Java 正在获取实时摄影机的RGB值,错误NullPointerException
[更新]:已添加屏幕截图 我在学习《基础教程》Java 正在获取实时摄影机的RGB值,错误NullPointerException,java,android,opencv,opencv4android,Java,Android,Opencv,Opencv4android,[更新]:已添加屏幕截图 我在学习《基础教程》tutorial-1-camerapreviewfrom。 我想在屏幕上点击并获得该xy位置的RGB颜色。 我得到了以下方面的帮助(从相机预览中的触摸事件中检索精确的RGB值): 获取x-y坐标: @SuppressWarnings("deprecation") @Override public boolean onTouchEvent(MotionEvent event) { x = (int)event.getX(
tutorial-1-camerapreview
from。
我想在屏幕上点击并获得该x
y
位置的RGB颜色。
我得到了以下方面的帮助(从相机预览中的触摸事件中检索精确的RGB值):
获取x-y坐标:
@SuppressWarnings("deprecation")
@Override
public boolean onTouchEvent(MotionEvent event) {
x = (int)event.getX();
y = (int)event.getY();
return super.onTouchEvent(event);
}
onCameraFrame作为:
public Mat onCameraFrame(CvCameraViewFrame inputFrame) {
mRgba = inputFrame.rgba();
if(x != -1 && y != -1) { //if this is true, you've touched something
rgb = mRgba.get(x,y);
Log.d(TAG, "Touch coordinates--> " + "x: " + String.valueOf(x)
+ " y: " + String.valueOf(y) + " \n"
+ "RGB values--> "
+ " Red: " + rgb[0]
+ " Green: " + rgb[1]
+ " Blue: " + rgb[2]);
x = -1;
y = -1;
}
return mRgba;
}
我发现以下错误:
E/AndroidRuntime:致命异常:线程-904
java.lang.NullPointerException
位于test.com.imagecolortest.MainActivity.onCameraFrame(MainActivity.java:104)
位于org.opencv.android.CameraBridgeViewBase.deliverAndDrawFrame(CameraBridgeViewBase.java:392)
位于org.opencv.android.JavaCameraView$CameraWorker.run(JavaCameraView.java:373)
运行(Thread.java:838)
注意:
@SuppressWarnings("deprecation")
@Override
public boolean onTouchEvent(MotionEvent event) {
x = (int)event.getX();
y = (int)event.getY();
return super.onTouchEvent(event);
}
第104行(MainActivity.java:104)是:
- y:“+String.valueOf(y)+”\n
rgb[0]
值为0
时,Log.d
会触发三次。不知道为什么
[编辑]:我们可以在稍后返回super.onTouchEvent(event)
时解决此问题,而不是返回true
。我稍后会补充
我的代码:MainActivity.java
package test.com.imagecolortest;
import org.opencv.android.BaseLoaderCallback;
import org.opencv.android.CameraBridgeViewBase.CvCameraViewFrame;
import org.opencv.android.LoaderCallbackInterface;
import org.opencv.android.OpenCVLoader;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.android.CameraBridgeViewBase;
import org.opencv.android.CameraBridgeViewBase.CvCameraViewListener2;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.SurfaceView;
import android.view.WindowManager;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity implements CvCameraViewListener2 {
private static final String TAG = "OCVSample::Activity";
private CameraBridgeViewBase mOpenCvCameraView;
private boolean mIsJavaCamera = true;
private MenuItem mItemSwitchCamera = null;
private Mat mRgba;
int x = -1, y = -1;
double [] rgb;
TextView touchView;
private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {
@Override
public void onManagerConnected(int status) {
switch (status) {
case LoaderCallbackInterface.SUCCESS: {
Log.i(TAG, "OpenCV loaded successfully");
mOpenCvCameraView.enableView();
} break;
default: {
super.onManagerConnected(status);
