Improve large table cell page break handling

This update should address the potential for Dompdf to enter an infinite loop attempting to page a table row when one of the cells inside that row is larger than the page size.

See dompdf#98

Author: bsweeney

src/FrameDecorator/AbstractFrameDecorator.php

@@ -695,6 +695,7 @@ function split(Frame $child = null, $force_pagebreak = false)
         $split->reset();
         $split->get_original_style()->text_indent = 0;
         $split->_splitted = true;
+        $split->_already_pushed = true;
 
         // The body's properties must be kept
         if ($node->nodeName !== "body") {

src/FrameDecorator/Page.php

@@ -11,6 +11,8 @@
 use Dompdf\Dompdf;
 use Dompdf\Helpers;
 use Dompdf\Frame;
+use Dompdf\FrameDecorator\Table as TableFrameDecorator;
+use Dompdf\FrameDecorator\TableRow as TableRowFrameDecorator;
 use Dompdf\Renderer;
 
 /**
@@ -192,7 +194,6 @@ function check_forced_page_break(Frame $frame)
         }
 
         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
@@ -277,7 +278,6 @@ function check_forced_page_break(Frame $frame)
      */
     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;
@@ -399,13 +399,14 @@ protected function _page_break_allowed(Frame $frame)
 
                 return true;
 
-                // Table-rows
+            // 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);
+                    $table = Table::find_parent_table($frame);
 
+                    $p = $table;
                     while ($p) {
                         if ($p->get_style()->page_break_inside === "avoid") {
                             Helpers::dompdf_debug("page-break", "parent->inside: avoid");
@@ -416,7 +417,7 @@ protected function _page_break_allowed(Frame $frame)
                     }
 
                     // Avoid breaking after the first row of a table
-                    if ($p && $p->get_first_child() === $frame) {
+                    if ($table && $table->get_first_child() === $frame || $table->get_first_child()->get_first_child() === $frame) {
                         Helpers::dompdf_debug("page-break", "table: first-row");
 
                         return false;
@@ -460,30 +461,55 @@ protected function _page_break_allowed(Frame $frame)
      */
     function check_page_break(Frame $frame)
     {
+        //FIXME: should not need to do this since we're tracking table status in `$this->_in_table`
+        $p = $frame;
+        $in_table = false;
+        while ($p) {
+            if ($p->is_table()) { $in_table = true; break; }
+            $p = $p->get_parent();
+        }
         // Do not split if we have already or if the frame was already
         // pushed to the next page (prevents infinite loops)
-        if ($this->_page_full || $frame->_already_pushed) {
+        if ($in_table) {
+            if ($this->_page_full && $frame->_already_pushed) {
+                return false;
+            }
+        } elseif ($this->_page_full || $frame->_already_pushed) {
+            return false;
+        }
+
+        //FIXME: work-around for infinite loop due to tables 
+        if ($in_table && $frame->_already_pushed) {
             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 of fixed it shouldn't break
         $p = $frame;
         do {
             if ($p->is_absolute()) {
                 return false;
             }
+
+            // FIXME If the row is taller than the page and
+            // if it the first of the page, we don't break
+            $display = $p->get_style()->display;
+            if ($display === "table-row"
+                && !$p->get_prev_sibling()
+                && $p->get_margin_height() > $this->get_margin_height()
+            ) {
+                return false;
+            }
         } while ($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;
 
@@ -578,11 +604,15 @@ function check_page_break(Frame $frame)
         // If we are in a table, backtrack to the nearest top-level table row
         if ($this->_in_table) {
             $iter = $frame;
-            while ($iter && $iter->get_style()->display !== "table-row" && $iter->get_style()->display !== 'table-row-group') {
+            while ($iter && $iter->get_style()->display !== "table-row" && $iter->get_style()->display !== 'table-row-group' && $iter->_already_pushed === false) {
                 $iter = $iter->get_parent();
             }
 
-            $iter->split(null, true);
+            if ($iter) {
+                $iter->split(null, true);
+            } else {
+                return false;
+            }
         } else {
             $frame->split(null, true);
         }

src/FrameDecorator/TableRow.php

@@ -53,4 +53,16 @@ function normalise()
             $p->move_after($frame);
         }
     }
+
+    function split(Frame $child = null, $force_pagebreak = false)
+    {
+        $this->_already_pushed = true;
+        
+        if (is_null($child)) {
+            parent::split();
+            return;
+        }
+
+        parent::split($child, $force_pagebreak);
+    }
 }