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<?php
/**
* @package dompdf
* @link http://dompdf.github.com/
* @author Benj Carson <benjcarson@digitaljunkies.ca>
* @license http://www.gnu.org/copyleft/lesser.html GNU Lesser General Public License
*/
namespace Dompdf\FrameDecorator;
use Dompdf\Css\Style;
use Dompdf\Dompdf;
use Dompdf\Helpers;
use Dompdf\Frame;
use Dompdf\Renderer;
/**
* Decorates frames for page layout
*
* @access private
* @package dompdf
*/
class Page extends AbstractFrameDecorator
{
/**
* y value of bottom page margin
*
* @var float
*/
protected $_bottom_page_margin;
/**
* Flag indicating page is full.
*
* @var bool
*/
protected $_page_full;
/**
* Number of tables currently being reflowed
*
* @var int
*/
protected $_in_table;
/**
* The pdf renderer
*
* @var Renderer
*/
protected $_renderer;
/**
* This page's floating frames
*
* @var array
*/
protected $_floating_frames = array();
//........................................................................
/**
* Class constructor
*
* @param Frame $frame the frame to decorate
* @param Dompdf $dompdf
*/
function __construct(Frame $frame, Dompdf $dompdf)
{
parent::__construct($frame, $dompdf);
$this->_page_full = false;
$this->_in_table = 0;
$this->_bottom_page_margin = null;
}
/**
* Set the renderer used for this pdf
*
* @param Renderer $renderer the renderer to use
*/
function set_renderer($renderer)
{
$this->_renderer = $renderer;
}
/**
* Return the renderer used for this pdf
*
* @return Renderer
*/
function get_renderer()
{
return $this->_renderer;
}
/**
* Set the frame's containing block. Overridden to set $this->_bottom_page_margin.
*
* @param float $x
* @param float $y
* @param float $w
* @param float $h
*/
function set_containing_block($x = null, $y = null, $w = null, $h = null)
{
parent::set_containing_block($x, $y, $w, $h);
//$w = $this->get_containing_block("w");
if (isset($h)) {
$this->_bottom_page_margin = $h;
} // - $this->_frame->get_style()->length_in_pt($this->_frame->get_style()->margin_bottom, $w);
}
/**
* Returns true if the page is full and is no longer accepting frames.
*
* @return bool
*/
function is_full()
{
return $this->_page_full;
}
/**
* Start a new page by resetting the full flag.
*/
function next_page()
{
$this->_floating_frames = array();
$this->_renderer->new_page();
$this->_page_full = false;
}
/**
* Indicate to the page that a table is currently being reflowed.
*/
function table_reflow_start()
{
$this->_in_table++;
}
/**
* Indicate to the page that table reflow is finished.
*/
function table_reflow_end()
{
$this->_in_table--;
}
/**
* Return whether we are currently in a nested table or not
*
* @return bool
*/
function in_nested_table()
{
return $this->_in_table > 1;
}
/**
* Check if a forced page break is required before $frame. This uses the
* frame's page_break_before property as well as the preceeding frame's
* page_break_after property.
*
* @link http://www.w3.org/TR/CSS21/page.html#forced
*
* @param Frame $frame the frame to check
*
* @return bool true if a page break occured
*/
function check_forced_page_break(Frame $frame)
{
// Skip check if page is already split
if ($this->_page_full) {
return null;
}
$block_types = array("block", "list-item", "table", "inline");
$page_breaks = array("always", "left", "right");
$style = $frame->get_style();
if (!in_array($style->display, $block_types)) {
return false;
}
// Find the previous block-level sibling
$prev = $frame->get_prev_sibling();
while ($prev && !in_array($prev->get_style()->display, $block_types)) {
$prev = $prev->get_prev_sibling();
}
if (in_array($style->page_break_before, $page_breaks)) {
// Prevent cascading splits
$frame->split(null, true);
// We have to grab the style again here because split() resets
// $frame->style to the frame's orignal style.
$frame->get_style()->page_break_before = "auto";
$this->_page_full = true;
return true;
}
if ($prev && in_array($prev->get_style()->page_break_after, $page_breaks)) {
// Prevent cascading splits
$frame->split(null, true);
$prev->get_style()->page_break_after = "auto";
$this->_page_full = true;
return true;
}
if ($prev && $prev->get_last_child() && $frame->get_node()->nodeName != "body") {
$prev_last_child = $prev->get_last_child();
if (in_array($prev_last_child->get_style()->page_break_after, $page_breaks)) {
$frame->split(null, true);
$prev_last_child->get_style()->page_break_after = "auto";
$this->_page_full = true;
return true;
}
}
return false;
}
/**
* 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");
Helpers::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) {
Helpers::dompdf_debug("page-break", "In table: " . $this->_in_table);
return false;
}
// Rules A & B
if ($frame->get_style()->page_break_before === "avoid") {
Helpers::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") {
Helpers::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 && $parent->get_style()->page_break_inside === "avoid") {
Helpers::dompdf_debug("page-break", "parent inside: avoid");
return false;
}
// To prevent cascading page breaks when a top-level element has
// page-break-inside: avoid, ensure that at least one frame is
// on the page before splitting.