} break;
}
}
};
public MainActivity() {
Log.i(TAG, "Instantiated new " + this.getClass());
}
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
Log.i(TAG, "called onCreate");
super.onCreate(savedInstanceState);
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
setContentView(R.layout.activity_main);
mOpenCvCameraView = (CameraBridgeViewBase) findViewById(R.id.activity_main);
mOpenCvCameraView.setVisibility(SurfaceView.VISIBLE);
mOpenCvCameraView.setCvCameraViewListener(this);
touchView = (TextView)findViewById(R.id.textView);
}
@Override
public void onPause(){
super.onPause();
if (mOpenCvCameraView != null)
mOpenCvCameraView.disableView();
}
@Override
public void onResume(){
super.onResume();
if (!OpenCVLoader.initDebug()) {
Log.d(TAG, "Internal OpenCV library not found. Using OpenCV Manager for initialization");
OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_3_0_0, this, mLoaderCallback);
} else {
Log.d(TAG, "OpenCV library found inside package. Using it!");
mLoaderCallback.onManagerConnected(LoaderCallbackInterface.SUCCESS);
}
}
public void onDestroy() {
super.onDestroy();
if (mOpenCvCameraView != null)
mOpenCvCameraView.disableView();
}
public void onCameraViewStarted(int width, int height) {
mRgba = new Mat(height, width, CvType.CV_8UC4);
}
public void onCameraViewStopped() {
mRgba.release();
}
public Mat onCameraFrame(CvCameraViewFrame inputFrame) {
mRgba = inputFrame.rgba();
if(x != -1 && y != -1) { //if this is true, you've touched something
rgb = mRgba.get(x,y);
Log.d(TAG, "Touch coordinates--> " + "x: " + String.valueOf(x)
+ " y: " + String.valueOf(y) + " \n"
+ "RGB values--> "
+ "Red: " + rgb[0]
+ " Green: " + rgb[1]
+ " Blue: " + rgb[2]);
// touchView.setText("Touch coordinates--> " + "x: " + String.valueOf(x)
// + " y: " + String.valueOf(y) + " \n" + "RGB values--> " + "Red: " + rgb[0]
// + " Green: " + rgb[1] + " Blue: " + rgb[2]);
x = -1;
y = -1;
}
return mRgba;
}
//detects touches on screen
@SuppressWarnings("deprecation")
@Override
public boolean onTouchEvent(MotionEvent event) {
x = (int)event.getX();
y = (int)event.getY();
//Display display = getWindowManager().getDefaultDisplay();
//int width = display.getWidth();
//int height = display.getHeight();
//double [] rgb = mRgba.get(width,height);
// touchView.setText("Touch coordinates--> " + "x: " + String.valueOf(x)
// + " y: " + String.valueOf(y) + " \n" + "RGB values--> " + "Red: " + rgb[0]
// + " Green: " + rgb[1] + " Blue: " + rgb[2]);
return super.onTouchEvent(event);
}
}
活动\u main.xml
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:opencv="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<org.opencv.android.JavaCameraView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:visibility="gone"
android:id="@+id/activity_main"
opencv:show_fps="true"
opencv:camera_id="any" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceMedium"
android:text="Medium Text"
