我找到了一些使用相机的教程。模拟器上没有错误，但它在设备上崩溃了，为什么？我只是创建简单的代码来预览图片。
我正在测试的设备是HTC Wildfire Android 2.2
Mainclass
private Camera camera;
private boolean isPreviewRunning = false;
private SimpleDateFormat timeStampFormat = new SimpleDateFormat("yyyyMMddHHmmssSS");
private SurfaceView surfaceView;
private SurfaceHolder surfaceHolder;
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
protected void onRestoreInstanceState(Bundle savedInstanceState)
{
super.onRestoreInstanceState(savedInstanceState);
}
Camera.PictureCallback mPictureCallbackRaw = new Camera.PictureCallback()
{
public void onPictureTaken(byte[] data, Camera c)
{
Log.e(getClass().getSimpleName(), "PICTURE CALLBACK RAW: " + data);
camera.startPreview();
}
};
Camera.PictureCallback mPictureCallbackJpeg= new Camera.PictureCallback()
{
public void onPictureTaken(byte[] data, Camera c)
{
Log.e(getClass().getSimpleName(), "PICTURE CALLBACK JPEG: data.length = " + data);
}
};
Camera.ShutterCallback mShutterCallback = new Camera.ShutterCallback()
{
public void onShutter()
{
Log.e(getClass().getSimpleName(), "SHUTTER CALLBACK");
}
};
public boolean onKeyDown(int keyCode, KeyEvent event)
{
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;
}
protected void onResume()
{
Log.e(getClass().getSimpleName(), "onResume");
super.onResume();
}
protected void onSaveInstanceState(Bundle outState)
{
super.onSaveInstanceState(outState);
}
protected void onStop()
{
Log.e(getClass().getSimpleName(), "onStop");
super.onStop();
}
public void surfaceCreated(SurfaceHolder holder)
{
Log.e(getClass().getSimpleName(), "surfaceCreated");
camera = Camera.open();
}
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;
}
public void surfaceDestroyed(SurfaceHolder holder)
{
Log.e(getClass().getSimpleName(), "surfaceDestroyed");
camera.stopPreview();
isPreviewRunning = false;
camera.release();
}
}
ImageCaptureCallBack
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();
}
}
}
和清单
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.photo.test"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk android:minSdkVersion="8" />
<uses-feature android:name="android.hardware.camera" />
<uses-feature android:name="android.hardware.camera.autofocus" />
<uses-permission android:name="android.permission.CAMERA" />
<uses-permission android:name="android.permission.RECORD_AUDIO" />
<application
android:icon="@drawable/ic_launcher"
android:label="@string/app_name" >
<activity
android:label="@string/app_name"
android:name=".Main" >
<intent-filter >
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
答案 0 :(得分：5)
相机预览在不同设备上的工作方式非常不同。我们在mixare增强现实引擎中遇到了很多问题。
首先，最好使用兼容性类让代码在旧设备上运行。你可以在这里看到代码：
https://github.com/mixare/mixare/blob/master/src/org/mixare/Compatibility.java
然后，正如您在此处所见，您有责任在系统提供的预览列表中选择正确的一个： https://github.com/mixare/mixare/blob/master/src/org/mixare/MixView.java在第871行和正在进行中。
List<Camera.Size> supportedSizes = null;
//On older devices (<1.6) the following will fail
//the camera will work nevertheless
supportedSizes = Compatibility.getSupportedPreviewSizes(parameters);
//preview form factor
float ff = (float)w/h;
Log.d("Mixare", "Screen res: w:"+ w + " h:" + h + " aspect ratio:" + ff);
//holder for the best form factor and size
float bff = 0;
int bestw = 0;
int besth = 0;
Iterator<Camera.Size> itr = supportedSizes.iterator();
//we look for the best preview size, it has to be the closest to the
//screen form factor, and be less wide than the screen itself
//the latter requirement is because the HTC Hero with update 2.1 will
//report camera preview sizes larger than the screen, and it will fail
//to initialize the camera
//other devices could work with previews larger than the screen though
while(itr.hasNext()) {
Camera.Size element = itr.next();
//current form factor
float cff = (float)element.width/element.height;
//check if the current element is a candidate to replace the best match so far
//current form factor should be closer to the bff
//preview width should be less than screen width
//preview width should be more than current bestw
//this combination will ensure that the highest resolution will win
Log.d("Mixare", "Candidate camera element: w:"+ element.width + " h:" + element.height + " aspect ratio:" + cff);
if ((ff-cff <= ff-bff) && (element.width <= w) && (element.width >= bestw)) {
bff=cff;
bestw = element.width;
besth = element.height;
}
}
Log.d("Mixare", "Chosen camera element: w:"+ bestw + " h:" + besth + " aspect ratio:" + bff);
//Some Samsung phones will end up with bestw and besth = 0 because their minimum preview size is bigger then the screen size.
//In this case, we use the default values: 480x320
if ((bestw == 0) || (besth == 0)){
Log.d("Mixare", "Using default camera parameters!");
bestw = 480;
besth = 320;
}
parameters.setPreviewSize(bestw, besth);
HTH 丹尼尔