Merge pull request #18264 from making

* pr/18264:
  Add ANSI 8-bit color image banner support
  Polish 'Add ANSI 8-bit color support'
  Add ANSI 8-bit color support

Closes gh-18264

Author: philwebb

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/ImageBanner.java

@@ -37,6 +37,7 @@
 import org.springframework.boot.ansi.AnsiBackground;
 import org.springframework.boot.ansi.AnsiColor;
 import org.springframework.boot.ansi.AnsiColors;
+import org.springframework.boot.ansi.AnsiColors.BitDepth;
 import org.springframework.boot.ansi.AnsiElement;
 import org.springframework.boot.ansi.AnsiOutput;
 import org.springframework.core.env.Environment;
@@ -102,16 +103,22 @@ private void printBanner(Environment environment, PrintStream out) throws IOExce
 		int height = getProperty(environment, "height", Integer.class, 0);
 		int margin = getProperty(environment, "margin", Integer.class, 2);
 		boolean invert = getProperty(environment, "invert", Boolean.class, false);
+		BitDepth bitDepth = getBitDepthProperty(environment);
 		Frame[] frames = readFrames(width, height);
 		for (int i = 0; i < frames.length; i++) {
 			if (i > 0) {
 				resetCursor(frames[i - 1].getImage(), out);
 			}
-			printBanner(frames[i].getImage(), margin, invert, out);
+			printBanner(frames[i].getImage(), margin, invert, bitDepth, out);
 			sleep(frames[i].getDelayTime());
 		}
 	}
 
+	private BitDepth getBitDepthProperty(Environment environment) {
+		Integer bitDepth = getProperty(environment, "bitdepth", Integer.class, null);
+		return (bitDepth != null) ? BitDepth.of(bitDepth) : BitDepth.FOUR;
+	}
+
 	private <T> T getProperty(Environment environment, String name, Class<T> targetType, T defaultValue) {
 		return environment.getProperty(PROPERTY_PREFIX + name, targetType, defaultValue);
 	}
@@ -190,20 +197,21 @@ private void resetCursor(BufferedImage image, PrintStream out) {
 		out.print("\033[" + lines + "A\r");
 	}
 
-	private void printBanner(BufferedImage image, int margin, boolean invert, PrintStream out) {
+	private void printBanner(BufferedImage image, int margin, boolean invert, BitDepth bitDepth, 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;
+		AnsiElement lastColor = AnsiColor.DEFAULT;
+		AnsiColors colors = new AnsiColors(bitDepth);
 		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);
+				AnsiElement ansiColor = colors.findClosest(color);
 				if (ansiColor != lastColor) {
 					out.print(AnsiOutput.encode(ansiColor));
 					lastColor = ansiColor;

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/ResourceBanner.java

@@ -43,6 +43,7 @@
  *
  * @author Phillip Webb
  * @author Vedran Pavic
+ * @author Toshiaki Maki
  * @since 1.2.0
  */
 public class ResourceBanner implements Banner {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/ansi/Ansi8BitColor.java

@@ -0,0 +1,88 @@
+/*
+ * Copyright 2012-2019 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.ansi;
+
+import org.springframework.util.Assert;
+
+/**
+ * {@link AnsiElement} implementation for ANSI 8-bit foreground or background color codes.
+ *
+ * @author Toshiaki Maki
+ * @author Phillip Webb
+ * @since 2.2.0
+ * @see #foreground(int)
+ * @see #background(int)
+ */
+public final class Ansi8BitColor implements AnsiElement {
+
+	private final String prefix;
+
+	private final int code;
+
+	/**
+	 * Create a new {@link Ansi8BitColor} instance.
+	 * @param prefix the prefix escape chars
+	 * @param code color code (must be 0-255)
+	 * @throws IllegalArgumentException if color code is not between 0 and 255.
+	 */
+	private Ansi8BitColor(String prefix, int code) {
+		Assert.isTrue(code >= 0 && code <= 255, "Code must be between 0 and 255");
+		this.prefix = prefix;
+		this.code = code;
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj) {
+			return true;
+		}
+		if (obj == null || getClass() != obj.getClass()) {
+			return false;
+		}
+		Ansi8BitColor other = (Ansi8BitColor) obj;
+		return this.prefix.equals(other.prefix) && this.code == other.code;
+	}
+
+	@Override
+	public int hashCode() {
+		return this.prefix.hashCode() * 31 + this.code;
+	}
+
+	@Override
+	public String toString() {
+		return this.prefix + this.code;
+	}
+
+	/**
+	 * Return a foreground ANSI color code instance for the given code.
+	 * @param code the color code
+	 * @return an ANSI color code instance
+	 */
+	public static Ansi8BitColor foreground(int code) {
+		return new Ansi8BitColor("38;5;", code);
+	}
+
+	/**
+	 * Return a background ANSI color code instance for the given code.
+	 * @param code the color code
+	 * @return an ANSI color code instance
+	 */
+	public static Ansi8BitColor background(int code) {
+		return new Ansi8BitColor("48;5;", code);
+	}
+
+}

