相机焦距

Question

我正在尝试从 Android 相机读取焦距（照片中拍摄对象的距离）。即使 HTC Desire 正确自动对焦，我的所有焦距始终为 0。这是整个应用程序，仅适用于 v2.3.3 及更高版本。

ImageCapture.java

package test.test;

import java.io.IOException;
import java.io.OutputStream;
import java.text.SimpleDateFormat;

import android.app.Activity;
import android.content.Intent;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.hardware.Camera.AutoFocusCallback;
import android.hardware.Camera.PictureCallback;
import android.net.Uri;
import android.os.Bundle;
import android.provider.MediaStore.Images.Media;
import android.util.Log;
import android.view.KeyEvent;
import android.view.MenuItem;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

//THIS CLASS READS THE FOCUS DISTANCES
class ImageFocusCallback implements AutoFocusCallback {
    @Override
    public void onAutoFocus(boolean success, Camera camera) {
        //READ FOCUS DISTANCES HERE
        Camera.Parameters parameters = camera.getParameters();
        float[] distances = new float[3];
        if (success) {
            // Only available with Android 9 (2.3)
            // Focus Mode is always reported as auto but
            // distances do not appear to be updating
            // always: 0.1, 1.2, Infinity, (on my device it's 0,0,0)
            Log.d("Focus Mode: ", parameters.getFocusMode());
            parameters.getFocusDistances(distances);
            Log.d("focus distance near", Float.toString(distances[0]));
            Log.d("focus distance optimum", Float.toString(distances[1]));
            Log.d("focus distance far", Float.toString(distances[2]));
        }
    }
}

public class ImageCapture extends Activity implements SurfaceHolder.Callback {
    //CALL AUTO FOCUS HERE
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER) {
            ImageFocusCallback autoFocusCallBack = new ImageFocusCallback();
            //AUTOFOCUS IS CALLED HERE
            camera.autoFocus(autoFocusCallBack);
            return true;
        }
        return false;
    }

    //REST OF THE CODE
    private Camera           camera;
    private boolean          isPreviewRunning = false;
    private SimpleDateFormat timeStampFormat  = new SimpleDateFormat("yyyyMMddHHmmssSS");

    private SurfaceView      surfaceView;
    private SurfaceHolder    surfaceHolder;
    private Uri              target           = Media.EXTERNAL_CONTENT_URI;


    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        Log.e(getClass().getSimpleName(), "onCreate");
        getWindow().setFormat(PixelFormat.TRANSLUCENT);
        setContentView(R.layout.main);
        surfaceView = (SurfaceView) findViewById(R.id.surface);
        surfaceHolder = surfaceView.getHolder();
        surfaceHolder.addCallback(this);
        surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

    }

    @Override
    public boolean onCreateOptionsMenu(android.view.Menu menu) {
        MenuItem item = menu.add(0, 0, 0, "goto gallery");
        item.setOnMenuItemClickListener(new MenuItem.OnMenuItemClickListener() {
            @Override
            public boolean onMenuItemClick(MenuItem item) {
                Intent intent = new Intent(Intent.ACTION_VIEW, target);
                startActivity(intent);
                return true;
            }
        });
        return true;
    }

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

    Camera.PictureCallback mPictureCallbackRaw  = new Camera.PictureCallback() {
                                                    @Override
                                                    public void onPictureTaken(byte[] data, Camera c) {
                                                        Log.e(getClass().getSimpleName(), "PICTURE CALLBACK RAW: " + data);
                                                        camera.startPreview();
                                                    }
                                                };

    Camera.PictureCallback mPictureCallbackJpeg = new Camera.PictureCallback() {
                                                    @Override
                                                    public void onPictureTaken(byte[] data, Camera c) {
                                                        Log.e(getClass().getSimpleName(), "PICTURE CALLBACK JPEG: data.length = " + data);
                                                    }
                                                };

    Camera.ShutterCallback mShutterCallback     = new Camera.ShutterCallback() {
                                                    @Override
                                                    public void onShutter() {
                                                        Log.e(getClass().getSimpleName(), "SHUTTER CALLBACK");
                                                    }
                                                };




    // ImageCaptureCallback iccb = null;
    // if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER) {
    // try {
    // String filename = timeStampFormat.format(new Date());
    // ContentValues values = new ContentValues();
    // values.put(Media.TITLE, filename);
    // values.put(Media.DESCRIPTION, "Image capture by camera");
    // Uri uri = getContentResolver().insert(Media.EXTERNAL_CONTENT_URI,
    // values);
    // // String filename = timeStampFormat.format(new Date());
    // iccb = new
    // ImageCaptureCallback(getContentResolver().openOutputStream(uri));
    // } catch (Exception ex) {
    // ex.printStackTrace();
    // Log.e(getClass().getSimpleName(), ex.getMessage(), ex);
    // }
    // }
    // if (keyCode == KeyEvent.KEYCODE_BACK) {
    // return super.onKeyDown(keyCode, event);
    // }
    //
    // if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER) {
    // camera.takePicture(mShutterCallback, mPictureCallbackRaw, iccb);
    // return true;
    // }
    //
    // return false;
    // }

