/**
* Determine if a page break is allowed before $frame
* http://www.w3.org/TR/CSS21/page.html#allowed-page-breaks
*
* In the normal flow, page breaks can occur at the following places:
*
* 1. In the vertical margin between block boxes. When a page
* break occurs here, the used values of the relevant
* 'margin-top' and 'margin-bottom' properties are set to '0'.
* 2. Between line boxes inside a block box.
*
* These breaks are subject to the following rules:
*
* * Rule A: Breaking at (1) is allowed only if the
* 'page-break-after' and 'page-break-before' properties of
* all the elements generating boxes that meet at this margin
* allow it, which is when at least one of them has the value
* 'always', 'left', or 'right', or when all of them are
* 'auto'.
*
* * Rule B: However, if all of them are 'auto' and the
* nearest common ancestor of all the elements has a
* 'page-break-inside' value of 'avoid', then breaking here is
* not allowed.
*
* * Rule C: Breaking at (2) is allowed only if the number of
* line boxes between the break and the start of the enclosing
* block box is the value of 'orphans' or more, and the number
* of line boxes between the break and the end of the box is
* the value of 'widows' or more.
*
* * Rule D: In addition, breaking at (2) is allowed only if
* the 'page-break-inside' property is 'auto'.
*
* If the above doesn't provide enough break points to keep
* content from overflowing the page boxes, then rules B and D are
* dropped in order to find additional breakpoints.
*
* If that still does not lead to sufficient break points, rules A
* and C are dropped as well, to find still more break points.
*
* We will also allow breaks between table rows. However, when
* splitting a table, the table headers should carry over to the
* next page (but they don't yet).
*
* @param Frame $frame the frame to check
* @return bool true if a break is allowed, false otherwise
*/
protected function _page_break_allowed(Frame $frame)
{
$block_types = array("block", "list-item", "table", "-dompdf-image");
dompdf_debug("page-break", "_page_break_allowed(" . $frame->get_node()->nodeName . ")");
$display = $frame->get_style()->display;
// Block Frames (1):
if (in_array($display, $block_types)) {
// Avoid breaks within table-cells
if ($this->_in_table) {
dompdf_debug("page-break", "In table: " . $this->_in_table);
return false;
}
// Rules A & B
if ($frame->get_style()->page_break_before === "avoid") {
dompdf_debug("page-break", "before: avoid");
return false;
}
// Find the preceeding block-level sibling
$prev = $frame->get_prev_sibling();
while ($prev && !in_array($prev->get_style()->display, $block_types)) {
$prev = $prev->get_prev_sibling();
}
// Does the previous element allow a page break after?
if ($prev && $prev->get_style()->page_break_after === "avoid") {
dompdf_debug("page-break", "after: avoid");
return false;
}
// If both $prev & $frame have the same parent, check the parent's
// page_break_inside property.
$parent = $frame->get_parent();
if ($prev && $parent && $parent->get_style()->page_break_inside === "avoid") {
dompdf_debug("page-break", "parent inside: avoid");
return false;
}
// To prevent cascading page breaks when a top-level element has
// page-break-inside: avoid, ensure that at least one frame is
// on the page before splitting.
if ($parent->get_node()->nodeName === "body" && !$prev) {
// We are the body's first child
dompdf_debug("page-break", "Body's first child.");
return false;
}
// If the frame is the first block-level frame, use the value from
// $frame's parent instead.
if (!$prev && $parent) {
return $this->_page_break_allowed($parent);
}
dompdf_debug("page-break", "block: break allowed");
return true;
} else {
if (in_array($display, Style::$INLINE_TYPES)) {
// Avoid breaks within table-cells
if ($this->_in_table) {
dompdf_debug("page-break", "In table: " . $this->_in_table);
return false;
}
// Rule C
$block_parent = $frame->find_block_parent();
if (count($block_parent->get_line_boxes()) < $frame->get_style()->orphans) {
dompdf_debug("page-break", "orphans");
return false;
}
// FIXME: Checking widows is tricky without having laid out the
// remaining line boxes. Just ignore it for now...
// Rule D
$p = $block_parent;
while ($p) {
if ($p->get_style()->page_break_inside === "avoid") {
dompdf_debug("page-break", "parent->inside: avoid");
return false;
}
$p = $p->find_block_parent();
}
// To prevent cascading page breaks when a top-level element has
// page-break-inside: avoid, ensure that at least one frame with
// some content is on the page before splitting.
