如何计算bgcolor属性?
可能重复:
为什么HTML认为“chucknorris”是一种颜色?
如何计算bgcolor
属性?
当我使用下面的HTML代码...
<body bgcolor="#Deine Mutter hat eine Farbe und die ist grün."></body>
...我得到的是以下颜色。
顺便说一下:当我尝试在CSS中使用它时,它不会工作,并将应用标准颜色:
body{
color: #IchwillGOLD;
}
为什么?
我的第一个尝试就是对错误进行一点试验,虽然我发现系统有一些有趣的属性,但还不足以形成答案。 接下来,我将注意力转向标准。 我相信这是标准的原因是我在三个不同的浏览器上测试了它们,并且他们实际上都做了同样的事情。 使用标准我发现了会发生什么:
De
通过这种方式,你会看到你得到00FA00
Deine Mutter hat eine Farbe und die ist grün.
00FA00
Deine Mutter hat eine Farbe und die ist grün.
html5标准更准确地描述了这个过程,并且在这里描述了更多的情况:http://www.w3.org/TR/html5/common-microsyntax.html#colors“解析遗留颜色值的规则”
正如我在评论中所述,HTMLParser将它添加为一个CSS属性,并且Jasper已经回答了,它是通过规范。
履行
Webkit解析HTMLParser.cpp中的html,如果Parser在inBody中,它将bgColor属性添加为HTMLBodyElement.cpp中的CssColor
// Color parsing that matches HTML's "rules for parsing a legacy color value"
void HTMLElement::addHTMLColorToStyle(StylePropertySet* style, CSSPropertyID propertyID, const String& attributeValue)
{
// An empty string doesn't apply a color. (One containing only whitespace does, which is why this check occurs before stripping.)
if (attributeValue.isEmpty())
return;
String colorString = attributeValue.stripWhiteSpace();
// "transparent" doesn't apply a color either.
if (equalIgnoringCase(colorString, "transparent"))
return;
// If the string is a named CSS color or a 3/6-digit hex color, use that.
Color parsedColor(colorString);
if (!parsedColor.isValid())
parsedColor.setRGB(parseColorStringWithCrazyLegacyRules(colorString));
style->setProperty(propertyID, cssValuePool().createColorValue(parsedColor.rgb()));
}
你有很好的机会结束这种方法:
static RGBA32 parseColorStringWithCrazyLegacyRules(const String& colorString)
我认为它是支持像这样的传统颜色:body bgcolor = ff0000(Mozilla Gecko Test)。
Webkit / HTMLElement.cpp代码:parseColorStringWithCrazyLegacyRules:
static RGBA32 parseColorStringWithCrazyLegacyRules(const String& colorString)
{
// Per spec, only look at the first 128 digits of the string.
const size_t maxColorLength = 128;
// We'll pad the buffer with two extra 0s later, so reserve two more than the max.
Vector<char, maxColorLength+2> digitBuffer;
size_t i = 0;
// Skip a leading #.
if (colorString[0] == '#')
i = 1;
// Grab the first 128 characters, replacing non-hex characters with 0.
// Non-BMP characters are replaced with "00" due to them appearing as two "characters" in the String.
for (; i < colorString.length() && digitBuffer.size() < maxColorLength; i++) {
if (!isASCIIHexDigit(colorString[i]))
digitBuffer.append('0');
else
digitBuffer.append(colorString[i]);
}
if (!digitBuffer.size())
return Color::black;
// Pad the buffer out to at least the next multiple of three in size.
digitBuffer.append('0');
digitBuffer.append('0');
if (digitBuffer.size() < 6)
return makeRGB(toASCIIHexValue(digitBuffer[0]), toASCIIHexValue(digitBuffer[1]), toASCIIHexValue(digitBuffer[2]));
// Split the digits into three components, then search the last 8 digits of each component.
ASSERT(digitBuffer.size() >= 6);
size_t componentLength = digitBuffer.size() / 3;
size_t componentSearchWindowLength = min<size_t>(componentLength, 8);
size_t redIndex = componentLength - componentSearchWindowLength;
size_t greenIndex = componentLength * 2 - componentSearchWindowLength;
size_t blueIndex = componentLength * 3 - componentSearchWindowLength;
// Skip digits until one of them is non-zero,
// or we've only got two digits left in the component.
while (digitBuffer[redIndex] == '0' && digitBuffer[greenIndex] == '0'
&& digitBuffer[blueIndex] == '0' && (componentLength - redIndex) > 2) {
redIndex++;
greenIndex++;
blueIndex++;
}
ASSERT(redIndex + 1 < componentLength);
ASSERT(greenIndex >= componentLength);
ASSERT(greenIndex + 1 < componentLength * 2);
ASSERT(blueIndex >= componentLength * 2);
ASSERT(blueIndex + 1 < digitBuffer.size());
int redValue = toASCIIHexValue(digitBuffer[redIndex], digitBuffer[redIndex + 1]);
int greenValue = toASCIIHexValue(digitBuffer[greenIndex], digitBuffer[greenIndex + 1]);
int blueValue = toASCIIHexValue(digitBuffer[blueIndex], digitBuffer[blueIndex + 1]);
return makeRGB(redValue, greenValue, blueValue);
}
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