{"id":57589,"date":"2022-11-23T03:01:30","date_gmt":"2022-11-22T17:01:30","guid":{"rendered":"http:\/\/www.rjmprogramming.com.au\/ITblog\/?p=57589"},"modified":"2025-04-02T15:22:37","modified_gmt":"2025-04-02T05:22:37","slug":"animated-gif-imagemagick-cache-backup-tutorial","status":"publish","type":"post","link":"https:\/\/www.rjmprogramming.com.au\/ITblog\/animated-gif-imagemagick-cache-backup-tutorial\/","title":{"rendered":"Animated GIF ImageMagick Cache Backup Tutorial"},"content":{"rendered":"
\"Animated<\/a>

Animated GIF ImageMagick Cache Backup Tutorial<\/p><\/div>\n

As a programmer, am sure am no “Robinson Crusoe” thinking that we wish more often the web browser cache would come to our rescue, especially when web server tidying up results in the “rug being pulled from under” a programmatical arrangement we code for.<\/p>\n

Improving on yesterday’s Animated GIF ImageMagick Commercial Considerations Tutorial<\/a> can be such a case. Here’s the scenario for our ImageMagick simulate<\/i> functionality …<\/p>\n

    \n
  1. a popup window is opened initially just showing the first proposed animated GIF slide …<\/li>\n
  2. in the background we program to get ImageMagick<\/a> to construct its animated GIF version of the slides, in total …<\/li>\n
  3. in the case that there are no errors, the meta “refresh” popup window webpages (the contents for which exist on the web server and reference the IP address and web browser “brand”) continue to look for this ImageMagick animated GIF (the contents for which exist on the web server and whose name references the IP address and web browser “brand”), and if found …<\/li>\n
  4. is represented within a details\/summary “reveal” part of that webpage … all continuing along until …<\/li>\n
  5. eventually some “peer to peer” style PHP tidying up code may undermine the arrangement by deleting that popup window webpage (the contents for which exist on the web server and reference the IP address and web browser “brand”) and may rename the ImageMagick animated GIF (the contents for which exist on the web server and whose name references the IP address and web browser “brand”) to agif_slide.GIF should it be the latest ImageMagick animated GIF creation … at which point …<\/li>\n
  6. before today, that would have always caused an error 404 (Page not found, and shown that way to the user) back at the RJM Programming’s (Apache\/PHP\/MySql Linux web server) Document Root 404.shtml webpage (as last discussed with Page Not Found Error Message Email Subject Tutorial<\/a>)<\/li>\n<\/ol>\n

    So sad. But picture this. We add some PHP code up the top of our animated GIF creator PHP code, as per …<\/p>\n

    <?php
    \n
    \nif (isset($_GET['wasip'])) {
    \n sleep(20);
    \n $ipis=str_replace('+',' ',urldecode($_GET['wasip']));
    \n if (strpos('~' . str_replace('+',' ',urldecode($_GET['wasip'])), '~' . server_remote_addr()) !== false) { $ipis=server_remote_addr(); }
    \n if (file_exists('agif_slide' . $ipis . '.gif')) { \/\/ && file_exists('lastrefreshsize.txt')) {
    \n \/\/$fsz='' . filesize('agif_slide' . str_replace('+',' ',urldecode($_GET['wasip'])) . '.gif');
    \n \/\/$fvs='~' . file_get_contents('lastrefreshsize.txt');
    \n \/\/if (strpos($fvs, '~' . $fsz . ' ') !== false) {
    \n \/\/if (strpos($fvs, str_replace('+',' ',urldecode($_GET['wasip']))) !== false) {
    \n echo \"<html><head><!--meta http-equiv='Refresh' content=\\\"60; URL='.\/tutorial_to_animated_gif.php?wasip=\" . $_GET['wasip'] . \"'--><\/head><body><img id=thisim src='.\/agif_slide\" . $ipis . \".gif'><\/img><\/body><\/html>\";
    \n \/\/}
    \n \/\/}
    \n } else if (file_exists('agif_slide' . $ipis . '.gif') && file_exists('lastrefreshsize.txt')) {
    \n $fsz='' . filesize('agif_slide' . $ipis . '.gif');
    \n $fvs='~' . file_get_contents('lastrefreshsize.txt');
    \n if (strpos($fvs, '~' . $fsz . ' ') !== false) {
    \n if (strpos($fvs, $ipis) !== false) {
    \n echo \"<html><head><!--meta http-equiv='Refresh' content=\\\"60; URL='.\/tutorial_to_animated_gif.php?wasip=\" . $_GET['wasip'] . \"'--><\/head><body><img id=thisim src='.\/agif_slide\" . $ipis . \".gif'><\/img><\/body><\/html>\";
    \n }
    \n }
    \n } else if (file_exists('agif_slide.GIF') && file_exists('lastrefreshsize.txt')) {
    \n $fsz='' . filesize('agif_slide.GIF');
    \n $fvs='~' . file_get_contents('lastrefreshsize.txt');
    \n if (strpos($fvs, '~' . $fsz . ' ') !== false) {
    \n if (strpos($fvs, $ipis) !== false) {
    \n echo \"<html><head><!--meta http-equiv='Refresh' content=\\\"60; URL='.\/tutorial_to_animated_gif.php?wasip=\" . $_GET['wasip'] . \"'--><\/head><body><img id=thisim src='.\/agif_slide.GIF'><\/img><\/body><\/html>\";
    \n }
    \n }
    \n }
    \n exit;
    \n}
    \n<\/code>
    \n?><\/p>\n

