Metodi di conversione all'interno dell'API no, non credo proprio.
Ma online ho trovato un esempio di quello che cerchi:
https://stackoverflow.com/questions/4126029/java-color-code-convert-to-color-name.
Ci sono diverse risposte, posto il codice di quella che mi sembra più completa:
import java.awt.Color;
import java.util.ArrayList;
/**
* Java Code to get a color name from rgb/hex value/awt color
*
* The part of looking up a color name from the rgb values is edited from
* https://gist.github.com/nightlark/6482130#file-gistfile1-java (that has some errors) by Ryan Mast (nightlark)
*
* @author Xiaoxiao Li
*
*/
public class ColorUtils {
/**
* Initialize the color list that we have.
*/
private ArrayList<ColorName> initColorList() {
ArrayList<ColorName> colorList = new ArrayList<ColorName>();
colorList.add(new ColorName("AliceBlue", 0xF0, 0xF8, 0xFF));
colorList.add(new ColorName("AntiqueWhite", 0xFA, 0xEB, 0xD7));
colorList.add(new ColorName("Aqua", 0x00, 0xFF, 0xFF));
colorList.add(new ColorName("Aquamarine", 0x7F, 0xFF, 0xD4));
colorList.add(new ColorName("Azure", 0xF0, 0xFF, 0xFF));
colorList.add(new ColorName("Beige", 0xF5, 0xF5, 0xDC));
colorList.add(new ColorName("Bisque", 0xFF, 0xE4, 0xC4));
colorList.add(new ColorName("Black", 0x00, 0x00, 0x00));
colorList.add(new ColorName("BlanchedAlmond", 0xFF, 0xEB, 0xCD));
colorList.add(new ColorName("Blue", 0x00, 0x00, 0xFF));
colorList.add(new ColorName("BlueViolet", 0x8A, 0x2B, 0xE2));
colorList.add(new ColorName("Brown", 0xA5, 0x2A, 0x2A));
colorList.add(new ColorName("BurlyWood", 0xDE, 0xB8, 0x87));
colorList.add(new ColorName("CadetBlue", 0x5F, 0x9E, 0xA0));
colorList.add(new ColorName("Chartreuse", 0x7F, 0xFF, 0x00));
colorList.add(new ColorName("Chocolate", 0xD2, 0x69, 0x1E));
colorList.add(new ColorName("Coral", 0xFF, 0x7F, 0x50));
colorList.add(new ColorName("CornflowerBlue", 0x64, 0x95, 0xED));
colorList.add(new ColorName("Cornsilk", 0xFF, 0xF8, 0xDC));
colorList.add(new ColorName("Crimson", 0xDC, 0x14, 0x3C));
colorList.add(new ColorName("Cyan", 0x00, 0xFF, 0xFF));
colorList.add(new ColorName("DarkBlue", 0x00, 0x00, 0x8B));
colorList.add(new ColorName("DarkCyan", 0x00, 0x8B, 0x8B));
colorList.add(new ColorName("DarkGoldenRod", 0xB8, 0x86, 0x0B));
colorList.add(new ColorName("DarkGray", 0xA9, 0xA9, 0xA9));
colorList.add(new ColorName("DarkGreen", 0x00, 0x64, 0x00));
colorList.add(new ColorName("DarkKhaki", 0xBD, 0xB7, 0x6B));
colorList.add(new ColorName("DarkMagenta", 0x8B, 0x00, 0x8B));
colorList.add(new ColorName("DarkOliveGreen", 0x55, 0x6B, 0x2F));
colorList.add(new ColorName("DarkOrange", 0xFF, 0x8C, 0x00));
colorList.add(new ColorName("DarkOrchid", 0x99, 0x32, 0xCC));
colorList.add(new ColorName("DarkRed", 0x8B, 0x00, 0x00));
colorList.add(new ColorName("DarkSalmon", 0xE9, 0x96, 0x7A));
colorList.add(new ColorName("DarkSeaGreen", 0x8F, 0xBC, 0x8F));
colorList.add(new ColorName("DarkSlateBlue", 0x48, 0x3D, 0x8B));
colorList.add(new ColorName("DarkSlateGray", 0x2F, 0x4F, 0x4F));
