codeshell · julesbsz · Dec 21, 2025 · Dec 21, 2025 · Dec 21, 2025 · Dec 21, 2025
diff --git a/.DS_Store b/.DS_Store
diff --git a/.gitignore b/.gitignore
@@ -1,5 +1,7 @@
 composer.phar
+composer.lock
 /vendor/
+/migration_todo.txt
 
 # Commit your application's lock file http://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file
 # You may choose to ignore a library lock file http://getcomposer.org/doc/02-libraries.md#lock-file

diff --git a/README.md b/README.md
@@ -1,138 +1,126 @@
-# PDF Form Filling with FPDM
+# FPDM - PDF Form Data Merge
 
-## Package
+A PHP library for filling PDF forms by merging data into form fields.
 
-The FPDM class allows to fill out PDF forms, i.e. populate fields of a PDF file. It is **developed by Olivier Plathey**, author of the [FDPF Library](http://www.fpdf.org/), and has been released as [Skript 93](http://www.fpdf.org/en/script/script93.php).
+> **Fork Notice**: This is a **PHP 8.x compatible fork** of [codeshell/fpdm](https://github.com/codeshell/fpdm), originally based on [Olivier Plathey's FPDM script](http://www.fpdf.org/en/script/script93.php).
 
-I created this repository for the following reasons:
+## Features
 
-- make the current FPDM source available via [composer](https://packagist.org/packages/tmw/fpdm), autoload via classmaps
-- bugfixing
-    - FIX: compatibility issues with PHP 7.x [e376dc1](https://github.com/codeshell/fpdm/commit/e376dc157655ded24c61e098199586f3325d63c1) v2.9.1
-    - FIX: filling forms in multiple files (wrong buffer usage, invalid offsets) [e376dc1](https://github.com/codeshell/fpdm/commit/e376dc157655ded24c61e098199586f3325d63c1) v2.9.1
-    - FIX: convert ASCII object names to utf-8 [1eddba7](https://github.com/codeshell/fpdm/commit/1eddba76f610690821e8c0b3753df337a6cf65f7) v2.9.2
-- improvements (changes to the original codebase are prefixed with `//FIX: change description` and ended with `//ENDFIX`)
-    - ADD: support for checkboxes (disabled by default, activate with `$pdf->useCheckboxParser = true;`) [0375dd9](https://github.com/codeshell/fpdm/commit/0375dd95f05fd2d8d32d9ae1ab882fa0895b07b3) v2.9.2
+- Fill PDF text fields from PHP arrays or FDF files
+- Checkbox support with automatic state detection
+- Native form flattening (experimental) - make fields read-only without external tools
+- PHP 8.0+ compatible
+- No external dependencies (pure PHP)
 
-## Version
-
-Based on version 2.9 (2017-05-11) available from [fpdf.org/en/script/script93.php](http://www.fpdf.org/en/script/script93.php).
-
-_Note: If you find that a new version has been hosted on fpdf.org, please do not hesitate to drop me [a short note](https://github.com/codeshell/fpdm/issues) to make sure I do not miss it out._
-
-This repository only contains the separate php class written for form filling (FPD**M**). If you are looking for a repository containing the main FPD**F** Library, please head over to [github.com/Setasign/FPDF](https://github.com/Setasign/FPDF).
-
-Once again, all credits to Olivier Plathey for providing an easy to use script for form filling in addition to his FPDF library!
-
-## Installation 
+## Installation
 
 ### Composer
 
-The preferred way of making FPDM available in your app is to install it via composer with
-
-`composer require tmw/fpdm`
-
-## Usage
-
-### Composer (autoload)
-
-[autoload](https://getcomposer.org/doc/01-basic-usage.md#autoloading) FPDM class files by adding this to your code:
-
-`require 'vendor/autoload.php';`
-
-### Standalone Script (legacy)
-
-Load the top level entry point by calling
-
-`require_once '/abolute/path/to/fpdm.php';`
-
-or
-
-`require_once './relative/path/to/fpdm.php';`
+```bash
+composer require tmw/fpdm
+```
 
-## Customization to original code
+### Manual
 
-### classmaps vs. psr-4 (or: legacy code vs modern frameworks á la Laravel)
+```php
+require_once 'path/to/fpdm.php';
+```
 
-Autoloading classes with [namespaces](https://www.php.net/manual/en/language.namespaces.basics.php) and following [PSR-4: Autoloader](https://www.php-fig.org/psr/psr-4/) would be desireable. Especially reducing the risk of naming conflicts by using vendor namespaces.
+## Usage
 
