Mega Code Archive
Utility for checking colors given either hexa or natural language string descriptions
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import java.awt.*;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.HashMap;
import java.util.Map;
/**
* Utility for checking colors given either hexa or "natural language" string descriptions.
* <p>For all assertEquals/equals methods, the "expected" parameter can be either:
* <ul>
* <li>A <code>Color</code> object specifying the exact color</li>
* <li>A <code>String</code> object containing the hexadecimal description of the exact color</li>
* <li>A <code>String</code> object containing the name of a color for an approximate comparison.
* The authorized names are those of the predefined Color objects defined in the Java
* <a href="http://java.sun.com/j2se/1.4.2/docs/api/java/awt/Color.html">Color</a> class.</li>
* </ul>
* </p>
*
* @see <a href="http://www.uispec4j.org/usingcolors.html">Using colors</a>
*/
public final class ColorUtils {
private static final Map<String, Color> nameToColorMap = buildNameToColorMap();
static final String UNEXPECTED_COLOR_CLASS = "Expected color should be an instance of Color or String";
public static boolean equals(Object expectedColor, Color actual) {
if (expectedColor instanceof Color) {
return expectedColor.equals(actual);
}
else if (expectedColor instanceof String) {
return equals((String)expectedColor, actual);
}
throw new IllegalArgumentException(UNEXPECTED_COLOR_CLASS);
}
public static boolean equals(String expectedColor, Color actual) {
Color foundColor = nameToColorMap.get(expectedColor.toUpperCase());
if (foundColor != null) {
return equals(foundColor, actual, true);
}
try {
foundColor = getColor(expectedColor);
return equals(foundColor, actual, false);
}
catch (NumberFormatException e) {
throw new IllegalArgumentException("'" + expectedColor + "' does not seem to be a color");
}
}
public static Color getColor(String hexaString) {
return new Color(Integer.parseInt(hexaString, 16));
}
/**
* Returns a normalized string description given a Color or another String description
*/
public static String getColorDescription(Object color) {
if (color instanceof Color) {
return getColorDescription((Color)color);
}
else if (color instanceof String) {
return getColorDescription((String)color);
}
throw new IllegalArgumentException(UNEXPECTED_COLOR_CLASS);
}
/**
* Returns a description string for a given Color object
*/
public static String getColorDescription(Color color) {
return toHexString(color).toUpperCase();
}
/**
* Normalizes a given color description string
*/
public static String getColorDescription(String color) {
return color.toUpperCase();
}
private static boolean equals(Color expected, Color actual, boolean matchBySimilarity) {
if (matchBySimilarity) {
return computeHSBDistance(expected, actual) < 0.9;
}
else {
return expected.equals(actual);
}
}
private static Color getColor(Object input) {
if (input instanceof Color) {
return (Color)input;
}
else if (input instanceof String) {
Color namedColor = nameToColorMap.get(((String)input).toUpperCase());
if (namedColor != null) {
return namedColor;
}
return getColor((String)input);
}
throw new IllegalArgumentException(UNEXPECTED_COLOR_CLASS);
}
private static double computeHSBDistance(Color expected, Color actual) {
float[] expectedHSB = toHSB(expected);
float[] actualHSB = toHSB(actual);
return Math.sqrt(Math.pow((expectedHSB[0] - actualHSB[0]) * 20, 2)
+ Math.pow(expectedHSB[1] - actualHSB[1], 2)
+ Math.pow((expectedHSB[2] - actualHSB[2]) * 2, 2));
}
private static float[] toHSB(Color aColor) {
return Color.RGBtoHSB(aColor.getRed(), aColor.getGreen(), aColor.getBlue(), null);
}
private static Map<String, Color> buildNameToColorMap() {
Map<String, Color> colorMap = new HashMap<String, Color>();
for (Field field : Color.class.getDeclaredFields()) {
if (isConstantColorField(field)) {
try {
Color color = (Color)field.get(null);
colorMap.put(field.getName().toUpperCase(), color);
}
catch (IllegalAccessException e) {
// Should not occur because the field is public and static
}
}
}
colorMap.put("DARKGREY", getColor("555555"));
colorMap.put("DARKBLUE", getColor("000055"));
colorMap.put("DARKRED", getColor("550000"));
colorMap.put("DARKGREEN", getColor("005500"));
colorMap.put("DARK_GREY", getColor("555555"));
colorMap.put("DARK_BLUE", getColor("000055"));
colorMap.put("DARK_RED", getColor("550000"));
colorMap.put("DARK_GREEN", getColor("005500"));
return colorMap;
}
private static boolean isConstantColorField(Field field) {
return Modifier.isPublic(field.getModifiers()) && Modifier.isStatic(field.getModifiers())
&& Color.class == field.getType();
}
private static String toHexString(Color color) {
return Integer.toHexString(color.getRGB()).substring(2);
}
}
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