colorList.add(new ColorName("DarkTurquoise", 0x00, 0xCE, 0xD1));
colorList.add(new ColorName("DarkViolet", 0x94, 0x00, 0xD3));
colorList.add(new ColorName("DeepPink", 0xFF, 0x14, 0x93));
colorList.add(new ColorName("DeepSkyBlue", 0x00, 0xBF, 0xFF));
colorList.add(new ColorName("DimGray", 0x69, 0x69, 0x69));
colorList.add(new ColorName("DodgerBlue", 0x1E, 0x90, 0xFF));
colorList.add(new ColorName("FireBrick", 0xB2, 0x22, 0x22));
colorList.add(new ColorName("FloralWhite", 0xFF, 0xFA, 0xF0));
colorList.add(new ColorName("ForestGreen", 0x22, 0x8B, 0x22));
colorList.add(new ColorName("Fuchsia", 0xFF, 0x00, 0xFF));
colorList.add(new ColorName("Gainsboro", 0xDC, 0xDC, 0xDC));
colorList.add(new ColorName("GhostWhite", 0xF8, 0xF8, 0xFF));
colorList.add(new ColorName("Gold", 0xFF, 0xD7, 0x00));
colorList.add(new ColorName("GoldenRod", 0xDA, 0xA5, 0x20));
colorList.add(new ColorName("Gray", 0x80, 0x80, 0x80));
colorList.add(new ColorName("Green", 0x00, 0x80, 0x00));
colorList.add(new ColorName("GreenYellow", 0xAD, 0xFF, 0x2F));
colorList.add(new ColorName("HoneyDew", 0xF0, 0xFF, 0xF0));
colorList.add(new ColorName("HotPink", 0xFF, 0x69, 0xB4));
colorList.add(new ColorName("IndianRed", 0xCD, 0x5C, 0x5C));
colorList.add(new ColorName("Indigo", 0x4B, 0x00, 0x82));
colorList.add(new ColorName("Ivory", 0xFF, 0xFF, 0xF0));
colorList.add(new ColorName("Khaki", 0xF0, 0xE6, 0x8C));
colorList.add(new ColorName("Lavender", 0xE6, 0xE6, 0xFA));
colorList.add(new ColorName("LavenderBlush", 0xFF, 0xF0, 0xF5));
colorList.add(new ColorName("LawnGreen", 0x7C, 0xFC, 0x00));
colorList.add(new ColorName("LemonChiffon", 0xFF, 0xFA, 0xCD));
colorList.add(new ColorName("LightBlue", 0xAD, 0xD8, 0xE6));
colorList.add(new ColorName("LightCoral", 0xF0, 0x80, 0x80));
colorList.add(new ColorName("LightCyan", 0xE0, 0xFF, 0xFF));
colorList.add(new ColorName("LightGoldenRodYellow", 0xFA, 0xFA, 0xD2));
colorList.add(new ColorName("LightGray", 0xD3, 0xD3, 0xD3));
colorList.add(new ColorName("LightGreen", 0x90, 0xEE, 0x90));
colorList.add(new ColorName("LightPink", 0xFF, 0xB6, 0xC1));
colorList.add(new ColorName("LightSalmon", 0xFF, 0xA0, 0x7A));
colorList.add(new ColorName("LightSeaGreen", 0x20, 0xB2, 0xAA));
colorList.add(new ColorName("LightSkyBlue", 0x87, 0xCE, 0xFA));
colorList.add(new ColorName("LightSlateGray", 0x77, 0x88, 0x99));
colorList.add(new ColorName("LightSteelBlue", 0xB0, 0xC4, 0xDE));
colorList.add(new ColorName("LightYellow", 0xFF, 0xFF, 0xE0));
colorList.add(new ColorName("Lime", 0x00, 0xFF, 0x00));
colorList.add(new ColorName("LimeGreen", 0x32, 0xCD, 0x32));
colorList.add(new ColorName("Linen", 0xFA, 0xF0, 0xE6));
colorList.add(new ColorName("Magenta", 0xFF, 0x00, 0xFF));
colorList.add(new ColorName("Maroon", 0x80, 0x00, 0x00));
colorList.add(new ColorName("MediumAquaMarine", 0x66, 0xCD, 0xAA));
colorList.add(new ColorName("MediumBlue", 0x00, 0x00, 0xCD));
colorList.add(new ColorName("MediumOrchid", 0xBA, 0x55, 0xD3));
colorList.add(new ColorName("MediumPurple", 0x93, 0x70, 0xDB));
