处理多项检查的最佳方式 ruby

Question

所以我正在尝试编写一个 HSL 到 RGB 的转换器（并最终转换为十六进制）我正在关注这个 colorspace conversion theory，但我似乎卡在了第 6 步

Now we need to do up to 3 tests to select the correct formula for each color channel. Let’s start with Red.

test 1 – If 6 x temporary_R is smaller then 1, Red = temporary_2 + (temporary_1 – temporary_2) x 6 x temporary_R In the case the first test is larger then 1 check the following

test 2 – If 2 x temporary_R is smaller then 1, Red = temporary_1 In the case the second test also is larger then 1 do the following

test 3 – If 3 x temporary_R is smaller then 2, Red = temporary_2 + (temporary_1 – temporary_2) x (0.666 – temporary_R) x 6 In the case the third test also is larger then 2 you do the following

Red = temporary_2

Ok lets do it for our Red value

6 x temporary_R = 6 x 0.869 = 5.214, so it’s larger then 1, we need to do test 2 2 x temporary_R = 2 x 0.869 = 1.738, it’s also larger then 1, we need to do test 3 3 x temporary_R = 3 x 0.869 = 2.607, it’s larger then 2, so we go for the last formula Red = temporary_2 = 0.0924 which rounded down is 0.09, which is a number we recognize from the RGB to HSL conversion

到目前为止，我已经猴子修补了一个函数来获取我的 HSL 颜色

def toRGB(hue, sat, lum)
  temp_1 =
  case lum
   when lum < 0.0
     lum x (1.0 * sat)
   when lum > 0.0
     (lum + sat) - lum
  end
  temp_2 = (2 * lum) - temp_1.to_f
  h = (hue/360.0).round(4)
  temp_r = (h + 0.333).round(4)
  temp_r = temp_r + 1 if temp_r < 0
  temp_r = temp_r - 1 if temp_r > 1
  temp_g = h 
  temp_b = (h - 0.333).round(4)
  temp_b = temp_b + 1 if temp_b < 0
  temp_b = temp_b - 1 if temp_b > 1
  red = 
  #test 1
  #test 2
  #test 3
  "#{red}"
end

我试图使用 case 语句

red = 
  case temp_r
    when 6 * temp_r < 1
      temp_2 + (temp_1 - temp_2) * 6 * temp_r
    when 2 * temp_r < 1
      temp_1
    when 3 * temp_r < 2
      temp_2 + (temp_1 - temp_2) * (0.666 - temp_r * 6)
  end

但后来我开始重新阅读说明，现在我真的看不出有什么方法可以在 ruby 中完成我需要的事情。可能是我多虑了。

如果您想在上下文中查看我的其余代码，您 can see it here

Answer 1

我在您的代码片段中注意到两件事：

您在 ruby 中混合了两种类型的 switch case 语句。

case a
when 1..5
 "It's between 1 and 5"
when 6
 "It's 6"
end

case
when a > 1 && a < 5
 "It's between 1 and 5"
when a == 6
 "It's 6"
end

看到区别，在第一种情况下，当你直接比较案例时，你必须提到你正在比较的变量名称，而在第二种情况下，你通过显式地放置一个条件来比较 true & false 条件在你的变量上，所以你不需要把它放在大小写旁边。

第二件事是根据你的条件语句，你的 case 语句中需要一个 else case。

red = 
  case
    when 6 * temp_r < 1
      temp_2 + (temp_1 - temp_2) * 6 * temp_r
    when 2 * temp_r < 1
      temp_1
    when 3 * temp_r < 2
      temp_2 + (temp_1 - temp_2) * (0.666 - temp_r * 6)
    else
      temp_2
  end

处理多项检查的最佳方式 ruby

Best way to handle multiple checks ruby

ruby

hsl

rgb

colors