Add coloring modes to the blame page (issue-2, pull request #125)

Blame output is now colored according to Commit (default), Author or
Age. Both Commit and Author output uses random colors whereas Age uses a
single color with varying tints applied to indicate the age.  White
indicates the eldest commit with the tint darkening as the commits get
younger.

Change-Id: I045458329af4765e91d5829ce3e8d28e21eeb66e

1 files changed, 135 insertions, 0 deletions

diff --git a/src/main/java/com/gitblit/utils/ColorFactory.java b/src/main/java/com/gitblit/utils/ColorFactory.java
new file mode 100644
index 00000000..b40735a0
--- /dev/null
+++ b/src/main/java/com/gitblit/utils/ColorFactory.java
@@ -0,0 +1,135 @@
+/*
+ * Copyright 2013 Alex Lewis.
+ * Copyright 2013 gitblit.com.
+ *
+ * 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
+ *
+ *     http://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 com.gitblit.utils;
+
+import java.awt.Color;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Random;
+import java.util.Set;
+
+/**
+ * Factory for creating color maps.
+ *
+ * @author Alex Lewis
+ */
+public class ColorFactory {
+
+	private static final double MAX_TINT_FACTOR = 1;
+
+	private static final double MIN_TINT_FACTOR = 0.2;
+
+	private static final double FIXED_TINT_FACTOR = 0.875;
+
+	/**
+	 * Builds a map of the supplied keys to a random color tinted according to
+	 * the key's position in the set.
+	 *
+	 * Depending on the number of keys in the set a tint is calculated from 1.0
+	 * (I.e. white) to a minimum tint. The keys are sorted such that the
+	 * "lowest" value will have a full tint applied to it (1.0) with an equally
+	 * decreasing tint applied to each key thereafter.
+	 *
+	 * @param keys
+	 *            The keys to create a tinted color for.
+	 * @param baseColor
+	 *            the base color (optional)
+	 * @return The map of key to tinted color.
+	 */
+	public <T> Map<T, String> getGraduatedColorMap(Set<T> keys, Color baseColor) {
+		Map<T, String> colorMap = new HashMap<T, String>();
+
+		if (baseColor == null) {
+			baseColor = getRandomColor();
+		}
+		double tintStep = (MAX_TINT_FACTOR - MIN_TINT_FACTOR) / keys.size();
+
+		double currentTint = MAX_TINT_FACTOR;
+		for (T key : keys) {
+			Color color = tintColor(baseColor, currentTint);
+
+			colorMap.put(key, getColorString(color));
+
+			currentTint -= tintStep;
+		}
+
+		return colorMap;
+	}
+
+	/**
+	 * Builds a map of the supplied keys to random colors.
+	 *
+	 * Each color is selected randomly and tinted with a fixed tint.
+	 *
+	 * @param keys The keys to create the mapped colors.
+	 * @return The map of key to random color.
+	 */
+	public <T> Map<T, String> getRandomColorMap(Set<T> keys) {
+		Map<T, String> colorMap = new HashMap<T, String>();
+
+		for (T key : keys) {
+			Color color = tintColor(getRandomColor(), FIXED_TINT_FACTOR);
+			colorMap.put(key, getColorString(color));
+		}
+
+		return colorMap;
+	}
+
+	private Color getRandomColor() {
+		Random random = new Random();
+
+		Color randomColor = new Color(random.nextInt(256), random.nextInt(256),
+				random.nextInt(256));
+
+		return randomColor;
+	}
+
+	private Color tintColor(Color origColor, double tintFactor) {
+		int tintedRed = applyTint(origColor.getRed(), tintFactor);
+		int tintedGreen = applyTint(origColor.getGreen(), tintFactor);
+		int tintedBlue = applyTint(origColor.getBlue(), tintFactor);
+
+		Color tintedColor = new Color(tintedRed, tintedGreen, tintedBlue);
+
+		return tintedColor;
+	}
+
+	/**
+	 * Convert the color to an HTML compatible color string in hex format E.g.
+	 * #FF0000
+	 *
+	 * @param color The color to convert
+	 * @return The string version of the color I.e. #RRGGBB
+	 */
+	private String getColorString(Color color) {
+		return "#" + Integer.toHexString(color.getRGB() & 0x00ffffff);
+	}
+
+	/**
+	 * Tint the supplied color with a tint factor (0 to 1 inclusive) to make the
+	 * colour more pale I.e. closer to white.
+	 *
+	 * A Tint of 0 has no effect, a Tint of 1 turns the color white.
+	 *
+	 * @param color The original color
+	 * @param tintFactor The factor - 0 to 1 inclusive
+	 * @return The tinted color.
+	 */
+	private int applyTint(int color, double tintFactor) {
+		return (int) (color + ((255 - color) * tintFactor));
+	}
+}