/**
* See also CSS 2.1, p 10.3.7 Absolutely positioned, non-replaced
* elements
*/
function apply(&$box, &$context)
{
$containing_block =& $box->_get_containing_block();
$containing_block_width = $containing_block['right'] - $containing_block['left'];
$right =& $box->get_css_property(CSS_RIGHT);
$left =& $box->get_css_property(CSS_LEFT);
$wc =& $box->get_css_property(CSS_WIDTH);
// For the purposes of this section and the next, the term "static
// position" (of an element) refers, roughly, to the position an
// element would have had in the normal flow. More precisely:
//
// * The static position for 'left' is the distance from the left
// edge of the containing block to the left margin edge of a
// hypothetical box that would have been the first box of the
// element if its 'position' property had been 'static' and
// 'float' had been 'none'. The value is negative if the
// hypothetical box is to the left of the containing block.
//
// * The static position for 'right' is the distance from the
// right edge of the containing block to the right margin edge
// of the same hypothetical box as above. The value is positive
// if the hypothetical box is to the left of the containing
// block's edge.
//
// For the purposes of calculating the static position, the
// containing block of fixed positioned elements is the initial
// containing block instead of the viewport, and all scrollable
// boxes should be assumed to be scrolled to their origin.
//
// @todo: implement
$static_left = 0;
$static_right = 0;
// Calculation of the shrink-to-fit width is similar to
// calculating the width of a table cell using the automatic table
// layout algorithm. Roughly: calculate the preferred width by
// formatting the content without breaking lines other than where
// explicit line breaks occur, and also calculate the preferred
// minimum width, e.g., by trying all possible line breaks. CSS
// 2.1 does not define the exact algorithm. Thirdly, calculate the
// available width: this is found by solving for 'width' after
// setting 'left' (in case 1) or 'right' (in case 3) to 0.
//
// Then the shrink-to-fit width is: min(max(preferred minimum
// width, available width), preferred width).
$preferred_minimum_width = $box->get_preferred_minimum_width($context);
$available_width = $containing_block_width - ($left->isAuto() ? 0 : $left->getPoints($containing_block_width)) - ($right->isAuto() ? 0 : $right->getPoints($containing_block_width)) - $box->_get_hor_extra();
$preferred_width = $box->get_preferred_width($context);
$shrink_to_fit_width = min(max($preferred_minimum_width, $available_width), $preferred_width);
// The constraint that determines the used values for these
// elements is:
//
// 'left' + 'margin-left' + 'border-left-width' + 'padding-left' +
// 'width' + 'padding-right' + 'border-right-width' +
// 'margin-right' + 'right' + scrollbar width (if any) = width of
// containing block
// If all three of 'left', 'width', and 'right' are 'auto': First
// set any 'auto' values for 'margin-left' and 'margin-right' to
// 0. Then, if the 'direction' property of the containing block is
// 'ltr' set 'left' to the static position and apply rule number
// three below; otherwise, set 'right' to the static position and
// apply rule number one below.
if ($left->isAuto() && $right->isAuto() && $wc->isNull()) {
// @todo: support 'direction' property for the containing block
$box->setCSSProperty(CSS_LEFT, ValueLeft::fromString('0'));
}
// If none of the three is 'auto': If both 'margin-left' and
// 'margin-right' are 'auto', solve the equation under the extra
// constraint that the two margins get equal values, unless this
// would make them negative, in which case when direction of the
// containing block is 'ltr' ('rtl'), set 'margin-left'
// ('margin-right') to zero and solve for 'margin-right'
// ('margin-left'). If one of 'margin-left' or 'margin-right' is
// 'auto', solve the equation for that value. If the values are
// over-constrained, ignore the value for 'left' (in case the
// 'direction' property of the containing block is 'rtl') or
// 'right' (in case 'direction' is 'ltr') and solve for that
// value.
if (!$left->isAuto() && !$right->isAuto() && !$wc->isNull()) {
// @todo: implement
$box->put_width($wc->apply($box->get_width(), $containing_block_width));
}
// Otherwise, set 'auto' values for 'margin-left' and
// 'margin-right' to 0, and pick the one of the following six
// rules that applies.
// Case 1 ('left' and 'width' are 'auto' and 'right' is not
// 'auto', then the width is shrink-to-fit. Then solve for 'left')
if ($left->isAuto() && !$right->isAuto() && $wc->isNull()) {
$box->put_width($shrink_to_fit_width);
}
// Case 2 ('left' and 'right' are 'auto' and 'width' is not
// 'auto', then if the 'direction' property of the containing
// block is 'ltr' set 'left' to the static position, otherwise set
// 'right' to the static position. Then solve for 'left' (if
// 'direction is 'rtl') or 'right' (if 'direction' is 'ltr').)
if ($left->isAuto() && $right->isAuto() && !$wc->isNull()) {
// @todo: implement 'direction' support
$box->put_width($wc->apply($box->get_width(), $containing_block_width));
}
// Case 3 ('width' and 'right' are 'auto' and 'left' is not
// 'auto', then the width is shrink-to-fit . Then solve for
// 'right')
if (!$left->isAuto() && $right->isAuto() && $wc->isNull()) {
$box->put_width($shrink_to_fit_width);
}
// Case 4 ('left' is 'auto', 'width' and 'right' are not 'auto',
// then solve for 'left')
if ($left->isAuto() && !$right->isAuto() && !$wc->isNull()) {
$box->put_width($wc->apply($box->get_width(), $containing_block_width));
}
// Case 5 ('width' is 'auto', 'left' and 'right' are not 'auto',
// then solve for 'width')
if (!$left->isAuto() && !$right->isAuto() && $wc->isNull()) {
$box->put_width($containing_block_width - $left->getPoints($containing_block_width) - $right->getPoints($containing_block_width));
}
// Case 6 ('right' is 'auto', 'left' and 'width' are not 'auto',
// then solve for 'right')
if (!$left->isAuto() && $right->isAuto() && !$wc->isNull()) {
$box->put_width($wc->apply($box->get_width(), $containing_block_width));
}
/**
* After this we should remove width constraints or we may encounter problem
* in future when we'll try to call get_..._width functions for this box
*
* @todo Update the family of get_..._width function so that they would apply constraint
* using the containing block width, not "real" parent width
*/
$box->setCSSProperty(CSS_WIDTH, new WCConstant($box->get_width()));
}
function parse($value)
{
return ValueLeft::fromString($value);
}
