Problem facing while Dynamic Image Creation to replace Font Embedding

[neovantage]

Hey all,

I am using a PHP script which creates headings at run time in a sense at page execution. I am stuck a with a very little problem which i am sure i will have the solution from experts.

The problem is when it creates transparent PNG format image then and it pixel ate the image. e.g.

If i am using a gradient in background then it vary in color range. Now when i used that php script it generates image successfully but it pixel ate the image.

So my question how can i fix that. i am attaching the code which i am using for that and a *.jpg of screen shot for better understanding of my problem.

generate-headings.php Page

$font_file  = 'fonts/arial.ttf' ;
    $font_size  = 20 ;
    $font_color = '#ffffff' ;
    $background_color = '#ffffff' ;
    $transparent_background  = true ;
    $cache_images = true ;
    $cache_folder = 'cache' ;
 
    $mime_type = 'image/png' ;
    $extension = '.png' ;
    $send_buffer_size = 4096 ;
 
    $text = $_GET['text'];
 
    if(get_magic_quotes_gpc()){
        $text = stripslashes($text) ;
    }
    $text = javascript_to_html($text) ;
 
    // look for cached copy, send if it exists
    $hash = md5(basename($font_file) . $font_size . $font_color . $background_color . $transparent_background . $text) ;
    $cache_filename = $cache_folder . '/' . $hash . $extension ;
    if($cache_images && ($file = @fopen($cache_filename,'rb'))){
        header('Content-type: ' . $mime_type) ;
        while(!feof($file))
            print(($buffer = fread($file,$send_buffer_size))) ;
        fclose($file) ;
        exit ;
    }
 
    // check font availability
    $font_found = is_readable($font_file) ;
    if(!$font_found){
        //fatal_error('Error: The server is missing the specified font.') ;
    }
 
    // create image
    $background_rgb = hex_to_rgb($background_color) ;
    $font_rgb = hex_to_rgb($font_color) ;
    $dip = get_dip($font_file,$font_size) ;
    $box = @ImageTTFBBox($font_size,0,$font_file,$text) ;
    $image = @ImageCreate(abs($box[2]-$box[0]),abs($box[5]-$dip)) ;
    if(!$image || !$box){
        fatal_error('Error: The server could not create this heading image.') ;
    }
 
    // allocate colors and draw text
    $background_color = @ImageColorAllocate($image,$background_rgb['red'],$background_rgb['green'],$background_rgb['blue']) ;
    $font_color = ImageColorAllocate($image,$font_rgb['red'],$font_rgb['green'],$font_rgb['blue']) ;   
    ImageTTFText($image,$font_size,0,-$box[0],abs($box[5]-$box[3])-$box[1],$font_color,$font_file,$text) ;
 
    // set transparency
    if($transparent_background)
        ImageColorTransparent($image,$background_color) ;
 
    header('Content-type: ' . $mime_type) ;
    ImagePNG($image) ;
 
    // save copy of image for cache
    if($cache_images){
        @ImagePNG($image,$cache_filename) ;
    }
 
    ImageDestroy($image) ;
    exit ;
 
    /*$im = imagecreatetruecolor(300, 18);
    $white = imagecolorallocate($im, 255, 255, 255);
    $black = imagecolorallocate($im, 0, 0, 0);
    imagefilledrectangle($im, 0, 0, imagesx($im), imagesy($im), gd_bkg());
    $text = $_GET[hd];
    $font = "fonts/Abduction.ttf";
    imagettftext($im,14,0,0,13,$black,$font,$text);
    imagepng($im);
    imagedestroy($im);
 
    $background_rgb = hex_to_rgb($background_color) ;
    $background_color = @ImageColorAllocate($image,$background_rgb['red'],*/
 
 
    //=============================== FUNCTIONS =================
    function javascript_to_html($text){
        $matches = null ;
        preg_match_all('/%u([0-9A-F]{4})/i',$text,$matches) ;
        if(!empty($matches)) for($i=0;$i<sizeof($matches[0]);$i++)
            $text = str_replace($matches[0][$i],'&#'.hexdec($matches[1][$i]).';',$text) ;
        return $text ;
    }
    function hex_to_rgb($hex){
        // remove '#'
        if(substr($hex,0,1) == '#')
            $hex = substr($hex,1) ;
 
