Handle indirect references in annotation dictionaries

src/FpdfTrait.php

@@ -14,6 +14,7 @@
 use setasign\Fpdi\PdfParser\PdfParserException;
 use setasign\Fpdi\PdfParser\Type\PdfIndirectObject;
 use setasign\Fpdi\PdfParser\Type\PdfNull;
+use setasign\Fpdi\PdfParser\Type\PdfType;
 
 /**
  * This trait is used for the implementation of FPDI in FPDF and tFPDF.
@@ -142,20 +143,6 @@ protected function _putlinks($n)
                 $this->_put('/A <</S /URI /URI ' . $this->_textstring($pl[4]) . '>>');
                 if (isset($pl['importedLink'])) {
                     $values = $pl['importedLink']['pdfObject']->value;
-                    unset(
-                        $values['P'],
-                        $values['NM'],
-                        $values['AP'],
-                        $values['AS'],
-                        $values['Type'],
-                        $values['Subtype'],
-                        $values['Rect'],
-                        $values['A'],
-                        $values['QuadPoints'],
-                        $values['Rotate'],
-                        $values['M'],
-                        $values['StructParent']
-                    );
 
                     foreach ($values as $name => $entry) {
                         $this->_put('/' . $name . ' ', false);

src/PdfParser/Type/PdfType.php

@@ -69,6 +69,34 @@ protected static function ensureType($type, $value, $errorMessage)
         return $value;
     }
 
+    /**
+     * Flatten indirect object references to direct objects.
+     *
+     * @param PdfType $value
+     * @param PdfParser $parser
+     * @return PdfType
+     * @throws CrossReferenceException
+     * @throws PdfParserException
+     */
+    public static function flatten(PdfType $value, PdfParser $parser)
+    {
+        if ($value instanceof PdfIndirectObjectReference) {
+            return self::flatten(self::resolve($value, $parser), $parser);
+        }
+
+        if ($value instanceof PdfDictionary || $value instanceof PdfArray) {
+            foreach ($value->value as $key => $_value) {
+                $value->value[$key] = self::flatten($_value, $parser);
+            }
+        }
+
+        if ($value instanceof PdfStream) {
+            throw new PdfTypeException('There is a stream object found which cannot be flattened to a direct object.');
+        }
+
+        return $value;
+    }
+
     /**
      * The value of the PDF type.
      *

src/PdfReader/Page.php

@@ -381,6 +381,29 @@ public function getExternalLinks($box = PageBoundaries::CROP_BOX)
                     }
                 }
 
+                // we remove unsupported/unneeded values here
+                unset(
+                    $annotation->value['P'],
+                    $annotation->value['NM'],
+                    $annotation->value['AP'],
+                    $annotation->value['AS'],
+                    $annotation->value['Type'],
+                    $annotation->value['Subtype'],
+                    $annotation->value['Rect'],
+                    $annotation->value['A'],
+                    $annotation->value['QuadPoints'],
+                    $annotation->value['Rotate'],
+                    $annotation->value['M'],
+                    $annotation->value['StructParent'],
+                    $annotation->value['OC']
+                );
+
+                // ...and flatten the PDF object to eliminate any indirect references.
+                // Indirect references are a problem when writing the output in FPDF
+                // because FPDF uses pre-calculated object numbers while FPDI creates
+                // them at runtime.
+                $annotation = PdfType::flatten($annotation, $this->parser);
+
                 $links[] = [
                     'rect' => $normalizedRect,
                     'quadPoints' => $normalizedQuadPoints,

src/Tcpdf/Fpdi.php

@@ -303,21 +303,8 @@ protected function adjustLastLink($externalLink, $xPt, $scaleX, $yPt, $newHeight
         // ensure we have a default value - otherwise TCPDF will set it to 4 throughout
         $lastAnnotationOpt['f'] = 0;
 
+        // values in this dictonary are all direct objects and we don't need to resolve them here again.
         $values = $externalLink['pdfObject']->value;
-        unset(
-            $values['P'],
-            $values['NM'],
-            $values['AP'],
-            $values['AS'],
-            $values['Type'],
-            $values['Subtype'],
-            $values['Rect'],
-            $values['A'],
-            $values['QuadPoints'],
-            $values['Rotate'],
-            $values['M'],
-            $values['StructParent']
-        );
 
         foreach ($values as $key => $value) {
             try {
@@ -326,17 +313,17 @@ protected function adjustLastLink($externalLink, $xPt, $scaleX, $yPt, $newHeight
                         $value = PdfDictionary::ensure($value);
                         $bs = [];
                         if (isset($value->value['W'])) {
-                            $bs['w'] = PdfNumeric::ensure(PdfType::resolve($value->value['W'], $parser))->value;
+                            $bs['w'] = PdfNumeric::ensure($value->value['W'])->value;
                         }
 
                         if (isset($value->value['S'])) {
-                            $bs['s'] = PdfName::ensure(PdfType::resolve($value->value['S'], $parser))->value;
+                            $bs['s'] = PdfName::ensure($value->value['S'])->value;
                         }
 
