Android在Facedetection API中敬酒

Question

Fairly simple Android trouble: I'm trying to show an Android "Toast" on the Android Cookbook example for the face detection. However, it seems the Toast method is not allowed in the FaceDetectionView.java I included below towards end of the code. The error code I get is below:

Error:(113, 22) error: no suitable method found for makeText(FaceDetectionView,float,int)
method Toast.makeText(Context,int,int) is not applicable
(actual argument FaceDetectionView cannot be converted to Context by method invocation conversion)
method Toast.makeText(Context,CharSequence,int) is not applicable
(actual argument FaceDetectionView cannot be converted to Context by method invocation conversion)

This is the Main.java:

package com.examples.androface;

import android.app.Activity;
import android.os.Bundle;

public class Main extends Activity
    {
        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState)
            {
                super.onCreate(savedInstanceState);
                setContentView(new FaceDetectionView(this, "face5.JPG"));
            }
    }

This is the FaceDetectionView.java:

package com.examples.androface;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PointF;
import android.graphics.Rect;
import android.media.FaceDetector;
import android.util.Log;
import android.view.View;
import android.widget.Toast;

/**
 * @author wdavid01
 * 
 */
public class FaceDetectionView extends View
  {
    private static final String tag = FaceDetectionView.class.getName();
    private static final int NUM_FACES = 10;
    private FaceDetector arrayFaces;
    private final FaceDetector.Face getAllFaces[] = new FaceDetector.Face[NUM_FACES];
    private FaceDetector.Face getFace = null;

    private final PointF eyesMidPts[] = new PointF[NUM_FACES];
    private final float eyesDistance[] = new float[NUM_FACES];

    private Bitmap sourceImage;

    private final Paint tmpPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    private final Paint pOuterBullsEye = new Paint(Paint.ANTI_ALIAS_FLAG);
    private final Paint pInnerBullsEye = new Paint(Paint.ANTI_ALIAS_FLAG);

    private int picWidth, picHeight;
    private float xRatio, yRatio;
    private ImageLoader mImageLoader = null;

    public FaceDetectionView(Context context, String imagePath)
      {
        super(context);
        init();
        mImageLoader = ImageLoader.getInstance(context);
        sourceImage = mImageLoader.loadFromFile(imagePath);
        detectFaces();

      }

    private void init()
      {
        Log.d(tag, "Init()...");
        pInnerBullsEye.setStyle(Paint.Style.FILL);
        pInnerBullsEye.setColor(Color.RED);
        pOuterBullsEye.setStyle(Paint.Style.STROKE);
        pOuterBullsEye.setColor(Color.RED);
        tmpPaint.setStyle(Paint.Style.STROKE);
        tmpPaint.setTextAlign(Paint.Align.CENTER);
        BitmapFactory.Options bfo = new BitmapFactory.Options();
        bfo.inPreferredConfig = Bitmap.Config.RGB_565;

      }

    private void loadImage(String imagePath)
      {
        sourceImage = mImageLoader.loadFromFile(imagePath);
      }

    @Override
    protected void onDraw(Canvas canvas)
      {
        Log.d(tag, "onDraw()...");

        xRatio = getWidth() * 1.0f / picWidth;
        yRatio = getHeight() * 1.0f / picHeight;
        canvas.drawBitmap(sourceImage, null, new Rect(0, 0, getWidth(), getHeight()), tmpPaint);
        for (int i = 0; i < eyesMidPts.length; i++)
          {
            if (eyesMidPts[i] != null)
              {
                pOuterBullsEye.setStrokeWidth(eyesDistance[i] / 6);
                canvas.drawCircle(eyesMidPts[i].x * xRatio, eyesMidPts[i].y * yRatio, eyesDistance[i] / 2, pOuterBullsEye);
                canvas.drawCircle(eyesMidPts[i].x * xRatio, eyesMidPts[i].y * yRatio, eyesDistance[i] / 6, pInnerBullsEye);
              }
          }
      }

    private void detectFaces()
      {
        Log.d(tag, "detectFaces()...");

        picWidth = sourceImage.getWidth();
        picHeight = sourceImage.getHeight();

        arrayFaces = new FaceDetector(picWidth, picHeight, NUM_FACES);
        arrayFaces.findFaces(sourceImage, getAllFaces);

        for (int i = 0; i < getAllFaces.length; i++)
          {
            getFace = getAllFaces[i];
            try
              {
                PointF eyesMP = new PointF();
                getFace.getMidPoint(eyesMP);
                eyesDistance[i] = getFace.eyesDistance();
                eyesMidPts[i] = eyesMP;

