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phena109/AnimatedGif.php

Created March 8, 2019 05:11
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Class to generate animated Gif
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AnimatedGif.php
<?php
/*
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
:: Formerly known as:::
:: GIFEncoder Version 2.0 by László Zsidi, http://gifs.hu
::
:: This class is a rewritten 'GifMerge.class.php' version.
::
:: Modification:
:: - Simplified and easy code,
:: - Ultra fast encoding,
:: - Built-in errors,
:: - Stable working
::
::
:: Updated at 2007. 02. 13. '00.05.AM'
::
::
::
:: Try on-line GIFBuilder Form demo based on GIFEncoder.
::
:: http://gifs.hu/phpclasses/demos/GifBuilder/
::
:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
*/
/*
08 Mar 2019
Lightly modernised by phena109
*/
/**
* Encode animated gifs
*/
class AnimatedGif
{
/**
* The built gif image
* @var resource
*/
private $image = '';
/**
* The array of images to stack
* @var array
*/
private $buffer = [];
/**
* How many times to loop? 0 = infinite
* @var int
*/
private $number_of_loops = 0;
/**
*
* @var int
*/
private $DIS = 2;
/**
* Which colour is transparent
* @var int
*/
private $transparent_colour = -1;
/**
* Is this the first frame
* @var int
*/
private $first_frame = true;
/**
* Encode an animated gif
* @param array $source_images An array of binary source images
* @param array $image_delays The delays associated with the source images
* @param int $number_of_loops The number of times to loop
* @param int $transparent_colour_red
* @param int $transparent_colour_green
* @param int $transparent_colour_blue
*/
function __construct(
array $source_images,
array $image_delays,
$number_of_loops,
$transparent_colour_red = -1,
$transparent_colour_green = -1,
$transparent_colour_blue = -1
) {
/**
* I have no idea what these even do, they appear to do nothing to the image so far
*/
$transparent_colour_red = 0;
$transparent_colour_green = 0;
$transparent_colour_blue = 0;
$this->number_of_loops = ($number_of_loops > -1) ? $number_of_loops : 0;
$this->set_transparent_colour($transparent_colour_red,
$transparent_colour_green, $transparent_colour_blue);
$this->buffer_images($source_images);
$this->addHeader();
for ($i = 0; $i < count($this->buffer); $i++) {
$this->addFrame($i, $image_delays [$i]);
}
}
/**
* Set the transparent colour
* @param int $red
* @param int $green
* @param int $blue
*/
private function set_transparent_colour($red, $green, $blue)
{
$this->transparent_colour = ($red > -1 && $green > -1 && $blue > -1) ?
($red | ($green << 8) | ($blue << 16)) : -1;
}
/**
* Buffer the images and check to make sure they are vaild
* @param array $source_images the array of source images
* @throws Exception
*/
private function buffer_images($source_images)
{
for ($i = 0; $i < count($source_images); $i++) {
$this->buffer [] = $source_images [$i];
if (substr($this->buffer [$i], 0,
6) != "GIF87a" && substr($this->buffer [$i], 0,
6) != "GIF89a") {
throw new \Exception('Image at position ' . $i . ' is not a gif');
}
for ($j = (13 + 3 * (2 << (ord($this->buffer [$i]{10}) & 0x07))), $k = true; $k; $j++) {
switch ($this->buffer [$i]{$j}) {
case "!":
if ((substr($this->buffer [$i], ($j + 3),
8)) == "NETSCAPE") {
throw new \Exception('You cannot make an animation from an animated gif.');
}
break;
case ";":
$k = false;
break;
}
}
}
}
/**
* Add the gif header to the image
*/
private function addHeader()
{
$cmap = 0;
$this->image = 'GIF89a';
if (ord($this->buffer [0]{10}) & 0x80) {
$cmap = 3 * (2 << (ord($this->buffer [0]{10}) & 0x07));
$this->image .= substr($this->buffer [0], 6, 7);
$this->image .= substr($this->buffer [0], 13, $cmap);
$this->image .= "!\377\13NETSCAPE2.0\3\1" . $this->word($this->number_of_loops) . "\0";
}
}
/**
* Add a frame to the animation
* @param int $frame The frame to be added
* @param int $delay The delay associated with the frame
*/
private function addFrame($frame, $delay)
{
$Locals_str = 13 + 3 * (2 << (ord($this->buffer [$frame]{10}) & 0x07));
$Locals_end = strlen($this->buffer [$frame]) - $Locals_str - 1;
$Locals_tmp = substr($this->buffer [$frame], $Locals_str, $Locals_end);
$Global_len = 2 << (ord($this->buffer [0]{10}) & 0x07);
$Locals_len = 2 << (ord($this->buffer [$frame]{10}) & 0x07);
$Global_rgb = substr($this->buffer [0], 13,
3 * (2 << (ord($this->buffer [0]{10}) & 0x07)));
$Locals_rgb = substr($this->buffer [$frame], 13,
3 * (2 << (ord($this->buffer [$frame]{10}) & 0x07)));
$Locals_ext = "!\xF9\x04" . chr(($this->DIS << 2) + 0) .
