尽管设置了预览大小，setParameters（）仍会失败

Question

我正在制作一个简单的演示，我可以在我的活动中将相机预览提供给SurfaceView。我发现如果你没有设置支持的大小，setParameters（）会失败。但即使我这样做，我也得到同样的致命异常。请帮忙！

码：

package ank.altcamera;

import java.io.IOException;
import java.util.List;

import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.ImageView;
import android.widget.SeekBar;
import android.widget.Switch;
import android.widget.Toast;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.ImageFormat;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.hardware.Camera.Size;

public class CameraActivity extends Activity implements SurfaceHolder.Callback{

    Switch sw_flash;
    SeekBar sb_zoom;

    Camera cam;
    SurfaceView surf_view;
    SurfaceHolder surf_holder;
    boolean preview;

    final int TAKE_PICTURE = 100;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_camera);

        sw_flash = (Switch) findViewById(R.id.sw_flash);
        sb_zoom = (SeekBar) findViewById(R.id.seekBar1);

        //camera settings
        surf_view = (SurfaceView) findViewById(R.id.surfaceView);
        surf_holder = surf_view.getHolder();
        surf_holder.addCallback(CameraActivity.this);
    }

    /* Must implement Interface methods */

    //onClickListener for the button
    public void takePicture (View v) {

    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width,
            int height) {
        // TODO Auto-generated method stub
        if (preview) {
            cam.stopPreview();
        }

        Camera.Parameters p = cam.getParameters();

        //check for supported sizes to avoid exceptions
        Size size = getBestPreviewSize(width, height, p);
        p.setPreviewSize(size.width, size.height);
        //move ahead
        p.setPreviewFormat(ImageFormat.JPEG);
        cam.setParameters(p);

        //start the preview
        try {
            cam.setPreviewDisplay(surf_holder);
            cam.startPreview();
            preview = true;
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        // TODO Auto-generated method stub

        cam = Camera.open();

        if (cam != null){
            Camera.Parameters params = cam.getParameters();
            cam.setParameters(params);
        }
        else {
            Toast.makeText(getApplicationContext(), "Camera error.", Toast.LENGTH_LONG).show();
            finish();
        }
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        // TODO Auto-generated method stub
        cam.stopPreview();
        preview = false;
        cam.release();

    }

    private Camera.Size getBestPreviewSize(int width, int height, Camera.Parameters parameters){
         Size bestSize = null;
         List<Camera.Size> sizeList = parameters.getSupportedPreviewSizes();

         bestSize = sizeList.get(0);

         for(int i = 1; i < sizeList.size(); i++){
          if((sizeList.get(i).width * sizeList.get(i).height) >
            (bestSize.width * bestSize.height)){
           bestSize = sizeList.get(i);
          }
         }

         return bestSize;
        }
}

这是我的布局XML文件：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/LinearLayout1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/background_main"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".CameraActivity" >

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_marginBottom="18dp"
        android:minWidth="100dp"
        android:text="Awesome Camera"
        android:textColor="#fff"
        android:textSize="25sp"
        android:textStyle="bold" />

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

        <TextView
            android:id="@+id/textView1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginRight="10dp"
            android:layout_marginTop="5dp"
            android:text="Zoom"
            android:textColor="#fff"
            android:textStyle="bold" />

        <SeekBar
            android:id="@+id/seekBar1"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:layout_marginLeft="5dp" />
    </LinearLayout>

    <Switch
        android:id="@+id/sw_flash"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Flash"
        android:textColor="#fff"
        android:textStyle="bold" />

    <SurfaceView
        android:id="@+id/surfaceView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" 
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="20dp"
        />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="20dp"
        android:background="#fff"
        android:onClick="takePicture"
        android:paddingLeft="10dp"
        android:paddingRight="10dp"
        android:text="Take Picture" />