-However, FPDM has been around for a long time and as such is used in many projects that use non-namespaced code (I refer to them as legacy projects). Legacy projects instantiate FPDM by calling `$mypdf = new FPDM()` which is unqualified but defaults to the global namespace with non-namespaced code.
+### Basic Text Fields
 
-Using psr-4 would autoload the class to a subnamespace (e.g. \codeshell\fpdm\FPDM) instead of the global namespace (e.g. \FPDM) thus breaking any legacy code no matter if it used `new FPDM()` or `new \FPDM()`.
+```php
+<?php
+require 'vendor/autoload.php';
 
-__Classmaps are a compromise.__ They allow taking advantage of composers autoloading and dependency management. Yet classes are added to the global namespace. Legacy projects can switch to composer without having to refactor their code. __Newer projects (e.g. utilizing frameworks like laravel, that heavily rely on namespaces) can still use legacy classes__ by using the fully qualified name (in this case the class name prefixed with global prefix operator as in `new \FPDM()`).
+$fields = array(
+    'name'    => 'John Doe',
+    'address' => '123 Main St',
+    'city'    => 'New York',
+);
 
-That's my reasoning for using classmaps over psr-4 for FPDM. Please let me know if there are use cases where classmaps won't work with modern frameworks.
+$pdf = new FPDM('template.pdf');
+$pdf->Load($fields, true); // true = UTF-8, false = ISO-8859-1
+$pdf->Merge();
+$pdf->Output('F', 'filled.pdf'); // Save to file
+```
 
 ### Checkboxes
 
-I added support for checkboxes. The feature is not heavily tested but works for me. Can be enabled with `useCheckboxParser = true` like so:
+Enable checkbox support to toggle checkboxes in your PDF forms:
 
 ```php
 <?php
 $fields = array(
-    'my_checkbox'    => 'anything that evaluates to true.', // checkbox will be checked;  Careful, that includes ANY non-empty string (even "no" or "unchecked")
-    'another_checkbox' => false, // checkbox will be UNchecked; empty string or 0 work as well
+    'agree_terms' => true,   // Checked
+    'newsletter'  => false,  // Unchecked
 );
 
-$pdf = new FPDM('template.pdf');
-$pdf->useCheckboxParser = true; // Checkbox parsing is ignored (default FPDM behaviour) unless enabled with this setting
+$pdf = new FPDM('form.pdf');
+$pdf->useCheckboxParser = true; // Enable checkbox support
 $pdf->Load($fields, true);
 $pdf->Merge();
 $pdf->Output();
 ```
 
-You don't have to figure out the technical names of checkbox states. They are retrieved during the parsing process.
+Checkbox state names (e.g., `Yes`/`Off`, `Oui`/`Off`) are automatically detected during parsing.
 
-## Original Info Page
-_Everything below is mirrored from http://www.fpdf.org/en/script/script93.php ._
+### Flatten (Experimental)
 
-### Information
+Make form fields read-only after filling to prevent users from editing:
 
-Author: Olivier
+```php
+<?php
+$pdf = new FPDM('form.pdf');
+$pdf->Load(['name' => 'John Doe']);
+$pdf->Flatten(); // Enable flatten mode
+$pdf->Merge();
+$pdf->Output('F', 'flattened.pdf');
 
-License: FPDF
+// Or use shorthand:
+$pdf->Merge(true); // true = flatten
+```
 
-### Description
+> **⚠️ Experimental**: This feature sets the ReadOnly flag on all form fields. The form structure is preserved but fields cannot be edited. This is a native PHP implementation that doesn't require external tools like pdftk.
 
-This script allows to merge data into a PDF form. Given a template PDF with text fields, it's
-possible to inject values in two different ways:
+## Output Options
 
-- from a PHP array
-- from an <abbr title="Forms Data Format">FDF</abbr> file
+```php
+$pdf->Output();              // Send to browser (inline)
+$pdf->Output('D', 'f.pdf');  // Force download
+$pdf->Output('F', 'f.pdf');  // Save to file
+$pdf->Output('S');           // Return as string
+```
 
-The resulting document is produced by the Output() method, which works the same as for FPDF.
+## Debugging
 
-Note: if your template PDF is not compatible with this script, you can process it with
-[PDFtk](https://www.pdflabs.com/tools/pdftk-server/) this way:
+Enable verbose mode to see parsing details:
 
-`pdftk modele.pdf output modele2.pdf`
+```php
+$pdf->set_modes('verbose', true);
+$pdf->set_modes('verbose_level', 3); // 1-4, higher = more detail
+```
 
-Then try again with modele2.pdf.
+> **Note**: Disable verbose mode before generating PDF output.
 
