--- /dev/null
+<?php
+
+/**
+ * PEL: PHP Exif Library.
+ * A library with support for reading and
+ * writing all Exif headers in JPEG and TIFF images using PHP.
+ *
+ * Copyright (C) 2004, 2005, 2006, 2007 Martin Geisler.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program in the file COPYING; if not, write to the
+ * Free Software Foundation, Inc., 51 Franklin St, Fifth Floor,
+ * Boston, MA 02110-1301 USA
+ */
+namespace lsolesen\pel;
+
+/**
+ * The window.
+ *
+ * @package PEL
+ */
+class PelDataWindow
+{
+
+ /**
+ * The data held by this window.
+ *
+ * The string can contain any kind of data, including binary data.
+ *
+ * @var string
+ */
+ private $data = '';
+
+ /**
+ * The byte order currently in use.
+ *
+ * This will be the byte order used when data is read using the for
+ * example the {@link getShort} function. It must be one of {@link
+ * PelConvert::LITTLE_ENDIAN} and {@link PelConvert::BIG_ENDIAN}.
+ *
+ * @var PelByteOrder
+ * @see setByteOrder, getByteOrder
+ */
+ private $order;
+
+ /**
+ * The start of the current window.
+ *
+ * All offsets used for access into the data will count from this
+ * offset, effectively limiting access to a window starting at this
+ * byte.
+ *
+ * @var int
+ * @see setWindowStart
+ */
+ private $start = 0;
+
+ /**
+ * The size of the current window.
+ *
+ * All offsets used for access into the data will be limited by this
+ * variable. A valid offset must be strictly less than this
+ * variable.
+ *
+ * @var int
+ * @see setWindowSize
+ */
+ private $size = 0;
+
+ /**
+ * Construct a new data window with the data supplied.
+ *
+ * @param mixed $data
+ * the data that this window will contain. This can
+ * either be given as a string (interpreted litteraly as a sequence
+ * of bytes) or a PHP image resource handle. The data will be copied
+ * into the new data window.
+ *
+ * @param boolean $endianess
+ * the initial byte order of the window. This must
+ * be either {@link PelConvert::LITTLE_ENDIAN} or {@link
+ * PelConvert::BIG_ENDIAN}. This will be used when integers are
+ * read from the data, and it can be changed later with {@link
+ * setByteOrder()}.
+ */
+ public function __construct($data = '', $endianess = PelConvert::LITTLE_ENDIAN)
+ {
+ if (is_string($data)) {
+ $this->data = $data;
+ } elseif (is_resource($data) && get_resource_type($data) == 'gd') {
+ /*
+ * The ImageJpeg() function insists on printing the bytes
+ * instead of returning them in a more civil way as a string, so
+ * we have to buffer the output...
+ */
+ ob_start();
+ ImageJpeg($data, null, Pel::getJPEGQuality());
+ $this->data = ob_get_clean();
+ } else {
+ throw new PelInvalidArgumentException('Bad type for $data: %s', gettype($data));
+ }
+
+ $this->order = $endianess;
+ $this->size = strlen($this->data);
+ }
+
+ /**
+ * Get the size of the data window.
+ *
+ * @return integer the number of bytes covered by the window. The
+ * allowed offsets go from 0 up to this number minus one.
+ *
+ * @see getBytes()
+ */
+ public function getSize()
+ {
+ return $this->size;
+ }
+
+ /**
+ * Change the byte order of the data.
+ *
+ * @param integer $order
+ * the new byte order. This must be either
+ * {@link PelConvert::LITTLE_ENDIAN} or {@link
+ * PelConvert::BIG_ENDIAN}.
+ */
+ public function setByteOrder($order)
+ {
+ $this->order = $order;
+ }
+
+ /**
+ * Get the currently used byte order.
+ *
+ * @return integer this will be either {@link
+ * PelConvert::LITTLE_ENDIAN} or {@link PelConvert::BIG_ENDIAN}.
+ */
+ public function getByteOrder()
+ {
+ return $this->order;
+ }
+
+ /**
+ * Move the start of the window forward.
+ *
+ * @param integer $start
+ * the new start of the window. All new offsets will be
+ * calculated from this new start offset, and the size of the window
+ * will shrink to keep the end of the window in place.
