Add image transformation feature, closes #73

webcam-capture/src/example/java/com/github/sarxos/webcam/example/ImageTransformerExample.java

@@ -0,0 +1,46 @@
+package com.github.sarxos.webcam.example;
+
+import java.awt.image.BufferedImage;
+
+import javax.swing.JFrame;
+
+import com.github.sarxos.webcam.Webcam;
+import com.github.sarxos.webcam.WebcamImageTransformer;
+import com.github.sarxos.webcam.WebcamPanel;
+import com.github.sarxos.webcam.WebcamResolution;
+import com.github.sarxos.webcam.util.jh.JHGrayFilter;
+
+
+public class ImageTransformerExample implements WebcamImageTransformer {
+
+	private static final JHGrayFilter GRAY = new JHGrayFilter();
+
+	@Override
+	public BufferedImage transform(BufferedImage image) {
+		return GRAY.filter(image, null);
+	}
+
+	public ImageTransformerExample() {
+
+		Webcam webcam = Webcam.getDefault();
+		webcam.setViewSize(WebcamResolution.VGA.getSize());
+		webcam.setImageTransformer(this);
+		webcam.open();
+
+		JFrame window = new JFrame("Test Transformer");
+
+		WebcamPanel panel = new WebcamPanel(webcam);
+		panel.setFPSDisplayed(true);
+		panel.setFillArea(true);
+
+		window.add(panel);
+		window.pack();
+		window.setVisible(true);
+		window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
+	}
+
+	public static void main(String[] args) {
+		new ImageTransformerExample();
+	}
+
+}

webcam-capture/src/main/java/com/github/sarxos/webcam/Webcam.java

@@ -117,6 +117,11 @@ public class Webcam {
 	 */
 	private WebcamUpdater updater = new WebcamUpdater(this);
 
+	/**
+	 * IMage transformer.
+	 */
+	private volatile WebcamImageTransformer transformer = null;
+
 	/**
 	 * Webcam class.
 	 * 
@@ -262,6 +267,87 @@ public boolean close() {
 		return true;
 	}
 
+	/**
+	 * Return underlying webcam device. Depending on the driver used to discover
+	 * devices, this method can return instances of different class. By default
+	 * {@link WebcamDefaultDevice} is returned when no external driver is used.
+	 * 
+	 * @return Underlying webcam device instance
+	 */
+	public WebcamDevice getDevice() {
+		assert device != null;
+		return device;
+	}
+
+	/**
+	 * Completely dispose capture device. After this operation webcam cannot be
+	 * used any more and full reinstantiation is required.
+	 */
+	protected void dispose() {
+
+		assert disposed != null;
+		assert open != null;
+		assert driver != null;
+		assert device != null;
+		assert listeners != null;
+
+		if (!disposed.compareAndSet(false, true)) {
+			return;
+		}
+
+		open.set(false);
+
+		LOG.info("Disposing webcam {}", getName());
+
+		WebcamDisposeTask task = new WebcamDisposeTask(driver, device);
+		try {
+			task.dispose();
+		} catch (InterruptedException e) {
+			LOG.error("Processor has been interrupted before webcam was disposed!", e);
+			return;
+		}
+
+		WebcamEvent we = new WebcamEvent(WebcamEventType.DISPOSED, this);
+		for (WebcamListener l : listeners) {
+			try {
+				l.webcamClosed(we);
+				l.webcamDisposed(we);
+			} catch (Exception e) {
+				LOG.error(String.format("Notify webcam disposed, exception when calling %s listener", l.getClass()), e);
+			}
+		}
+
+		// hook can be null because there is a possibility that webcam has never
+		// been open and therefore hook was not created
+		if (hook != null) {
+			try {
+				Runtime.getRuntime().removeShutdownHook(hook);
+			} catch (IllegalStateException e) {
+				LOG.trace("Shutdown in progress, cannot remove hook");
+			}
+		}
+
+		LOG.debug("Webcam disposed {}", getName());
+	}
+
+	/**
+	 * TRansform image using image transformer. If image transformer has not
+	 * been set, this method return instance passed in the argument, without any
+	 * modifications.
+	 * 
+	 * @param image the image to be transformed
+	 * @return Transformed image (if transformer is set)
+	 */
+	protected BufferedImage transform(BufferedImage image) {
+		if (image != null) {
+			WebcamImageTransformer tr = getImageTransformer();
+			if (tr != null) {
+				return tr.transform(image);
+			}
+		}
+		return image;
+	}
+
 	/**
 	 * Is webcam open?
 	 * 
@@ -412,7 +498,7 @@ public BufferedImage getImage() {
 			// get image
 