$prev = $frame->get_prev_sibling();
while ($prev && ($prev->is_text_node() && trim($prev->get_node()->nodeValue) == "")) {
$prev = $prev->get_prev_sibling();
}
if ($block_parent->get_node()->nodeName === "body" && !$prev) {
// We are the body's first child
dompdf_debug("page-break", "Body's first child.");
return false;
}
// Skip breaks on empty text nodes
if ($frame->is_text_node() && $frame->get_node()->nodeValue == "") {
return false;
}
dompdf_debug("page-break", "inline: break allowed");
return true;
// Table-rows
} else {
if ($display === "table-row") {
// Simply check if the parent table's page_break_inside property is
// not 'avoid'
$p = Table_Frame_Decorator::find_parent_table($frame);
while ($p) {
if ($p->get_style()->page_break_inside === "avoid") {
dompdf_debug("page-break", "parent->inside: avoid");
return false;
}
$p = $p->find_block_parent();
}
// Avoid breaking after the first row of a table
if ($p && $p->get_first_child() === $frame) {
dompdf_debug("page-break", "table: first-row");
return false;
}
// If this is a nested table, prevent the page from breaking
if ($this->_in_table > 1) {
dompdf_debug("page-break", "table: nested table");
return false;
}
dompdf_debug("page-break", "table-row/row-groups: break allowed");
return true;
} else {
if (in_array($display, Table_Frame_Decorator::$ROW_GROUPS)) {
// Disallow breaks at row-groups: only split at row boundaries
return false;
} else {
dompdf_debug("page-break", "? " . $frame->get_style()->display . "");
return false;
}
}
}
}
}
/**
* Determine if a page break is allowed before $frame
*
* @param Frame $frame the frame to check
* @return bool true if a break is allowed, false otherwise
*/
protected function _page_break_allowed(Frame $frame)
{
/**
*
* http://www.w3.org/TR/CSS21/page.html#allowed-page-breaks
* /*
* In the normal flow, page breaks can occur at the following places:
*
* 1. In the vertical margin between block boxes. When a page
* break occurs here, the used values of the relevant
* 'margin-top' and 'margin-bottom' properties are set to '0'.
* 2. Between line boxes inside a block box.
*
* These breaks are subject to the following rules:
*
* * Rule A: Breaking at (1) is allowed only if the
* 'page-break-after' and 'page-break-before' properties of
* all the elements generating boxes that meet at this margin
* allow it, which is when at least one of them has the value
* 'always', 'left', or 'right', or when all of them are
* 'auto'.
*
* * Rule B: However, if all of them are 'auto' and the
* nearest common ancestor of all the elements has a
* 'page-break-inside' value of 'avoid', then breaking here is
* not allowed.
*
* * Rule C: Breaking at (2) is allowed only if the number of
* line boxes between the break and the start of the enclosing
* block box is the value of 'orphans' or more, and the number
* of line boxes between the break and the end of the box is
* the value of 'widows' or more.
*
* * Rule D: In addition, breaking at (2) is allowed only if
* the 'page-break-inside' property is 'auto'.
*
* If the above doesn't provide enough break points to keep
* content from overflowing the page boxes, then rules B and D are
* dropped in order to find additional breakpoints.
*
* If that still does not lead to sufficient break points, rules A
* and C are dropped as well, to find still more break points.
*
* [endquote]
*
* We will also allow breaks between table rows. However, when
* splitting a table, the table headers should carry over to the
* next page (but they don't yet).
*/
$block_types = array("block", "list-item", "table");
// echo "\nbreak_allowed: " . $frame->get_node()->nodeName ."\n";
$display = $frame->get_style()->display;
// Block Frames (1):
if (in_array($display, $block_types)) {
// Avoid breaks within table-cells
if ($this->_in_table) {
// echo "In table: " . $this->_in_table ."\n";
return false;
}
// Rules A & B
if ($frame->get_style()->page_break_before == "avoid") {
// echo "before: avoid\n";
return false;
}
// Find the preceeding block-level sibling
$prev = $frame->get_prev_sibling();
while ($prev && !in_array($prev->get_style()->display, $block_types)) {
$prev = $prev->get_prev_sibling();
}
// Does the previous element allow a page break after?
if ($prev && $prev->get_style()->page_break_after == "avoid") {
// echo "after: avoid\n";
return false;
}
// If both $prev & $frame have the same parent, check the parent's
// page_break_inside property.