    … called back at 404.shtml as per the new Javascript<\/font> …<\/p>\n


    \n<script type='text\/javascript'>
    \n
    \n var cbderrors='';
    \n var bih='';<\/font>
    \n
    \n if (document.URL.indexOf('.au\/drupal') != -1) {
    \n location.href='\/\/www.rjmprogramming.com.au\/drupal\/index.htm';
    \n exit;
    \n } \/\/else if (document.URL.indexOf('PHP\/animegif\/outtemp') != -1 && document.URL.indexOf('irefresh=') != -1 && cbderrors == '') {
    \n \/\/location.href='\/PHP\/animegif\/tutorial_to_animated_gif.php?wasip=' + encodeURIComponent(document.URL.split('PHP\/animegif\/outtemp')[1].split('.htm')[0]) + '&toidea=' + encodeURIComponent('agif_slide.GIF');
    \n \/\/exit;
    \n \/\/}<\/font>
    \n
    \n function bitlaterdo() {
    \n if (document.URL.indexOf('PHP\/animegif\/outtemp') != -1 && document.URL.indexOf('irefresh=') != -1 && cbderrors == '') {
    \n location.href='\/PHP\/animegif\/tutorial_to_animated_gif.php?wasip=' + encodeURIComponent(document.URL.split('PHP\/animegif\/outtemp')[1].split('.htm')[0]) + '&toidea=' + encodeURIComponent('agif_slide.GIF');
    \n exit;
    \n } else if (document.URL.indexOf('PHP\/animegif\/outtemp') != -1 && document.URL.indexOf('irefresh=') != -1) {
    \n document.body.innerHTML=bih; \/\/document.body.style.visible='visible';
    \n document.body.style.cursor='pointer';
    \n }
    \n }<\/font>
    \n
    \n function onPageUnload() {
    \n }
    \n
    \n function onPageLoad() {
    \n if (document.URL.indexOf('PHP\/animegif\/outtemp') != -1 && document.URL.indexOf('irefresh=') != -1) {
    \n bih=document.body.innerHTML;
    \n document.body.innerHTML='<p>&nbsp;<br>&nbsp;<br>&nbsp;<br>&nbsp;<br>&nbsp;<br>&nbsp;<br>&nbsp;<br>&nbsp;<br>&nbsp;<br>&nbsp;<br><\/p>';
    \n document.body.style.cursor='progress';
    \n setTimeout(bitlaterdo, 3000);
    \n }<\/font>
    \n if (document.URL.indexOf('.au\/drupal') != -1) {
    \n location.href='\/\/www.rjmprogramming.com.au\/drupal\/index.htm';
    \n exit;
    \n }
    \n if (document.URL.indexOf('square_hr_tracing.htm%') != -1) {
    \n location.href=document.URL.replace('%3F','?').replace(\/\\%23\/g, '#').replace(\/\\%26\/g, '&');
    \n exit;
    \n }
    \n }
    \n
    \nfunction checkife(iois) {
    \n if (iois != null) {
    \n \/\/alert(1);
    \n var aconto = (iois.contentWindow || iois.contentDocument);
    \n \/\/alert(11);
    \n if (aconto != null) {
    \n \/\/alert(111);
    \n if (aconto.document) { aconto = aconto.document; }
    \n \/\/alert(1111);
    \n if (aconto.body != null) {
    \n \/\/alert(2);
    \n \/\/if (aconto.body.innerHTML.indexOf('@ error\/') != -1) { cbderrors=aconto.body.innerHTML; }
    \n if (aconto.body.innerHTML.indexOf('error') != -1) { cbderrors=aconto.body.innerHTML; }
    \n }
    \n }
    \n }
    \n}<\/font>
    \n<\/script>
    \n<\/code><\/p>\n

    … and new HTML iframe, helping check for ImageMagick animated GIF creation errors (in which case, no redirections should take place) …<\/p>\n


    \n<iframe onload=checkife(this); src='\/PHP\/animegif\/cbd.cbd'><\/iframe>
    \n<\/code><\/p>\n

    … working with the changed<\/a> tutorial_to_animated_gif.php<\/a> our inhouse Animated GIF Creator helper PHP web application<\/a>.<\/p>\n

    Then, as long as that 404.shtml proposed redirection timing hits on an existent ImageMagick animated GIF (in either filenaming guise) we can count on the web browser cache to help us out with this animated GIF display continuing (rather than seeing an error 404 Page not found display), even if further down the track the situation changes, again, with the contents of that agif_slide.GIF “latest ImageMagick animated GIF backup” arrangement, because the web browser cache is being used.<\/p>\n

    \n

    \n

    Previous relevant Animated GIF ImageMagick Commercial Considerations Tutorial<\/a> is shown below.<\/p>\n

    \"Animated<\/a>

    Animated GIF ImageMagick Commercial Considerations Tutorial<\/p><\/div>\n

    Up to, and including yesterday’s Animated GIF Meta Refresh Simulation ImageMagick Switches Tutorial<\/a> our PHP code has assumed file naming logic that could be prematurely interrupted when any more than one user is using the ImageMagick simulated<\/i> animated GIF creation logic, at the same time.<\/p>\n

    This affects functionality in two categories of concern …<\/p>\n