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/ansi/AnsiColors.java

@@ -20,8 +20,8 @@
 import java.awt.color.ColorSpace;
 import java.util.Collections;
 import java.util.EnumMap;
+import java.util.LinkedHashMap;
 import java.util.Map;
-import java.util.Map.Entry;
 
 import org.springframework.util.Assert;
 
@@ -36,7 +36,7 @@
  */
 public final class AnsiColors {
 
-	private static final Map<AnsiColor, LabColor> ANSI_COLOR_MAP;
+	private static final Map<AnsiElement, LabColor> ANSI_COLOR_MAP;
 
 	static {
 		Map<AnsiColor, LabColor> colorMap = new EnumMap<>(AnsiColor.class);
@@ -59,24 +59,86 @@ public final class AnsiColors {
 		ANSI_COLOR_MAP = Collections.unmodifiableMap(colorMap);
 	}
 
-	private AnsiColors() {
+	private static final int[] ANSI_8BIT_COLOR_CODE_LOOKUP = new int[] { 0x000000, 0x800000, 0x008000, 0x808000,
+			0x000080, 0x800080, 0x008080, 0xc0c0c0, 0x808080, 0xff0000, 0x00ff00, 0xffff00, 0x0000ff, 0xff00ff,
+			0x00ffff, 0xffffff, 0x000000, 0x00005f, 0x000087, 0x0000af, 0x0000d7, 0x0000ff, 0x005f00, 0x005f5f,
+			0x005f87, 0x005faf, 0x005fd7, 0x005fff, 0x008700, 0x00875f, 0x008787, 0x0087af, 0x0087d7, 0x0087ff,
+			0x00af00, 0x00af5f, 0x00af87, 0x00afaf, 0x00afd7, 0x00afff, 0x00d700, 0x00d75f, 0x00d787, 0x00d7af,
+			0x00d7d7, 0x00d7ff, 0x00ff00, 0x00ff5f, 0x00ff87, 0x00ffaf, 0x00ffd7, 0x00ffff, 0x5f0000, 0x5f005f,
+			0x5f0087, 0x5f00af, 0x5f00d7, 0x5f00ff, 0x5f5f00, 0x5f5f5f, 0x5f5f87, 0x5f5faf, 0x5f5fd7, 0x5f5fff,
+			0x5f8700, 0x5f875f, 0x5f8787, 0x5f87af, 0x5f87d7, 0x5f87ff, 0x5faf00, 0x5faf5f, 0x5faf87, 0x5fafaf,
+			0x5fafd7, 0x5fafff, 0x5fd700, 0x5fd75f, 0x5fd787, 0x5fd7af, 0x5fd7d7, 0x5fd7ff, 0x5fff00, 0x5fff5f,
+			0x5fff87, 0x5fffaf, 0x5fffd7, 0x5fffff, 0x870000, 0x87005f, 0x870087, 0x8700af, 0x8700d7, 0x8700ff,
+			0x875f00, 0x875f5f, 0x875f87, 0x875faf, 0x875fd7, 0x875fff, 0x878700, 0x87875f, 0x878787, 0x8787af,
+			0x8787d7, 0x8787ff, 0x87af00, 0x87af5f, 0x87af87, 0x87afaf, 0x87afd7, 0x87afff, 0x87d700, 0x87d75f,
+			0x87d787, 0x87d7af, 0x87d7d7, 0x87d7ff, 0x87ff00, 0x87ff5f, 0x87ff87, 0x87ffaf, 0x87ffd7, 0x87ffff,
+			0xaf0000, 0xaf005f, 0xaf0087, 0xaf00af, 0xaf00d7, 0xaf00ff, 0xaf5f00, 0xaf5f5f, 0xaf5f87, 0xaf5faf,
+			0xaf5fd7, 0xaf5fff, 0xaf8700, 0xaf875f, 0xaf8787, 0xaf87af, 0xaf87d7, 0xaf87ff, 0xafaf00, 0xafaf5f,
+			0xafaf87, 0xafafaf, 0xafafd7, 0xafafff, 0xafd700, 0xafd75f, 0xafd787, 0xafd7af, 0xafd7d7, 0xafd7ff,
+			0xafff00, 0xafff5f, 0xafff87, 0xafffaf, 0xafffd7, 0xafffff, 0xd70000, 0xd7005f, 0xd70087, 0xd700af,
+			0xd700d7, 0xd700ff, 0xd75f00, 0xd75f5f, 0xd75f87, 0xd75faf, 0xd75fd7, 0xd75fff, 0xd78700, 0xd7875f,
+			0xd78787, 0xd787af, 0xd787d7, 0xd787ff, 0xd7af00, 0xd7af5f, 0xd7af87, 0xd7afaf, 0xd7afd7, 0xd7afff,
+			0xd7d700, 0xd7d75f, 0xd7d787, 0xd7d7af, 0xd7d7d7, 0xd7d7ff, 0xd7ff00, 0xd7ff5f, 0xd7ff87, 0xd7ffaf,
+			0xd7ffd7, 0xd7ffff, 0xff0000, 0xff005f, 0xff0087, 0xff00af, 0xff00d7, 0xff00ff, 0xff5f00, 0xff5f5f,
+			0xff5f87, 0xff5faf, 0xff5fd7, 0xff5fff, 0xff8700, 0xff875f, 0xff8787, 0xff87af, 0xff87d7, 0xff87ff,
+			0xffaf00, 0xffaf5f, 0xffaf87, 0xffafaf, 0xffafd7, 0xffafff, 0xffd700, 0xffd75f, 0xffd787, 0xffd7af,
+			0xffd7d7, 0xffd7ff, 0xffff00, 0xffff5f, 0xffff87, 0xffffaf, 0xffffd7, 0xffffff, 0x080808, 0x121212,
+			0x1c1c1c, 0x262626, 0x303030, 0x3a3a3a, 0x444444, 0x4e4e4e, 0x585858, 0x626262, 0x6c6c6c, 0x767676,
+			0x808080, 0x8a8a8a, 0x949494, 0x9e9e9e, 0xa8a8a8, 0xb2b2b2, 0xbcbcbc, 0xc6c6c6, 0xd0d0d0, 0xdadada,
+			0xe4e4e4, 0xeeeeee };
+
+	private final Map<AnsiElement, LabColor> lookup;
+
+	/**
+	 * Create a new {@link AnsiColors} instance with the specified bit depth.
+	 * @param bitDepth the required bit depth
+	 */
+	public AnsiColors(BitDepth bitDepth) {
+		this.lookup = getLookup(bitDepth);
 	}
 
