Rework ImageBanner Support

Refactor several aspects of the ImageBanner:

- Extract a few new classes and methods from the previous code
- Directly encode ANSI rather than using `${}` properties
- Rework the scaling algorithm to prefer a fixed width
- Allow ImageBanner and TextBanner to be used together
- Rename several of the `banner.image` properties
- Add support for a left hand margin
- Add property meta-data

See spring-projectsgh-4647

Author: philwebb

spring-boot-samples/spring-boot-sample-simple/src/main/resources/application.properties

@@ -1 +1 @@
-name: Phil
+name: Phil

spring-boot-samples/spring-boot-sample-simple/src/main/resources/banner.jpg

@@ -0,0 +1 @@
+${Ansi.GREEN} :: Sample application build with Spring Boot${spring-boot.formatted-version} ::${Ansi.DEFAULT}

spring-boot-samples/spring-boot-sample-simple/src/main/resources/banner.txt

@@ -18,26 +18,24 @@
 
 import java.awt.Color;
 import java.awt.Image;
-import java.awt.color.ColorSpace;
-
 import java.awt.image.BufferedImage;
-
+import java.io.IOException;
+import java.io.InputStream;
 import java.io.PrintStream;
 
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Map.Entry;
-
 import javax.imageio.ImageIO;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
-import org.springframework.boot.ansi.AnsiPropertySource;
+import org.springframework.boot.ansi.AnsiBackground;
+import org.springframework.boot.ansi.AnsiColor;
+import org.springframework.boot.ansi.AnsiColors;
+import org.springframework.boot.ansi.AnsiElement;
+import org.springframework.boot.ansi.AnsiOutput;
+import org.springframework.boot.bind.RelaxedPropertyResolver;
 import org.springframework.core.env.Environment;
-import org.springframework.core.env.MutablePropertySources;
 import org.springframework.core.env.PropertyResolver;
-import org.springframework.core.env.PropertySourcesPropertyResolver;
 import org.springframework.core.io.Resource;
 import org.springframework.util.Assert;
 
@@ -46,271 +44,137 @@
  * {@link Resource}.
  *
  * @author Craig Burke
+ * @author Phillip Webb
+ * @since 1.4.0
  */
 public class ImageBanner implements Banner {
 
 	private static final Log log = LogFactory.getLog(ImageBanner.class);
 
-	private static final double RED_WEIGHT = 0.2126d;
-	private static final double GREEN_WEIGHT = 0.7152d;
-	private static final double BLUE_WEIGHT = 0.0722d;
+	private static final double[] RGB_WEIGHT = { 0.2126d, 0.7152d, 0.0722d };
+
+	private static final char[] PIXEL = { ' ', '.', '*', ':', 'o', '&', '8', '#', '@' };
 
-	private static final int DEFAULT_MAX_WIDTH = 72;
-	private static final double DEFAULT_ASPECT_RATIO = 0.5d;
-	private static final boolean DEFAULT_DARK = false;
+	private static final int LUMINANCE_INCREMENT = 10;
 
-	private Resource image;
-	private Map<String, Color> colors = new HashMap<String, Color>();
+	private static final int LUMINANCE_START = LUMINANCE_INCREMENT * PIXEL.length;
+
+	private final Resource image;
 
 	public ImageBanner(Resource image) {
 		Assert.notNull(image, "Image must not be null");
 		Assert.isTrue(image.exists(), "Image must exist");
 		this.image = image;
-		colorsInit();
-	}
-
-	private void colorsInit() {
-		this.colors.put("BLACK", new Color(0, 0, 0));
-		this.colors.put("RED", new Color(170, 0, 0));
-		this.colors.put("GREEN", new Color(0, 170, 0));
-		this.colors.put("YELLOW", new Color(170, 85, 0));
-		this.colors.put("BLUE", new Color(0, 0, 170));
-		this.colors.put("MAGENTA", new Color(170, 0, 170));
-		this.colors.put("CYAN", new Color(0, 170, 170));
-		this.colors.put("WHITE", new Color(170, 170, 170));
-
-		this.colors.put("BRIGHT_BLACK", new Color(85, 85, 85));
-		this.colors.put("BRIGHT_RED", new Color(255, 85, 85));
-		this.colors.put("BRIGHT_GREEN", new Color(85, 255, 85));
-		this.colors.put("BRIGHT_YELLOW", new Color(255, 255, 85));
-		this.colors.put("BRIGHT_BLUE", new Color(85, 85, 255));
-		this.colors.put("BRIGHT_MAGENTA", new Color(255, 85, 255));
-		this.colors.put("BRIGHT_CYAN", new Color(85, 255, 255));
-		this.colors.put("BRIGHT_WHITE", new Color(255, 255, 255));
 	}
 