colorList.add(new ColorName("MediumSeaGreen", 0x3C, 0xB3, 0x71));
colorList.add(new ColorName("MediumSlateBlue", 0x7B, 0x68, 0xEE));
colorList.add(new ColorName("MediumSpringGreen", 0x00, 0xFA, 0x9A));
colorList.add(new ColorName("MediumTurquoise", 0x48, 0xD1, 0xCC));
colorList.add(new ColorName("MediumVioletRed", 0xC7, 0x15, 0x85));
colorList.add(new ColorName("MidnightBlue", 0x19, 0x19, 0x70));
colorList.add(new ColorName("MintCream", 0xF5, 0xFF, 0xFA));
colorList.add(new ColorName("MistyRose", 0xFF, 0xE4, 0xE1));
colorList.add(new ColorName("Moccasin", 0xFF, 0xE4, 0xB5));
colorList.add(new ColorName("NavajoWhite", 0xFF, 0xDE, 0xAD));
colorList.add(new ColorName("Navy", 0x00, 0x00, 0x80));
colorList.add(new ColorName("OldLace", 0xFD, 0xF5, 0xE6));
colorList.add(new ColorName("Olive", 0x80, 0x80, 0x00));
colorList.add(new ColorName("OliveDrab", 0x6B, 0x8E, 0x23));
colorList.add(new ColorName("Orange", 0xFF, 0xA5, 0x00));
colorList.add(new ColorName("OrangeRed", 0xFF, 0x45, 0x00));
colorList.add(new ColorName("Orchid", 0xDA, 0x70, 0xD6));
colorList.add(new ColorName("PaleGoldenRod", 0xEE, 0xE8, 0xAA));
colorList.add(new ColorName("PaleGreen", 0x98, 0xFB, 0x98));
colorList.add(new ColorName("PaleTurquoise", 0xAF, 0xEE, 0xEE));
colorList.add(new ColorName("PaleVioletRed", 0xDB, 0x70, 0x93));
colorList.add(new ColorName("PapayaWhip", 0xFF, 0xEF, 0xD5));
colorList.add(new ColorName("PeachPuff", 0xFF, 0xDA, 0xB9));
colorList.add(new ColorName("Peru", 0xCD, 0x85, 0x3F));
colorList.add(new ColorName("Pink", 0xFF, 0xC0, 0xCB));
colorList.add(new ColorName("Plum", 0xDD, 0xA0, 0xDD));
colorList.add(new ColorName("PowderBlue", 0xB0, 0xE0, 0xE6));
colorList.add(new ColorName("Purple", 0x80, 0x00, 0x80));
colorList.add(new ColorName("Red", 0xFF, 0x00, 0x00));
colorList.add(new ColorName("RosyBrown", 0xBC, 0x8F, 0x8F));
colorList.add(new ColorName("RoyalBlue", 0x41, 0x69, 0xE1));
colorList.add(new ColorName("SaddleBrown", 0x8B, 0x45, 0x13));
colorList.add(new ColorName("Salmon", 0xFA, 0x80, 0x72));
colorList.add(new ColorName("SandyBrown", 0xF4, 0xA4, 0x60));
colorList.add(new ColorName("SeaGreen", 0x2E, 0x8B, 0x57));
colorList.add(new ColorName("SeaShell", 0xFF, 0xF5, 0xEE));
colorList.add(new ColorName("Sienna", 0xA0, 0x52, 0x2D));
colorList.add(new ColorName("Silver", 0xC0, 0xC0, 0xC0));
colorList.add(new ColorName("SkyBlue", 0x87, 0xCE, 0xEB));
colorList.add(new ColorName("SlateBlue", 0x6A, 0x5A, 0xCD));
colorList.add(new ColorName("SlateGray", 0x70, 0x80, 0x90));
colorList.add(new ColorName("Snow", 0xFF, 0xFA, 0xFA));
colorList.add(new ColorName("SpringGreen", 0x00, 0xFF, 0x7F));
colorList.add(new ColorName("SteelBlue", 0x46, 0x82, 0xB4));
colorList.add(new ColorName("Tan", 0xD2, 0xB4, 0x8C));
colorList.add(new ColorName("Teal", 0x00, 0x80, 0x80));
colorList.add(new ColorName("Thistle", 0xD8, 0xBF, 0xD8));
colorList.add(new ColorName("Tomato", 0xFF, 0x63, 0x47));
colorList.add(new ColorName("Turquoise", 0x40, 0xE0, 0xD0));
colorList.add(new ColorName("Violet", 0xEE, 0x82, 0xEE));
