我正在制作一个虚拟现实应用程序,相机应该检测到面部,找到它们并在相机预览中显示它们的位置。
我知道有3种方法可以做到这一点,我想尽可能快地使用GLSurfaceView(according to this post),但目前我正在尝试使用相同的 SurfaceView用于预览的相机。我的回调就是onFaceDetection
就像这样:
public class MyActivity extends Activity implements SurfaceHolder.Callback, Camera.FaceDetectionListener {
Camera camera;
SurfaceView svPreview;
SurfaceHolder previewHolder;
TextView tvInfo;
Paint red;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
svPreview = (SurfaceView) findViewById(R.id.svPreview);
tvInfo = (TextView) findViewById(R.id.tvInfo);
red = new Paint();
red.setStyle(Paint.Style.STROKE);
red.setStrokeWidth(3);
previewHolder = svPreview.getHolder();
previewHolder.addCallback(this);
previewHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
}
public void surfaceCreated(SurfaceHolder arg0) {
camera = Camera.open();
try {
camera.setDisplayOrientation(90);
camera.setFaceDetectionListener(this);
camera.setPreviewDisplay(previewHolder);
}
catch (IOException e) {
e.printStackTrace();
}
}
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
// . . .
camera.startPreview();
camera.autoFocus(null);
camera.startFaceDetection();
}
public void surfaceDestroyed(SurfaceHolder arg0) {
camera.stopFaceDetection();
camera.cancelAutoFocus();
camera.stopPreview();
camera.release();
camera = null;
}
public void onFaceDetection(Face[] faces, Camera camera) {
tvInfo.setText("Faces: " + String.valueOf(faces.length));
Canvas canvas = previewHolder.lockCanvas();
for(int i=0; i < faces.length; i++) {
Point leftEye = faces[i].leftEye;
Point rightEye = faces[i].rightEye;
// this is not working
canvas.drawPoint(leftEye.x, leftEye.y, red);
}
previewHolder.unlockCanvasAndPost(canvas);
}
}
使用此代码,我不断收到此错误:
09-03 19:35:42.743: E/SurfaceHolder(19394): Exception locking surface
09-03 19:35:42.743: E/SurfaceHolder(19394): java.lang.IllegalArgumentException
09-03 19:35:42.743: E/SurfaceHolder(19394): at android.view.Surface.lockCanvasNative(Native Method)
09-03 19:35:42.743: E/SurfaceHolder(19394): at android.view.Surface.lockCanvas(Surface.java:76)
09-03 19:35:42.743: E/SurfaceHolder(19394): at android.view.SurfaceView$4.internalLockCanvas(SurfaceView.java:744)
09-03 19:35:42.743: E/SurfaceHolder(19394): at android.view.SurfaceView$4.lockCanvas(SurfaceView.java:720)
09-03 19:35:42.743: E/SurfaceHolder(19394): at com.bluetooth.activities.MyActivity.onFaceDetection(MyActivity.java:90)
09-03 19:35:42.743: E/SurfaceHolder(19394): at android.hardware.Camera$EventHandler.handleMessage(Camera.java:729)
09-03 19:35:42.743: E/SurfaceHolder(19394): at android.os.Handler.dispatchMessage(Handler.java:99)
09-03 19:35:42.743: E/SurfaceHolder(19394): at android.os.Looper.loop(Looper.java:137)
09-03 19:35:42.743: E/SurfaceHolder(19394): at android.app.ActivityThread.main(ActivityThread.java:4424)
09-03 19:35:42.743: E/SurfaceHolder(19394): at java.lang.reflect.Method.invokeNative(Native Method)
09-03 19:35:42.743: E/SurfaceHolder(19394): at java.lang.reflect.Method.invoke(Method.java:511)
09-03 19:35:42.743: E/SurfaceHolder(19394): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
09-03 19:35:42.743: E/SurfaceHolder(19394): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
