|
||||||
|
Example OpenCV Android app
Activity Interface in XML
...... includes a SPINNER and a TEXT
<?xml version="1.0" encoding="utf-8"?>
|
 |
strings.xml file (used to create string-array for an adapter to fill in spinner choices)
<resources> |
Code - Activity File (get zip of project --but, your verison of Android SDK may be different so can't use directly)
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import org.opencv.android.BaseLoaderCallback;
import org.opencv.android.CameraBridgeViewBase;
import org.opencv.android.LoaderCallbackInterface;
import org.opencv.android.OpenCVLoader;
import org.opencv.android.CameraBridgeViewBase.CvCameraViewListener2;
import org.opencv.core.Mat;
import org.opencv.android.CameraBridgeViewBase.CvCameraViewFrame;
import org.opencv.imgproc.Imgproc;
import android.widget.AdapterView.OnItemSelectedListener;
import java.util.Random;
public class HelloOpenCvActivity extends AppCompatActivity implements CvCameraViewListener2, OnItemSelectedListener
{
CameraBridgeViewBase mOpenCvCameraView;// will point to our View widget for our image
Spinner spinner_menu;
//grab array of possible menu items from strings.xml file
String[] menu_items;
String menu_item_selected;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_hello_open_cv);
//setup menu from strings.xml file
this.menu_items = getResources().getStringArray(R.array.spinner_menu);
this.menu_item_selected = menu_items[0]; //initialize to first item in arry
Log.i("SPINNER", "menu item is " + this.menu_item_selected);
//grab a handle to spinner_menu in the XML interface
spinner_menu = (Spinner)findViewById(R.id.spinner_menu);
// Create an ArrayAdapter using the string array and a default spinner layout
ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this, R.array.spinner_menu, android.R.layout.simple_spinner_item);
// Specify the layout to use when the list of choices appears
adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
// Apply the adapter to the spinner
spinner_menu.setAdapter(adapter);
spinner_menu.setSelection(0);//initialize to first item in menu
//set this activity to listen to the menu choice in spinner
spinner_menu.setOnItemSelectedListener(this);
//grab a "handle" to the OpenCV class responsible for viewing Image
// look at the XML the id of our CamerBridgeViewBase is HelloOpenCVView
mOpenCvCameraView = (CameraBridgeViewBase) findViewById(R.id.HelloOpenCvView);
mOpenCvCameraView.setVisibility(CameraBridgeViewBase.VISIBLE);
mOpenCvCameraView.setCvCameraViewListener(this); //the activity will listen to events on Camera
}
//Code will tell us when camera connected it will enable the mOpenCVCameraView
private BaseLoaderCallback mLoaderCallback = new BaseLoaderCallback(this) {
@Override
public void onManagerConnected(int status) {
switch (status) {
case LoaderCallbackInterface.SUCCESS:
{
Log.i("OPENCV", "OpenCV loaded successfully");
mOpenCvCameraView.enableView();
} break;
default:
{
super.onManagerConnected(status);
} break;
}
}
};
@Override public void onResume() {
super.onResume();
OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_3_1_0, this, mLoaderCallback);
}
@Override
public void onPause() {
super.onPause();
if (mOpenCvCameraView != null)
mOpenCvCameraView.disableView();
}
public void onDestroy() {
super.onDestroy();
if (mOpenCvCameraView != null)
mOpenCvCameraView.disableView(); }
public void onCameraViewStarted(int width, int height) { }
public void onCameraViewStopped() { }
// THIS IS THE main method that is called each time you get a new Frame/Image
// it should return a Mat that will be displayed in the corresponding JavaCameraView widget that should be part of the
// xml interface for this activity that is associated with this class's variable mOpenCvCameraView which is
// associated with JavaCameraView widget (see onCreate method above)
public Mat onCameraFrame(CameraBridgeViewBase.CvCameraViewFrame inputFrame) {
Mat imageMat = inputFrame.rgba();
Mat gray = inputFrame.gray();
// now you use the Mat class to represent the Image and you can use method calls
// make calls like to get a pixel at i,j imageMat.get
// double pixel[] = new double[3];
// pixel = imageMat.get(20,10); this wil retrieve pixel and column = 20, row =10
//similarly can set a pixel in Mat via imageMat.set(i,j,pixel);
// read API on Mat class for OPenCV
// A VERY USEFUL class to call image processing routines is ImagProc
// This code in comments shows how to do the Sobel Edge Detection on our image in imageMat
/*
Mat gray = inputFrame.gray();
Mat mIntermediateMat = new Mat();
Imgproc.Sobel(gray, mIntermediateMat, CvType.CV_8U, 1, 1);
Core.convertScaleAbs(mIntermediateMat, mIntermediateMat, 10, 0);
Imgproc.cvtColor(mIntermediateMat, imageMat, Imgproc.COLOR_GRAY2BGRA, 4);
*/
//Based on spinner menu selected item stored as this.menu_item_selected perform appropriate
// operation and return a Mat
if(this.menu_item_selected.equals("Random")) { //Random
//return imageMat;
//create random number 0 to 1 and return color if < .5 and grey otherwise
Random rand = new Random(System.currentTimeMillis());
if (rand.nextDouble() < 0.5)
{ Log.d("SPINNER", "return color"); return imageMat;}
else
{ Log.d("SPINNER", "return greyscale"); return gray;}
}
else if(this.menu_item_selected.equals("Greyscale")) { //Greyscale
Log.d("SPINNER", "return greyscale");
return gray;
}
else if(this.menu_item_selected.equals("Threshold")) { //currently always threshold the greyscale image at value of 50
/* FROM OPENCV DOCUMENTATION : threshold(Mat src,Mat dst,double thresh, double maxval,int type)
The function applies fixed-level thresholding to a single-channel array.
The function is typically used to get a bi-level (binary) image out of a grayscale image
type = THRESH_BINARY
if src(x,y) > thresh then dest(x,y) = maxval; 0 otherwise
*/
Log.i("SPINNER", "performing thresholding");
Imgproc.threshold(gray,gray, 50.0, 255.0, Imgproc.THRESH_BINARY );
return gray;
}
else //for now return color for all other choices
{
return gray;
}
}
//Spinner Menu Selection response method
public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) {
// An item was selected. You can retrieve the selected item using
this.menu_item_selected = parent.getItemAtPosition(pos).toString();
Log.i("SPINNER", "choice is" + this.menu_item_selected);
}
public void onNothingSelected(AdapterView<?> parent) {
this.menu_item_selected = this.menu_items[0];
}
Random selected = Output sometimes grey sometimes color (note is emulator running with emulated camera)
Greyscale selected =
Threshold selected=
