update to Java 8 and improve the conversion between Mat and Image

README.md

@@ -2,8 +2,8 @@
 
 *Computer Vision course - [Politecnico di Torino](http://www.polito.it)*
 
-A project, made in Eclipse (Mars), for capturing a video from a webcam and manipulating its frames: add a logo in the corner of the video player, convert the video in grayscale, and show the histogram of each frame.
+A project, made in Eclipse (Neon), for capturing a video from a webcam and manipulating its frames: add a logo in the corner of the video player, convert the video in grayscale, and show the histogram of each frame.
 
-Please, note that the project is an Eclipse project, made for teaching purposes. Before using it, you need to install the OpenCV library (version 3.0) and JavaFX (version 2 or superior) and create a `User Library` named `opencv` that links to the OpenCV jar and native libraries.
+Please, note that the project is an Eclipse project, made for teaching purposes. Before using it, you need to install the OpenCV library (version 3.x) and JavaFX 8 and create a `User Library` named `opencv` that links to the OpenCV jar and native libraries.
 
 A guide for getting started with OpenCV and Java is available at [http://opencv-java-tutorials.readthedocs.org/en/latest/index.html](http://opencv-java-tutorials.readthedocs.org/en/latest/index.html).

src/it/polito/elite/teaching/cv/utils/Utils.java

@@ -0,0 +1,89 @@
+package it.polito.elite.teaching.cv.utils;
+
+import java.awt.image.BufferedImage;
+import java.awt.image.DataBufferByte;
+
+import org.opencv.core.Mat;
+
+import javafx.application.Platform;
+import javafx.beans.property.ObjectProperty;
+import javafx.embed.swing.SwingFXUtils;
+import javafx.scene.image.Image;
+
+/**
+ * Provide general purpose methods for handling OpenCV-JavaFX data conversion.
+ * Moreover, expose some "low level" methods for matching few JavaFX behavior.
+ *
+ * @author <a href="mailto:luigi.derussis@polito.it">Luigi De Russis</a>
+ * @author <a href="http://max-z.de">Maximilian Zuleger</a>
+ * @version 1.0 (2016-09-17)
+ * @since 1.0
+ * 
+ */
+public final class Utils
+{
+	/**
+	 * Convert a Mat object (OpenCV) in the corresponding Image for JavaFX
+	 *
+	 * @param frame
+	 *            the {@link Mat} representing the current frame
+	 * @return the {@link Image} to show
+	 */
+	public static Image mat2Image(Mat frame)
+	{
+		try
+		{
+			return SwingFXUtils.toFXImage(matToBufferedImage(frame), null);
+		}
+		catch (Exception e)
+		{
+			System.err.println("Cannot convert the Mat obejct: " + e);
+			return null;
+		}
+	}
+
+	/**
+	 * Generic method for putting element running on a non-JavaFX thread on the
+	 * JavaFX thread, to properly update the UI
+	 * 
+	 * @param property
+	 *            a {@link ObjectProperty}
+	 * @param value
+	 *            the value to set for the given {@link ObjectProperty}
+	 */
+	public static <T> void onFXThread(final ObjectProperty<T> property, final T value)
+	{
+		Platform.runLater(() -> {
+			property.set(value);
+		});
+	}
+
+	/**
+	 * Support for the {@link mat2image()} method
+	 * 
+	 * @param original
+	 *            the {@link Mat} object in BGR or grayscale
+	 * @return the corresponding {@link BufferedImage}
+	 */
+	private static BufferedImage matToBufferedImage(Mat original)
+	{
+		// init
+		BufferedImage image = null;
+		int width = original.width(), height = original.height(), channels = original.channels();
+		byte[] sourcePixels = new byte[width * height * channels];
+		original.get(0, 0, sourcePixels);
+
+		if (original.channels() > 1)
+		{
+			image = new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR);
+		}
+		else
+		{
+			image = new BufferedImage(width, height, BufferedImage.TYPE_BYTE_GRAY);
+		}
+		final byte[] targetPixels = ((DataBufferByte) image.getRaster().getDataBuffer()).getData();
+		System.arraycopy(sourcePixels, 0, targetPixels, 0, sourcePixels.length);
+
+		return image;
+	}
+}

src/it/polito/teaching/cv/Video.java

@@ -1,10 +1,12 @@
 package it.polito.teaching.cv;
 
 import javafx.application.Application;
+import javafx.event.EventHandler;
 import javafx.fxml.FXMLLoader;
 import javafx.scene.Scene;
 import javafx.scene.layout.BorderPane;
 import javafx.stage.Stage;
+import javafx.stage.WindowEvent;
 
 import org.opencv.core.Core;
 
@@ -17,7 +19,7 @@
  * histogram and it is possible to add a logo in a corner of the video.
  * 
  * @author <a href="mailto:luigi.derussis@polito.it">Luigi De Russis</a>
- * @version 1.1 (2015-10-20)
+ * @version 2.0 (2017-03-10)
  * @since 1.0 (2013-11-20)
  * 
  */
@@ -42,6 +44,15 @@ public void start(Stage primaryStage)
 			// show the GUI
 			primaryStage.show();
 