09-03 19:35:42.743: E/SurfaceHolder(19394): at dalvik.system.NativeStart.main(Native Method)
09-03 19:35:42.743: W/dalvikvm(19394): threadid=1: thread exiting with uncaught exception (group=0x40a561f8)
09-03 19:35:42.766: E/AndroidRuntime(19394): FATAL EXCEPTION: main
09-03 19:35:42.766: E/AndroidRuntime(19394): java.lang.IllegalArgumentException
09-03 19:35:42.766: E/AndroidRuntime(19394): at android.view.Surface.unlockCanvasAndPost(Native Method)
09-03 19:35:42.766: E/AndroidRuntime(19394): at android.view.SurfaceView$4.unlockCanvasAndPost(SurfaceView.java:775)
09-03 19:35:42.766: E/AndroidRuntime(19394): at com.bluetooth.activities.MyActivity.onFaceDetection(MyActivity.java:99)
09-03 19:35:42.766: E/AndroidRuntime(19394): at android.hardware.Camera$EventHandler.handleMessage(Camera.java:729)
09-03 19:35:42.766: E/AndroidRuntime(19394): at android.os.Handler.dispatchMessage(Handler.java:99)
09-03 19:35:42.766: E/AndroidRuntime(19394): at android.os.Looper.loop(Looper.java:137)
09-03 19:35:42.766: E/AndroidRuntime(19394): at android.app.ActivityThread.main(ActivityThread.java:4424)
09-03 19:35:42.766: E/AndroidRuntime(19394): at java.lang.reflect.Method.invokeNative(Native Method)
09-03 19:35:42.766: E/AndroidRuntime(19394): at java.lang.reflect.Method.invoke(Method.java:511)
09-03 19:35:42.766: E/AndroidRuntime(19394): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
09-03 19:35:42.766: E/AndroidRuntime(19394): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
09-03 19:35:42.766: E/AndroidRuntime(19394): at dalvik.system.NativeStart.main(Native Method)
相机试图在同一SurfaceView上绘制预览面部检测回调是否有问题?如何在不分层SurfaceViews的情况下完成此操作?
答案 0 :(得分:7)
你无法锁定和绘制SurfaceView
Type.PUSH_BUFFERS
,SurfaceView
(你要显示帧的那个)。您必须在Z方向上创建原始视图上方的另一个视图,并在View
中的main.xml
上绘制。
因此,在FrameLayout
SurfaceView
中,在原始视图下方创建自定义视图。
在您的活动视图中创建并处理SurfaceHolder
。将此视图添加到“相机”预览显示中。通过{{1}}开始自定义视图。在此视图中,您可以在画布上锁定和绘制。
答案 1 :(得分:6)
正如詹姆斯指出你需要创建扩展SurfaceView的自定义表面(我通常也实现SurfaceHolder.Callback):
public class CameraSurfacePreview extends SurfaceView implements SurfaceHolder.Callback
构造函数将类似于:
public CameraSurfacePreview(Context context) {
super(context);
...
mHolder = getHolder();
mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
...
你需要在相机打开调用后将相机与你的表面绑定(如果你实现了SurfaceHolder.Callback实现,将它放在重写的surfaceCreated中):
mCamera = Camera.open();
mCamera.setPreviewDisplay(mHolder);
最后,您需要在活动内容视图中添加自定义曲面的实例:
CameraSurfacePreview cameraSurfacePreview = new CameraSurfacePreview(this);
//camera surface preview is first child!
((ViewGroup)findViewById(R.id.cameraLayout)).addView(cameraSurfacePreview, 0);
在我的示例中,活动的布局看起来像(我在主框架布局中显示相机预览):
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_gravity="top|left"
android:id="@+id/cameraLayout">
答案 2 :(得分:0)
使用openGL时,lockcanvas / unlockcanvas和post方法不合适,因为openGL代码正在控制和锁定曲面。如果要使用标准的2d API,请不要使用OpenGL。
答案 3 :(得分:-1)
我可以说,
这不是关于线程的。
这不是因为这条线也造成错误。
canvas.drawPoint(leftEye.x, leftEye.y, red);
因为画布仍在使用而无法锁定它
如果仔细检查,你会看到你得到的这个画布是== null
canvas = canvasHolder.lockCanvas();
if (canvas == null) Log.i("Error", "Canvas == null!");
您可能有疑问,它已经在哪里使用?
它已用于显示以显示正在发生的事情!那是
camera.setPreviewDisplay(previewHolder);
所以,我建议,如果你想在你的眼睛上绘制Point,你可能需要在SurfaceView上有另一个SurfaceView / SurfaceHolder用于预览相机:]