| <Website> | getID3 |  |
|
| Size: | 20727 |
| Storage flags: | strip |
<?php
class getid3_png extends getid3_handler
{
public function Analyze() {
$info = &$this->getid3->info;
$info['png'] = array();
$thisfile_png = &$info['png'];
$info['fileformat'] = 'png';
$info['video']['dataformat'] = 'png';
$info['video']['lossless'] = false;
$this->fseek($info['avdataoffset']);
$PNGfiledata = $this->fread($this->getid3->fread_buffer_size());
$offset = 0;
$PNGidentifier = substr($PNGfiledata, $offset, 8);
$offset += 8;
if ($PNGidentifier != "\x89\x50\x4E\x47\x0D\x0A\x1A\x0A") {
$info['error'][] = 'First 8 bytes of file ('.getid3_lib::PrintHexBytes($PNGidentifier).') did not match expected PNG identifier';
unset($info['fileformat']);
return false;
}
while ((($this->ftell() - (strlen($PNGfiledata) - $offset)) < $info['filesize'])) {
$chunk['data_length'] = getid3_lib::BigEndian2Int(substr($PNGfiledata, $offset, 4));
$offset += 4;
while (((strlen($PNGfiledata) - $offset) < ($chunk['data_length'] + 4)) && ($this->ftell() < $info['filesize'])) {
$PNGfiledata .= $this->fread($this->getid3->fread_buffer_size());
}
$chunk['type_text'] = substr($PNGfiledata, $offset, 4);
$offset += 4;
$chunk['type_raw'] = getid3_lib::BigEndian2Int($chunk['type_text']);
$chunk['data'] = substr($PNGfiledata, $offset, $chunk['data_length']);
$offset += $chunk['data_length'];
$chunk['crc'] = getid3_lib::BigEndian2Int(substr($PNGfiledata, $offset, 4));
$offset += 4;
$chunk['flags']['ancilliary'] = (bool) ($chunk['type_raw'] & 0x20000000);
$chunk['flags']['private'] = (bool) ($chunk['type_raw'] & 0x00200000);
$chunk['flags']['reserved'] = (bool) ($chunk['type_raw'] & 0x00002000);
$chunk['flags']['safe_to_copy'] = (bool) ($chunk['type_raw'] & 0x00000020);
$thisfile_png[$chunk['type_text']] = array();
$thisfile_png_chunk_type_text = &$thisfile_png[$chunk['type_text']];
switch ($chunk['type_text']) {
case 'IHDR':
$thisfile_png_chunk_type_text['header'] = $chunk;
$thisfile_png_chunk_type_text['width'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 4));
$thisfile_png_chunk_type_text['height'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 4, 4));
$thisfile_png_chunk_type_text['raw']['bit_depth'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 8, 1));
$thisfile_png_chunk_type_text['raw']['color_type'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 9, 1));
$thisfile_png_chunk_type_text['raw']['compression_method'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 10, 1));
$thisfile_png_chunk_type_text['raw']['filter_method'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 11, 1));
$thisfile_png_chunk_type_text['raw']['interlace_method'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 12, 1));
$thisfile_png_chunk_type_text['compression_method_text'] = $this->PNGcompressionMethodLookup($thisfile_png_chunk_type_text['raw']['compression_method']);
$thisfile_png_chunk_type_text['color_type']['palette'] = (bool) ($thisfile_png_chunk_type_text['raw']['color_type'] & 0x01);
$thisfile_png_chunk_type_text['color_type']['true_color'] = (bool) ($thisfile_png_chunk_type_text['raw']['color_type'] & 0x02);
$thisfile_png_chunk_type_text['color_type']['alpha'] = (bool) ($thisfile_png_chunk_type_text['raw']['color_type'] & 0x04);
$info['video']['resolution_x'] = $thisfile_png_chunk_type_text['width'];
$info['video']['resolution_y'] = $thisfile_png_chunk_type_text['height'];