chr(($delay >> 0) & 0xFF) . chr(($delay >> 8) & 0xFF) . "\x0\x0";
if ($this->transparent_colour > -1 && ord($this->buffer [$frame]{10}) & 0x80) {
for ($j = 0; $j < (2 << (ord($this->buffer [$frame]{10}) & 0x07)); $j++) {
if (
ord($Locals_rgb{3 * $j + 0}) == (($this->transparent_colour >> 16) & 0xFF) &&
ord($Locals_rgb{3 * $j + 1}) == (($this->transparent_colour >> 8) & 0xFF) &&
ord($Locals_rgb{3 * $j + 2}) == (($this->transparent_colour >> 0) & 0xFF)
) {
$Locals_ext = "!\xF9\x04" . chr(($this->DIS << 2) + 1) .
chr(($delay >> 0) & 0xFF) . chr(($delay >> 8) & 0xFF) . chr($j) . "\x0";
break;
}
}
}
switch ($Locals_tmp{0}) {
case "!":
$Locals_img = substr($Locals_tmp, 8, 10);
$Locals_tmp = substr($Locals_tmp, 18, strlen($Locals_tmp) - 18);
break;
case ",":
$Locals_img = substr($Locals_tmp, 0, 10);
$Locals_tmp = substr($Locals_tmp, 10, strlen($Locals_tmp) - 10);
break;
}
if (ord($this->buffer [$frame]{10}) & 0x80 && $this->first_frame === false) {
if ($Global_len == $Locals_len) {
if ($this->blockCompare($Global_rgb, $Locals_rgb,
$Global_len)) {
$this->image .= ($Locals_ext . $Locals_img . $Locals_tmp);
} else {
$byte = ord($Locals_img{9});
$byte |= 0x80;
$byte &= 0xF8;
$byte |= (ord($this->buffer [0]{10}) & 0x07);
$Locals_img{9} = chr($byte);
$this->image .= ($Locals_ext . $Locals_img . $Locals_rgb . $Locals_tmp);
}
} else {
$byte = ord($Locals_img{9});
$byte |= 0x80;
$byte &= 0xF8;
$byte |= (ord($this->buffer [$frame]{10}) & 0x07);
$Locals_img{9} = chr($byte);
$this->image .= ($Locals_ext . $Locals_img . $Locals_rgb . $Locals_tmp);
}
} else {
$this->image .= ($Locals_ext . $Locals_img . $Locals_tmp);
}
$this->first_frame = false;
}
/**
* Add the gif footer
*/
private function addFooter()
{
$this->image .= ";";
}
/**
* Compare gif blocks? What is a block?
* @param type $GlobalBlock
* @param type $LocalBlock
* @param int $Len
* @return bool
*/
private function blockCompare($GlobalBlock, $LocalBlock, $Len)
{
for ($i = 0; $i < $Len; $i++) {
if (
$GlobalBlock{3 * $i + 0} != $LocalBlock{3 * $i + 0} ||
$GlobalBlock{3 * $i + 1} != $LocalBlock{3 * $i + 1} ||
$GlobalBlock{3 * $i + 2} != $LocalBlock{3 * $i + 2}
) {
return false;
}
}
return true;
}
/**
* No clue
* @param int $int
* @return string the char you meant?
*/
private function word($int)
{
return (chr($int & 0xFF) . chr(($int >> 8) & 0xFF));
}
/**
* Return the animated gif
* @return resource
*/
function getAnimation()
{
return $this->image;
}
/**
* Return the animated gif
* @return void
*/
function display()
{
//late footer add
$this->addFooter();
header('Content-type:image/gif');
echo $this->image;
}
}
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