[英]Converting from HSV (HSB in Java) to RGB without using java.awt.Color (disallowed on Google App Engine)
我想我应该发布这个问题,即使我已经找到了解决方案,因为当我搜索它时,Java实现并不容易获得。
使用HSV代替RGB可以生成具有相同饱和度和亮度的颜色(我想要的东西)。
Google App Engine不允许使用java.awt.Color,因此执行以下操作以在HSV和RGB之间进行转换不是一个选项:
Color c = Color.getHSBColor(hue, saturation, value);
String rgb = Integer.toHexString(c.getRGB());
编辑:我按照尼克约翰逊的评论中的描述移动了我的答案。
前animo, - 亚历山大。
我对颜色数学一无所知,但是我可以为代码提供这种替代结构,这让我的审美感觉更加刺激,因为它让我明白6个案例中的每一个是如何只是一个不同的价值排列,t和p 。 (此外,我对长期的if-else链条也有一种非理性的恐惧。)
public static String hsvToRgb(float hue, float saturation, float value) {
int h = (int)(hue * 6);
float f = hue * 6 - h;
float p = value * (1 - saturation);
float q = value * (1 - f * saturation);
float t = value * (1 - (1 - f) * saturation);
switch (h) {
case 0: return rgbToString(value, t, p);
case 1: return rgbToString(q, value, p);
case 2: return rgbToString(p, value, t);
case 3: return rgbToString(p, q, value);
case 4: return rgbToString(t, p, value);
case 5: return rgbToString(value, p, q);
default: throw new RuntimeException("Something went wrong when converting from HSV to RGB. Input was " + hue + ", " + saturation + ", " + value);
}
}
public static String rgbToString(float r, float g, float b) {
String rs = Integer.toHexString((int)(r * 256));
String gs = Integer.toHexString((int)(g * 256));
String bs = Integer.toHexString((int)(b * 256));
return rs + gs + bs;
}
您应该使用Oracle提供的HSBtoRGB实现,将其源代码复制到您的项目中。 java.awt.Color是开源的。 Peter Recore和Yngling提供的算法不健全,并且对于某些输入将返回非法RGB值,如“256,256,0”。 Oracle的实现非常强大,而是使用它。
使用提供的ColorUtils
HSLToColor(float\[\] hsl)
和
[RGBToHSL(int r, int g, int b, float\[\] hsl)]
方法很容易互相转换!
例如:
float[] hsl = new float[]{1.5, 2.0, 1.5};
int color = ColorUtils.HSLToColor(hsl);
现在得到颜色
float[] hslStub = new float[3];
float[] hslFromColor = ColorUtils.colorToHSL(color, hslStub);
现在得到hsl
这是源代码 。
我的转换代码:
/**
* @param H
* 0-360
* @param S
* 0-100
* @param V
* 0-100
* @return color in hex string
*/
public static String hsvToRgb(float H, float S, float V) {
float R, G, B;
H /= 360f;
S /= 100f;
V /= 100f;
if (S == 0)
{
R = V * 255;
G = V * 255;
B = V * 255;
} else {
float var_h = H * 6;
if (var_h == 6)
var_h = 0; // H must be < 1
int var_i = (int) Math.floor((double) var_h); // Or ... var_i =
// floor( var_h )
float var_1 = V * (1 - S);
float var_2 = V * (1 - S * (var_h - var_i));
float var_3 = V * (1 - S * (1 - (var_h - var_i)));
float var_r;
float var_g;
float var_b;
if (var_i == 0) {
var_r = V;
var_g = var_3;
var_b = var_1;
} else if (var_i == 1) {
var_r = var_2;
var_g = V;
var_b = var_1;
} else if (var_i == 2) {
var_r = var_1;
var_g = V;
var_b = var_3;
} else if (var_i == 3) {
var_r = var_1;
var_g = var_2;
var_b = V;
} else if (var_i == 4) {
var_r = var_3;
var_g = var_1;
var_b = V;
} else {
var_r = V;
var_g = var_1;
var_b = var_2;
}
R = var_r * 255; // RGB results from 0 to 255
G = var_g * 255;
B = var_b * 255;
}
