1<?php
2
3/////////////////////////////////////////////////////////////////
4/// getID3() by James Heinrich <info@getid3.org>               //
5//  available at https://github.com/JamesHeinrich/getID3       //
6//            or https://www.getid3.org                        //
7//            or http://getid3.sourceforge.net                 //
8//  see readme.txt for more details                            //
9/////////////////////////////////////////////////////////////////
10//                                                             //
11// module.graphic.gif.php                                      //
12// module for analyzing GIF Image files                        //
13// dependencies: NONE                                          //
14//                                                            ///
15/////////////////////////////////////////////////////////////////
16
17/**
18 * @link https://www.w3.org/Graphics/GIF/spec-gif89a.txt
19 * @link http://www.matthewflickinger.com/lab/whatsinagif/bits_and_bytes.asp
20 */
21
22if (!defined('GETID3_INCLUDEPATH')) { // prevent path-exposing attacks that access modules directly on public webservers
23	exit;
24}
25
26class getid3_gif extends getid3_handler
27{
28	/**
29	 * @return bool
30	 */
31	public function Analyze() {
32		$info = &$this->getid3->info;
33
34		$info['fileformat']                  = 'gif';
35		$info['video']['dataformat']         = 'gif';
36		$info['video']['lossless']           = true;
37		$info['video']['pixel_aspect_ratio'] = (float) 1;
38
39		$this->fseek($info['avdataoffset']);
40		$GIFheader = $this->fread(13);
41		$offset = 0;
42
43		$info['gif']['header']['raw']['identifier']            =                              substr($GIFheader, $offset, 3);
44		$offset += 3;
45
46		$magic = 'GIF';
47		if ($info['gif']['header']['raw']['identifier'] != $magic) {
48			$this->error('Expecting "'.getid3_lib::PrintHexBytes($magic).'" at offset '.$info['avdataoffset'].', found "'.getid3_lib::PrintHexBytes($info['gif']['header']['raw']['identifier']).'"');
49			unset($info['fileformat']);
50			unset($info['gif']);
51			return false;
52		}
53
54		//if (!$this->getid3->option_extra_info) {
55		//	$this->warning('GIF Extensions and Global Color Table not returned due to !getid3->option_extra_info');
56		//}
57
58		$info['gif']['header']['raw']['version']               =                              substr($GIFheader, $offset, 3);
59		$offset += 3;
60		$info['gif']['header']['raw']['width']                 = getid3_lib::LittleEndian2Int(substr($GIFheader, $offset, 2));
61		$offset += 2;
62		$info['gif']['header']['raw']['height']                = getid3_lib::LittleEndian2Int(substr($GIFheader, $offset, 2));
63		$offset += 2;
64		$info['gif']['header']['raw']['flags']                 = getid3_lib::LittleEndian2Int(substr($GIFheader, $offset, 1));
65		$offset += 1;
66		$info['gif']['header']['raw']['bg_color_index']        = getid3_lib::LittleEndian2Int(substr($GIFheader, $offset, 1));
67		$offset += 1;
68		$info['gif']['header']['raw']['aspect_ratio']          = getid3_lib::LittleEndian2Int(substr($GIFheader, $offset, 1));
69		$offset += 1;
70
71		$info['video']['resolution_x']                         = $info['gif']['header']['raw']['width'];
72		$info['video']['resolution_y']                         = $info['gif']['header']['raw']['height'];
73		$info['gif']['version']                                = $info['gif']['header']['raw']['version'];
74		$info['gif']['header']['flags']['global_color_table']  = (bool) ($info['gif']['header']['raw']['flags'] & 0x80);
75		if ($info['gif']['header']['raw']['flags'] & 0x80) {
76			// Number of bits per primary color available to the original image, minus 1
77			$info['gif']['header']['bits_per_pixel']  = 3 * ((($info['gif']['header']['raw']['flags'] & 0x70) >> 4) + 1);
78		} else {
79			$info['gif']['header']['bits_per_pixel']  = 0;
80		}
81		$info['gif']['header']['flags']['global_color_sorted'] = (bool) ($info['gif']['header']['raw']['flags'] & 0x40);
82		if ($info['gif']['header']['flags']['global_color_table']) {
83			// the number of bytes contained in the Global Color Table. To determine that
84			// actual size of the color table, raise 2 to [the value of the field + 1]
85			$info['gif']['header']['global_color_size'] = pow(2, ($info['gif']['header']['raw']['flags'] & 0x07) + 1);
86			$info['video']['bits_per_sample']           = ($info['gif']['header']['raw']['flags'] & 0x07) + 1;
87		} else {
88			$info['gif']['header']['global_color_size'] = 0;
89		}
90		if ($info['gif']['header']['raw']['aspect_ratio'] != 0) {
91			// Aspect Ratio = (Pixel Aspect Ratio + 15) / 64
92			$info['gif']['header']['aspect_ratio'] = ($info['gif']['header']['raw']['aspect_ratio'] + 15) / 64;
93		}
94
95		if ($info['gif']['header']['flags']['global_color_table']) {
96			$GIFcolorTable = $this->fread(3 * $info['gif']['header']['global_color_size']);
97			if ($this->getid3->option_extra_info) {
98				$offset = 0;