$info['video']['bits_per_sample'] = $this->IHDRcalculateBitsPerSample($thisfile_png_chunk_type_text['raw']['color_type'], $thisfile_png_chunk_type_text['raw']['bit_depth']);
break;
case 'PLTE':
$thisfile_png_chunk_type_text['header'] = $chunk;
$paletteoffset = 0;
for ($i = 0; $i <= 255; $i++) {
$red = getid3_lib::BigEndian2Int(substr($chunk['data'], $paletteoffset++, 1));
$green = getid3_lib::BigEndian2Int(substr($chunk['data'], $paletteoffset++, 1));
$blue = getid3_lib::BigEndian2Int(substr($chunk['data'], $paletteoffset++, 1));
$thisfile_png_chunk_type_text[$i] = (($red << 16) | ($green << 8) | ($blue));
}
break;
case 'tRNS':
$thisfile_png_chunk_type_text['header'] = $chunk;
switch ($thisfile_png['IHDR']['raw']['color_type']) {
case 0:
$thisfile_png_chunk_type_text['transparent_color_gray'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 2));
break;
case 2:
$thisfile_png_chunk_type_text['transparent_color_red'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 2));
$thisfile_png_chunk_type_text['transparent_color_green'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 2, 2));
$thisfile_png_chunk_type_text['transparent_color_blue'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 4, 2));
break;
case 3:
for ($i = 0; $i < strlen($chunk['data']); $i++) {
$thisfile_png_chunk_type_text['palette_opacity'][$i] = getid3_lib::BigEndian2Int(substr($chunk['data'], $i, 1));
}
break;
case 4:
case 6:
$info['error'][] = 'Invalid color_type in tRNS chunk: '.$thisfile_png['IHDR']['raw']['color_type'];
default:
$info['warning'][] = 'Unhandled color_type in tRNS chunk: '.$thisfile_png['IHDR']['raw']['color_type'];
break;
}
break;
case 'gAMA':
$thisfile_png_chunk_type_text['header'] = $chunk;
$thisfile_png_chunk_type_text['gamma'] = getid3_lib::BigEndian2Int($chunk['data']) / 100000;
break;
case 'cHRM':
$thisfile_png_chunk_type_text['header'] = $chunk;
$thisfile_png_chunk_type_text['white_x'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 4)) / 100000;
$thisfile_png_chunk_type_text['white_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 4, 4)) / 100000;
$thisfile_png_chunk_type_text['red_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 8, 4)) / 100000;
$thisfile_png_chunk_type_text['red_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 12, 4)) / 100000;
$thisfile_png_chunk_type_text['green_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 16, 4)) / 100000;
$thisfile_png_chunk_type_text['green_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 20, 4)) / 100000;
$thisfile_png_chunk_type_text['blue_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 24, 4)) / 100000;
$thisfile_png_chunk_type_text['blue_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 28, 4)) / 100000;
break;
case 'sRGB':
$thisfile_png_chunk_type_text['header'] = $chunk;
$thisfile_png_chunk_type_text['reindering_intent'] = getid3_lib::BigEndian2Int($chunk['data']);
$thisfile_png_chunk_type_text['reindering_intent_text'] = $this->PNGsRGBintentLookup($thisfile_png_chunk_type_text['reindering_intent']);
break;
case 'iCCP':
$thisfile_png_chunk_type_text['header'] = $chunk;
list($profilename, $compressiondata) = explode("\x00", $chunk['data'], 2);
$thisfile_png_chunk_type_text['profile_name'] = $profilename;
$thisfile_png_chunk_type_text['compression_method'] = getid3_lib::BigEndian2Int(substr($compressiondata, 0, 1));
$thisfile_png_chunk_type_text['compression_profile'] = substr($compressiondata, 1);