$parent = $frame->get_parent();
if ($prev && $parent && $parent->get_style()->page_break_inside == "avoid") {
// echo "parent inside: avoid\n";
return false;
}
// To prevent cascading page breaks when a top-level element has
// page-break-inside: avoid, ensure that at least one frame is
// on the page before splitting.
if ($parent->get_node()->nodeName == "body" && !$prev) {
// We are the body's first child
// echo "Body's first child.\n";
return false;
}
// If the frame is the first block-level frame, use the value from
// $frame's parent instead.
if (!$prev && $parent) {
return $this->_page_break_allowed($parent);
}
// echo "block: break allowed\n";
return true;
} else {
if (in_array($display, Style::$INLINE_TYPES)) {
// Avoid breaks within table-cells
if ($this->_in_table) {
// echo "In table: " . $this->_in_table ."\n";
return false;
}
// Rule C
$block_parent = $frame->find_block_parent();
if (count($block_parent->get_lines()) < $frame->get_style()->orphans) {
// echo "orphans\n";
return false;
}
// FIXME: Checking widows is tricky without having laid out the
// remaining line boxes. Just ignore it for now...
// Rule D
if ($block_parent->get_style()->page_break_inside == "avoid") {
// echo "parent->inside: avoid\n";
return false;
}
// To prevent cascading page breaks when a top-level element has
// page-break-inside: avoid, ensure that at least one frame with
// some content is on the page before splitting.
$prev = $frame->get_prev_sibling();
while ($prev && ($prev->get_node()->nodeName == "#text" && trim($prev->get_node()->nodeValue) == "")) {
$prev = $prev->get_prev_sibling();
}
if ($block_parent->get_node()->nodeName == "body" && !$prev) {
// We are the body's first child
// echo "Body's first child.\n";
return false;
}
// Skip breaks on empty text nodes
if ($frame->get_node()->nodeName == "#text" && $frame->get_node()->nodeValue == "") {
return false;
}
// echo "inline: break allowed\n";
return true;
// Table-rows
} else {
if ($display == "table-row") {
// Simply check if the parent table's page_break_inside property is
// not 'avoid'
$p = Table_Frame_Decorator::find_parent_table($frame);
if ($p->get_style()->page_break_inside == "avoid") {
// echo "table: page-break-inside: avoid\n";
return false;
}
// Check the table's parent element
$table_parent = $p->get_parent();
if ($table_parent->get_style()->page_break_inside == "avoid") {
// echo "table->parent: page-break-inside: avoid\n";
return false;
}
// Avoid breaking after the first row of a table
if ($p->get_first_child() === $frame) {
// echo "table: first-row\n";
return false;
}
// echo "table-row/row-groups: break allowed\n";
return true;
} else {
if (in_array($display, Table_Frame_Decorator::$ROW_GROUPS)) {
// Disallow breaks at row-groups: only split at row boundaries
return false;
} else {
// echo "? " . $frame->get_style()->display . "\n";
return false;
}
}
}
}
}
/**
* Parses the CSS "content" property
*
* @return string The resulting string
*/
protected function _parse_content()
{
// Matches generated content
$re = "/\n" . "\\s(counters?\\([^)]*\\))|\n" . "\\A(counters?\\([^)]*\\))|\n" . "\\s([\"']) ( (?:[^\"']|\\\\[\"'])+ )(?<!\\\\)\\3|\n" . "\\A([\"']) ( (?:[^\"']|\\\\[\"'])+ )(?<!\\\\)\\5|\n" . "\\s([^\\s\"']+)|\n" . "\\A([^\\s\"']+)\n" . "/xi";
$content = $this->_frame->get_style()->content;
$quotes = $this->_parse_quotes();
// split on spaces, except within quotes
if (!preg_match_all($re, $content, $matches, PREG_SET_ORDER)) {
return;
}
$text = "";
foreach ($matches as $match) {
if (isset($match[2]) && $match[2] !== "") {
$match[1] = $match[2];
}
if (isset($match[6]) && $match[6] !== "") {
$match[4] = $match[6];
}
if (isset($match[8]) && $match[8] !== "") {
$match[7] = $match[8];
}
if (isset($match[1]) && $match[1] !== "") {
// counters?(...)
$match[1] = mb_strtolower(trim($match[1]));
// Handle counter() references:
// http://www.w3.org/TR/CSS21/generate.html#content
$i = mb_strpos($match[1], ")");
if ($i === false) {
continue;
}
$args = explode(",", mb_substr($match[1], 8, $i - 8));
$counter_id = $args[0];
if ($match[1][7] === "(") {
// counter(name [,style])
if (isset($args[1])) {
$type = trim($args[1]);
} else {
$type = null;
}
$p = $this->_frame->find_block_parent();
$text .= $p->counter_value($counter_id, $type);
} else {
if ($match[1][7] === "s") {
// counters(name, string [,style])
if (isset($args[1])) {
$string = $this->_parse_string(trim($args[1]));
} else {
$string = "";
}
if (isset($args[2])) {
$type = $args[2];
} else {
$type = null;
}
$p = $this->_frame->find_block_parent();
$tmp = "";
while ($p) {
$tmp = $p->counter_value($counter_id, $type) . $string . $tmp;
$p = $p->find_block_parent();
}
$text .= $tmp;
} else {
// countertops?