99				for ($i = 0; $i < $info['gif']['header']['global_color_size']; $i++) {
100					$red   = getid3_lib::LittleEndian2Int(substr($GIFcolorTable, $offset++, 1));
101					$green = getid3_lib::LittleEndian2Int(substr($GIFcolorTable, $offset++, 1));
102					$blue  = getid3_lib::LittleEndian2Int(substr($GIFcolorTable, $offset++, 1));
103					$info['gif']['global_color_table'][$i] = (($red << 16) | ($green << 8) | ($blue));
104					$info['gif']['global_color_table_rgb'][$i] = sprintf('%02X%02X%02X', $red, $green, $blue);
105				}
106			}
107		}
108
109		// Image Descriptor
110		$info['gif']['animation']['animated'] = false;
111		while (!feof($this->getid3->fp)) {
112			$NextBlockTest = $this->fread(1);
113			switch ($NextBlockTest) {
114
115/*
116				case ',': // ',' - Image separator character
117					$ImageDescriptorData = $NextBlockTest.$this->fread(9);
118					$ImageDescriptor = array();
119					$ImageDescriptor['image_left']   = getid3_lib::LittleEndian2Int(substr($ImageDescriptorData, 1, 2));
120					$ImageDescriptor['image_top']    = getid3_lib::LittleEndian2Int(substr($ImageDescriptorData, 3, 2));
121					$ImageDescriptor['image_width']  = getid3_lib::LittleEndian2Int(substr($ImageDescriptorData, 5, 2));
122					$ImageDescriptor['image_height'] = getid3_lib::LittleEndian2Int(substr($ImageDescriptorData, 7, 2));
123					$ImageDescriptor['flags_raw']    = getid3_lib::LittleEndian2Int(substr($ImageDescriptorData, 9, 1));
124					$ImageDescriptor['flags']['use_local_color_map'] = (bool) ($ImageDescriptor['flags_raw'] & 0x80);
125					$ImageDescriptor['flags']['image_interlaced']    = (bool) ($ImageDescriptor['flags_raw'] & 0x40);
126					$info['gif']['image_descriptor'][] = $ImageDescriptor;
127
128					if ($ImageDescriptor['flags']['use_local_color_map']) {
129
130						$this->warning('This version of getID3() cannot parse local color maps for GIFs');
131						return true;
132
133					}
134					$RasterData = array();
135					$RasterData['code_size']        = getid3_lib::LittleEndian2Int($this->fread(1));
136					$RasterData['block_byte_count'] = getid3_lib::LittleEndian2Int($this->fread(1));
137					$info['gif']['raster_data'][count($info['gif']['image_descriptor']) - 1] = $RasterData;
138
139					$CurrentCodeSize = $RasterData['code_size'] + 1;
140					for ($i = 0; $i < pow(2, $RasterData['code_size']); $i++) {
141						$DefaultDataLookupTable[$i] = chr($i);
142					}
143					$DefaultDataLookupTable[pow(2, $RasterData['code_size']) + 0] = ''; // Clear Code
144					$DefaultDataLookupTable[pow(2, $RasterData['code_size']) + 1] = ''; // End Of Image Code
145
146					$NextValue = $this->GetLSBits($CurrentCodeSize);
147					echo 'Clear Code: '.$NextValue.'<BR>';
148
149					$NextValue = $this->GetLSBits($CurrentCodeSize);
150					echo 'First Color: '.$NextValue.'<BR>';
151
152					$Prefix = $NextValue;
153					$i = 0;
154					while ($i++ < 20) {
155						$NextValue = $this->GetLSBits($CurrentCodeSize);
156						echo $NextValue.'<br>';
157					}
158					echo 'escaping<br>';
159					return true;
160					break;
161*/
162
163				case '!':
164					// GIF Extension Block
165					$ExtensionBlockData = $NextBlockTest.$this->fread(2);
166					$ExtensionBlock = array();
167					$ExtensionBlock['function_code']  = getid3_lib::LittleEndian2Int(substr($ExtensionBlockData, 1, 1));
168					$ExtensionBlock['byte_length']    = getid3_lib::LittleEndian2Int(substr($ExtensionBlockData, 2, 1));
169					$ExtensionBlock['data']           = (($ExtensionBlock['byte_length'] > 0) ? $this->fread($ExtensionBlock['byte_length']) : null);
170
171					if (substr($ExtensionBlock['data'], 0, 11) == 'NETSCAPE2.0') { // Netscape Application Block (NAB)
172						$ExtensionBlock['data'] .= $this->fread(4);
173						if (substr($ExtensionBlock['data'], 11, 2) == "\x03\x01") {
174							$info['gif']['animation']['animated']   = true;
175							$info['gif']['animation']['loop_count'] = getid3_lib::LittleEndian2Int(substr($ExtensionBlock['data'], 13, 2));
176						} else {
177							$this->warning('Expecting 03 01 at offset '.($this->ftell() - 4).', found "'.getid3_lib::PrintHexBytes(substr($ExtensionBlock['data'], 11, 2)).'"');
178						}
179					}
180
181					if ($this->getid3->option_extra_info) {
182						$info['gif']['extension_blocks'][] = $ExtensionBlock;
183					}
184					break;
185
186				case ';':
187					$info['gif']['terminator_offset'] = $this->ftell() - 1;
188					// GIF Terminator
189					break;
190
191				default:
192					break;
193
194
195			}
196		}
197
198		return true;
199	}
200
201	/**
202	 * @param int $bits
203	 *
204	 * @return float|int
205	 */
206	public function GetLSBits($bits) {
207		static $bitbuffer = '';
208		while (strlen($bitbuffer) < $bits) {
209			$bitbuffer = str_pad(decbin(ord($this->fread(1))), 8, '0', STR_PAD_LEFT).$bitbuffer;
210		}
211		$value = bindec(substr($bitbuffer, 0 - $bits));
212		$bitbuffer = substr($bitbuffer, 0, 0 - $bits);
213
214		return $value;
215	}
216
217}
218