colorList.add(new ColorName("Wheat", 0xF5, 0xDE, 0xB3));
colorList.add(new ColorName("White", 0xFF, 0xFF, 0xFF));
colorList.add(new ColorName("WhiteSmoke", 0xF5, 0xF5, 0xF5));
colorList.add(new ColorName("Yellow", 0xFF, 0xFF, 0x00));
colorList.add(new ColorName("YellowGreen", 0x9A, 0xCD, 0x32));
return colorList;
}
/**
* Get the closest color name from our list
*
* @param r
* @param g
* @param b
* @return
*/
public String getColorNameFromRgb(int r, int g, int b) {
ArrayList<ColorName> colorList = initColorList();
ColorName closestMatch = null;
int minMSE = Integer.MAX_VALUE;
int mse;
for (ColorName c : colorList) {
mse = c.computeMSE(r, g, b);
if (mse < minMSE) {
minMSE = mse;
closestMatch = c;
}
}
if (closestMatch != null) {
return closestMatch.getName();
} else {
return "No matched color name.";
}
}
/**
* Convert hexColor to rgb, then call getColorNameFromRgb(r, g, b)
*
* @param hexColor
* @return
*/
public String getColorNameFromHex(int hexColor) {
int r = (hexColor & 0xFF0000) >> 16;
int g = (hexColor & 0xFF00) >> 8;
int b = (hexColor & 0xFF);
return getColorNameFromRgb(r, g, b);
}
public int colorToHex(Color c) {
return Integer.decode("0x"
+ Integer.toHexString(c.getRGB()).substring(2));
}
public String getColorNameFromColor(Color color) {
return getColorNameFromRgb(color.getRed(), color.getGreen(),
color.getBlue());
}
/**
* SubClass of ColorUtils. In order to lookup color name
*
* @author Xiaoxiao Li
*
*/
public class ColorName {
public int r, g, b;
public String name;
public ColorName(String name, int r, int g, int b) {
this.r = r;
this.g = g;
this.b = b;
this.name = name;
}
public int computeMSE(int pixR, int pixG, int pixB) {
return (int) (((pixR - r) * (pixR - r) + (pixG - g) * (pixG - g) + (pixB - b)
* (pixB - b)) / 3);
}
public int getR() {
return r;
}
public int getG() {
return g;
}
public int getB() {
return b;
}
public String getName() {
return name;
}
}
}
Fondamentalmente ti preoccupi tu di definire un insieme di colori "noti", per cui definisci componenti e nomi, e poi vai a ricercare il colore a partire dalle tue componenti, che siano r,g,b (che a me pare il modo più semplice per generare un colore "casuale") o esadecimali.
Se vuoi una corrispondenza esatta, ovvero vuoi che le componenti siano esattamente quelle, puoi usare una mappa (diciamo
colorMap) e prendere il colore semplicemente con il get, ma avrai null per ogni combinazione non definita, quindi praticamente sempre, a meno che tu non voglia definirti 16 milioni e passa di colori
Altrimenti puoi cercare il colore più "vicino" a quello generato casualmente, in questo caso puoi usare una lista o un set per memorizzare i colori noti, e poi usi il concetto di "rgb distance", ovvero calcoli la somma dei valori assoluti degli scarti tra le componenti del colore originale e di ogni colore nella lista, prendendo il colore con la somma minore (o la somma dei quadrati degli scarti, come nel codice sopra, che si avvicina di più al concetto comune di "distanza").