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exports.name = "Color use";
exports.description = "Use colors that have sufficient contrast and avoid issues with common forms of color blindness.";
var fc = fiveui.color;
var AA_NORMAL = 4.5;
var AA_BIG = 3;
var AAA_NORMAL = 7;
var AAA_BIG = 4.5;
/**
* Compute the font size in points, assuming 96dpi.
*/
var fontSizePt = function(elt) {
var px = $(elt).css('font-size');
return parseInt(px) * 72 / 96;
};
var isBold = function(elt) {
return $(elt).css('font-weight') == 'bold';
};
/**
* See if the text counts as "large scale" according to the W3C:
* (http://www.w3.org/TR/2008/REC-WCAG20-20081211/#larger-scaledef)
*/
var isLargeScale = function(elt) {
var size = fontSizePt(elt);
var bld = isBold(elt);
return (18 <= size || (14 <= size && bld));
};
var getAARatio = function(elt) {
if (isLargeScale(elt)) {
return AA_BIG;
}
return AA_NORMAL;
};
var getAAARatio = function(elt) {
if (isLargeScale(elt)) {
return AAA_BIG;
}
return AAA_NORMAL;
};
exports.rule = function (report) {
$5('#mw-content-text *')
// filter for lowest level elts having non-empty text
.filter(function () {
var $this = $(this);
return $this.children().length === 0 && $.trim($this.text()).length > 0;
})
.filter(exceptions)
.each(function (i, elt) {
var fg = fc.colorToRGB($(this).css('color'));
var bg = fc.findBGColor($(this));
if (fg && bg) {
var ratio = fc.contrast(fc.luminance(fg), fc.luminance(bg));
if (ratio < getAARatio(elt)) {
report.error('Element has poor contrast: ' + ratio +
" ratio should be greater than " + getAARatio(elt), elt);
} else if (ratio < getAAARatio(elt)){
report.warning('Element has poor contrast: ' + ratio +
" ratio should be greater than " + getAAARatio(elt), elt);
}
}
});
};
function exceptions() {
var $elem = $(this);
return !isStandardLink($elem) &&
!isNavboxLink($elem);
}
function isStandardLink($elem) {
var standard = ['new', 'external', 'extiw'];
var $a = $elem.closest('a');
return $a.is('a') && standard.some(function(klass) {
return $a.hasClass(klass);
});
}
function isNavboxLink($elem) {
var $a = $elem.closest('a');
var $nav = $a.closest('th.navbox-group');
return $a.length > 0 && $nav.length > 0;
}
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