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