2

我是 android 开发的新手，我正在按照一些教程来创建第一个应用程序。当我想运行应用程序时，编译器没有显示错误，但在模拟器中显示“不幸的是，取景器已停止。”

编码：

AndroidManifest.xml 文件

<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
          package="com.example.viewfinderee368" 
          android:versionCode="1" 
          android:versionName="1.0">

    <application android:icon="@drawable/icon" 
                 android:label="@string/app_name">

        <activity android:name=".ViewfinderEE368" 
                  android:label="@string/app_name" 
                  android:screenOrientation="landscape">

                 <intent-filter>
                      <action android:name="android.intent.action.MAIN"/>
                      <category android:name="android.intent.category.LAUNCHER"/>
                 </intent-filter>
        </activity>
    </application>

    <uses-sdk android:minSdkVersion="6"/>
    <uses-permission android:name="android.permission.CAMERA"/>
    <uses-feature android:name="android.hardware.camera"/>
    <uses-feature android:name="android.hardware.camera.autofocus"/>

</manifest>

src/.java 文件

package com.example.viewfinderee368;

import java.io.IOException;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.RectF;
import android.hardware.Camera;
import android.hardware.Camera.PreviewCallback;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.view.ViewGroup.LayoutParams;

// ----------------------------------------------------------------------

public class ViewfinderEE368 extends Activity {    
    private Preview mPreview;
    private DrawOnTop mDrawOnTop;

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

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

        // Create our Preview view and set it as the content of our activity.
        // Create our DrawOnTop view.
        mDrawOnTop = new DrawOnTop(this);
        mPreview = new Preview(this, mDrawOnTop);
        setContentView(mPreview);
        addContentView(mDrawOnTop, new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
    }
}

//----------------------------------------------------------------------

class DrawOnTop extends View {
    Bitmap mBitmap;
    Paint mPaintBlack;
    Paint mPaintYellow;
    Paint mPaintRed;
    Paint mPaintGreen;
    Paint mPaintBlue;
    byte[] mYUVData;
    int[] mRGBData;
    int mImageWidth, mImageHeight;
    int[] mRedHistogram;
    int[] mGreenHistogram;
    int[] mBlueHistogram;
    double[] mBinSquared;

    public DrawOnTop(Context context) {
        super(context);

        mPaintBlack = new Paint();
        mPaintBlack.setStyle(Paint.Style.FILL);
        mPaintBlack.setColor(Color.BLACK);
        mPaintBlack.setTextSize(25);

        mPaintYellow = new Paint();
        mPaintYellow.setStyle(Paint.Style.FILL);
        mPaintYellow.setColor(Color.YELLOW);
        mPaintYellow.setTextSize(25);

        mPaintRed = new Paint();
        mPaintRed.setStyle(Paint.Style.FILL);
        mPaintRed.setColor(Color.RED);
        mPaintRed.setTextSize(25);

        mPaintGreen = new Paint();
        mPaintGreen.setStyle(Paint.Style.FILL);
        mPaintGreen.setColor(Color.GREEN);
        mPaintGreen.setTextSize(25);

        mPaintBlue = new Paint();
        mPaintBlue.setStyle(Paint.Style.FILL);
        mPaintBlue.setColor(Color.BLUE);
        mPaintBlue.setTextSize(25);

        mBitmap = null;
        mYUVData = null;
        mRGBData = null;
        mRedHistogram = new int[256];
        mGreenHistogram = new int[256];
        mBlueHistogram = new int[256];
        mBinSquared = new double[256];
        for (int bin = 0; bin < 256; bin++)
        {
            mBinSquared[bin] = ((double)bin) * bin;
        } // bin
    }

    @Override
    protected void onDraw(Canvas canvas) {
        if (mBitmap != null)
        {
            int canvasWidth = canvas.getWidth();
            int canvasHeight = canvas.getHeight();
            int newImageWidth = canvasWidth;
            int newImageHeight = canvasHeight;
            int marginWidth = (canvasWidth - newImageWidth)/2;

            // Convert from YUV to RGB
            decodeYUV420SP(mRGBData, mYUVData, mImageWidth, mImageHeight);

            // Draw bitmap
//          mBitmap.setPixels(mRGBData, 0, mImageWidth, 0, 0, 
//                  mImageWidth, mImageHeight);
//          Rect src = new Rect(0, 0, mImageWidth, mImageHeight);
//          Rect dst = new Rect(marginWidth, 0, 
//                  canvasWidth-marginWidth, canvasHeight);
//          canvas.drawBitmap(mBitmap, src, dst, mPaintBlack);

            // Draw black borders                       
//          canvas.drawRect(0, 0, marginWidth, canvasHeight, mPaintBlack);
//          canvas.drawRect(canvasWidth - marginWidth, 0, 
//                  canvasWidth, canvasHeight, mPaintBlack);