 	@Override
-	public void printBanner(Environment environment, Class<?> sourceClass, PrintStream out) {
-		String headlessProperty = System.getProperty("java.awt.headless");
+	public void printBanner(Environment environment, Class<?> sourceClass,
+			PrintStream out) {
+		String headless = System.getProperty("java.awt.headless");
 		try {
 			System.setProperty("java.awt.headless", "true");
-			BufferedImage sourceImage = ImageIO.read(this.image.getInputStream());
-
-			int maxWidth = environment.getProperty("banner.image.max-width",
-					Integer.class, DEFAULT_MAX_WIDTH);
-			Double aspectRatio = environment.getProperty("banner.image.aspect-ratio",
-					Double.class, DEFAULT_ASPECT_RATIO);
-			boolean invert = environment.getProperty("banner.image.dark", Boolean.class,
-					DEFAULT_DARK);
-
-			BufferedImage resizedImage = resizeImage(sourceImage, maxWidth, aspectRatio);
-			String banner = imageToBanner(resizedImage, invert);
-
-			PropertyResolver ansiResolver = getAnsiResolver();
-			banner = ansiResolver.resolvePlaceholders(banner);
-			out.println(banner);
+			printBanner(environment, out);
 		}
 		catch (Exception ex) {
 			log.warn("Image banner not printable: " + this.image + " (" + ex.getClass()
 					+ ": '" + ex.getMessage() + "')", ex);
 		}
 		finally {
-			System.setProperty("java.awt.headless", headlessProperty);
-		}
-	}
-
-	private PropertyResolver getAnsiResolver() {
-		MutablePropertySources sources = new MutablePropertySources();
-		sources.addFirst(new AnsiPropertySource("ansi", true));
-		return new PropertySourcesPropertyResolver(sources);
-	}
-
-	private String imageToBanner(BufferedImage image, boolean dark) {
-		StringBuilder banner = new StringBuilder();
-
-		for (int y = 0; y < image.getHeight(); y++) {
-			if (dark) {
-				banner.append("${AnsiBackground.BLACK}");
+			if (headless == null) {
+				System.clearProperty("java.awt.headless");
 			}
 			else {
-				banner.append("${AnsiBackground.DEFAULT}");
-			}
-			for (int x = 0; x < image.getWidth(); x++) {
-				Color color = new Color(image.getRGB(x, y), false);
-				banner.append(getFormatString(color, dark));
-			}
-			if (dark) {
-				banner.append("${AnsiBackground.DEFAULT}");
+				System.setProperty("java.awt.headless", headless);
 			}
-			banner.append("${AnsiColor.DEFAULT}\n");
 		}
-
-		return banner.toString();
 	}
 
-	protected String getFormatString(Color color, boolean dark) {
-		String matchedColorName = null;
-		Double minColorDistance = null;
-
-		for (Entry<String, Color> colorOption : this.colors.entrySet()) {
-			double distance = getColorDistance(color, colorOption.getValue());
-
-			if (minColorDistance == null || distance < minColorDistance) {
-				minColorDistance = distance;
-				matchedColorName = colorOption.getKey();
-			}
-		}
-
-		return "${AnsiColor." + matchedColorName + "}" + getAsciiCharacter(color, dark);
+	private void printBanner(Environment environment, PrintStream out)
+			throws IOException {
+		PropertyResolver properties = new RelaxedPropertyResolver(environment,
+				"banner.image.");
+		int width = properties.getProperty("width", Integer.class, 76);
+		int heigth = properties.getProperty("height", Integer.class, 0);
+		int margin = properties.getProperty("margin", Integer.class, 2);
+		boolean invert = properties.getProperty("invert", Boolean.class, false);
+		BufferedImage image = readImage(width, heigth);
+		printBanner(image, margin, invert, out);
 	}
 