+ */
+ public function setWindowStart($start)
+ {
+ if ($start < 0 || $start > $this->size) {
+ throw new PelDataWindowWindowException(
+ 'Window [%d, %d] does ' . 'not fit in window [0, %d]',
+ $start,
+ $this->size,
+ $this->size);
+ }
+ $this->start += $start;
+ $this->size -= $start;
+ }
+
+ /**
+ * Adjust the size of the window.
+ * The size can only be made smaller.
+ *
+ * @param integer $size
+ * the desired size of the window. If the argument is
+ * negative, the window will be shrunk by the argument.
+ */
+ public function setWindowSize($size)
+ {
+ if ($size < 0) {
+ $size += $this->size;
+ }
+ if ($size < 0 || $size > $this->size) {
+ throw new PelDataWindowWindowException(
+ 'Window [0, %d] ' . 'does not fit in window [0, %d]',
+ $size,
+ $this->size);
+ }
+ $this->size = $size;
+ }
+
+ /**
+ * Make a new data window with the same data as the this window.
+ *
+ * @param integer|NULL $start
+ * if an integer is supplied, then it will be the start
+ * of the window in the clone. If left unspecified, then the clone
+ * will inherit the start from this object.
+ *
+ * @param integer|NULL $size
+ * if an integer is supplied, then it will be the size
+ * of the window in the clone. If left unspecified, then the clone
+ * will inherit the size from this object.
+ *
+ * @return PelDataWindow a new window that operates on the same data
+ * as this window, but (optionally) with a smaller window size.
+ */
+ public function getClone($start = null, $size = null)
+ {
+ $c = clone $this;
+
+ if (is_int($start)) {
+ $c->setWindowStart($start);
+ }
+ if (is_int($size)) {
+ $c->setWindowSize($size);
+ }
+ return $c;
+ }
+
+ /**
+ * Validate an offset against the current window.
+ *
+ * @param integer $offset
+ * the offset to be validated. If the offset is negative
+ * or if it is greater than or equal to the current window size,
+ * then a {@link PelDataWindowOffsetException} is thrown.
+ *
+ * @return void if the offset is valid nothing is returned, if it is
+ * invalid a new {@link PelDataWindowOffsetException} is thrown.
+ * @throws PelDataWindowOffsetException
+ */
+ private function validateOffset($offset)
+ {
+ if ($offset < 0 || $offset >= $this->size) {
+ throw new PelDataWindowOffsetException('Offset %d not within [%d, %d]', $offset, 0, $this->size - 1);
+ }
+ }
+
+ /**
+ * Return some or all bytes visible in the window.
+ *
+ * This method works just like the standard {@link substr()}
+ * function in PHP with the exception that it works within the
+ * window of accessible bytes and does strict range checking.
+ *
+ * @param integer|NULL $start
+ * the offset to the first byte returned. If a negative
+ * number is given, then the counting will be from the end of the
+ * window. Invalid offsets will result in a {@link
+ * PelDataWindowOffsetException} being thrown.
+ *
+ * @param integer|NUL $size
+ * the size of the sub-window. If a negative number is
+ * given, then that many bytes will be omitted from the result.
+ *
+ * @return string a subset of the bytes in the window. This will
+ * always return no more than {@link getSize()} bytes.
+ * @throws PelDataWindowOffsetException
+ */
+ public function getBytes($start = null, $size = null)
+ {
+ if (is_int($start)) {
+ if ($start < 0) {
+ $start += $this->size;
+ }
+
+ $this->validateOffset($start);
+ } else {
+ $start = 0;
+ }
+
+ if (is_int($size)) {
+ if ($size <= 0) {
+ $size += $this->size - $start;
+ }
+
+ $this->validateOffset($start + $size);
+ } else {
+ $size = $this->size - $start;
+ }
+
+ return substr($this->data, $this->start + $start, $size);
+ }
+
+ /**
+ * Return an unsigned byte from the data.
+ *
+ * @param integer $offset
+ * the offset into the data. An offset of zero will
+ * return the first byte in the current allowed window. The last
+ * valid offset is equal to {@link getSize()}-1. Invalid offsets
+ * will result in a {@link PelDataWindowOffsetException} being
+ * thrown.