            // Calculate histogram
            calculateIntensityHistogram(mRGBData, mRedHistogram, 
                    mImageWidth, mImageHeight, 0);
            calculateIntensityHistogram(mRGBData, mGreenHistogram, 
                    mImageWidth, mImageHeight, 1);
            calculateIntensityHistogram(mRGBData, mBlueHistogram, 
                    mImageWidth, mImageHeight, 2);

            // Calculate mean
            double imageRedMean = 0, imageGreenMean = 0, imageBlueMean = 0;
            double redHistogramSum = 0, greenHistogramSum = 0, blueHistogramSum = 0;
            for (int bin = 0; bin < 256; bin++)
            {
                imageRedMean += mRedHistogram[bin] * bin;
                redHistogramSum += mRedHistogram[bin];
                imageGreenMean += mGreenHistogram[bin] * bin;
                greenHistogramSum += mGreenHistogram[bin];
                imageBlueMean += mBlueHistogram[bin] * bin;
                blueHistogramSum += mBlueHistogram[bin];
            } // bin
            imageRedMean /= redHistogramSum;
            imageGreenMean /= greenHistogramSum;
            imageBlueMean /= blueHistogramSum;

            // Calculate second moment
            double imageRed2ndMoment = 0, imageGreen2ndMoment = 0, imageBlue2ndMoment = 0;
            for (int bin = 0; bin < 256; bin++)
            {
                imageRed2ndMoment += mRedHistogram[bin] * mBinSquared[bin];
                imageGreen2ndMoment += mGreenHistogram[bin] * mBinSquared[bin];
                imageBlue2ndMoment += mBlueHistogram[bin] * mBinSquared[bin];
            } // bin
            imageRed2ndMoment /= redHistogramSum;
            imageGreen2ndMoment /= greenHistogramSum;
            imageBlue2ndMoment /= blueHistogramSum;
            double imageRedStdDev = Math.sqrt( imageRed2ndMoment - imageRedMean*imageRedMean );
            double imageGreenStdDev = Math.sqrt( imageGreen2ndMoment - imageGreenMean*imageGreenMean );
            double imageBlueStdDev = Math.sqrt( imageBlue2ndMoment - imageBlueMean*imageBlueMean );

            // Draw mean
            String imageMeanStr = "Mean (R,G,B): " + String.format("%.4g", imageRedMean) + ", " + String.format("%.4g", imageGreenMean) + ", " + String.format("%.4g", imageBlueMean);
            canvas.drawText(imageMeanStr, marginWidth+10-1, 30-1, mPaintBlack);
            canvas.drawText(imageMeanStr, marginWidth+10+1, 30-1, mPaintBlack);
            canvas.drawText(imageMeanStr, marginWidth+10+1, 30+1, mPaintBlack);
            canvas.drawText(imageMeanStr, marginWidth+10-1, 30+1, mPaintBlack);
            canvas.drawText(imageMeanStr, marginWidth+10, 30, mPaintYellow);

            // Draw standard deviation
            String imageStdDevStr = "Std Dev (R,G,B): " + String.format("%.4g", imageRedStdDev) + ", " + String.format("%.4g", imageGreenStdDev) + ", " + String.format("%.4g", imageBlueStdDev);
            canvas.drawText(imageStdDevStr, marginWidth+10-1, 60-1, mPaintBlack);
            canvas.drawText(imageStdDevStr, marginWidth+10+1, 60-1, mPaintBlack);
            canvas.drawText(imageStdDevStr, marginWidth+10+1, 60+1, mPaintBlack);
            canvas.drawText(imageStdDevStr, marginWidth+10-1, 60+1, mPaintBlack);
            canvas.drawText(imageStdDevStr, marginWidth+10, 60, mPaintYellow);

            // Draw red intensity histogram
            float barMaxHeight = 3000;
            float barWidth = ((float)newImageWidth) / 256;
            float barMarginHeight = 2;
            RectF barRect = new RectF();
            barRect.bottom = canvasHeight - 200;
            barRect.left = marginWidth;
            barRect.right = barRect.left + barWidth;
            for (int bin = 0; bin < 256; bin++)
            {
                float prob = (float)mRedHistogram[bin] / (float)redHistogramSum;
                barRect.top = barRect.bottom - 
                    Math.min(80,prob*barMaxHeight) - barMarginHeight;
                canvas.drawRect(barRect, mPaintBlack);
                barRect.top += barMarginHeight;
                canvas.drawRect(barRect, mPaintRed);
                barRect.left += barWidth;
                barRect.right += barWidth;
            } // bin