-### Example
+## Fork Changes
 
-This example shows how to merge data from an array:
+This fork includes:
 
-```php
-<?php
+- Full PHP 8.0 - 8.5 compatibility
+- Enhanced checkbox parser with support for indirect `/AP` references
+- Native form flattening (experimental) - sets ReadOnly flags without requiring pdftk
+- Replaced deprecated `create_function()` with closures
+- Fixed curly brace string access syntax
+- Fixed `implode()` parameter order
+- Added missing class property declarations
 
-/***************************
-  Sample using a PHP array
-****************************/
+## Credits
 
-$fields = array(
-    'name'    => 'My name',
-    'address' => 'My address',
-    'city'    => 'My city',
-    'phone'   => 'My phone number'
-);
+- **Original Author**: [Olivier Plathey](http://www.fpdf.org/) (FPDM v2.9)
+- **Upstream Fork**: [codeshell/fpdm](https://github.com/codeshell/fpdm)
 
-$pdf = new FPDM('template.pdf');
-$pdf->Load($fields, false); // second parameter: false if field values are in ISO-8859-1, true if UTF-8
-$pdf->Merge();
-$pdf->Output();
-?>
-```
+## License
 
-View the result [here](http://www.fpdf.org/en/script/ex93.pdf).
+FPDF License
diff --git a/composer.json b/composer.json
@@ -31,7 +31,7 @@
     }
   ],
   "require": {
-    "php": ">=5.3.0"
+    "php": ">=8.0"
   },
   "keywords": [
     "FPDM",
@@ -45,5 +45,9 @@
   "support": {
     "issues": "https://github.com/codeshell/fpdm/issues",
     "source": "https://github.com/codeshell/fpdm/tree/master"
+  },
+  "require-dev": {
+    "squizlabs/php_codesniffer": "^3.13",
+    "phpcompatibility/php-compatibility": "^9.3"
   }
 }
diff --git a/src/.DS_Store b/src/.DS_Store
diff --git a/src/ex-array.php b/src/ex-array.php
@@ -15,6 +15,7 @@
 
 $pdf = new FPDM('template.pdf');
 $pdf->Load($fields, false); // second parameter: false if field values are in ISO-8859-1, true if UTF-8
+$pdf->Flatten();
 $pdf->Merge();
-$pdf->Output();
+$pdf->Output('F', 'output.pdf');
 ?>
diff --git a/src/ex.pdf b/src/ex.pdf
diff --git a/src/export/fdf/forge_fdf.php b/src/export/fdf/forge_fdf.php
@@ -29,17 +29,17 @@ function escape_pdf_string( $ss )
   $ss_esc= '';
   $ss_len= strlen( $ss );
   for( $ii= 0; $ii< $ss_len; ++$ii ) {
-    if( ord($ss{$ii})== 0x28 ||  // open paren
-	ord($ss{$ii})== 0x29 ||  // close paren
-	ord($ss{$ii})== 0x5c )   // backslash
+    if( ord($ss[$ii])== 0x28 ||  // open paren
+	ord($ss[$ii])== 0x29 ||  // close paren
+	ord($ss[$ii])== 0x5c )   // backslash
       {
-	$ss_esc.= chr(0x5c).$ss{$ii}; // escape the character w/ backslash
+	$ss_esc.= chr(0x5c).$ss[$ii]; // escape the character w/ backslash
       }
-    else if( ord($ss{$ii}) < 32 || 126 < ord($ss{$ii}) ) {
-      $ss_esc.= sprintf( "\\%03o", ord($ss{$ii}) ); // use an octal code
+    else if( ord($ss[$ii]) < 32 || 126 < ord($ss[$ii]) ) {
+      $ss_esc.= sprintf( "\\%03o", ord($ss[$ii]) ); // use an octal code
     }
     else {
-      $ss_esc.= $ss{$ii};
+      $ss_esc.= $ss[$ii];
     }
   }
   return $ss_esc;
@@ -55,13 +55,13 @@ function escape_pdf_name( $ss )
   $ss_esc= '';
   $ss_len= strlen( $ss );
   for( $ii= 0; $ii< $ss_len; ++$ii ) {
-    if( ord($ss{$ii}) < 33 || 126 < ord($ss{$ii}) || 
-	ord($ss{$ii})== 0x23 ) // hash mark
+    if( ord($ss[$ii]) < 33 || 126 < ord($ss[$ii]) || 
+	ord($ss[$ii])== 0x23 ) // hash mark
       {
-	$ss_esc.= sprintf( "#%02x", ord($ss{$ii}) ); // use a hex code
+	$ss_esc.= sprintf( "#%02x", ord($ss[$ii]) ); // use a hex code
       }
     else {
-      $ss_esc.= $ss{$ii};
+      $ss_esc.= $ss[$ii];
     }
   }
   return $ss_esc;

