Question

我正在尝试使用我的Android应用程序中的Tom Gibaras实现（针对Android更改）实现canny边缘检测算法。应用程序使用相机捕捉图片，相机工作正常，拍摄照片，问题在于我想将其传递给算法并显示结果。而不是处理的图像和检测到的边缘然后显示，应用程序返回主屏幕下面的代码是我到目前为止的活动。我可以提供任何其他要求的代码，你能帮我吗？

/**
 * ShootActivity demonstrates capturing camera images
 * - user presses button to capture an image using the device camera
 */
public class ShootActivity extends Activity {
public static final int ACTION_TAKE_PHOTO_B = 1;

public String mCurrentPhotoPath;
public static final String BITMAP_STORAGE_KEY = "viewbitmap";
public static final String IMAGEVIEW_VISIBILITY_STORAGE_KEY = "imageviewvisibility";
public ImageView mImageView;
public Bitmap mImageBitmap;
public static final String JPEG_FILE_PREFIX = "IMG_";
public static final String JPEG_FILE_SUFFIX = ".jpg";

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mImageView = (ImageView) findViewById(R.id.imageView1);
    mImageBitmap = null;

    Button picBtn = (Button) findViewById(R.id.btnIntend);
    setBtnListenerOrDisable( 
            picBtn, 
            mTakePicOnClickListener,
            MediaStore.ACTION_IMAGE_CAPTURE
    );

}
/**
 * Click method to handle user pressing button to launch camera
 */

Button.OnClickListener mTakePicOnClickListener = 
        new Button.OnClickListener() {
        public void onClick(View v) {
            dispatchTakePictureIntent(ACTION_TAKE_PHOTO_B);
        }
    };


public File createImageFile() throws IOException {
    // Create an image file name
    String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
    String imageFileName = JPEG_FILE_PREFIX + timeStamp + "_";
    //File albumF = getAlbumDir();
    File imageF = File.createTempFile(imageFileName, JPEG_FILE_SUFFIX);
    return imageF;
}

public File setUpPhotoFile() throws IOException {

    File f = createImageFile();
    mCurrentPhotoPath = f.getAbsolutePath();

    return f;
}

public void setPic() {

    /* There isn't enough memory to open up more than a couple camera photos */
    /* So pre-scale the target bitmap into which the file is decoded */

    /* Get the size of the ImageView */
    int targetW = mImageView.getWidth();
    int targetH = mImageView.getHeight();

    /* Get the size of the image */
    BitmapFactory.Options bmOptions = new BitmapFactory.Options();
    bmOptions.inJustDecodeBounds = true;
    BitmapFactory.decodeFile(mCurrentPhotoPath, bmOptions);
    int photoW = bmOptions.outWidth;
    int photoH = bmOptions.outHeight;

    /* Figure out which way needs to be reduced less */
    int scaleFactor = 2;
    if ((targetW > 0) || (targetH > 0)) {
        scaleFactor = Math.min(photoW/targetW, photoH/targetH); 
    }

    /* Set bitmap options to scale the image decode target */
    bmOptions.inJustDecodeBounds = false;
    bmOptions.inSampleSize = scaleFactor;
    bmOptions.inPurgeable = true;

    /* Decode the JPEG file into a Bitmap */
    mImageBitmap = BitmapFactory.decodeFile(mCurrentPhotoPath, bmOptions);
    CannyEdgeDetection detector = new CannyEdgeDetection();
    detector.setLowThreshold(0.5f);
    detector.setHighThreshold(1f);
    detector.setSourceImage(mImageBitmap);
    detector.process();
    Bitmap edges = detector.getEdgesImage();
    /* Associate the Bitmap to the ImageView */
    mImageView.setImageBitmap(edges);
    mImageView.setVisibility(View.VISIBLE);
}

public void galleryAddPic() {
        Intent mediaScanIntent = new Intent("android.intent.action.MEDIA_SCANNER_SCAN_FILE");
        File f = new File(mCurrentPhotoPath);
        Uri contentUri = Uri.fromFile(f);
        mediaScanIntent.setData(contentUri);
        this.sendBroadcast(mediaScanIntent);
}

public void dispatchTakePictureIntent(int actionCode) {

    Intent takePictureIntent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);

        File f = null;

        try {
            f = setUpPhotoFile();
            mCurrentPhotoPath = f.getAbsolutePath();
            takePictureIntent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(f));
        } catch (IOException e) {
            e.printStackTrace();
            f = null;
            mCurrentPhotoPath = null;
        }


    startActivityForResult(takePictureIntent, 1102);
}
public void handleBigCameraPhoto()
{
    if (mCurrentPhotoPath != null) 
    {
        setPic();
        galleryAddPic();
        mCurrentPhotoPath = null;
    }
}
/**
 * Handle user returning from capturing the image
 */
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) 
{
    if(requestCode == 1102 && resultCode == Activity.RESULT_OK)
    {
        if(data != null)
        {
        handleBigCameraPhoto();
        }
    }

}
@Override
protected void onSaveInstanceState(Bundle outState) {
    outState.putParcelable(BITMAP_STORAGE_KEY, mImageBitmap);
    outState.putBoolean(IMAGEVIEW_VISIBILITY_STORAGE_KEY, (mImageBitmap != null) );
    super.onSaveInstanceState(outState);
}