+			// set the proper behavior on closing the application
+			VideoController controller = loader.getController();
+			primaryStage.setOnCloseRequest((new EventHandler<WindowEvent>() {
+				public void handle(WindowEvent we)
+				{
+					controller.setClosed();
+				}
+			}));
+
 		}
 		catch (Exception e)
 		{

src/it/polito/teaching/cv/VideoController.java

@@ -1,6 +1,5 @@
 package it.polito.teaching.cv;
 
-import java.io.ByteArrayInputStream;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.Executors;
@@ -10,7 +9,6 @@
 import org.opencv.core.Core;
 import org.opencv.core.CvType;
 import org.opencv.core.Mat;
-import org.opencv.core.MatOfByte;
 import org.opencv.core.MatOfFloat;
 import org.opencv.core.MatOfInt;
 import org.opencv.core.Point;
@@ -20,6 +18,7 @@
 import org.opencv.imgproc.Imgproc;
 import org.opencv.videoio.VideoCapture;
 
+import it.polito.elite.teaching.cv.utils.Utils;
 import javafx.fxml.FXML;
 import javafx.scene.control.Button;
 import javafx.scene.control.CheckBox;
@@ -33,7 +32,7 @@
  * controls and the histogram creation.
  * 
  * @author <a href="mailto:luigi.derussis@polito.it">Luigi De Russis</a>
- * @version 1.1 (2015-10-20)
+ * @version 2.0 (2017-03-10)
  * @since 1.0 (2013-11-20)
  * 		
  */
@@ -100,8 +99,11 @@ protected void startCamera()
 					@Override
 					public void run()
 					{
-						Image imageToShow = grabFrame();
-						currentFrame.setImage(imageToShow);
+						// effectively grab and process a single frame
+						Mat frame = grabFrame();
+						// convert and show the frame
+						Image imageToShow = Utils.mat2Image(frame);
+						updateImageView(currentFrame, imageToShow);
 					}
 				};
 
@@ -161,10 +163,8 @@ protected void loadLogo()
 	 * 
 	 * @return the {@link Image} to show
 	 */
-	private Image grabFrame()
+	private Mat grabFrame()
 	{
-		// init everything
-		Image imageToShow = null;
 		Mat frame = new Mat();
 
 		// check if the capture is open
@@ -200,9 +200,6 @@ private Image grabFrame()
 
 					// show the histogram
 					this.showHistogram(frame, grayscale.isSelected());
-
-					// convert the Mat object (OpenCV) to Image (JavaFX)
-					imageToShow = mat2Image(frame);
 				}
 
 			}
@@ -213,7 +210,7 @@ private Image grabFrame()
 			}
 		}
 
-		return imageToShow;
+		return frame;
 	}
 
 	/**
@@ -287,27 +284,57 @@ private void showHistogram(Mat frame, boolean gray)
 		}
 
 		// display the histogram...
-		Image histImg = mat2Image(histImage);
-		this.histogram.setImage(histImg);
+		Image histImg = Utils.mat2Image(histImage);
+		updateImageView(histogram, histImg);
 
 	}
 
 	/**
-	 * Convert a Mat object (OpenCV) in the corresponding Image for JavaFX
+	 * Stop the acquisition from the camera and release all the resources
+	 */
+	private void stopAcquisition()
+	{
+		if (this.timer!=null && !this.timer.isShutdown())
+		{
+			try
+			{
+				// stop the timer
+				this.timer.shutdown();
+				this.timer.awaitTermination(33, TimeUnit.MILLISECONDS);
+			}
+			catch (InterruptedException e)
+			{
+				// log any exception
+				System.err.println("Exception in stopping the frame capture, trying to release the camera now... " + e);
+			}
+		}
+
+		if (this.capture.isOpened())
+		{
+			// release the camera
+			this.capture.release();
+		}
+	}
+
+	/**
+	 * Update the {@link ImageView} in the JavaFX main thread
 	 * 
-	 * @param frame
-	 *            the {@link Mat} representing the current frame
-	 * @return the {@link Image} to show
+	 * @param view
+	 *            the {@link ImageView} to update
+	 * @param image
+	 *            the {@link Image} to show
+	 */
+	private void updateImageView(ImageView view, Image image)
+	{
+		Utils.onFXThread(view.imageProperty(), image);
+	}
+
+	/**
+	 * On application close, stop the acquisition from the camera
 	 */
-	private Image mat2Image(Mat frame)
+	protected void setClosed()
 	{
-		// create a temporary buffer
-		MatOfByte buffer = new MatOfByte();
-		// encode the frame in the buffer, according to the PNG format
-		Imgcodecs.imencode(".png", frame, buffer);
-		// build and return an Image created from the image encoded in the
-		// buffer
-		return new Image(new ByteArrayInputStream(buffer.toArray()));
+		this.stopAcquisition();
 	}