/**
* Calculate the ideal used value for the width property as per:
* http://www.w3.org/TR/CSS21/visudet.html#Computing_widths_and_margins
*
* @param float $width
* @return array
*/
protected function _calculate_width($width)
{
$style = $this->_frame->get_style();
$w = $this->_frame->get_containing_block("w");
if ($style->position === "fixed") {
$w = $this->_frame->get_parent()->get_containing_block("w");
}
$rm = $style->length_in_pt($style->margin_right, $w);
$lm = $style->length_in_pt($style->margin_left, $w);
$left = $style->length_in_pt($style->left, $w);
$right = $style->length_in_pt($style->right, $w);
// Handle 'auto' values
$dims = array($style->border_left_width, $style->border_right_width, $style->padding_left, $style->padding_right, $width !== "auto" ? $width : 0, $rm !== "auto" ? $rm : 0, $lm !== "auto" ? $lm : 0);
// absolutely positioned boxes take the 'left' and 'right' properties into account
if ($style->position === "absolute" || $style->position === "fixed") {
$absolute = true;
$dims[] = $left !== "auto" ? $left : 0;
$dims[] = $right !== "auto" ? $right : 0;
} else {
$absolute = false;
}
$sum = $style->length_in_pt($dims, $w);
// Compare to the containing block
$diff = $w - $sum;
if ($diff > 0) {
if ($absolute) {
// resolve auto properties: see
// http://www.w3.org/TR/CSS21/visudet.html#abs-non-replaced-width
if ($width === "auto" && $left === "auto" && $right === "auto") {
if ($lm === "auto") {
$lm = 0;
}
if ($rm === "auto") {
$rm = 0;
}
// Technically, the width should be "shrink-to-fit" i.e. based on the
// preferred width of the content... a little too costly here as a
// special case. Just get the width to take up the slack:
$left = 0;
$right = 0;
$width = $diff;
} else {
if ($width === "auto") {
if ($lm === "auto") {
$lm = 0;
}
if ($rm === "auto") {
$rm = 0;
}
if ($left === "auto") {
$left = 0;
}
if ($right === "auto") {
$right = 0;
}
$width = $diff;
} else {
if ($left === "auto") {
if ($lm === "auto") {
$lm = 0;
}
if ($rm === "auto") {
$rm = 0;
}
if ($right === "auto") {
$right = 0;
}
$left = $diff;
} else {
if ($right === "auto") {
if ($lm === "auto") {
$lm = 0;
}
if ($rm === "auto") {
$rm = 0;
}
$right = $diff;
}
}
}
}
} else {
// Find auto properties and get them to take up the slack
if ($width === "auto") {
$width = $diff;
} else {
if ($lm === "auto" && $rm === "auto") {
$lm = $rm = round($diff / 2);
} else {
if ($lm === "auto") {
$lm = $diff;
} else {
if ($rm === "auto") {
$rm = $diff;
}
}
}
}
}
} else {
if ($diff < 0) {
// We are over constrained--set margin-right to the difference
$rm = $diff;
}
}
return array("width" => $width, "margin_left" => $lm, "margin_right" => $rm, "left" => $left, "right" => $right);
}
