Android Open Source - edgefinder Edge View

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License

The source code is released under:

Apache License

Java Source Code

/*
 * Copyright (C) 2010 William Robert Beene
 */*w  w w .j a  va2  s .co m*/
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package bwr.edgefinder;

import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.OutputStream;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

import android.content.ContentValues;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.hardware.Camera;
import android.hardware.Camera.PreviewCallback;
import android.hardware.Camera.Size;
import android.net.Uri;
import android.provider.MediaStore;
import android.provider.MediaStore.Images.Media;
import android.view.View;

public class EdgeView extends View implements PreviewCallback {
  
  static {
    System.loadLibrary("edgefinder");
  }
  
  private static final int THRESHOLD = 30;
  
  private byte[] cameraPreview = null;
  private boolean cameraPreviewValid = false;
  private final Lock cameraPreviewLock = new ReentrantLock();
  private final Paint edgePaint = new Paint();
  private int width, height;
  private boolean captureNextFrame = false;
  
  public EdgeView(Context context) {
    super(context);
    edgePaint.setColor(Color.WHITE);
  }

  /**
   * Native method for calculating the edge image.
   * 
   * @param source - source image
   * @param width - width of the source image
   * @param height - height of the source image
   * @param canvas - canvas to draw on
   * @param paint - paint used to draw edges
   */
  private native void findEdges(int threshold, byte[] source, int width, int height, Canvas canvas, Paint paint);
  
  private void saveCapturedFrame(Bitmap image) {
    ContentValues metaData = new ContentValues(3);
    metaData.put(Media.TITLE, "Edge Finder Capture");
    metaData.put(Media.DESCRIPTION, "Edge Finder Capture");
    metaData.put(Media.MIME_TYPE, "image/png");

    Uri uri = getContext().getContentResolver().insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, metaData);
    OutputStream os = null;
    
    try {
      os = getContext().getContentResolver().openOutputStream(uri);
      image.compress(Bitmap.CompressFormat.PNG, 100, os);
    } catch (FileNotFoundException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }
    
    if(os != null) {
      try {
        os.close();
      } catch (IOException e) {
        e.printStackTrace();
      }
    }
  }
  
  public void captureNextFrame() {
    captureNextFrame = true;
  }
  
  @Override
  protected void onDraw(Canvas canvas) {
    canvas.drawColor(Color.BLACK);

    if (cameraPreviewLock.tryLock()) {
      try {
        if (cameraPreview != null && cameraPreviewValid) {
          if(captureNextFrame) {
            Bitmap edgeImage = Bitmap.createBitmap(width, height, Bitmap.Config.RGB_565);
            Canvas edgeImageCanvas = new Canvas(edgeImage);
                        
            findEdges(THRESHOLD, cameraPreview, width, height, edgeImageCanvas, edgePaint);
            
            canvas.drawBitmap(edgeImage, 0f, 0f, null);
            
            saveCapturedFrame(edgeImage);
            captureNextFrame = false;
          } else {
            findEdges(THRESHOLD, cameraPreview, width, height, canvas, edgePaint);
          }
          cameraPreviewValid = false;
        }
      } finally {
        cameraPreviewLock.unlock();
      }
    }
  }
  
  public void onPreviewFrame(byte[] data, Camera camera) {
    if (cameraPreviewLock.tryLock()) {
      try {
        if(!cameraPreviewValid) {
          cameraPreviewValid = true;

          final Size s = camera.getParameters().getPreviewSize();
          
          width = s.width;
          height = s.height;
          final int length = width * height;
          
          if(cameraPreview == null || cameraPreview.length != length) {
            cameraPreview = new byte[length];
          }
          
          System.arraycopy(data, 0, cameraPreview, 0, length);
        }
      } finally {
        cameraPreviewLock.unlock();
        postInvalidate();
      }
    }
  }

}

Java Source Code List

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