$thisfile_png_chunk_type_text['compression_method_text'] = $this->PNGcompressionMethodLookup($thisfile_png_chunk_type_text['compression_method']);
break;
case 'tEXt':
$thisfile_png_chunk_type_text['header'] = $chunk;
list($keyword, $text) = explode("\x00", $chunk['data'], 2);
$thisfile_png_chunk_type_text['keyword'] = $keyword;
$thisfile_png_chunk_type_text['text'] = $text;
$thisfile_png['comments'][$thisfile_png_chunk_type_text['keyword']][] = $thisfile_png_chunk_type_text['text'];
break;
case 'zTXt':
$thisfile_png_chunk_type_text['header'] = $chunk;
list($keyword, $otherdata) = explode("\x00", $chunk['data'], 2);
$thisfile_png_chunk_type_text['keyword'] = $keyword;
$thisfile_png_chunk_type_text['compression_method'] = getid3_lib::BigEndian2Int(substr($otherdata, 0, 1));
$thisfile_png_chunk_type_text['compressed_text'] = substr($otherdata, 1);
$thisfile_png_chunk_type_text['compression_method_text'] = $this->PNGcompressionMethodLookup($thisfile_png_chunk_type_text['compression_method']);
switch ($thisfile_png_chunk_type_text['compression_method']) {
case 0:
$thisfile_png_chunk_type_text['text'] = gzuncompress($thisfile_png_chunk_type_text['compressed_text']);
break;
default:
break;
}
if (isset($thisfile_png_chunk_type_text['text'])) {
$thisfile_png['comments'][$thisfile_png_chunk_type_text['keyword']][] = $thisfile_png_chunk_type_text['text'];
}
break;
case 'iTXt':
$thisfile_png_chunk_type_text['header'] = $chunk;
list($keyword, $otherdata) = explode("\x00", $chunk['data'], 2);
$thisfile_png_chunk_type_text['keyword'] = $keyword;
$thisfile_png_chunk_type_text['compression'] = (bool) getid3_lib::BigEndian2Int(substr($otherdata, 0, 1));
$thisfile_png_chunk_type_text['compression_method'] = getid3_lib::BigEndian2Int(substr($otherdata, 1, 1));
$thisfile_png_chunk_type_text['compression_method_text'] = $this->PNGcompressionMethodLookup($thisfile_png_chunk_type_text['compression_method']);
list($languagetag, $translatedkeyword, $text) = explode("\x00", substr($otherdata, 2), 3);
$thisfile_png_chunk_type_text['language_tag'] = $languagetag;
$thisfile_png_chunk_type_text['translated_keyword'] = $translatedkeyword;
if ($thisfile_png_chunk_type_text['compression']) {
switch ($thisfile_png_chunk_type_text['compression_method']) {
case 0:
$thisfile_png_chunk_type_text['text'] = gzuncompress($text);
break;
default:
break;
}
} else {
$thisfile_png_chunk_type_text['text'] = $text;
}
if (isset($thisfile_png_chunk_type_text['text'])) {
$thisfile_png['comments'][$thisfile_png_chunk_type_text['keyword']][] = $thisfile_png_chunk_type_text['text'];
}
break;
case 'bKGD':
$thisfile_png_chunk_type_text['header'] = $chunk;
switch ($thisfile_png['IHDR']['raw']['color_type']) {
case 0:
case 4:
$thisfile_png_chunk_type_text['background_gray'] = getid3_lib::BigEndian2Int($chunk['data']);
break;
case 2:
case 6:
$thisfile_png_chunk_type_text['background_red'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0 * $thisfile_png['IHDR']['raw']['bit_depth'], $thisfile_png['IHDR']['raw']['bit_depth']));
$thisfile_png_chunk_type_text['background_green'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 1 * $thisfile_png['IHDR']['raw']['bit_depth'], $thisfile_png['IHDR']['raw']['bit_depth']));
$thisfile_png_chunk_type_text['background_blue'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 2 * $thisfile_png['IHDR']['raw']['bit_depth'], $thisfile_png['IHDR']['raw']['bit_depth']));
break;
case 3:
$thisfile_png_chunk_type_text['background_index'] = getid3_lib::BigEndian2Int($chunk['data']);
break;
default:
break;
}
break;
case 'pHYs':
$thisfile_png_chunk_type_text['header'] = $chunk;
$thisfile_png_chunk_type_text['pixels_per_unit_x'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 4));
$thisfile_png_chunk_type_text['pixels_per_unit_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 4, 4));
$thisfile_png_chunk_type_text['unit_specifier'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 8, 1));
$thisfile_png_chunk_type_text['unit'] = $this->PNGpHYsUnitLookup($thisfile_png_chunk_type_text['unit_specifier']);
break;
case 'sBIT':
$thisfile_png_chunk_type_text['header'] = $chunk;
switch ($thisfile_png['IHDR']['raw']['color_type']) {
case 0:
$thisfile_png_chunk_type_text['significant_bits_gray'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 1));
break;
case 2:
case 3:
$thisfile_png_chunk_type_text['significant_bits_red'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 1));
$thisfile_png_chunk_type_text['significant_bits_green'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 1, 1));
$thisfile_png_chunk_type_text['significant_bits_blue'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 2, 1));
break;
case 4:
$thisfile_png_chunk_type_text['significant_bits_gray'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 1));
$thisfile_png_chunk_type_text['significant_bits_alpha'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 1, 1));
break;
case 6:
$thisfile_png_chunk_type_text['significant_bits_red'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 1));
$thisfile_png_chunk_type_text['significant_bits_green'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 1, 1));
$thisfile_png_chunk_type_text['significant_bits_blue'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 2, 1));
$thisfile_png_chunk_type_text['significant_bits_alpha'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 3, 1));
break;
default:
break;
}
break;
case 'sPLT':
$thisfile_png_chunk_type_text['header'] = $chunk;
list($palettename, $otherdata) = explode("\x00", $chunk['data'], 2);
$thisfile_png_chunk_type_text['palette_name'] = $palettename;
$sPLToffset = 0;
$thisfile_png_chunk_type_text['sample_depth_bits'] = getid3_lib::BigEndian2Int(substr($otherdata, $sPLToffset, 1));
$sPLToffset += 1;
$thisfile_png_chunk_type_text['sample_depth_bytes'] = $thisfile_png_chunk_type_text['sample_depth_bits'] / 8;
$paletteCounter = 0;
while ($sPLToffset < strlen($otherdata)) {
$thisfile_png_chunk_type_text['red'][$paletteCounter] = getid3_lib::BigEndian2Int(substr($otherdata, $sPLToffset, $thisfile_png_chunk_type_text['sample_depth_bytes']));
$sPLToffset += $thisfile_png_chunk_type_text['sample_depth_bytes'];
$thisfile_png_chunk_type_text['green'][$paletteCounter] = getid3_lib::BigEndian2Int(substr($otherdata, $sPLToffset, $thisfile_png_chunk_type_text['sample_depth_bytes']));
$sPLToffset += $thisfile_png_chunk_type_text['sample_depth_bytes'];
$thisfile_png_chunk_type_text['blue'][$paletteCounter] = getid3_lib::BigEndian2Int(substr($otherdata, $sPLToffset, $thisfile_png_chunk_type_text['sample_depth_bytes']));
$sPLToffset += $thisfile_png_chunk_type_text['sample_depth_bytes'];
$thisfile_png_chunk_type_text['alpha'][$paletteCounter] = getid3_lib::BigEndian2Int(substr($otherdata, $sPLToffset, $thisfile_png_chunk_type_text['sample_depth_bytes']));
$sPLToffset += $thisfile_png_chunk_type_text['sample_depth_bytes'];