-	public static AnsiColor getClosest(Color color) {
-		return getClosest(new LabColor(color));
+	private Map<AnsiElement, LabColor> getLookup(BitDepth bitDepth) {
+		if (bitDepth == BitDepth.EIGHT) {
+			Map<Ansi8BitColor, LabColor> lookup = new LinkedHashMap<>();
+			for (int i = 0; i < ANSI_8BIT_COLOR_CODE_LOOKUP.length; i++) {
+				lookup.put(Ansi8BitColor.foreground(i), new LabColor(ANSI_8BIT_COLOR_CODE_LOOKUP[i]));
+			}
+			return Collections.unmodifiableMap(lookup);
+		}
+		return ANSI_COLOR_MAP;
+	}
+
+	/**
+	 * Find the closest {@link AnsiElement ANSI color} to the given AWT {@link Color}.
+	 * @param color the AWT color
+	 * @return the closest ANSI color
+	 */
+	public AnsiElement findClosest(Color color) {
+		return findClosest(new LabColor(color));
 	}
 
-	private static AnsiColor getClosest(LabColor color) {
-		AnsiColor result = null;
-		double resultDistance = Float.MAX_VALUE;
-		for (Entry<AnsiColor, LabColor> entry : ANSI_COLOR_MAP.entrySet()) {
-			double distance = color.getDistance(entry.getValue());
-			if (result == null || distance < resultDistance) {
-				resultDistance = distance;
-				result = entry.getKey();
+	private AnsiElement findClosest(LabColor color) {
+		AnsiElement closest = null;
+		double closestDistance = Float.MAX_VALUE;
+		for (Map.Entry<AnsiElement, LabColor> entry : this.lookup.entrySet()) {
+			double candidateDistance = color.getDistance(entry.getValue());
+			if (closest == null || candidateDistance < closestDistance) {
+				closestDistance = candidateDistance;
+				closest = entry.getKey();
 			}
 		}
-		return result;
+		return closest;
+	}
+
+	/**
+	 * Get the closest {@link AnsiColor ANSI color} to the given AWT {@link Color}.
+	 * @param color the color to find
+	 * @return the closest color
+	 * @deprecated since 2.2.0 in favor of {@link #findClosest(Color)}
+	 */
+	@Deprecated
+	public static AnsiColor getClosest(Color color) {
+		return (AnsiColor) new AnsiColors(BitDepth.FOUR).findClosest(color);
 	}
 
 	/**
@@ -132,4 +194,38 @@ private double f(double t) {
 
 	}
 
+	/**
+	 * Bit depths supported by this class.
+	 */
+	public enum BitDepth {
+
+		/**
+		 * 4 bits (16 color).
+		 * @see AnsiColor
+		 */
+		FOUR(4),
+
+		/**
+		 * 8 bits (256 color).
+		 * @see Ansi8BitColor
+		 */
+		EIGHT(8);
+
+		private final int bits;
+
+		BitDepth(int bits) {
+			this.bits = bits;
+		}
+
+		public static BitDepth of(int bits) {
+			for (BitDepth candidate : values()) {
+				if (candidate.bits == bits) {
+					return candidate;
+				}
+			}
+			throw new IllegalArgumentException("Unsupported ANSI bit depth '" + bits + "'");
+		}
+
+	}
+
 }