+ *
+ * @return integer the unsigned byte found at offset.
+ * @throws PelDataWindowOffsetException
+ */
+ public function getByte($offset = 0)
+ {
+ /*
+ * Validate the offset --- this throws an exception if offset is
+ * out of range.
+ */
+ $this->validateOffset($offset);
+
+ /* Translate the offset into an offset into the data. */
+ $offset += $this->start;
+
+ /* Return an unsigned byte. */
+ return PelConvert::bytesToByte($this->data, $offset);
+ }
+
+ /**
+ * Return a signed byte from the data.
+ *
+ * @param integer $offset
+ * the offset into the data. An offset of zero will
+ * return the first byte in the current allowed window. The last
+ * valid offset is equal to {@link getSize()}-1. Invalid offsets
+ * will result in a {@link PelDataWindowOffsetException} being
+ * thrown.
+ *
+ * @return integer the signed byte found at offset.
+ * @throws PelDataWindowOffsetException
+ */
+ public function getSByte($offset = 0)
+ {
+ /*
+ * Validate the offset --- this throws an exception if offset is
+ * out of range.
+ */
+ $this->validateOffset($offset);
+
+ /* Translate the offset into an offset into the data. */
+ $offset += $this->start;
+
+ /* Return a signed byte. */
+ return PelConvert::bytesToSByte($this->data, $offset);
+ }
+
+ /**
+ * Return an unsigned short read from the data.
+ *
+ * @param integer $offset
+ * the offset into the data. An offset of zero will
+ * return the first short available in the current allowed window.
+ * The last valid offset is equal to {@link getSize()}-2. Invalid
+ * offsets will result in a {@link PelDataWindowOffsetException}
+ * being thrown.
+ *
+ * @return integer the unsigned short found at offset.
+ * @throws PelDataWindowOffsetException
+ */
+ public function getShort($offset = 0)
+ {
+ /*
+ * Validate the offset+1 to see if we can safely get two bytes ---
+ * this throws an exception if offset is out of range.
+ */
+ $this->validateOffset($offset);
+ $this->validateOffset($offset + 1);
+
+ /* Translate the offset into an offset into the data. */
+ $offset += $this->start;
+
+ /* Return an unsigned short. */
+ return PelConvert::bytesToShort($this->data, $offset, $this->order);
+ }
+
+ /**
+ * Return a signed short read from the data.
+ *
+ * @param integer $offset
+ * the offset into the data. An offset of zero will
+ * return the first short available in the current allowed window.
+ * The last valid offset is equal to {@link getSize()}-2. Invalid
+ * offsets will result in a {@link PelDataWindowOffsetException}
+ * being thrown.
+ *
+ * @return integer the signed short found at offset.
+ * @throws PelDataWindowOffsetException
+ */
+ public function getSShort($offset = 0)
+ {
+ /*
+ * Validate the offset+1 to see if we can safely get two bytes ---
+ * this throws an exception if offset is out of range.
+ */
+ $this->validateOffset($offset);
+ $this->validateOffset($offset + 1);
+
+ /* Translate the offset into an offset into the data. */
+ $offset += $this->start;
+
+ /* Return a signed short. */
+ return PelConvert::bytesToSShort($this->data, $offset, $this->order);
+ }
+
+ /**
+ * Return an unsigned long read from the data.
+ *
+ * @param integer $offset
+ * the offset into the data. An offset of zero will
+ * return the first long available in the current allowed window.
+ * The last valid offset is equal to {@link getSize()}-4. Invalid
+ * offsets will result in a {@link PelDataWindowOffsetException}
+ * being thrown.
+ *
+ * @return integer the unsigned long found at offset.
+ * @throws PelDataWindowOffsetException
+ */
+ public function getLong($offset = 0)
+ {
+ /*
+ * Validate the offset+3 to see if we can safely get four bytes
+ * --- this throws an exception if offset is out of range.
+ */
+ $this->validateOffset($offset);
+ $this->validateOffset($offset + 3);
+
+ /* Translate the offset into an offset into the data. */
+ $offset += $this->start;
+
+ /* Return an unsigned long. */
+ return PelConvert::bytesToLong($this->data, $offset, $this->order);
+ }
+
+ /**
+ * Return a signed long read from the data.
