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<?php
/**
* @package dompdf
* @link https://github.com/dompdf/dompdf
* @license http://www.gnu.org/copyleft/lesser.html GNU Lesser General Public License
*/
namespace Dompdf\FrameDecorator;
use Dompdf\Dompdf;
use Dompdf\Helpers;
use Dompdf\Frame;
use Dompdf\Renderer;
/**
* Decorates frames for page layout
*
* @package dompdf
*/
class Page extends AbstractFrameDecorator
{
/**
* The y value of the bottom edge of the page area.
*
* https://www.w3.org/TR/CSS21/page.html#page-margins
*
* @var float
*/
protected $bottom_page_edge;
/**
* 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 = [];
//........................................................................
/**
* 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_edge = 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;
}
/**
* Calculate the bottom edge of the page area after margins have been
* applied for the current page.
*/
public function calculate_bottom_page_edge(): void
{
[, , , $cbh] = $this->get_containing_block();
$style = $this->get_style();
$margin_bottom = (float) $style->length_in_pt($style->margin_bottom, $cbh);
$this->bottom_page_edge = $cbh - $margin_bottom;
}
/**
* 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 = [];
$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 preceding frame's
* page_break_after property.
*
* @link http://www.w3.org/TR/CSS21/page.html#forced
*
* @param AbstractFrameDecorator $frame the frame to check
*
* @return bool true if a page break occurred
*/
function check_forced_page_break(Frame $frame)
{
// Skip check if page is already split and for the body
if ($this->_page_full || $frame->get_node()->nodeName === "body") {
return false;
}
$page_breaks = ["always", "left", "right"];
$style = $frame->get_style();
if (($frame->is_block_level() || $style->display === "table-row")
&& in_array($style->page_break_before, $page_breaks, true)
) {
// Prevent cascading splits
$frame->split(null, true, true);
$style->page_break_before = "auto";
$this->_page_full = true;
$frame->_already_pushed = true;
return true;
}
// Find the preceding block-level sibling (or table row). Inline
// elements are treated as if wrapped in an anonymous block container
// here. See https://www.w3.org/TR/CSS21/visuren.html#anonymous-block-level
$prev = $frame->get_prev_sibling();
while ($prev && (($prev->is_text_node() && $prev->get_node()->nodeValue === "")
|| $prev->get_node()->nodeName === "bullet")
) {
$prev = $prev->get_prev_sibling();
}
if ($prev && ($prev->is_block_level() || $prev->get_style()->display === "table-row")) {
if (in_array($prev->get_style()->page_break_after, $page_breaks, true)) {
// Prevent cascading splits
$frame->split(null, true, true);
$prev->get_style()->page_break_after = "auto";
$this->_page_full = true;
$frame->_already_pushed = true;
return true;
}
$prev_last_child = $prev->get_last_child();
while ($prev_last_child && (($prev_last_child->is_text_node() && $prev_last_child->get_node()->nodeValue === "")
|| $prev_last_child->get_node()->nodeName === "bullet")
) {
$prev_last_child = $prev_last_child->get_prev_sibling();
}
if ($prev_last_child
&& $prev_last_child->is_block_level()
&& in_array($prev_last_child->get_style()->page_break_after, $page_breaks, true)
) {
$frame->split(null, true, true);
$prev_last_child->get_style()->page_break_after = "auto";
$this->_page_full = true;
$frame->_already_pushed = true;
return true;
}
}
return false;
}
/**
* Check for a gap between the top content edge of a frame and its child
* content.
*
* Additionally, the top margin, border, and padding of the frame must fit
* on the current page.
*
* @param float $childPos The top margin or line-box edge of the child content.
* @param Frame $frame The parent frame to check.