continue;
}
}
} else {
if (isset($match[4]) && $match[4] !== "") {
// String match
$text .= $this->_parse_string($match[4]);
} else {
if (isset($match[7]) && $match[7] !== "") {
// Directive match
if ($match[7] === "open-quote") {
// FIXME: do something here
$text .= $quotes[0][0];
} else {
if ($match[7] === "close-quote") {
// FIXME: do something else here
$text .= $quotes[0][1];
} else {
if ($match[7] === "no-open-quote") {
// FIXME:
} else {
if ($match[7] === "no-close-quote") {
// FIXME:
} else {
if (mb_strpos($match[7], "attr(") === 0) {
$i = mb_strpos($match[7], ")");
if ($i === false) {
continue;
}
$attr = mb_substr($match[7], 5, $i - 5);
if ($attr == "") {
continue;
}
$text .= $this->_frame->get_parent()->get_node()->getAttribute($attr);
} else {
continue;
}
}
}
}
}
}
}
}
}
return $text;
}
protected function _page_break_allowed(Frame $frame)
{
$block_types = array("block", "list-item", "table", "-dompdf-image");
dompdf_debug("page-break", "_page_break_allowed(" . $frame->get_node()->nodeName . ")");
$display = $frame->get_style()->display;
if (in_array($display, $block_types)) {
if ($this->_in_table) {
dompdf_debug("page-break", "In table: " . $this->_in_table);
return false;
}
if ($frame->get_style()->page_break_before === "avoid") {
dompdf_debug("page-break", "before: avoid");
return false;
}
$prev = $frame->get_prev_sibling();
while ($prev && !in_array($prev->get_style()->display, $block_types)) {
$prev = $prev->get_prev_sibling();
}
if ($prev && $prev->get_style()->page_break_after === "avoid") {
dompdf_debug("page-break", "after: avoid");
return false;
}
$parent = $frame->get_parent();
if ($prev && $parent && $parent->get_style()->page_break_inside === "avoid") {
dompdf_debug("page-break", "parent inside: avoid");
return false;
}
if ($parent->get_node()->nodeName === "body" && !$prev) {
dompdf_debug("page-break", "Body's first child.");
return false;
}
if (!$prev && $parent) {
return $this->_page_break_allowed($parent);
}
dompdf_debug("page-break", "block: break allowed");
return true;
} else {
if (in_array($display, Style::$INLINE_TYPES)) {
if ($this->_in_table) {
dompdf_debug("page-break", "In table: " . $this->_in_table);
return false;
}
$block_parent = $frame->find_block_parent();
if (count($block_parent->get_line_boxes()) < $frame->get_style()->orphans) {
dompdf_debug("page-break", "orphans");
return false;
}
$p = $block_parent;
while ($p) {
if ($p->get_style()->page_break_inside === "avoid") {
dompdf_debug("page-break", "parent->inside: avoid");
return false;
}
$p = $p->find_block_parent();
}
$prev = $frame->get_prev_sibling();
while ($prev && ($prev->is_text_node() && trim($prev->get_node()->nodeValue) == "")) {
$prev = $prev->get_prev_sibling();
}
if ($block_parent->get_node()->nodeName === "body" && !$prev) {
dompdf_debug("page-break", "Body's first child.");
return false;
}
if ($frame->is_text_node() && $frame->get_node()->nodeValue == "") {
return false;
}
dompdf_debug("page-break", "inline: break allowed");
return true;
} else {
if ($display === "table-row") {
$p = Table_Frame_Decorator::find_parent_table($frame);
while ($p) {
if ($p->get_style()->page_break_inside === "avoid") {
dompdf_debug("page-break", "parent->inside: avoid");
return false;
}
$p = $p->find_block_parent();
}
if ($p && $p->get_first_child() === $frame) {
dompdf_debug("page-break", "table: first-row");
return false;
}
if ($this->_in_table > 1) {
dompdf_debug("page-break", "table: nested table");
return false;
}
dompdf_debug("page-break", "table-row/row-groups: break allowed");
return true;
} else {
if (in_array($display, Table_Frame_Decorator::$ROW_GROUPS)) {
return false;
} else {
dompdf_debug("page-break", "? " . $frame->get_style()->display . "");
return false;
}
}
}
}
}