String rs = Integer.toHexString((int) (R));
String gs = Integer.toHexString((int) (G));
String bs = Integer.toHexString((int) (B));
if (rs.length() == 1)
rs = "0" + rs;
if (gs.length() == 1)
gs = "0" + gs;
if (bs.length() == 1)
bs = "0" + bs;
return "#" + rs + gs + bs;
}
在Android上使用的示例:
tv.setBackgroundColor(Color.parseColor((ColorOperations.hsvToRgb(100, 100, 57))));
@Peter Recore的回答不使用舍入。
可能更正确的方法是使用它来复制java.awt.Color中的内容,这就是它在Java 6中的样子:
public static int HSBtoRGB(float hue, float saturation, float brightness) {
int r = 0, g = 0, b = 0;
if (saturation == 0) {
r = g = b = (int) (brightness * 255.0f + 0.5f);
} else {
float h = (hue - (float)Math.floor(hue)) * 6.0f;
float f = h - (float)java.lang.Math.floor(h);
float p = brightness * (1.0f - saturation);
float q = brightness * (1.0f - saturation * f);
float t = brightness * (1.0f - (saturation * (1.0f - f)));
switch ((int) h) {
case 0:
r = (int) (brightness * 255.0f + 0.5f);
g = (int) (t * 255.0f + 0.5f);
b = (int) (p * 255.0f + 0.5f);
break;
case 1:
r = (int) (q * 255.0f + 0.5f);
g = (int) (brightness * 255.0f + 0.5f);
b = (int) (p * 255.0f + 0.5f);
break;
case 2:
r = (int) (p * 255.0f + 0.5f);
g = (int) (brightness * 255.0f + 0.5f);
b = (int) (t * 255.0f + 0.5f);
break;
case 3:
r = (int) (p * 255.0f + 0.5f);
g = (int) (q * 255.0f + 0.5f);
b = (int) (brightness * 255.0f + 0.5f);
break;
case 4:
r = (int) (t * 255.0f + 0.5f);
g = (int) (p * 255.0f + 0.5f);
b = (int) (brightness * 255.0f + 0.5f);
break;
case 5:
r = (int) (brightness * 255.0f + 0.5f);
g = (int) (p * 255.0f + 0.5f);
b = (int) (q * 255.0f + 0.5f);
break;
}
}
return 0xff000000 | (r << 16) | (g << 8) | (b << 0);
}
这里的舍入似乎是正确的。
解决方案在这里找到: http : //martin.ankerl.com/2009/12/09/how-to-create-random-colors-programmatically/
Martin Ankerl提供了关于这个主题的好文章,并提供了Ruby脚本。 对于那些忙于(或懒惰)在Java中实现它的人来说,这就是我所做的(我相信它可以更有效地编写,请随时发表评论):
public static String hsvToRgb(float hue, float saturation, float value) {
float r, g, b;
int h = (int)(hue * 6);
float f = hue * 6 - h;
float p = value * (1 - saturation);
float q = value * (1 - f * saturation);
float t = value * (1 - (1 - f) * saturation);
if (h == 0) {
r = value;
g = t;
b = p;
} else if (h == 1) {
r = q;
g = value;
b = p;
} else if (h == 2) {
r = p;
g = value;
b = t;
} else if (h == 3) {
r = p;
g = q;
b = value;
} else if (h == 4) {
r = t;
g = p;
b = value;
} else if (h <= 6) {
r = value;
g = p;
b = q;
} else {
throw new RuntimeException("Something went wrong when converting from HSV to RGB. Input was " + hue + ", " + saturation + ", " + value);
}
String rs = Integer.toHexString((int)(r * 255));
String gs = Integer.toHexString((int)(g * 255));
String bs = Integer.toHexString((int)(b * 255));
return rs + gs + bs;
}
使用SWT,您可以使用以下代码段:
RGB rgb = new RGB(r, g, b);
float[] hsbColor = rgb.getHSB();
rgb = new RGB(hsbColor[0], hsbColor[1], hsbColor[2]);
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