            // Draw green intensity histogram
            barRect.bottom = canvasHeight - 100;
            barRect.left = marginWidth;
            barRect.right = barRect.left + barWidth;
            for (int bin = 0; bin < 256; bin++)
            {
                barRect.top = barRect.bottom - Math.min(80, ((float)mGreenHistogram[bin])/((float)greenHistogramSum) * barMaxHeight) - barMarginHeight;
                canvas.drawRect(barRect, mPaintBlack);
                barRect.top += barMarginHeight;
                canvas.drawRect(barRect, mPaintGreen);
                barRect.left += barWidth;
                barRect.right += barWidth;
            } // bin

            // Draw blue intensity histogram
            barRect.bottom = canvasHeight;
            barRect.left = marginWidth;
            barRect.right = barRect.left + barWidth;
            for (int bin = 0; bin < 256; bin++)
            {
                barRect.top = barRect.bottom - Math.min(80, ((float)mBlueHistogram[bin])/((float)blueHistogramSum) * barMaxHeight) - barMarginHeight;
                canvas.drawRect(barRect, mPaintBlack);
                barRect.top += barMarginHeight;
                canvas.drawRect(barRect, mPaintBlue);
                barRect.left += barWidth;
                barRect.right += barWidth;
            } // bin
        } // end if statement

        super.onDraw(canvas);

    } // end onDraw method

    static public void decodeYUV420SP(int[] rgb, byte[] yuv420sp, int width, int height) {
        final int frameSize = width * height;

        for (int j = 0, yp = 0; j < height; j++) {
            int uvp = frameSize + (j >> 1) * width, u = 0, v = 0;
            for (int i = 0; i < width; i++, yp++) {
                int y = (0xff & ((int) yuv420sp[yp])) - 16;
                if (y < 0) y = 0;
                if ((i & 1) == 0) {
                    v = (0xff & yuv420sp[uvp++]) - 128;
                    u = (0xff & yuv420sp[uvp++]) - 128;
                }

                int y1192 = 1192 * y;
                int r = (y1192 + 1634 * v);
                int g = (y1192 - 833 * v - 400 * u);
                int b = (y1192 + 2066 * u);

                if (r < 0) r = 0; else if (r > 262143) r = 262143;
                if (g < 0) g = 0; else if (g > 262143) g = 262143;
                if (b < 0) b = 0; else if (b > 262143) b = 262143;

                rgb[yp] = 0xff000000 | ((r << 6) & 0xff0000) | ((g >> 2) & 0xff00) | ((b >> 10) & 0xff);
            }
        }
    }

    static public void decodeYUV420SPGrayscale(int[] rgb, byte[] yuv420sp, int width, int height)
    {
        final int frameSize = width * height;

        for (int pix = 0; pix < frameSize; pix++)
        {
            int pixVal = (0xff & ((int) yuv420sp[pix])) - 16;
            if (pixVal < 0) pixVal = 0;
            if (pixVal > 255) pixVal = 255;
            rgb[pix] = 0xff000000 | (pixVal << 16) | (pixVal << 8) | pixVal;
        } // pix
    }

    static public void calculateIntensityHistogram(int[] rgb, int[] histogram, int width, int height, int component)
    {
        for (int bin = 0; bin < 256; bin++)
        {
            histogram[bin] = 0;
        } // bin
        if (component == 0) // red
        {
            for (int pix = 0; pix < width*height; pix += 3)
            {
                int pixVal = (rgb[pix] >> 16) & 0xff;
                histogram[ pixVal ]++;
            } // pix
        }
        else if (component == 1) // green
        {
            for (int pix = 0; pix < width*height; pix += 3)
            {
                int pixVal = (rgb[pix] >> 8) & 0xff;
                histogram[ pixVal ]++;
            } // pix
        }
        else // blue
        {
            for (int pix = 0; pix < width*height; pix += 3)
            {
                int pixVal = rgb[pix] & 0xff;
                histogram[ pixVal ]++;
            } // pix
        }
    }
} 

// ----------------------------------------------------------------------

class Preview extends SurfaceView implements SurfaceHolder.Callback {
    SurfaceHolder mHolder;
    Camera mCamera;
    DrawOnTop mDrawOnTop;
    boolean mFinished;

    Preview(Context context, DrawOnTop drawOnTop) {
        super(context);

        mDrawOnTop = drawOnTop;
        mFinished = false;

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

    public void surfaceCreated(SurfaceHolder holder) {
        mCamera = Camera.open();
        try {
           mCamera.setPreviewDisplay(holder);

           // Preview callback used whenever new viewfinder frame is available
           mCamera.setPreviewCallback(new PreviewCallback() {
              public void onPreviewFrame(byte[] data, Camera camera)
              {
                  if ( (mDrawOnTop == null) || mFinished )
                      return;

                  if (mDrawOnTop.mBitmap == null)
                  {
                      // Initialize the draw-on-top companion
                      Camera.Parameters params = camera.getParameters();
                      mDrawOnTop.mImageWidth = params.getPreviewSize().width;
                      mDrawOnTop.mImageHeight = params.getPreviewSize().height;
                      mDrawOnTop.mBitmap = Bitmap.createBitmap(mDrawOnTop.mImageWidth, 
                              mDrawOnTop.mImageHeight, Bitmap.Config.RGB_565);
                      mDrawOnTop.mRGBData = new int[mDrawOnTop.mImageWidth * mDrawOnTop.mImageHeight]; 
                      mDrawOnTop.mYUVData = new byte[data.length];                    
                  }

