我正在尝试在我的自定义相机中实现放大和缩小功能。
NullPointerException: zoomControls.setVisibility(View.GONE);
我用这个：Zoom Control in Camera is not working in Android
PreviewSurface：爪哇：
public class PreviewSurface extends SurfaceView implements
SurfaceHolder.Callback {
public static final String LOG_TAG = "CameraPreview";
private SurfaceHolder mSurfaceHolder;
SurfaceView mSurfaceView;
private Camera mCamera;
Camera.Parameters params ;
int currentZoomLevel = 0, maxZoomLevel = 0;
// Constructor that obtains context and camera
@SuppressWarnings("deprecation")
public PreviewSurface(Context context, Camera camera) {
super(context);
this.mCamera = camera;
mSurfaceView = (SurfaceView) findViewById(R.id.surfaceView);
this.mSurfaceHolder = this.getHolder();
this.mSurfaceHolder.addCallback(this);
this.mSurfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
this.mSurfaceHolder.setFixedSize(100, 100);
}
@Override
public void surfaceCreated(SurfaceHolder surfaceHolder) {
try {
mCamera.setPreviewDisplay(surfaceHolder);
mCamera.startPreview();
} catch (IOException e) {
// left blank for now
}
}
@Override
public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
mCamera.stopPreview();
mCamera.release();
}
@Override
public void surfaceChanged(SurfaceHolder surfaceHolder, int format,
int width, int height) {
ZoomControls zoomControls = (ZoomControls) findViewById(R.id.CAMERA_ZOOM_CONTROLS);
params = mCamera.getParameters();
if (params.isZoomSupported() && params.isSmoothZoomSupported()) {
//most phones
maxZoomLevel = params.getMaxZoom();
zoomControls.setIsZoomInEnabled(true);
zoomControls.setIsZoomOutEnabled(true);
zoomControls.setOnZoomInClickListener(new OnClickListener() {
public void onClick(View v) {
if (currentZoomLevel < maxZoomLevel) {
currentZoomLevel++;
mCamera.startSmoothZoom(currentZoomLevel);
}
}
});
zoomControls.setOnZoomOutClickListener(new OnClickListener() {
public void onClick(View v) {
if (currentZoomLevel > 0) {
currentZoomLevel--;
mCamera.startSmoothZoom(currentZoomLevel);
}
}
});
} else if (params.isZoomSupported() && !params.isSmoothZoomSupported()){
//stupid HTC phones
maxZoomLevel = params.getMaxZoom();
zoomControls.setIsZoomInEnabled(true);
zoomControls.setIsZoomOutEnabled(true);
zoomControls.setOnZoomInClickListener(new OnClickListener() {
public void onClick(View v) {
if (currentZoomLevel < maxZoomLevel) {
currentZoomLevel++;
params.setZoom(currentZoomLevel);
mCamera.setParameters(params);
}
}
});
zoomControls.setOnZoomOutClickListener(new OnClickListener() {
public void onClick(View v) {
if (currentZoomLevel > 0) {
currentZoomLevel--;
params.setZoom(currentZoomLevel);
mCamera.setParameters(params);
}
}
});
}else{
//no zoom on phone
zoomControls.setVisibility(View.GONE);
}
// start preview with new settings
try {
mCamera.setDisplayOrientation(90);
mCamera.setPreviewDisplay(surfaceHolder);
mCamera.startPreview();
} catch (Exception e) {
// intentionally left blank for a test
}
}
}
活动摄像机.xml:-
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="horizontal" >
<FrameLayout
android:id="@+id/camera_preview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_toLeftOf="@+id/btnView" />
<SurfaceView
android:id="@+id/surfaceView"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
<ZoomControls
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/camera_preview"
android:layout_centerInParent="true"
android:id="@+id/CAMERA_ZOOM_CONTROLS" />
<TextView
android:id="@+id/title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_marginTop="18dp"
android:layout_toRightOf="@+id/camera_preview"
android:maxLines="1"
android:visibility="gone"
android:textAppearance="?android:attr/textAppearanceSmall" />
<Button
android:id="@+id/btnSettings"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/btnView"
android:layout_alignParentBottom="true"
android:layout_marginBottom="50dp"
android:background="@drawable/settings" />
<Button
android:id="@+id/btnView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:layout_alignParentTop="true"
android:layout_marginTop="50dp"
android:background="@drawable/gallery" />
<Button
android:id="@+id/btnCapture"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerVertical="true"