$thisfile_png_chunk_type_text['frequency'][$paletteCounter] = getid3_lib::BigEndian2Int(substr($otherdata, $sPLToffset, 2));
$sPLToffset += 2;
$paletteCounter++;
}
break;
case 'hIST':
$thisfile_png_chunk_type_text['header'] = $chunk;
$hISTcounter = 0;
while ($hISTcounter < strlen($chunk['data'])) {
$thisfile_png_chunk_type_text[$hISTcounter] = getid3_lib::BigEndian2Int(substr($chunk['data'], $hISTcounter / 2, 2));
$hISTcounter += 2;
}
break;
case 'tIME':
$thisfile_png_chunk_type_text['header'] = $chunk;
$thisfile_png_chunk_type_text['year'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 2));
$thisfile_png_chunk_type_text['month'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 2, 1));
$thisfile_png_chunk_type_text['day'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 3, 1));
$thisfile_png_chunk_type_text['hour'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 4, 1));
$thisfile_png_chunk_type_text['minute'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 5, 1));
$thisfile_png_chunk_type_text['second'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 6, 1));
$thisfile_png_chunk_type_text['unix'] = gmmktime($thisfile_png_chunk_type_text['hour'], $thisfile_png_chunk_type_text['minute'], $thisfile_png_chunk_type_text['second'], $thisfile_png_chunk_type_text['month'], $thisfile_png_chunk_type_text['day'], $thisfile_png_chunk_type_text['year']);
break;
case 'oFFs':
$thisfile_png_chunk_type_text['header'] = $chunk;
$thisfile_png_chunk_type_text['position_x'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 4), false, true);
$thisfile_png_chunk_type_text['position_y'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 4, 4), false, true);
$thisfile_png_chunk_type_text['unit_specifier'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 8, 1));
$thisfile_png_chunk_type_text['unit'] = $this->PNGoFFsUnitLookup($thisfile_png_chunk_type_text['unit_specifier']);
break;
case 'pCAL':
$thisfile_png_chunk_type_text['header'] = $chunk;
list($calibrationname, $otherdata) = explode("\x00", $chunk['data'], 2);
$thisfile_png_chunk_type_text['calibration_name'] = $calibrationname;
$pCALoffset = 0;
$thisfile_png_chunk_type_text['original_zero'] = getid3_lib::BigEndian2Int(substr($chunk['data'], $pCALoffset, 4), false, true);
$pCALoffset += 4;
$thisfile_png_chunk_type_text['original_max'] = getid3_lib::BigEndian2Int(substr($chunk['data'], $pCALoffset, 4), false, true);
$pCALoffset += 4;
$thisfile_png_chunk_type_text['equation_type'] = getid3_lib::BigEndian2Int(substr($chunk['data'], $pCALoffset, 1));
$pCALoffset += 1;
$thisfile_png_chunk_type_text['equation_type_text'] = $this->PNGpCALequationTypeLookup($thisfile_png_chunk_type_text['equation_type']);
$thisfile_png_chunk_type_text['parameter_count'] = getid3_lib::BigEndian2Int(substr($chunk['data'], $pCALoffset, 1));
$pCALoffset += 1;
$thisfile_png_chunk_type_text['parameters'] = explode("\x00", substr($chunk['data'], $pCALoffset));
break;
case 'sCAL':
$thisfile_png_chunk_type_text['header'] = $chunk;
$thisfile_png_chunk_type_text['unit_specifier'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 1));
$thisfile_png_chunk_type_text['unit'] = $this->PNGsCALUnitLookup($thisfile_png_chunk_type_text['unit_specifier']);
list($pixelwidth, $pixelheight) = explode("\x00", substr($chunk['data'], 1));
$thisfile_png_chunk_type_text['pixel_width'] = $pixelwidth;
$thisfile_png_chunk_type_text['pixel_height'] = $pixelheight;
break;