-	private static int getLuminance(Color color, boolean inverse) {
-		double red = color.getRed();
-		double green = color.getGreen();
-		double blue = color.getBlue();
-
-		double luminance;
-
-		if (inverse) {
-			luminance = (RED_WEIGHT * (255.0d - red)) + (GREEN_WEIGHT * (255.0d - green))
-					+ (BLUE_WEIGHT * (255.0d - blue));
+	private BufferedImage readImage(int width, int heigth) throws IOException {
+		InputStream inputStream = this.image.getInputStream();
+		try {
+			BufferedImage image = ImageIO.read(inputStream);
+			return resizeImage(image, width, heigth);
 		}
-		else {
-			luminance = (RED_WEIGHT * red) + (GREEN_WEIGHT * green)
-					+ (BLUE_WEIGHT * blue);
+		finally {
+			inputStream.close();
 		}
-
-		return (int) Math.ceil((luminance / 255.0d) * 100);
 	}
 
-	private static char getAsciiCharacter(Color color, boolean dark) {
-		double luminance = getLuminance(color, dark);
-
-		if (luminance >= 90) {
-			return ' ';
-		}
-		else if (luminance >= 80) {
-			return '.';
-		}
-		else if (luminance >= 70) {
-			return '*';
-		}
-		else if (luminance >= 60) {
-			return ':';
-		}
-		else if (luminance >= 50) {
-			return 'o';
+	private BufferedImage resizeImage(BufferedImage image, int width, int height) {
+		if (width < 1) {
+			width = 1;
 		}
-		else if (luminance >= 40) {
-			return '&';
-		}
-		else if (luminance >= 30) {
-			return '8';
-		}
-		else if (luminance >= 20) {
-			return '#';
-		}
-		else {
-			return '@';
+		if (height <= 0) {
+			double aspectRatio = (double) width / image.getWidth() * 0.5;
+			height = (int) Math.ceil(image.getHeight() * aspectRatio);
 		}
+		BufferedImage resized = new BufferedImage(width, height,
+				BufferedImage.TYPE_INT_RGB);
+		Image scaled = image.getScaledInstance(width, height, Image.SCALE_DEFAULT);
+		resized.getGraphics().drawImage(scaled, 0, 0, null);
+		return resized;
 	}
 
-	private static BufferedImage resizeImage(BufferedImage sourceImage, int maxWidth,
-			double aspectRatio) {
-		int width;
-		double resizeRatio;
-		if (sourceImage.getWidth() > maxWidth) {
-			resizeRatio = (double) maxWidth / (double) sourceImage.getWidth();
-			width = maxWidth;
-		}
-		else {
-			resizeRatio = 1.0d;
-			width = sourceImage.getWidth();
+	private void printBanner(BufferedImage image, int margin, boolean invert,
+			PrintStream out) {
+		AnsiElement background = (invert ? AnsiBackground.BLACK : AnsiBackground.DEFAULT);
+		out.print(AnsiOutput.encode(AnsiColor.DEFAULT));
+		out.print(AnsiOutput.encode(background));
+		out.println();
+		out.println();
+		AnsiColor lastColor = AnsiColor.DEFAULT;
+		for (int y = 0; y < image.getHeight(); y++) {
+			for (int i = 0; i < margin; i++) {
+				out.print(" ");
+			}
+			for (int x = 0; x < image.getWidth(); x++) {
+				Color color = new Color(image.getRGB(x, y), false);
+				AnsiColor ansiColor = AnsiColors.getClosest(color);
+				if (ansiColor != lastColor) {
+					out.print(AnsiOutput.encode(ansiColor));
+					lastColor = ansiColor;
+				}
+				out.print(getAsciiPixel(color, invert));
+			}
+			out.println();
 		}
-
-		int height = (int) (Math.ceil(resizeRatio * aspectRatio
-				* (double) sourceImage.getHeight()));
-		Image image = sourceImage.getScaledInstance(width, height, Image.SCALE_DEFAULT);
-
-		BufferedImage resizedImage = new BufferedImage(image.getWidth(null),
-				image.getHeight(null), BufferedImage.TYPE_INT_RGB);
-
-		resizedImage.getGraphics().drawImage(image, 0, 0, null);
-		return resizedImage;
+		out.print(AnsiOutput.encode(AnsiColor.DEFAULT));
+		out.print(AnsiOutput.encode(AnsiBackground.DEFAULT));
+		out.println();
 	}
 