if ($parent->get_node()->nodeName === "body" && !$prev) {
// We are the body's first child
Helpers::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);
}
Helpers::dompdf_debug("page-break", "block: break allowed");
return true;
} // Inline frames (2):
else {
if (in_array($display, Style::$INLINE_TYPES)) {
// Avoid breaks within table-cells
if ($this->_in_table) {
Helpers::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) {
Helpers::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") {
Helpers::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" && !$prev) {
// We are the body's first child
Helpers::dompdf_debug("page-break", "Body's first child.");
return false;
}
// Skip breaks on empty text nodes
if ($frame->is_text_node() &&
$frame->get_node()->nodeValue == ""
) {
return false;
}
Helpers::dompdf_debug("page-break", "inline: break allowed");
return true;
// Table-rows
} else {
if ($display === "table-row") {
// Simply check if the parent table's page_break_inside property is
// not 'avoid'
$p = Table::find_parent_table($frame);
while ($p) {
if ($p->get_style()->page_break_inside === "avoid") {
Helpers::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() === $frame) {
Helpers::dompdf_debug("page-break", "table: first-row");
return false;
}
// If this is a nested table, prevent the page from breaking
if ($this->_in_table > 1) {
Helpers::dompdf_debug("page-break", "table: nested table");
return false;
}
Helpers::dompdf_debug("page-break", "table-row/row-groups: break allowed");
return true;
} else {
if (in_array($display, Table::$ROW_GROUPS)) {
// Disallow breaks at row-groups: only split at row boundaries
return false;
} else {
Helpers::dompdf_debug("page-break", "? " . $frame->get_style()->display . "");
return false;
}
}
}
}
}
/**
* Check if $frame will fit on the page. If the frame does not fit,
* the frame tree is modified so that a page break occurs in the
* correct location.
*
* @param Frame $frame the frame to check
*
* @return bool
*/
function check_page_break(Frame $frame)
{
// Do not split if we have already or if the frame was already
// pushed to the next page (prevents infinite loops)
if ($this->_page_full || $frame->_already_pushed) {
return false;
}
// If the frame is absolute of fixed it shouldn't break
$p = $frame;
do {
if ($p->is_absolute())
return false;
} while ($p = $p->get_parent());
$margin_height = $frame->get_margin_height();
// FIXME If the row is taller than the page and
// if it the first of the page, we don't break
if ($frame->get_style()->display === "table-row" &&
!$frame->get_prev_sibling() &&
$margin_height > $this->get_margin_height()
)
return false;
// Determine the frame's maximum y value
$max_y = (float)$frame->get_position("y") + $margin_height;
// If a split is to occur here, then the bottom margins & paddings of all
// parents of $frame must fit on the page as well:
$p = $frame->get_parent();
while ($p) {
$max_y += $p->get_style()->computed_bottom_spacing();
$p = $p->get_parent();
}
// Check if $frame flows off the page
if ($max_y <= $this->_bottom_page_margin)
// no: do nothing
return false;
Helpers::dompdf_debug("page-break", "check_page_break");
Helpers::dompdf_debug("page-break", "in_table: " . $this->_in_table);
// yes: determine page break location
$iter = $frame;
$flg = false;
$in_table = $this->_in_table;
Helpers::dompdf_debug("page-break", "Starting search");
while ($iter) {
// echo "\nbacktrack: " .$iter->get_node()->nodeName ." ".spl_object_hash($iter->get_node()). "";
if ($iter === $this) {
Helpers::dompdf_debug("page-break", "reached root.");
// We've reached the root in our search. Just split at $frame.
break;
}
if ($this->_page_break_allowed($iter)) {
Helpers::dompdf_debug("page-break", "break allowed, splitting.");
$iter->split(null, true);
$this->_page_full = true;
$this->_in_table = $in_table;
$frame->_already_pushed = true;
return true;
}
if (!$flg && $next = $iter->get_last_child()) {
Helpers::dompdf_debug("page-break", "following last child.");
if ($next->is_table())
$this->_in_table++;
$iter = $next;
continue;
}
if ($next = $iter->get_prev_sibling()) {
Helpers::dompdf_debug("page-break", "following prev sibling.");
if ($next->is_table() && !$iter->is_table())
$this->_in_table++;
else if (!$next->is_table() && $iter->is_table())
$this->_in_table--;
$iter = $next;
$flg = false;
continue;
}
if ($next = $iter->get_parent()) {
Helpers::dompdf_debug("page-break", "following parent.");
if ($iter->is_table())
$this->_in_table--;
$iter = $next;
$flg = true;
continue;
}
break;
}
$this->_in_table = $in_table;
// No valid page break found. Just break at $frame.
Helpers::dompdf_debug("page-break", "no valid break found, just splitting.");
// If we are in a table, backtrack to the nearest top-level table row
if ($this->_in_table) {
$iter = $frame;
while ($iter && $iter->get_style()->display !== "table-row" && $iter->get_style()->display !== 'table-row-group')
$iter = $iter->get_parent();
$iter->split(null, true);
} else {
$frame->split(null, true);
}
$this->_page_full = true;
$frame->_already_pushed = true;
return true;
}
//........................................................................
/**
* @param Frame|null $frame
* @param bool $force_pagebreak
*/
function split(Frame $frame = null, $force_pagebreak = false)
{
// Do nothing
}
/**
* Add a floating frame
*
* @param Frame $frame
*
* @return void
*/
function add_floating_frame(Frame $frame)
{
array_unshift($this->_floating_frames, $frame);
}
/**
* @return Frame[]
*/
function get_floating_frames()
{
return $this->_floating_frames;
}
/**
* @param $key
*/
public function remove_floating_frame($key)
{
unset($this->_floating_frames[$key]);
}
/**
* @param Frame $child
* @return int|mixed
*/
public function get_lowest_float_offset(Frame $child)
{
$style = $child->get_style();
$side = $style->clear;
$float = $style->float;
$y = 0;
if ($float === "none") {
foreach ($this->_floating_frames as $key => $frame) {
if ($side === "both" || $frame->get_style()->float === $side) {
$y = max($y, $frame->get_position("y") + $frame->get_margin_height());
}
$this->remove_floating_frame($key);
}
}
if ($y > 0) {
$y++; // add 1px buffer from float
}
return $y;
}
}
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