为什么领先的“＃FF”在十六进制颜色值？ [英] Why the leading "#FF" in hexadecimal color values?

问题描述

我使用Expression Blend 3并手工编写了一些XAML，特别是控件的颜色值。

我有一个已经转换的RGB颜色列表以十六进制。我只需要将十六进制值插入到我的XAML中。

最初，我将来自电子邮件的十六进制值粘贴到适当的属性中。在我完成之前，Blend开始适应，突出显示颜色属性，并用一个工具提示告诉我令牌无效。经过一番研究后，我发现在十六进制值前面加上一个英镑符号（＃）解决了这个问题。

在研究这个问题的过程中，我开始通过Blend中的颜色选择器改变颜色。我很快发现Blend插入的值不仅以磅符号开始，而且还以FF开头。我正在粘贴的值是有效的十六进制格式的有效颜色。但是，当将RGB值输入到Blend并让Blend插入十六进制值时，我注意到所有mycolors都以#FF作为前缀。正如我已经指出的那样，删除＃会产生错误，但是删除FF将根本没有任何效果。

在十六进制颜色的世界里，颜色＃5A7F39真的和＃FF5A7F39一样吗？为什么FF？他们是两个不同的十六进制值，对吗？但在屏幕上显示完全相同。为什么区别？

解决方案

这可能是颜色的alpha分量，代表不透明度（00-> transparent，FF - > opaque）。

MSDN似乎同意这一点： http://msdn.microsoft.com/en-us/library/bb980062（VS.95）.aspx

16位十六进制，alpha - #AARRGGBB

I'm using Expression Blend 3 and writing some of the XAML by hand, specifically the color values of controls.

I have a list of RGB colors already converted to hexadecimal. I just need to insert the hex value into my XAML.

Initially, I pasted the hex value from an email into the appropriate properties. Before I could finish, Blend started having a fit, underlining the color property with a squiggle and a tooltip telling me "Token is not valid." After some research, I found placing a pound sign ("#") in front of the hex value resolved this issue.

In the process of researching this problem, I started chaning colors via the color picker in Blend. I quickly found the values Blend was inserting not only started with the pound sign but also "FF". The values I was pasting were valid colors in valid hex format. But when entering the RGB values into Blend and letting Blend insert the hex value, I noticed all mycolors were prefixed with "#FF". Removing the #, as i already pointed out, generated errors but removing the "FF" seamed to have no effect at all.

In the world of hexadecimal colors, is the color #5A7F39 really the same as #FF5A7F39 ? Why the FF ? They are two different hex values, right? But appear identical onscreen. Why the difference?

解决方案

That may be the alpha component of the color, which represents the opacity (00 -> transparent, FF -> opaque).

MSDN seems to agree with this : http://msdn.microsoft.com/en-us/library/bb980062(VS.95).aspx

16-bit hexadecimal, alpha -- #AARRGGBB

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