 			t1 = System.currentTimeMillis();
-			BufferedImage image = new WebcamReadImageTask(driver, device).getImage();
+			BufferedImage image = transform(new WebcamReadImageTask(driver, device).getImage());
 			t2 = System.currentTimeMillis();
 
 			if (image == null) {
@@ -822,69 +908,6 @@ public static void registerDriver(String clazzName) {
 		DRIVERS_LIST.add(clazzName);
 	}
 
-	/**
-	 * Return underlying webcam device. Depending on the driver used to discover
-	 * devices, this method can return instances of different class. By default
-	 * {@link WebcamDefaultDevice} is returned when no external driver is used.
-	 * 
-	 * @return Underlying webcam device instance
-	 */
-	public WebcamDevice getDevice() {
-		assert device != null;
-		return device;
-	}
-
-	/**
-	 * Completely dispose capture device. After this operation webcam cannot be
-	 * used any more and full reinstantiation is required.
-	 */
-	protected void dispose() {
-
-		assert disposed != null;
-		assert open != null;
-		assert driver != null;
-		assert device != null;
-		assert listeners != null;
-
-		if (!disposed.compareAndSet(false, true)) {
-			return;
-		}
-
-		open.set(false);
-
-		LOG.info("Disposing webcam {}", getName());
-
-		WebcamDisposeTask task = new WebcamDisposeTask(driver, device);
-		try {
-			task.dispose();
-		} catch (InterruptedException e) {
-			LOG.error("Processor has been interrupted before webcam was disposed!", e);
-			return;
-		}
-
-		WebcamEvent we = new WebcamEvent(WebcamEventType.DISPOSED, this);
-		for (WebcamListener l : listeners) {
-			try {
-				l.webcamClosed(we);
-				l.webcamDisposed(we);
-			} catch (Exception e) {
-				LOG.error(String.format("Notify webcam disposed, exception when calling %s listener", l.getClass()), e);
-			}
-		}
-
-		// hook can be null because there is a possibility that webcam has never
-		// been open and therefore hook was not created
-		if (hook != null) {
-			try {
-				Runtime.getRuntime().removeShutdownHook(hook);
-			} catch (IllegalStateException e) {
-				LOG.trace("Shutdown in progress, cannot remove hook");
-			}
-		}
-
-		LOG.debug("Webcam disposed {}", getName());
-	}
-
 	/**
 	 * <b>CAUTION!!!</b><br>
 	 * <br>
@@ -979,4 +1002,22 @@ public static synchronized WebcamDiscoveryService getDiscoveryService() {
 		}
 		return discovery;
 	}
+
+	/**
+	 * Return image transformer.
+	 * 
+	 * @return Transformer instance
+	 */
+	public WebcamImageTransformer getImageTransformer() {
+		return transformer;
+	}
+
+	/**
+	 * Set image transformer.
+	 * 
+	 * @param transformer the transformer to be set
+	 */
+	public void setImageTransformer(WebcamImageTransformer transformer) {
+		this.transformer = transformer;
+	}
 }

webcam-capture/src/main/java/com/github/sarxos/webcam/WebcamImageTransformer.java

@@ -0,0 +1,10 @@
+package com.github.sarxos.webcam;
+
+import java.awt.image.BufferedImage;
+
+
+public interface WebcamImageTransformer {
+
+	BufferedImage transform(BufferedImage image);
+
+}

webcam-capture/src/main/java/com/github/sarxos/webcam/WebcamUpdater.java

@@ -156,10 +156,19 @@ public void run() {
 
 		// Calculate time required to fetch 1 picture.
 
+		WebcamDriver driver = Webcam.getDriver();
+		WebcamDevice device = webcam.getDevice();
+
+		assert driver != null;
+		assert device != null;
+
+		BufferedImage img = null;
+
 		t1 = System.currentTimeMillis();
-		image.set(new WebcamReadImageTask(Webcam.getDriver(), webcam.getDevice()).getImage());
+		img = webcam.transform(new WebcamReadImageTask(driver, device).getImage());
 		t2 = System.currentTimeMillis();
 
+		image.set(img);
 		imageNew = true;
 
 		// Calculate delay required to achieve target FPS. In some cases it can