-	/**
-	 * Computes the CIE94 distance between two colors.
-	 *
-	 * Contributed by michael-simons
-	 * (original implementation https://github.com/michael-simons/dfx-mosaic/blob/public/src/main/java/de/dailyfratze/mosaic/images/CIE94ColorDistance.java)
-	 *
-	 * @param color1 the first color
-	 * @param color2 the second color
-	 * @return the distance between the colors
-	 */
-	private static double getColorDistance(final Color color1, final Color color2) {
-		// Convert to L*a*b* color space
-		float[] lab1 = toLab(color1);
-		float[] lab2 = toLab(color2);
-
-		// Make it more readable
-		double L1 = lab1[0];
-		double a1 = lab1[1];
-		double b1 = lab1[2];
-		double L2 = lab2[0];
-		double a2 = lab2[1];
-		double b2 = lab2[2];
-
-		// CIE94 coefficients for graphic arts
-		double kL = 1;
-		double K1 = 0.045;
-		double K2 = 0.015;
-		// Weighting factors
-		double sl = 1.0;
-		double kc = 1.0;
-		double kh = 1.0;
-
-		// See http://en.wikipedia.org/wiki/Color_difference#CIE94
-		double c1 = Math.sqrt(a1 * a1 + b1 * b1);
-		double deltaC = c1 - Math.sqrt(a2 * a2 + b2 * b2);
-		double deltaA = a1 - a2;
-		double deltaB = b1 - b2;
-		double deltaH = Math.sqrt(Math.max(0.0, deltaA * deltaA + deltaB * deltaB - deltaC * deltaC));
-
-		return Math.sqrt(Math.max(0.0, Math.pow((L1 - L2) / (kL * sl), 2) + Math.pow(deltaC / (kc * (1 + K1 * c1)), 2) + Math.pow(deltaH / (kh * (1 + K2 * c1)), 2.0)));
+	private char getAsciiPixel(Color color, boolean dark) {
+		double luminance = getLuminance(color, dark);
+		for (int i = 0; i < PIXEL.length; i++) {
+			if (luminance >= (LUMINANCE_START - (i * LUMINANCE_INCREMENT))) {
+				return PIXEL[i];
+			}
+		}
+		return PIXEL[PIXEL.length - 1];
 	}
 
-	/**
-	 * Returns the CIE L*a*b* values of this color.
-	 *
-	 * Implements the forward transformation described in
-	 * https://en.wikipedia.org/wiki/Lab_color_space
-	 *
-	 * @param color the color to convert
-	 * @return the xyz color components
-	 */
-	static float[] toLab(Color color) {
-		float[] xyz = color.getColorComponents(
-				ColorSpace.getInstance(ColorSpace.CS_CIEXYZ), null);
-
-		return xyzToLab(xyz);
+	private int getLuminance(Color color, boolean inverse) {
+		double luminance = 0.0;
+		luminance += getLuminance(color.getRed(), inverse, RGB_WEIGHT[0]);
+		luminance += getLuminance(color.getGreen(), inverse, RGB_WEIGHT[1]);
+		luminance += getLuminance(color.getBlue(), inverse, RGB_WEIGHT[2]);
+		return (int) Math.ceil((luminance / 0xFF) * 100);
 	}
 
-	static float[] xyzToLab(float[] colorvalue) {
-		double l = f(colorvalue[1]);
-		double L = 116.0 * l - 16.0;
-		double a = 500.0 * (f(colorvalue[0]) - l);
-		double b = 200.0 * (l - f(colorvalue[2]));
-		return new float[]{(float) L, (float) a, (float) b};
+	private double getLuminance(int component, boolean inverse, double weight) {
+		return (inverse ? 0xFF - component : component) * weight;
 	}
 
-	private static double f(double t) {
-		if (t > 216.0 / 24389.0) {
-			return Math.cbrt(t);
-		}
-		else {
-			return (1.0 / 3.0) * Math.pow(29.0 / 6.0, 2) * t + (4.0 / 29.0);
-		}
-	}
 }