@Override
protected void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);
    mImageBitmap = savedInstanceState.getParcelable(BITMAP_STORAGE_KEY);
    mImageView.setImageBitmap(mImageBitmap);
    mImageView.setVisibility(savedInstanceState.getBoolean(IMAGEVIEW_VISIBILITY_STORAGE_KEY) ? ImageView.VISIBLE : ImageView.INVISIBLE);
}
public static boolean isIntentAvailable(Context context, String action) {
    final PackageManager packageManager = context.getPackageManager();
    final Intent intent = new Intent(action);
    List<ResolveInfo> list =
        packageManager.queryIntentActivities(intent,
                PackageManager.MATCH_DEFAULT_ONLY);
    return list.size() > 0;
}


public void setBtnListenerOrDisable( 
        Button btn, 
        Button.OnClickListener onClickListener,
        String intentName
) {
    if (isIntentAvailable(this, intentName)) {
        btn.setOnClickListener(onClickListener);            
    } else {
        btn.setText( 
            getText(R.string.cannot).toString() + " " + btn.getText());
        btn.setClickable(false);
    }
}

}

03-27 02:47:37.310: E/AndroidRuntime(6513): FATAL EXCEPTION: main
03-27 02:47:37.310: E/AndroidRuntime(6513): java.lang.RuntimeException: Failure delivering result ResultInfo{who=null, request=1102, result=-1, data=null} to activity {com.example.f_y_p/com.example.f_y_p.ShootActivity}: java.lang.NullPointerException
03-27 02:47:37.310: E/AndroidRuntime(6513):     at android.app.ActivityThread.deliverResults(ActivityThread.java:3182)
03-27 02:47:37.310: E/AndroidRuntime(6513):     at android.app.ActivityThread.handleSendResult(ActivityThread.java:3225)
03-27 02:47:37.310: E/AndroidRuntime(6513):     at android.app.ActivityThread.access$1100(ActivityThread.java:140)
03-27 02:47:37.310: E/AndroidRuntime(6513):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1275)
03-27 02:47:37.310: E/AndroidRuntime(6513):     at android.os.Handler.dispatchMessage(Handler.java:99)
03-27 02:47:37.310: E/AndroidRuntime(6513):     at android.os.Looper.loop(Looper.java:137)
03-27 02:47:37.310: E/AndroidRuntime(6513):     at android.app.ActivityThread.main(ActivityThread.java:4898)
03-27 02:47:37.310: E/AndroidRuntime(6513):     at java.lang.reflect.Method.invokeNative(Native Method)
03-27 02:47:37.310: E/AndroidRuntime(6513):     at java.lang.reflect.Method.invoke(Method.java:511)
03-27 02:47:37.310: E/AndroidRuntime(6513):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1006)
03-27 02:47:37.310: E/AndroidRuntime(6513):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:773)
03-27 02:47:37.310: E/AndroidRuntime(6513):     at dalvik.system.NativeStart.main(Native Method)
03-27 02:47:37.310: E/AndroidRuntime(6513): Caused by: java.lang.NullPointerException
03-27 02:47:37.310: E/AndroidRuntime(6513):     at com.example.f_y_p.CannyEdgeDetection.setSourceImage(CannyEdgeDetection.java:75)
03-27 02:47:37.310: E/AndroidRuntime(6513):     at com.example.f_y_p.ShootActivity.setPic(ShootActivity.java:114)
03-27 02:47:37.310: E/AndroidRuntime(6513):     at com.example.f_y_p.ShootActivity.handleBigCameraPhoto(ShootActivity.java:153)
03-27 02:47:37.310: E/AndroidRuntime(6513):     at com.example.f_y_p.ShootActivity.onActivityResult(ShootActivity.java:166)
03-27 02:47:37.310: E/AndroidRuntime(6513):     at android.app.Activity.dispatchActivityResult(Activity.java:5390)    
 032702:47:37.310:E/AndroidRuntime(6513):atandroid.app.ActivityThread.deliverResults(ActivityThread.java:3178)
03-27 02:47:37.310: E/AndroidRuntime(6513):     ... 11 more

03-27 02：47：48.535：I / Process（6513）：发送信号。 PID：6513 SIG：9

Answer 1

<强>崩溃：

您的应用程序返回主屏幕，因为发生了崩溃。崩溃可能是由于NullPointerException。

可能是因为这一行：

Bitmap mBitmap = (Bitmap) data.getExtras().get("data");

<强> logcat的：

您可以通过查看LogCat输出确定崩溃的确切位置。请发布LogCat输出或只扫描它并确定应用程序崩溃的位置。

照片位置：

现在是坏消息。您无法通过Extras Bundle以您尝试的方式从相机拍摄照片。此函数最多将返回一个小缩略图，该缩略图不适合您的图像处理算法。您的图片更有可能位于outputFileUri指定的位置。

如何从图库中捕获和选择：

请参阅此帖：Allow user to select camera or gallery for image。寻找标题为“如何启动单个Intent以从Gallery或Camera中选择图像，或者注册以浏览文件系统的任何应用程序”的答案。您将不得不使用此方法或类似方法从相机获取图像的路径。

<强>比例：

此外，您还有另外一个问题需要处理。很可能无法打开图像的单个全尺寸Bitmap表示。它太大了，无法容纳Android设备的可用堆内存。因此，您必须打开图像的缩小版本。幸运的是，使用BitmapFactory.decodeFile(String pathName, BitmapFactory.Options opts)并不是很困难。

示例：

BitmapFactory.Options options = new BitmapFactory.Options();
options.inSampleSize = 4; // Arbitrary, your mileage may vary.
return BitmapFactory.decodeFile(path, options);

您可以使用inSampleSize将图像缩小1,2,3等等。甚至有计算inSampleSize的方法，例如将Bitmap保持在特定字节大小之下。

适用于Android的Canny边缘探测器

1 个答案: