Fix HeadlessException in Travis build

.travis.yml

@@ -12,7 +12,7 @@ script:
   - mvn test -B
 
 after_success:
-  - mvn clean cobertura:cobertura coveralls:report -B -P ci
+  - mvn cobertura:cobertura coveralls:report -B -P ci
 
 branches:
   except:

webcam-capture/src/test/java/com/github/sarxos/webcam/ScreenImage.java

@@ -0,0 +1,203 @@
+package com.github.sarxos.webcam;
+import java.awt.AWTException;
+import java.awt.Component;
+import java.awt.Container;
+import java.awt.Dimension;
+import java.awt.Graphics2D;
+import java.awt.Point;
+import java.awt.Rectangle;
+import java.awt.Robot;
+import java.awt.Toolkit;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.List;
+
+import javax.imageio.ImageIO;
+import javax.swing.JComponent;
+import javax.swing.SwingUtilities;
+
+
+/*
+ *  Convenience class to create and optionally save to a file a
+ *  BufferedImage of an area on the screen. Generally there are
+ *  four different scenarios. Create an image of:
+ *
+ *  a) an entire component
+ *  b) a region of the component
+ *  c) the entire desktop
+ *  d) a region of the desktop
+ *
+ *  The first two use the Swing paint() method to draw the
+ *  component image to the BufferedImage. The latter two use the
+ *  AWT Robot to create the BufferedImage.
+ *
+ *	The created image can then be saved to a file by usig the
+ *  writeImage(...) method. The type of file must be supported by the
+ *  ImageIO write method.
+ *
+ *  Although this class was originally designed to create an image of a
+ *  component on the screen it can be used to create an image of components
+ *  not displayed on a GUI. Behind the scenes the component will be given a
+ *  size and the component will be layed out. The default size will be the
+ *  preferred size of the component although you can invoke the setSize()
+ *  method on the component before invoking a createImage(...) method. The
+ *  default functionality should work in most cases. However the only
+ *  foolproof way to get a image to is make sure the component has been
+ *  added to a realized window with code something like the following:
+ *
+ *  JFrame frame = new JFrame();
+ *  frame.setContentPane( someComponent );
+ *  frame.pack();
+ *  ScreenImage.createImage( someComponent );
+ *
+ */
+public class ScreenImage {
+
+	private static List<String> types = Arrays.asList(ImageIO.getWriterFileSuffixes());
+
+	/*
+	 * Create a BufferedImage for Swing components. The entire component will be captured to an
+	 * image.
+	 * @param component Swing component to create image from
+	 * @return image the image for the given region
+	 */
+	public static BufferedImage createImage(JComponent component) {
+		Dimension d = component.getSize();
+
+		if (d.width == 0 || d.height == 0) {
+			d = component.getPreferredSize();
+			component.setSize(d);
+		}
+
+		Rectangle region = new Rectangle(0, 0, d.width, d.height);
+		return ScreenImage.createImage(component, region);
+	}
+
+	/*
+	 * Create a BufferedImage for Swing components. All or part of the component can be captured to
+	 * an image.
+	 * @param component Swing component to create image from
+	 * @param region The region of the component to be captured to an image
+	 * @return image the image for the given region
+	 */
+	public static BufferedImage createImage(JComponent component, Rectangle region) {
+		// Make sure the component has a size and has been layed out.
+		// (necessary check for components not added to a realized frame)
+
+		if (!component.isDisplayable()) {
+			Dimension d = component.getSize();
+
+			if (d.width == 0 || d.height == 0) {
+				d = component.getPreferredSize();
+				component.setSize(d);
+			}
+
+			layoutComponent(component);
+		}
+
+		BufferedImage image = new BufferedImage(region.width, region.height, BufferedImage.TYPE_INT_RGB);
+		Graphics2D g2d = image.createGraphics();
+
+		// Paint a background for non-opaque components,
+		// otherwise the background will be black
+
+		if (!component.isOpaque()) {
+			g2d.setColor(component.getBackground());
+			g2d.fillRect(region.x, region.y, region.width, region.height);
+		}
+
+		g2d.translate(-region.x, -region.y);
+		component.print(g2d);
+		g2d.dispose();
+		return image;
+	}
+
+	/**
+	 * Convenience method to create a BufferedImage of the desktop
+	 *
+	 * @param fileName name of file to be created or null
+	 * @return image the image for the given region
+	 * @exception AWTException see Robot class constructors
+	 * @exception IOException if an error occurs during writing
+	 */
+	public static BufferedImage createDesktopImage()
+		throws AWTException, IOException {
+		Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
+		Rectangle region = new Rectangle(0, 0, d.width, d.height);
+		return ScreenImage.createImage(region);
+	}
+
+	/*
+	 * Create a BufferedImage for AWT components. This will include Swing components JFrame, JDialog
+	 * and JWindow which all extend from Component, not JComponent.
+	 * @param component AWT component to create image from
+	 * @return image the image for the given region
+	 * @exception AWTException see Robot class constructors
+	 */
+	public static BufferedImage createImage(Component component)
+		throws AWTException {
+		Point p = new Point(0, 0);
+		SwingUtilities.convertPointToScreen(p, component);
+		Rectangle region = component.getBounds();
+		region.x = p.x;
+		region.y = p.y;
+		return ScreenImage.createImage(region);
+	}
+
+	/**
+	 * Create a BufferedImage from a rectangular region on the screen.
+	 *
+	 * @param region region on the screen to create image from
+	 * @return image the image for the given region
+	 * @exception AWTException see Robot class constructors
+	 */
+	public static BufferedImage createImage(Rectangle region)
+		throws AWTException {
+		BufferedImage image = new Robot().createScreenCapture(region);
+		return image;
+	}
+
+	/**
+	 * Write a BufferedImage to a File.
+	 *
+	 * @param image image to be written
+	 * @param fileName name of file to be created
+	 * @exception IOException if an error occurs during writing
+	 */
+	public static void writeImage(BufferedImage image, String fileName)
+		throws IOException {
+		if (fileName == null)
+			return;
+
+		int offset = fileName.lastIndexOf(".");
+
+		if (offset == -1) {
+			String message = "file suffix was not specified";
+			throw new IOException(message);
+		}
+
+		String type = fileName.substring(offset + 1);
+
+		if (types.contains(type)) {
+			ImageIO.write(image, type, new File(fileName));
+		} else {
+			String message = "unknown writer file suffix (" + type + ")";
+			throw new IOException(message);
+		}
+	}
+
+	static void layoutComponent(Component component) {
+		synchronized (component.getTreeLock()) {
+			component.doLayout();
+
+			if (component instanceof Container) {
+				for (Component child : ((Container) component).getComponents()) {
+					layoutComponent(child);
+				}
+			}
+		}
+	}
+
+}