android:id="@+id/textView"
android:layout_gravity="left|bottom" />
</FrameLayout>
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="test.com.imagecolortest">
<uses-permission android:name="android.permission.CAMERA"/>
<uses-feature android:name="android.hardware.camera" android:required="false"/>
<uses-feature android:name="android.hardware.camera.autofocus" android:required="false"/>
<uses-feature android:name="android.hardware.camera.front" android:required="false"/>
<uses-feature android:name="android.hardware.camera.front.autofocus" android:required="false"/>
<application
android:allowBackup="true"
android:icon="@mipmap/ic_launcher"
android:label="@string/app_name"
android:supportsRtl="true"
android:theme="@style/AppTheme"
>
<activity android:name=".MainActivity"
android:screenOrientation="landscape"
android:configChanges="keyboardHidden|orientation">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<supports-screens android:resizeable="true"
android:smallScreens="true"
android:normalScreens="true"
android:largeScreens="true"
android:anyDensity="true" />
</manifest>
我注意到一些非常奇怪的行为。y
(垂直)值正常。但当我将手指从左向右滑动时,x
值在0-599
范围内工作良好,当它触及600
值时,应用程序突然崩溃。
请参阅附件照片:
14.93FPS@800x600R:134.0g:155.0b:151.0
x:371 y:488
- 红点显示,我的手指现在在哪里李>
- 红色的矩形(实际上是正方形)显示,当我在这里面触摸时,我的应用程序工作,但当它超出(最右边)时,它崩溃了
rgb=mRgba.get(x,y)代码>因此您将x作为行传递,y作为列传递,当x>=600时,这将超出800x600显示的范围
) 为什么需要String.valueOf
?只需将x
和y
直接添加到字符串中,我怀疑inputFrame.rgba()
为null或inputFrame==null
。你能检查两个吗?嗨@cricket\u 007如果(inputFrame==null)
Android Studio给我这个警告:条件“inputFrame==null”总是“false”
。在我的例子中,if(inputFrame.rgba()==null)
给出了false
,非null
。通过这样做:if(null!=y)
AndroidStudio v2.1.2给出了这个错误Operator'!='无法应用于“null”、“int”
。抄送:@Khanal,我不认为x
&y
为空或存在问题。我可以Log.d(标记“x:+x+”y:+y)代码>通过触摸屏幕上的任意位置。我只是把这些注释掉:rgb[0]、rgb[1]、rgb[2]
似乎有一些问题:rgb=mRgba.get(x,y)代码>我再次感觉到,我没有为应用程序定义屏幕大小。我使用的是华为荣誉h30-u10,当我在上面的应用程序中打开时,我的屏幕上只显示了部分摄像头预览,屏幕左右两侧都有黑条(横向)。这迫使我认为屏幕上可见的摄像头具有x
i-e:width等于600
。我可能错了。但当我点击黑屏的左上角(前摄像头的正下方)时,我可以得到x
和y
的值。我相信这是一个积极的发现。非常感谢您的回答,我会检查并很快回来@Chungzuwalla有一个问题。如果我的屏幕处于横向
模式(如图所示,我在清单中将其强制为:android:screenOrientation=“横向”
),那么在这种情况下,我的x
是行
,而y
是列
,我附加的图片显示行
像素是:800
。那我为什么会出错呢?我的x
是800
。我说的对吗?我不知道Android开发,只知道OpenCV。所以我不知道屏幕方向对代码有什么影响。但是,显示分辨率通常表示为宽度x高(例如,对于HD,为1920x1080,而不是1080x1920),并且在2D图形中通常使用x、y顺序,而矩阵尺寸通常写为行×列,并以行第一()为索引。在代码中适当的位置切换这两个符号是使用OpenCV编程图形系统的一部分。在C++中,避免这种错误的一种方法是总是用CV::点来索引CV::MAT,因为点构造函数采用通常的2D图形顺序(x,y):<代码> uCHAR Val= Mat。AT(CV::点(x,y));Hello我将public void onCameraViewStarted(int-width,int-height){mRgba=new Mat(height,width,CvType.CV_8UC4);}
更改为public void onCameraViewStarted(int-width,int-height){mRgba=new Mat(width,height,CvType.CV_8UC4);}
因此这使得垂直y
完美,但x
没有超出599
。还改变了rgb=mRgba.get(x,y)中x
和y
的顺序代码>但它不起作用;int width2=display.getWidth();int h
Imgproc.putText() as: Imgproc.putText(mRgba,"R:"+rgb[0] + " G:"+rgb[1] +" B:"+rgb[2] + "x: " + x + " y: " + y, new Point(10,52), Core.FONT_HERSHEY_COMPLEX,.7, new Scalar(5,255,255),2,8,false );