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exports.name = "colorDifference";
exports.description = "Elements should provide sufficient color difference";
exports.rule = function(report) {
/* Checkpoint 2.1 ***********************************************************/
// TODO: not sure about the best way to test that information isn't hidden
// when colors go away.
/* Checkpoint 2.2 ***********************************************************/
var fc = fiveui.color;
var MIN_COLOR_DIFF = 500; // http://www.w3.org/TR/2000/WD-AERT-20000426#color
/**
* Return the absolute "color difference" between two * given RGB color
* objects.
* Input is two RGB color objects.
*/
var colorDiff = function (c1, c2) {
return Math.abs(c1.r - c2.r) +
Math.abs(c1.g - c2.g) +
Math.abs(c1.b - c2.b);
};
fiveui.query('*')
.filter(function () { // filter for lowest level elts having non-empty text
var $this = $(this);
return $this.children().length == 0 && $.trim($this.text()).length > 0;
})
.each(function (i) {
// TODO take into account fg alpha values
var fg = fc.colorToRGB($(this).css('color'));
var bg = fc.findBGColor($(this));
if (fg && bg) {
var diff = colorDiff(fg, bg);
if (diff < MIN_COLOR_DIFF) {
report.error('Element has poor color difference: ' + diff, this);
}
}
});
};
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