webcam-capture/src/test/java/com/github/sarxos/webcam/WebcamPanelTest.java

@@ -3,8 +3,6 @@
 import java.awt.Dimension;
 import java.awt.image.BufferedImage;
 
-import javax.swing.JFrame;
-
 import org.assertj.core.api.Assertions;
 import org.junit.Test;
 
@@ -79,14 +77,10 @@ public void test_modeFill() throws InterruptedException {
 			.assertThat(p.getDrawMode())
 			.isEqualTo(DrawMode.FILL);
 
-		final JFrame frame = new JFrame();
-		frame.setContentPane(p);
-		frame.pack();
+		ScreenImage.createImage(p);
 
 		Thread.sleep(100);
 
-		frame.dispose();
-
 		p.stop();
 		w.close();
 	}
@@ -107,14 +101,10 @@ public void test_modeFit() throws InterruptedException {
 			.assertThat(p.getDrawMode())
 			.isEqualTo(DrawMode.FIT);
 
-		final JFrame frame = new JFrame();
-		frame.setContentPane(p);
-		frame.pack();
+		ScreenImage.createImage(p);
 
 		Thread.sleep(100);
 
-		frame.dispose();
-
 		p.stop();
 		w.close();
 	}
@@ -135,14 +125,10 @@ public void test_modeNone() throws InterruptedException {
 			.assertThat(p.getDrawMode())
 			.isEqualTo(DrawMode.NONE);
 
-		final JFrame frame = new JFrame();
-		frame.setContentPane(p);
-		frame.pack();
+		ScreenImage.createImage(p);
 
 		Thread.sleep(100);
 
-		frame.dispose();
-
 		p.stop();
 		w.close();
 	}