                         if (isset($value->value['D'])) {
                             $d = [];
-                            foreach (PdfArray::ensure(PdfType::resolve($value->value['D'], $parser))->value as $item) {
-                                $d[] = PdfNumeric::ensure(PdfType::resolve($item, $parser))->value;
+                            foreach (PdfArray::ensure($value->value['D'])->value as $item) {
+                                $d[] = PdfNumeric::ensure($item)->value;
                             }
                             $bs['d'] = $d;
                         }
@@ -345,20 +332,20 @@ protected function adjustLastLink($externalLink, $xPt, $scaleX, $yPt, $newHeight
                         break;
 
                     case 'Border':
-                        $borderArray = PdfArray::ensure(PdfType::resolve($value, $parser))->value;
+                        $borderArray = PdfArray::ensure($value)->value;
                         if (count($borderArray) < 3) {
                             continue 2;
                         }
 
                         $border = [
-                            PdfNumeric::ensure(PdfType::resolve($borderArray[0], $parser))->value,
-                            PdfNumeric::ensure(PdfType::resolve($borderArray[1], $parser))->value,
-                            PdfNumeric::ensure(PdfType::resolve($borderArray[2], $parser))->value,
+                            PdfNumeric::ensure($borderArray[0])->value,
+                            PdfNumeric::ensure($borderArray[1])->value,
+                            PdfNumeric::ensure($borderArray[2])->value,
                         ];
                         if (isset($borderArray[3])) {
                             $dashArray = [];
-                            foreach (PdfArray::ensure(PdfType::resolve($borderArray[3], $parser))->value as $item) {
-                                $dashArray[] = PdfNumeric::ensure(PdfType::resolve($item, $parser))->value;
+                            foreach (PdfArray::ensure($borderArray[3])->value as $item) {
+                                $dashArray[] = PdfNumeric::ensure($item)->value;
                             }
                             $border[] = $dashArray;
                         }
@@ -371,7 +358,7 @@ protected function adjustLastLink($externalLink, $xPt, $scaleX, $yPt, $newHeight
                         $colors = PdfArray::ensure(PdfType::resolve($value, $parser))->value;
                         $m = count($colors) === 4 ? 100 : 255;
                         foreach ($colors as $item) {
-                            $c[] = PdfNumeric::ensure(PdfType::resolve($item, $parser))->value * $m;
+                            $c[] = PdfNumeric::ensure($item)->value * $m;
                         }
                         $lastAnnotationOpt['c'] = $c;
                         break;

tests/_files/pdfs/links/update-links.pdf.php

@@ -0,0 +1,42 @@
+<?php
+/* A simple helper script to modify links.pdf in view to indirect references in annotation dictionaries.
+ * We used SetaPDF-Core for doing such low-level modifications.
+ */
+
+require_once __DIR__ . '/../../../../../SetaPDF/library/SetaPDF/Autoload.php';
+
+$writer = new SetaPDF_Core_Writer_File('links-with-indirect-references.pdf');
+$document = SetaPDF_Core_Document::loadByFilename('links.pdf', $writer);
+
+$pages = $document->getCatalog()->getPages();
+$page = $pages->getPage(1);
+
+$annotations = $page->getAnnotations();
+$allAnnots = $annotations->getAll();
+
+$dict = $allAnnots[0]->getDictionary();
+$bs = $dict->getValue('BS');
+$d = $bs->getValue('D');
+$bs->offsetSet('D', $document->createNewObject($d));
+$dict->offsetSet('BS', $document->createNewObject($bs));
+
+$dict = $allAnnots[1]->getDictionary();
+$c = $dict->getValue('C');
+$object = $document->createNewObject($c);
+$ref = new SetaPDF_Core_Type_IndirectReference($object, 0, $document);
+$dict->offsetSet('C', $document->createNewObject($ref));
+
+
+$dict = $allAnnots[5]->getDictionary();
+$border = $dict->getValue('Border');
+$dict->offsetSet('Border', $document->createNewObject($border));
+
+$page = $pages->getPage(2);
+$annotations = $page->getAnnotations();
+$allAnnots = $annotations->getAll();
+
+$dict = $allAnnots[0]->getDictionary();
+$rect = $dict->getValue('Rect');
+$dict->offsetSet('Rect', $document->createNewObject($rect));
+
+$document->save()->finish();

tests/functional/LinkHandling/AbstractTest.php

@@ -33,7 +33,6 @@ protected function compatAssertEqualsWithDelta($expected, $actual, $message = ''
         }
     }
 
-
     protected function save($pdf)
     {
         return $pdf->Output('S');
@@ -131,11 +130,11 @@ public function testDoNotImportLinks()
      * This test simply imports a page with several links including quad-points
      * and place it resized and compressed onto a new page.
      */
-    public function testLinkHandling1()
+    public function testLinkHandling1($filename = __DIR__ . '/../../_files/pdfs/links/links.pdf')
     {
         $pdf = $this->getInstance();
         $pdf->AddPage();
-        $pdf->setSourceFile(__DIR__ . '/../../_files/pdfs/links/links.pdf');
+        $pdf->setSourceFile($filename);
         $tplId = $pdf->importPage(1, PageBoundaries::CROP_BOX, true, true);
         $pdf->useTemplate($tplId, [
             'x' => 20,
@@ -235,6 +234,18 @@ public function testLinkHandling1()
         return $pdfString;
     }
 
+    /**
+     * This test imports annotations with indirect references in their properties which should be flattened.
+     *
+     * The original file links.pdf was modified appropriately.
+     *
+     * @return void
+     */
+    public function testLinkHandlingWithIndirectReferencesInAnnotation()
+    {
+        $this->testLinkHandling1(__DIR__ . '/../../_files/pdfs/links/links-with-indirect-references.pdf');
+    }
+
     /**
      * Take the result of testLinkHandling1 and re-place it with the same settings.
      * @depends testLinkHandling1