diff --git a/src/export/pdf/pdftk.php b/src/export/pdf/pdftk.php
@@ -15,8 +15,7 @@
 	******************************************************************/
 
 	if (!defined('URL_TOOLBOX')) die("Requires the URL_TOOLBOX package!");
-
-	define("PHP5_ENGINE",version_compare(phpversion(), "5"));
+
 
 	//!NOTE try to detect your OS
 
@@ -104,22 +103,12 @@ function pdftk($pdf_file,$fdf_file,$settings) {
 
 			//echo htmlentities("$cmdline , $descriptorspec, $cwd, $env");
 
-			if(PHP5_ENGINE) { // Php5
-				$process = proc_open($cmdline, $descriptorspec, $pipes, $cwd, $env);
-			}else { //Php4
-				$process = proc_open($cmdline, $descriptorspec, $pipes);
-			}
+			$process = proc_open($cmdline, $descriptorspec, $pipes, $cwd, $env);
 
 			if (is_resource($process)) {
 
-				if(PHP5_ENGINE) { 
-					$err=stream_get_contents($pipes[2]);
-				}else { //Php4
-					$err= "";
-					while (($str = fgets($pipes[2], 4096))) {
-						$err.= "$str\n";
-					}
-				}
+				$err=stream_get_contents($pipes[2]);
+
 
 				fclose($pipes[2]);
 

diff --git a/src/filters/FilterASCII85.php b/src/filters/FilterASCII85.php
@@ -26,8 +26,7 @@
 if (!defined('ORD_tilde'))
 	define('ORD_tilde', ord('~'));
 
-$__tmp = version_compare(phpversion(), "5") == -1 ? array('FilterASCII85') : array('FilterASCII85', false);
-if (!call_user_func_array('class_exists', $__tmp)) {
+if (!class_exists('FilterASCII85', false)) {
 
 
 	if(isset($FPDM_FILTERS)) array_push($FPDM_FILTERS,"ASCII85Decode");
@@ -103,6 +102,4 @@ function encode($in) {
             return $this->error("ASCII85 encoding not implemented.");
         }
     }
-}
-
-unset($__tmp);
+}
diff --git a/src/filters/FilterASCIIHex.php b/src/filters/FilterASCIIHex.php
@@ -16,7 +16,7 @@ class FilterASCIIHex {
 		*@internal same as _hex2bin ($hexString)
 		*@access public
 		*@note Function was written because PHP has a bin2hex, but not a hex2bin!
-		*@internal note pack(�C�,hexdec(substr($data,$i,2))) DOES NOT WORK
+		*@internal note pack(“C”,hexdec(substr($data,$i,2))) DOES NOT WORK
 		*
 		**/
 	  function decode($data) {
@@ -44,7 +44,7 @@ function decode($data) {
 		*
 		*@internal same as bin2hex
 		*@access public
-		*@internal  dechex(ord($str{$i})); is buggy because for hex value of 0-15 heading 0 is missing! Using sprintf() to get it right.
+		*@internal  dechex(ord($str[$i])); is buggy because for hex value of 0-15 heading 0 is missing! Using sprintf() to get it right.
 		*@param string $str a binary string
 		*@return string hex the hexified string
 		**/
@@ -54,7 +54,7 @@ function encode($data) {
 			$hex = "";
 			$i = 0;
 			do {
-				$hex .= sprintf("%02x", ord($str{$i}));
+				$hex .= sprintf("%02x", ord($str[$i]));
 				$i++;
 			} while ($i < strlen($str));
 			return $hex;

diff --git a/src/filters/FilterFlate.php b/src/filters/FilterFlate.php
@@ -4,8 +4,7 @@
 //  NOTE: requires ZLIB >= 1.0.9!
 //
 
-$__tmp = version_compare(phpversion(), "5") == -1 ? array('FilterFlateDecode') : array('FilterFlateDecode', false);
-if (!call_user_func_array('class_exists', $__tmp)) {
+if (!class_exists('FilterFlate', false)) {
 
 
 	if(isset($FPDM_FILTERS)) array_push($FPDM_FILTERS,"FlateDecode");