case 'gIFg':
$gIFgCounter = 0;
if (isset($thisfile_png_chunk_type_text) && is_array($thisfile_png_chunk_type_text)) {
$gIFgCounter = count($thisfile_png_chunk_type_text);
}
$thisfile_png_chunk_type_text[$gIFgCounter]['header'] = $chunk;
$thisfile_png_chunk_type_text[$gIFgCounter]['disposal_method'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 0, 1));
$thisfile_png_chunk_type_text[$gIFgCounter]['user_input_flag'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 1, 1));
$thisfile_png_chunk_type_text[$gIFgCounter]['delay_time'] = getid3_lib::BigEndian2Int(substr($chunk['data'], 2, 2));
break;
case 'gIFx':
$gIFxCounter = 0;
if (isset($thisfile_png_chunk_type_text) && is_array($thisfile_png_chunk_type_text)) {
$gIFxCounter = count($thisfile_png_chunk_type_text);
}
$thisfile_png_chunk_type_text[$gIFxCounter]['header'] = $chunk;
$thisfile_png_chunk_type_text[$gIFxCounter]['application_identifier'] = substr($chunk['data'], 0, 8);
$thisfile_png_chunk_type_text[$gIFxCounter]['authentication_code'] = substr($chunk['data'], 8, 3);
$thisfile_png_chunk_type_text[$gIFxCounter]['application_data'] = substr($chunk['data'], 11);
break;
case 'IDAT':
$idatinformationfieldindex = 0;
if (isset($thisfile_png['IDAT']) && is_array($thisfile_png['IDAT'])) {
$idatinformationfieldindex = count($thisfile_png['IDAT']);
}
unset($chunk['data']);
$thisfile_png_chunk_type_text[$idatinformationfieldindex]['header'] = $chunk;
break;
case 'IEND':
$thisfile_png_chunk_type_text['header'] = $chunk;
break;
default:
$thisfile_png_chunk_type_text['header'] = $chunk;
$info['warning'][] = 'Unhandled chunk type: '.$chunk['type_text'];
break;
}
}
return true;
}
public function PNGsRGBintentLookup($sRGB) {
static $PNGsRGBintentLookup = array(
0 => 'Perceptual',
1 => 'Relative colorimetric',
2 => 'Saturation',
3 => 'Absolute colorimetric'
);
return (isset($PNGsRGBintentLookup[$sRGB]) ? $PNGsRGBintentLookup[$sRGB] : 'invalid');
}
public function PNGcompressionMethodLookup($compressionmethod) {
static $PNGcompressionMethodLookup = array(
0 => 'deflate/inflate'
);
return (isset($PNGcompressionMethodLookup[$compressionmethod]) ? $PNGcompressionMethodLookup[$compressionmethod] : 'invalid');
}
public function PNGpHYsUnitLookup($unitid) {
static $PNGpHYsUnitLookup = array(
0 => 'unknown',
1 => 'meter'
);
return (isset($PNGpHYsUnitLookup[$unitid]) ? $PNGpHYsUnitLookup[$unitid] : 'invalid');
}
public function PNGoFFsUnitLookup($unitid) {
static $PNGoFFsUnitLookup = array(
0 => 'pixel',
1 => 'micrometer'
);
return (isset($PNGoFFsUnitLookup[$unitid]) ? $PNGoFFsUnitLookup[$unitid] : 'invalid');
}
public function PNGpCALequationTypeLookup($equationtype) {
static $PNGpCALequationTypeLookup = array(
0 => 'Linear mapping',
1 => 'Base-e exponential mapping',
2 => 'Arbitrary-base exponential mapping',
3 => 'Hyperbolic mapping'
);
return (isset($PNGpCALequationTypeLookup[$equationtype]) ? $PNGpCALequationTypeLookup[$equationtype] : 'invalid');
}
public function PNGsCALUnitLookup($unitid) {
static $PNGsCALUnitLookup = array(
0 => 'meter',
1 => 'radian'
);
return (isset($PNGsCALUnitLookup[$unitid]) ? $PNGsCALUnitLookup[$unitid] : 'invalid');
}
public function IHDRcalculateBitsPerSample($color_type, $bit_depth) {
switch ($color_type) {
case 0:
return $bit_depth;
break;
case 2:
return 3 * $bit_depth;
break;
case 3:
return $bit_depth;
break;
case 4:
return 2 * $bit_depth;
break;
case 6:
return 4 * $bit_depth;
break;
}
return false;
}
}