
      private static final String TAG = "CameraSourcePreview";
  
      private Context mContext;
      private SurfaceView mSurfaceView;
      private boolean mStartRequested;
      private boolean mSurfaceAvailable;
      private CameraSource mCameraSource;
  
      private GraphicOverlay mOverlay;
  
      public CameraSourcePreview(Context context, AttributeSet attrs) {
          super(context, attrs);
          mContext = context;
          mStartRequested = false;
          mSurfaceAvailable = false;
  
          mSurfaceView = new SurfaceView(context);
          mSurfaceView.getHolder().addCallback(new SurfaceCallback());
          addView(mSurfaceView);
      }
  
      @RequiresPermission(Manifest.permission.CAMERA)
      public void start(CameraSource cameraSource) throws IOException, SecurityException {
          if (cameraSource == null) {
              stop();
          }
  
          mCameraSource = cameraSource;
  
          if (mCameraSource != null) {
              mStartRequested = true;
              startIfReady();
          }
      }
  
      @RequiresPermission(Manifest.permission.CAMERA)
      public void start(CameraSource cameraSource, GraphicOverlay overlay) throws IOException, SecurityException {
          mOverlay = overlay;
          start(cameraSource);
      }
  
      public void stop() {
          if (mCameraSource != null) {
              mCameraSource.stop();
          }
      }
  
      public void release() {
          if (mCameraSource != null) {
              mCameraSource.release();
              mCameraSource = null;
          }
      }
  
      @RequiresPermission(Manifest.permission.CAMERA)
      private void startIfReady() throws IOException, SecurityException {
          if (mStartRequested && mSurfaceAvailable) {
              mCameraSource.start(mSurfaceView.getHolder());
              if (mOverlay != null) {
                  Size size = mCameraSource.getPreviewSize();
                  int min = Math.min(size.getWidth(), size.getHeight());
                  int max = Math.max(size.getWidth(), size.getHeight());
                  if (isPortraitMode()) {
                      // Swap width and height sizes when in portrait, since it will be rotated by
                      // 90 degrees
                      mOverlay.setCameraInfo(min, max, mCameraSource.getCameraFacing());
                  } else {
                      mOverlay.setCameraInfo(max, min, mCameraSource.getCameraFacing());
                  }
                  mOverlay.clear();
              }
              mStartRequested = false;
          }
      }
  
      private class SurfaceCallback implements SurfaceHolder.Callback {
          @Override
          public void surfaceCreated(SurfaceHolder surface) {
              mSurfaceAvailable = true;
              try {
                  startIfReady();
              } catch (SecurityException se) {
                  Log.e(TAG,"Do not have permission to start the camera", se);
              } catch (IOException e) {
                  Log.e(TAG, "Could not start camera source.", e);
              }
          }
  
          @Override
          public void surfaceDestroyed(SurfaceHolder surface) {
              mSurfaceAvailable = false;
          }
  
          @Override
          public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
          }
      }
  
      @Override
      protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
          int previewWidth = 320;
          int previewHeight = 240;
          if (mCameraSource != null) {
              Size size = mCameraSource.getPreviewSize();
              if (size != null) {
                  previewWidth = size.getWidth();
                  previewHeight = size.getHeight();
              }
          }
  
          // Swap width and height sizes when in portrait, since it will be rotated 90 degrees
          if (isPortraitMode()) {
              int tmp = previewWidth;
              previewWidth = previewHeight;
              previewHeight = tmp;
          }
  
          final int viewWidth = right - left;
          final int viewHeight = bottom - top;
  
          int childWidth;
          int childHeight;
          int childXOffset = 0;
          int childYOffset = 0;
          float widthRatio = (float) viewWidth / (float) previewWidth;
          float heightRatio = (float) viewHeight / (float) previewHeight;
  
          // To fill the view with the camera preview, while also preserving the correct aspect ratio,
          // it is usually necessary to slightly oversize the child and to crop off portions along one
          // of the dimensions.  We scale up based on the dimension requiring the most correction, and
          // compute a crop offset for the other dimension.
          if (widthRatio > heightRatio) {
              childWidth = viewWidth;
              childHeight = (int) ((float) previewHeight * widthRatio);
              childYOffset = (childHeight - viewHeight) / 2;
          } else {
              childWidth = (int) ((float) previewWidth * heightRatio);
              childHeight = viewHeight;
              childXOffset = (childWidth - viewWidth) / 2;
          }
  
          for (int i = 0; i < getChildCount(); ++i) {
              // One dimension will be cropped.  We shift child over or up by this offset and adjust
              // the size to maintain the proper aspect ratio.
              getChildAt(i).layout(
                      -1 * childXOffset, -1 * childYOffset,
                      childWidth - childXOffset, childHeight - childYOffset);
          }
  
          try {
              startIfReady();
          } catch (SecurityException se) {
              Log.e(TAG,"Do not have permission to start the camera", se);
          } catch (IOException e) {
              Log.e(TAG, "Could not start camera source.", e);
          }
      }
  
      private boolean isPortraitMode() {
          int orientation = mContext.getResources().getConfiguration().orientation;
          if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
              return false;
          }
          if (orientation == Configuration.ORIENTATION_PORTRAIT) {
              return true;
          }
  
          Log.d(TAG, "isPortraitMode returning false by default");
          return false;
      }
  }
  