+ *
+ * @param integer $offset
+ * the offset into the data. An offset of zero will
+ * return the first long available in the current allowed window.
+ * The last valid offset is equal to {@link getSize()}-4. Invalid
+ * offsets will result in a {@link PelDataWindowOffsetException}
+ * being thrown.
+ *
+ * @return integer the signed long found at offset.
+ * @throws PelDataWindowOffsetException
+ */
+ public function getSLong($offset = 0)
+ {
+ /*
+ * Validate the offset+3 to see if we can safely get four bytes
+ * --- this throws an exception if offset is out of range.
+ */
+ $this->validateOffset($offset);
+ $this->validateOffset($offset + 3);
+
+ /* Translate the offset into an offset into the data. */
+ $offset += $this->start;
+
+ /* Return a signed long. */
+ return PelConvert::bytesToSLong($this->data, $offset, $this->order);
+ }
+
+ /**
+ * Return an unsigned rational read from the data.
+ *
+ * @param integer $offset
+ * the offset into the data. An offset of zero will
+ * return the first rational available in the current allowed
+ * window. The last valid offset is equal to {@link getSize()}-8.
+ * Invalid offsets will result in a {@link
+ * PelDataWindowOffsetException} being thrown.
+ *
+ * @return array the unsigned rational found at offset. A rational
+ * number is represented as an array of two numbers: the enumerator
+ * and denominator. Both of these numbers will be unsigned longs.
+ * @throws PelDataWindowOffsetException
+ */
+ public function getRational($offset = 0)
+ {
+ return array(
+ $this->getLong($offset),
+ $this->getLong($offset + 4)
+ );
+ }
+
+ /**
+ * Return a signed rational read from the data.
+ *
+ * @param integer $offset
+ * the offset into the data. An offset of zero will
+ * return the first rational available in the current allowed
+ * window. The last valid offset is equal to {@link getSize()}-8.
+ * Invalid offsets will result in a {@link
+ * PelDataWindowOffsetException} being thrown.
+ *
+ * @return array the signed rational found at offset. A rational
+ * number is represented as an array of two numbers: the enumerator
+ * and denominator. Both of these numbers will be signed longs.
+ * @throws PelDataWindowOffsetException
+ */
+ public function getSRational($offset = 0)
+ {
+ return array(
+ $this->getSLong($offset),
+ $this->getSLong($offset + 4)
+ );
+ }
+
+ /**
+ * String comparison on substrings.
+ *
+ * @param integer $offset
+ * the offset into the data. An offset of zero will make
+ * the comparison start with the very first byte available in the
+ * window. The last valid offset is equal to {@link getSize()}
+ * minus the length of the string. If the string is too long, then
+ * a {@link PelDataWindowOffsetException} will be thrown.
+ *
+ * @param string $str
+ * the string to compare with.
+ *
+ * @return boolean true if the string given matches the data in the
+ * window, at the specified offset, false otherwise. The comparison
+ * will stop as soon as a mismatch if found.
+ * @throws PelDataWindowOffsetException
+ */
+ public function strcmp($offset, $str)
+ {
+ /*
+ * Validate the offset of the final character we might have to
+ * check.
+ */
+ $s = strlen($str);
+ $this->validateOffset($offset);
+ $this->validateOffset($offset + $s - 1);
+
+ /* Translate the offset into an offset into the data. */
+ $offset += $this->start;
+
+ /* Check each character, return as soon as the answer is known. */
+ for ($i = 0; $i < $s; $i ++) {
+ if ($this->data{$offset + $i} != $str{$i}) {
+ return false;
+ }
+ }
+
+ /* All characters matches each other, return true. */
+ return true;
+ }
+
+ /**
+ * Return a string representation of the data window.
+ *
+ * @return string a description of the window with information about
+ * the number of bytes accessible, the total number of bytes, and
+ * the window start and stop.
+ */
+ public function __toString()
+ {
+ return Pel::fmt(
+ 'DataWindow: %d bytes in [%d, %d] of %d bytes',
+ $this->size,
+ $this->start,
+ $this->start + $this->size,
+ strlen($this->data));
+ }
+}
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