android:layout_toRightOf="@+id/camera_preview"
android:background="@drawable/capture" />
</RelativeLayout>
JavaLaununcActudia. Java:
public class CameraLauncherActivity extends Activity {
private Camera mCamera;
private PreviewSurface mCameraPreview;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_camera);
mCamera = getCameraInstance();
mCameraPreview = new PreviewSurface(this, mCamera);
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
preview.addView(mCameraPreview);
}
private Camera getCameraInstance() {
Camera camera = null;
Log.d(CameraLauncherActivity.LOG_TAG, "getCameraInstance()Camera:: " + camera);
try {
camera = Camera.open(0);
Log.d(CameraLauncherActivity.LOG_TAG, "getCameraInstance()open:: " + camera);
} catch (Exception e) {
// cannot get camera or does not exist
}
return camera;
}
PictureCallback mPicture = new PictureCallback() {
@Override
public void onPictureTaken(byte[] data, Camera camera) {
File pictureFile = getOutputMediaFile();
camera.startPreview();
if (pictureFile == null) {
return;
}
try {
FileOutputStream fos = new FileOutputStream(pictureFile);
fos.write(data);
fos.close();
} catch (FileNotFoundException e) {
} catch (IOException e) {
}
}
};
static File getOutputMediaFile() {
// folder name
mediaStorageDir = new File(Environment .getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), "/MyImages/");
if (!mediaStorageDir.exists()) {
if (!mediaStorageDir.mkdirs()) {
Log.d("App", "failed to create directory");
}
}
/* yyyy-MM-dd'T'HH:mm:ss.SSSZ */
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss").format(new Date());
File mediaFile;
// file name
mediaFile = new File(mediaStorageDir.getPath() + File.separator + "IMG_" + timeStamp + ".jpg");
return mediaFile;
}
Logcat：
11-28 01:52:43.179: E/AndroidRuntime(2135): FATAL EXCEPTION: main
11-28 01:52:43.179: E/AndroidRuntime(2135): java.lang.NullPointerException
11-28 01:52:43.179: E/AndroidRuntime(2135): at app.pd.PreviewSurface.surfaceChanged(PreviewSurface.java:113)
11-28 01:52:43.179: E/AndroidRuntime(2135): at android.view.SurfaceView.updateWindow(SurfaceView.java:582)
11-28 01:52:43.179: E/AndroidRuntime(2135): at android.view.SurfaceView.access$000(SurfaceView.java:86)
11-28 01:52:43.179: E/AndroidRuntime(2135): at android.view.SurfaceView$3.onPreDraw(SurfaceView.java:175)
11-28 01:52:43.179: E/AndroidRuntime(2135): at android.view.ViewTreeObserver.dispatchOnPreDraw(ViewTreeObserver.java:833)
11-28 01:52:43.179: E/AndroidRuntime(2135): at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1860)
11-28 01:52:43.179: E/AndroidRuntime(2135): at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1004)
11-28 01:52:43.179: E/AndroidRuntime(2135): at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5481)
11-28 01:52:43.179: E/AndroidRuntime(2135): at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
11-28 01:52:43.179: E/AndroidRuntime(2135): at android.view.Choreographer.doCallbacks(Choreographer.java:562)
11-28 01:52:43.179: E/AndroidRuntime(2135): at android.view.Choreographer.doFrame(Choreographer.java:532)
11-28 01:52:43.179: E/AndroidRuntime(2135): at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
11-28 01:52:43.179: E/AndroidRuntime(2135): at android.os.Handler.handleCallback(Handler.java:730)
11-28 01:52:43.179: E/AndroidRuntime(2135): at android.os.Handler.dispatchMessage(Handler.java:92)
11-28 01:52:43.179: E/AndroidRuntime(2135): at android.os.Looper.loop(Looper.java:137)
11-28 01:52:43.179: E/AndroidRuntime(2135): at android.app.ActivityThread.main(ActivityThread.java:5103)
11-28 01:52:43.179: E/AndroidRuntime(2135): at java.lang.reflect.Method.invokeNative(Native Method)
11-28 01:52:43.179: E/AndroidRuntime(2135): at java.lang.reflect.Method.invoke(Method.java:525)
11-28 01:52:43.179: E/AndroidRuntime(2135): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
11-28 01:52:43.179: E/AndroidRuntime(2135): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-28 01:52:43.179: E/AndroidRuntime(2135): at dalvik.system.NativeStart.main(Native Method)
最佳答案
在代码中，params从未初始化，因此其值始终为空。如果尝试对空对象使用方法，则会导致NullPointerException。也许在构造函数中，您应该使用以下命令初始化它：
params = mCamera.getParameters();