    @Override
    protected void onResume() {
        Log.e(getClass().getSimpleName(), "onResume");
        super.onResume();
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
    }

    @Override
    protected void onStop() {
        Log.e(getClass().getSimpleName(), "onStop");
        super.onStop();
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        Log.e(getClass().getSimpleName(), "surfaceCreated");
        camera = Camera.open();
        Camera.Parameters parameters = camera.getParameters();
        float[] distances = new float[3];
        Log.d("Focus Mode: ", parameters.getFocusMode());
        parameters.getFocusDistances(distances);
        Log.d("focus distance 0", Float.toString(distances[0]));
        Log.d("focus distance 1", Float.toString(distances[1]));
        Log.d("focus distance 2", Float.toString(distances[2]));
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        Log.e(getClass().getSimpleName(), "surfaceChanged");
        if (isPreviewRunning) {
            camera.stopPreview();
        }
        Camera.Parameters p = camera.getParameters();
        p.setPreviewSize(w, h);
        camera.setParameters(p);
        try {
            camera.setPreviewDisplay(holder);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        camera.startPreview();
        isPreviewRunning = true;
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        Log.e(getClass().getSimpleName(), "surfaceDestroyed");
        camera.stopPreview();
        isPreviewRunning = false;
        camera.release();
    }

}



class ImageCaptureCallback implements PictureCallback {

    private OutputStream filoutputStream;

    public ImageCaptureCallback(OutputStream filoutputStream) {
        this.filoutputStream = filoutputStream;
    }

    @Override
    public void onPictureTaken(byte[] data, Camera camera) {
        try {
            Log.v(getClass().getSimpleName(), "onPictureTaken=" + data + " length = " + data.length);
            filoutputStream.write(data);
            filoutputStream.flush();
            filoutputStream.close();
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }

}
}

main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent" 
    android:orientation="vertical">
    <SurfaceView android:id="@+id/surface" 
    android:layout_width="fill_parent"
        android:layout_height="10dip" 
        android:layout_weight="1">
    </SurfaceView>
</LinearLayout>  

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="test.test"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="10" />
    <uses-permission android:name="android.permission.CAMERA" />
    <uses-feature android:name="android.hardware.camera" />
 <uses-feature android:name="android.hardware.camera.autofocus" />

    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".ImageCapture"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>

    </application>
</manifest>

难道是设备驱动程序有bug？在Android源Camera.java中调用native_autoFocus()和native_getParameters()来读取距离。有谁知道哪里可以获取本机调用的源代码？

Answer 1

在 Froyo 中，frameworks/base/core/jni/android_hardware_Camera.cpp 通过调用 android_hardware_Camera_autoFocus() 来实现 native_autoFocus()，这似乎在运行时绑定到设备/供应商特定的代码。

不幸的是，“如果相机不支持自动对焦并且调用了 autoFocus，则将立即调用 onAutoFocus，并将成功的假值设置为 true。”是记录的行为。

我很好奇您使用的哪些功能需要 2.3.3、API 级别 10。

Answer 2

可能是相机驱动程序中的一个错误，只有再次设置手机才能修复此问题，是的，我知道这真的很糟糕，但我也遇到了完全相同的问题。

但我选择为我的设备使用自定义 ROM。 Atm 我使用 Android Revolution HD 6.1.1
http://forum.xda-developers.com/showthread.php?t=840040

对于你的第二个问题，你可以从你下载的ROM包中取出相机应用程序的源文件。也许如果你改变它，它就会起作用。

此致

Answer 3

我不知道你可以在哪里获得本机调用的来源。但是如果 getFocusDistances(float[]) 方法中的所有焦距都为 0，您可以阅读 此问题。在那里你可以看到这个错误不是设备的错误而是Android SDK的错误。

Answer 4

这是错误 14341 - “无论实际焦距如何，Camera.Parameters.getFocusDistances() 返回的距离在 Nexus S 上都不会改变”。

首次报告于 2011 年 1 月 26 日，最后一次报告于 2014 年 3 月 18 日。因此，该 Bug 是在您遇到该错误之前不久报告的，并且至今尚未修复。这是专门针对您的设备进行报告的。

报告中的各种评论声称此错误影响“Nexus S”、“HTC Sensation”、“Galaxy S Plus”、“Galaxy S II”、“HTC Desire HD”、“Galaxy Nexus”、 “Xperia Mini ST15i”、“Nexus 5”、“Galaxy R”和“Galaxy Note II”；有一条评论声称它在“Galaxy Nexus”上完美运行。

参考：https://code.google.com/p/android/issues /detail?id=14341 。

这是您正在寻找的源代码吗： https://android.googlesource.com/platform/frameworks/base/+/froyo-release/core/jni/android_hardware_Camera.cpp