</LinearLayout>

最后，logcat输出：

06-22 10:26:50.421: D/TextLayoutCache(12360): Using debug level: 0 - Debug Enabled: 0
06-22 10:26:50.511: D/libEGL(12360): loaded /system/lib/egl/libGLES_android.so
06-22 10:26:50.561: D/libEGL(12360): loaded /system/lib/egl/libEGL_adreno200.so
06-22 10:26:50.601: D/libEGL(12360): loaded /system/lib/egl/libGLESv1_CM_adreno200.so
06-22 10:26:50.601: D/libEGL(12360): loaded /system/lib/egl/libGLESv2_adreno200.so
06-22 10:26:50.701: I/Adreno200-EGLSUB(12360): <ConfigWindowMatch:2218>: Format RGBA_8888.
06-22 10:26:50.711: D/memalloc(12360): /dev/pmem: Mapped buffer base:0x516f6000 size:5775360 offset:4239360 fd:58
06-22 10:26:50.711: D/OpenGLRenderer(12360): Enabling debug mode 0
06-22 10:26:51.491: D/AndroidRuntime(12360): Shutting down VM
06-22 10:26:51.491: W/dalvikvm(12360): threadid=1: thread exiting with uncaught exception (group=0x40c28a68)
06-22 10:26:51.501: E/AndroidRuntime(12360): FATAL EXCEPTION: main
06-22 10:26:51.501: E/AndroidRuntime(12360): java.lang.RuntimeException: setParameters failed
06-22 10:26:51.501: E/AndroidRuntime(12360):    at android.hardware.Camera.native_setParameters(Native Method)
06-22 10:26:51.501: E/AndroidRuntime(12360):    at android.hardware.Camera.setParameters(Camera.java:1476)
06-22 10:26:51.501: E/AndroidRuntime(12360):    at ank.altcamera.CameraActivity.surfaceChanged(CameraActivity.java:71)
06-22 10:26:51.501: E/AndroidRuntime(12360):    at android.view.SurfaceView.updateWindow(SurfaceView.java:591)
06-22 10:26:51.501: E/AndroidRuntime(12360):    at android.view.SurfaceView.access$000(SurfaceView.java:81)
06-22 10:26:51.501: E/AndroidRuntime(12360):    at android.view.SurfaceView$3.onPreDraw(SurfaceView.java:173)
06-22 10:26:51.501: E/AndroidRuntime(12360):    at android.view.ViewTreeObserver.dispatchOnPreDraw(ViewTreeObserver.java:590)
06-22 10:26:51.501: E/AndroidRuntime(12360):    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1799)
06-22 10:26:51.501: E/AndroidRuntime(12360):    at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2632)
06-22 10:26:51.501: E/AndroidRuntime(12360):    at android.os.Handler.dispatchMessage(Handler.java:99)
06-22 10:26:51.501: E/AndroidRuntime(12360):    at android.os.Looper.loop(Looper.java:137)
06-22 10:26:51.501: E/AndroidRuntime(12360):    at android.app.ActivityThread.main(ActivityThread.java:4517)
06-22 10:26:51.501: E/AndroidRuntime(12360):    at java.lang.reflect.Method.invokeNative(Native Method)
06-22 10:26:51.501: E/AndroidRuntime(12360):    at java.lang.reflect.Method.invoke(Method.java:511)
06-22 10:26:51.501: E/AndroidRuntime(12360):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:993)
06-22 10:26:51.501: E/AndroidRuntime(12360):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:760)
06-22 10:26:51.501: E/AndroidRuntime(12360):    at dalvik.system.NativeStart.main(Native Method)
06-22 10:27:00.301: I/Process(12360): Sending signal. PID: 12360 SIG: 9

请帮帮我！

Answer 1

documentation声称，当任何参数无效或不受支持时，setParameters会抛出RuntimeException。

您要更改的参数是大小和格式;但是，你从getSupportedPreviewSizes获取尺寸，所以它们一定不是问题。我猜问题是setPreviewFormat(ImageFormat.JPEG)。

Answer 2

确保检查相机要求设置的所有参数以确保您要求相机设置的每个参数都可用于相机，这一点非常重要。

Camera.Parameters parameters = myCamera.getParameters();

预览尺寸：

if (myCamera.getParameters().getSupportedPreviewSizes() != null){
     Camera.Size previewSize = getOptimalPreviewSize(myCamera.getParameters().getSupportedPreviewSizes(), width, height);;
     parameters.setPreviewSize(previewSize.width, previewSize.height);
}

使用闪光/对焦模式：

if(parameters.getSupportedFocusModes() != null && parameters.getSupportedFocusModes().contains(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE)){
     parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_PICTURE);
}

if (parameters.getSupportedFlashModes() != null && parameters.getSupportedFlashModes().contains(Camera.Parameters.FLASH_MODE_AUTO)){
    parameters.setFlashMode(Camera.Parameters.FLASH_MODE_AUTO);

}

myCamera.setParameters(parameters);

所有这些都包含在一个很好的try {} catch（）{}中。祝好运。

这是来自this great tutorial的getOptimalPreview大小：

private Camera.Size getOptimalPreviewSize(List<Camera.Size> sizes, int width, int height)
    {
        // Source: http://stackoverflow.com/questions/7942378/android-camera-will-not-work-startpreview-fails
        Camera.Size optimalSize = null;

        final double ASPECT_TOLERANCE = 0.1;
        double targetRatio = (double) height / width;

        // Try to find a size match which suits the whole screen minus the menu on the left.
        for (Camera.Size size : sizes){

            if (size.height != width) continue;
            double ratio = (double) size.width / size.height;
            if (ratio <= targetRatio + ASPECT_TOLERANCE && ratio >= targetRatio - ASPECT_TOLERANCE){
                optimalSize = size;
            }
        }

        // If we cannot find the one that matches the aspect ratio, ignore the requirement.
        if (optimalSize == null) {
            // TODO : Backup in case we don't get a size.
        }

        return optimalSize;
    }

Answer 3

您无法从它显示的消息文本中分辨出哪个参数导致运行时异常。你最好逐个检查参数。