* @return bool
*/
protected function hasGap(float $childPos, Frame $frame): bool
{
$style = $frame->get_style();
$cbw = $frame->get_containing_block("w");
$contentEdge = $frame->get_position("y") + (float) $style->length_in_pt([
$style->margin_top,
$style->border_top_width,
$style->padding_top
], $cbw);
return Helpers::lengthGreater($childPos, $contentEdge)
&& Helpers::lengthLessOrEqual($contentEdge, $this->bottom_page_edge);
}
/**
* 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 an
* unforced page break occurs here, the used values of the
* relevant 'margin-top' and 'margin-bottom' properties are set
* to '0'. When a forced page break occurs here, the used value
* of the relevant 'margin-bottom' property is set to '0'; the
* relevant 'margin-top' used value may either be set to '0' or
* retained.
* 2. Between line boxes inside a block container box.
* 3. Between the content edge of a block container box and the
* outer edges of its child content (margin edges of block-level
* children or line box edges for inline-level children) if there
* is a (non-zero) gap between them.
*
* 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 a 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) or (3) is allowed only
* if the 'page-break-inside' property of the element and all
* its ancestors is 'auto'.
*
* If the above does not provide enough break points to keep content
* from overflowing the page boxes, then rules A, B and D are
* dropped in order to find additional breakpoints.
*
* If that still does not lead to sufficient break points, rule C is
* dropped as well, to find still more break points.
*
* We also allow breaks between table rows.
*
* @param AbstractFrameDecorator $frame the frame to check
*
* @return bool true if a break is allowed, false otherwise
*/
protected function _page_break_allowed(Frame $frame)
{
Helpers::dompdf_debug("page-break", "_page_break_allowed(" . $frame->get_node()->nodeName . ")");
$display = $frame->get_style()->display;
// Block Frames (1):
if ($frame->is_block_level() || $display === "-dompdf-image") {
// Avoid breaks within table-cells
if ($this->_in_table > ($display === "table" ? 1 : 0)) {
Helpers::dompdf_debug("page-break", "In table: " . $this->_in_table);
return false;
}
// Rule A
if ($frame->get_style()->page_break_before === "avoid") {
Helpers::dompdf_debug("page-break", "before: avoid");
return false;
}
// Find the preceding block-level sibling. Inline elements are
// treated as if wrapped in an anonymous block container here. See
// https://www.w3.org/TR/CSS21/visuren.html#anonymous-block-level
$prev = $frame->get_prev_sibling();
while ($prev && (($prev->is_text_node() && $prev->get_node()->nodeValue === "")
|| $prev->get_node()->nodeName === "bullet")
) {
$prev = $prev->get_prev_sibling();
}
// Does the previous element allow a page break after?
if ($prev && ($prev->is_block_level() || $prev->get_style()->display === "-dompdf-image")
&& $prev->get_style()->page_break_after === "avoid"
) {
Helpers::dompdf_debug("page-break", "after: avoid");
return false;
}
// Rules B & D
$parent = $frame->get_parent();
$p = $parent;
while ($p) {
if ($p->get_style()->page_break_inside === "avoid") {
Helpers::dompdf_debug("page-break", "parent->inside: avoid");
return false;
}
$p = $p->find_block_parent();
}
// To prevent cascading page breaks when a top-level element has
// page-break-inside: avoid, ensure that at least one frame is
// on the page before splitting.
if ($parent->get_node()->nodeName === "body" && !$prev) {
// We are the body's first child
Helpers::dompdf_debug("page-break", "Body's first child.");
return false;
}
// Check for a possible type (3) break
if (!$prev && $parent && !$this->hasGap($frame->get_position("y"), $parent)) {
Helpers::dompdf_debug("page-break", "First block-level frame, no gap");
return false;
}
Helpers::dompdf_debug("page-break", "block: break allowed");
return true;
} // Inline frames (2):
else {
if ($frame->is_inline_level()) {
// 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();
$parent_style = $block_parent->get_style();
$line = $block_parent->get_current_line_box();
$line_count = count($block_parent->get_line_boxes());
$line_number = $frame->get_containing_line() && empty($line->get_frames())
? $line_count - 1
: $line_count;
// The line number of the frame can be less than the current
// number of line boxes, in case we are backtracking. As long as
// we are not checking for widows yet, just checking against the
// number of line boxes is sufficient in most cases, though.