                Log.i("Face", i + " " + getFace.confidence() + " " + getFace.eyesDistance() + " " + "Pose: (" + getFace.pose(FaceDetector.Face.EULER_X) + "," + getFace.pose(FaceDetector.Face.EULER_Y) + "," + getFace.pose(FaceDetector.Face.EULER_Z) + ")" + "Eyes Midpoint: (" + eyesMidPts[i].x + "," + eyesMidPts[i].y + ")");
                Toast.makeText(FaceDetectionView.this, getFace.confidence(),
                        Toast.LENGTH_LONG).show();
              }
            catch (Exception e)
              {
                Log.e("Face", i + " is null");
              }
          }
      }
  }

@RRR after applying the solution below even though the code is compiled when running I get this error message: It doesnt seem that the context is still created properly:

20106-20106/com.examples.androface E/AndroidRuntime: FATAL EXCEPTION: main
                                                                        Process: com.examples.androface, PID: 20106
                                                                        java.lang.RuntimeException: Unable to start activity ComponentInfo{com.examples.androface/com.examples.androface.Main}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
                                                                            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2325)
                                                                            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390)
                                                                            at android.app.ActivityThread.access$800(ActivityThread.java:151)
                                                                            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
                                                                            at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                            at android.os.Looper.loop(Looper.java:135)
                                                                            at android.app.ActivityThread.main(ActivityThread.java:5257)
                                                                            at java.lang.reflect.Method.invoke(Native Method)
                                                                            at java.lang.reflect.Method.invoke(Method.java:372)
                                                                            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
                                                                            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
                                                                         Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources android.content.Context.getResources()' on a null object reference
                                                                            at android.widget.Toast.<init>(Toast.java:101)
                                                                            at android.widget.Toast.makeText(Toast.java:258)
                                                                            at com.examples.androface.FaceDetectionView.detectFaces(FaceDetectionView.java:122)
                                                                            at com.examples.androface.FaceDetectionView.<init>(FaceDetectionView.java:52)
                                                                            at com.examples.androface.Main.onCreate(Main.java:13)
                                                                            at android.app.Activity.performCreate(Activity.java:5990)
                                                                            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
                                                                            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
                                                                            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2390) 
                                                                            at android.app.ActivityThread.access$800(ActivityThread.java:151) 
                                                                            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) 
                                                                            at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                            at android.os.Looper.loop(Looper.java:135) 
                                                                            at android.app.ActivityThread.main(ActivityThread.java:5257) 
                                                                            at java.lang.reflect.Method.invoke(Native Method) 
                                                                            at java.lang.reflect.Method.invoke(Method.java:372) 
                                                                            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) 
                                                                            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) 
01-04 05:27:26.006 20106-20112/com.examples.androface W/art: Suspending all threads took: 16.056ms
01-04 05:27:49.109 20106-20106/? I/Process: Sending signal. PID: 20106 SIG: 9

Answer 1

You can't use a View in your first argument for Toast.makeText .

Instead try

Toast.makeText(getContext(), getFace.confidence(),
                    Toast.LENGTH_LONG).show();

Answer 2

Try this: Add new variable for saving context

package com.examples.androface;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PointF;
import android.graphics.Rect;
import android.media.FaceDetector;
import android.util.Log;
import android.view.View;
import android.widget.Toast;