                  // Pass YUV data to draw-on-top companion
                  System.arraycopy(data, 0, mDrawOnTop.mYUVData, 0, data.length);
                  mDrawOnTop.invalidate();
              }
           });
        } 
        catch (IOException exception) {
            mCamera.release();
            mCamera = null;
        }
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // Surface will be destroyed when we return, so stop the preview.
        // Because the CameraDevice object is not a shared resource, it's very
        // important to release it when the activity is paused.
        mFinished = true;
        mCamera.setPreviewCallback(null);
        mCamera.stopPreview();
        mCamera.release();
        mCamera = null;
    }

    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(320, 240);
        parameters.setPreviewFrameRate(15);
        parameters.setSceneMode(Camera.Parameters.SCENE_MODE_NIGHT);
        parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);
        mCamera.setParameters(parameters);
        mCamera.startPreview();
    }

}

我尝试在模拟器和真实设备中运行该应用程序，并且错误是相同的。

谢谢！

编辑： LogCat

11-20 02:50:38.943: E/AndroidRuntime(614): FATAL EXCEPTION: main
11-20 02:50:38.943: E/AndroidRuntime(614): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.viewfinderee368/com.example.viewfinderee368.ViewfinderEE368}: android.util.AndroidRuntimeException: requestFeature() must be called before adding content
11-20 02:50:38.943: E/AndroidRuntime(614):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
11-20 02:50:38.943: E/AndroidRuntime(614):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
11-20 02:50:38.943: E/AndroidRuntime(614):  at android.app.ActivityThread.access$600(ActivityThread.java:130)
11-20 02:50:38.943: E/AndroidRuntime(614):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
11-20 02:50:38.943: E/AndroidRuntime(614):  at android.os.Handler.dispatchMessage(Handler.java:99)
11-20 02:50:38.943: E/AndroidRuntime(614):  at android.os.Looper.loop(Looper.java:137)
11-20 02:50:38.943: E/AndroidRuntime(614):  at android.app.ActivityThread.main(ActivityThread.java:4745)
11-20 02:50:38.943: E/AndroidRuntime(614):  at java.lang.reflect.Method.invokeNative(Native Method)
11-20 02:50:38.943: E/AndroidRuntime(614):  at java.lang.reflect.Method.invoke(Method.java:511)
11-20 02:50:38.943: E/AndroidRuntime(614):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
11-20 02:50:38.943: E/AndroidRuntime(614):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-20 02:50:38.943: E/AndroidRuntime(614):  at dalvik.system.NativeStart.main(Native Method)
11-20 02:50:38.943: E/AndroidRuntime(614): Caused by: android.util.AndroidRuntimeException: requestFeature() must be called before adding content
11-20 02:50:38.943: E/AndroidRuntime(614):  at com.android.internal.policy.impl.PhoneWindow.requestFeature(PhoneWindow.java:215)
11-20 02:50:38.943: E/AndroidRuntime(614):  at android.app.Activity.requestWindowFeature(Activity.java:3225)
11-20 02:50:38.943: E/AndroidRuntime(614):  at com.example.viewfinderee368.ViewfinderEE368.onCreate(ViewfinderEE368.java:52)
11-20 02:50:38.943: E/AndroidRuntime(614):  at android.app.Activity.performCreate(Activity.java:5008)
11-20 02:50:38.943: E/AndroidRuntime(614):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
11-20 02:50:38.943: E/AndroidRuntime(614):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
11-20 02:50:38.943: E/AndroidRuntime(614):  ... 11 more
4

3 回答 3

5

你需要在setContentView()旁边有一行super.onCreate(savedInstance)

  setContentView(R.layout.your_layout_filename);

在初始化任何 UI 组件之前总是调用setContentView()，否则你会得到问题。

于 2012-11-18T03:27:59.033 回答
1

看来您是 Android 新手。我强烈建议您通过

这个链接。它有大量的教程，肯定会有所帮助。

对于你遇到的问题，是因为Activity中没有指定布局。要了解 Activity 是什么，请浏览上面链接或 developer.android.com 上的 Android 教程

于 2012-11-18T04:59:53.730 回答
1

将您的 android 版本代码和版本名称更改为当前使用的版本代码和名称。

我一开始也遇到了同样的问题，但它已经解决了..

于 2013-01-22T05:19:57.637 回答