if ($line_number <= $parent_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" && !$prev) {
// We are the body's first child
Helpers::dompdf_debug("page-break", "Body's first child.");
return false;
}
Helpers::dompdf_debug("page-break", "inline: break allowed");
return true;
// Table-rows
} else {
if ($display === "table-row") {
// If this is a nested table, prevent the page from breaking
if ($this->_in_table > 1) {
Helpers::dompdf_debug("page-break", "table: nested table");
return false;
}
// Rule A (table row)
if ($frame->get_style()->page_break_before === "avoid") {
Helpers::dompdf_debug("page-break", "before: avoid");
return false;
}
// Find the preceding row
$prev = $frame->get_prev_sibling();
if (!$prev) {
$prev_group = $frame->get_parent()->get_prev_sibling();
if ($prev_group
&& in_array($prev_group->get_style()->display, Table::ROW_GROUPS, true)
) {
$prev = $prev_group->get_last_child();
}
}
// Check if a page break is allowed after the preceding row
if ($prev && $prev->get_style()->page_break_after === "avoid") {
Helpers::dompdf_debug("page-break", "after: avoid");
return false;
}
// Avoid breaking before the first row of a table
if (!$prev) {
Helpers::dompdf_debug("page-break", "table: first-row");
return false;
}
// Rule B (table row)
// Check if the page_break_inside property is not 'avoid'
// for the parent table or any of its ancestors
$table = Table::find_parent_table($frame);
$p = $table;
while ($p) {
if ($p->get_style()->page_break_inside === "avoid") {
Helpers::dompdf_debug("page-break", "parent->inside: avoid");
return false;
}
$p = $p->find_block_parent();
}
Helpers::dompdf_debug("page-break", "table-row: break allowed");
return true;
} else {
if (in_array($display, Table::ROW_GROUPS, true)) {
// Disallow breaks at row-groups: only split at row boundaries
return false;
} else {
Helpers::dompdf_debug("page-break", "? " . $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 AbstractFrameDecorator $frame the frame to check
*
* @return bool
*/
function check_page_break(Frame $frame)
{
if ($this->_page_full || $frame->_already_pushed
// Never check for breaks on empty text nodes
|| ($frame->is_text_node() && $frame->get_node()->nodeValue === "")
) {
return false;
}
$p = $frame;
do {
$display = $p->get_style()->display;
if ($display == "table-row") {
if ($p->_already_pushed) { return false; }
}
} while ($p = $p->get_parent());
// If the frame is absolute or 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();
// 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 && $p !== $this) {
$cbw = $p->get_containing_block("w");
$max_y += (float) $p->get_style()->computed_bottom_spacing($cbw);
$p = $p->get_parent();
}
// Check if $frame flows off the page
if (Helpers::lengthLessOrEqual($max_y, $this->bottom_page_edge)) {
// 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;
$pushed_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 $frame.
break;
}
if ($iter->_already_pushed) {
$pushed_flg = true;
} elseif ($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;
$iter->_already_pushed = true;
$frame->_already_pushed = true;
return true;
}
if (!$flg && $next = $iter->get_last_child()) {
Helpers::dompdf_debug("page-break", "following last child.");
if ($next->is_table()) {
$this->_in_table++;
}
$iter = $next;
$pushed_flg = false;
continue;
}
if ($pushed_flg) {
// The frame was already pushed, avoid breaking on a previous page
break;
}
$next = $iter->get_prev_sibling();
// Skip empty text nodes
while ($next && $next->is_text_node() && $next->get_node()->nodeValue === "") {
$next = $next->get_prev_sibling();
}
if ($next) {
Helpers::dompdf_debug("page-break", "following prev sibling.");
if ($next->is_table() && !$iter->is_table()) {
$this->_in_table++;
} elseif (!$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->_already_pushed === false) {
$iter = $iter->get_parent();
}
if ($iter) {
$iter->split(null, true);
$iter->_already_pushed = true;
} else {
return false;
}
} else {
$frame->split(null, true);
}
$this->_page_full = true;
$frame->_already_pushed = true;
return true;
}
//........................................................................
public function split(?Frame $child = null, bool $page_break = false, bool $forced = false): void
{
// 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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