/**
* @author wdavid01
* 
*/
public class FaceDetectionView extends View
{
private static final String tag = FaceDetectionView.class.getName();
private static final int NUM_FACES = 10;
private FaceDetector arrayFaces;
private final FaceDetector.Face getAllFaces[] = new FaceDetector.Face[NUM_FACES];
private FaceDetector.Face getFace = null;

private final PointF eyesMidPts[] = new PointF[NUM_FACES];
private final float eyesDistance[] = new float[NUM_FACES];

private Bitmap sourceImage;

private final Paint tmpPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
private final Paint pOuterBullsEye = new Paint(Paint.ANTI_ALIAS_FLAG);
private final Paint pInnerBullsEye = new Paint(Paint.ANTI_ALIAS_FLAG);

private int picWidth, picHeight;
private float xRatio, yRatio;
private ImageLoader mImageLoader = null;
private Context context;

public FaceDetectionView(Context context, String imagePath)
  {
    super(context);
    init();
    this.context = context;
    mImageLoader = ImageLoader.getInstance(context);
    sourceImage = mImageLoader.loadFromFile(imagePath);
    detectFaces();

  }

private void init()
  {
    Log.d(tag, "Init()...");
    pInnerBullsEye.setStyle(Paint.Style.FILL);
    pInnerBullsEye.setColor(Color.RED);
    pOuterBullsEye.setStyle(Paint.Style.STROKE);
    pOuterBullsEye.setColor(Color.RED);
    tmpPaint.setStyle(Paint.Style.STROKE);
    tmpPaint.setTextAlign(Paint.Align.CENTER);
    BitmapFactory.Options bfo = new BitmapFactory.Options();
    bfo.inPreferredConfig = Bitmap.Config.RGB_565;

  }

private void loadImage(String imagePath)
  {
    sourceImage = mImageLoader.loadFromFile(imagePath);
  }

@Override
protected void onDraw(Canvas canvas)
  {
    Log.d(tag, "onDraw()...");

    xRatio = getWidth() * 1.0f / picWidth;
    yRatio = getHeight() * 1.0f / picHeight;
    canvas.drawBitmap(sourceImage, null, new Rect(0, 0, getWidth(), getHeight()), tmpPaint);
    for (int i = 0; i < eyesMidPts.length; i++)
      {
        if (eyesMidPts[i] != null)
          {
            pOuterBullsEye.setStrokeWidth(eyesDistance[i] / 6);
            canvas.drawCircle(eyesMidPts[i].x * xRatio, eyesMidPts[i].y * yRatio, eyesDistance[i] / 2, pOuterBullsEye);
            canvas.drawCircle(eyesMidPts[i].x * xRatio, eyesMidPts[i].y * yRatio, eyesDistance[i] / 6, pInnerBullsEye);
          }
      }
  }

private void detectFaces()
  {
    Log.d(tag, "detectFaces()...");

    picWidth = sourceImage.getWidth();
    picHeight = sourceImage.getHeight();

    arrayFaces = new FaceDetector(picWidth, picHeight, NUM_FACES);
    arrayFaces.findFaces(sourceImage, getAllFaces);

    for (int i = 0; i < getAllFaces.length; i++)
      {
        getFace = getAllFaces[i];
        try
          {
            PointF eyesMP = new PointF();
            getFace.getMidPoint(eyesMP);
            eyesDistance[i] = getFace.eyesDistance();
            eyesMidPts[i] = eyesMP;

            Log.i("Face", i + " " + getFace.confidence() + " " + getFace.eyesDistance() + " " + "Pose: (" + getFace.pose(FaceDetector.Face.EULER_X) + "," + getFace.pose(FaceDetector.Face.EULER_Y) + "," + getFace.pose(FaceDetector.Face.EULER_Z) + ")" + "Eyes Midpoint: (" + eyesMidPts[i].x + "," + eyesMidPts[i].y + ")");
            Toast.makeText(context, getFace.confidence() + "",
                    Toast.LENGTH_LONG).show();
          }
        catch (Exception e)
          {
            Log.e("Face", i + " is null");
          }
      }
  }
}

Answer 3

Store Context in one variable

Context context;
public FaceDetectionView(Context context, String imagePath)
{
     this.context=context;
     //rest of your code
}

use context whenever you are trying to show Toast .

Toast.makeText(context, getFace.confidence(),
                    Toast.LENGTH_LONG).show();

make sure getFace.confidence() should be string value otherwise concate it with ""

Toast.makeText(context, ""+getFace.confidence(),
                    Toast.LENGTH_LONG).show();