        // expand short form ('fff') color
        if(strlen($hex) == 3){
            $hex = substr($hex,0,1) . substr($hex,0,1) . substr($hex,1,1) . substr($hex,1,1) . substr($hex,2,1) . substr($hex,2,1) ;
        }
 
        if(strlen($hex) != 6)
            fatal_error('Error: Invalid color "'.$hex.'"') ;
 
        // convert
        $rgb['red'] = hexdec(substr($hex,0,2)) ;
        $rgb['green'] = hexdec(substr($hex,2,2)) ;
        $rgb['blue'] = hexdec(substr($hex,4,2)) ;
 
        return $rgb ;
    }
    function get_dip($font,$size){
        $test_chars = 'abcdefghijklmnopqrstuvwxyz' .
                      'ABCDEFGHIJKLMNOPQRSTUVWXYZ' .
                      '1234567890' .
                      '!@#$%^&*()\'"\\/;.,`~<>[]{}-+_-=' ;
        $box = @ImageTTFBBox($size,0,$font,$test_chars) ;
        return $box[3] ;
    }
 

Javascript File which used to replace text with images

function com_stewartspeak_replacement() {
/*
    Dynamic Heading Generator
    By Stewart Rosenberger
    http://www.stewartspeak.com/headings/
 
    This script searches through a web page for specific or general elements
    and replaces them with dynamically generated images, in conjunction with
    a server-side script.
*/
 
 
replaceSelector("h2","generate-headings.php",true);
var testURL = "http://bytes.com/images/test.png" ;
 
var doNotPrintImages = false;
var printerCSS = "includes/replacement-print.css";
 
var hideFlicker = false;
var hideFlickerCSS = "includes/replacement-screen.css";
var hideFlickerTimeout = 1000;
 
 
 
 
/* ---------------------------------------------------------------------------
    For basic usage, you should not need to edit anything below this comment.
    If you need to further customize this script's abilities, make sure
    you're familiar with Javascript. And grab a soda or something.
*/
 
var items;
var imageLoaded = false;
var documentLoaded = false;
 
function replaceSelector(selector,url,wordwrap){
    if(typeof items == "undefined")
        items = new Array();
 
    items[items.length] = {selector: selector, url: url, wordwrap: wordwrap};
}
 
if(hideFlicker)
{        
    document.write('<link id="hide-flicker" rel="stylesheet" media="screen" href="' + hideFlickerCSS + '" />');        
    window.flickerCheck = function()
    {
        if(!imageLoaded)
            setStyleSheetState('hide-flicker',false);
    };
    setTimeout('window.flickerCheck();',hideFlickerTimeout)
}
 
if(doNotPrintImages)
    document.write('<link id="print-text" rel="stylesheet" media="print" href="' + printerCSS + '" />');
 
var test = new Image();
test.onload = function() { imageLoaded = true; if(documentLoaded) replacement(); };
test.src = testURL + "?date=" + (new Date()).getTime();
alert(test.src);
addLoadHandler(function(){ documentLoaded = true; if(imageLoaded) replacement(); });
 
 
function documentLoad()
{
    documentLoaded = true;
    if(imageLoaded)
        replacement();
}
 
function replacement()
{
    for(var i=0;i<items.length;i++)
    {
        var elements = getElementsBySelector(items[i].selector);
        if(elements.length > 0) for(var j=0;j<elements.length;j++)
        {
            if(!elements[j])
                continue ;
 
            var text = extractText(elements[j]);
            while(elements[j].hasChildNodes())
                elements[j].removeChild(elements[j].firstChild);
 
            var tokens = items[i].wordwrap ? text.split(' ') : [text] ;
            for(var k=0;k<tokens.length;k++)
            {
                var url = items[i].url + "?text="+escape(tokens[k]+' ')+"&selector="+escape(items[i].selector);
                var image = document.createElement("img");
                image.className = "replacement";
                image.alt = tokens[k] ;
                image.src = url;
                elements[j].appendChild(image);
            }
 
            if(doNotPrintImages)
            {
                var span = document.createElement("span");
                span.style.display = 'none';
                span.className = "print-text";
                span.appendChild(document.createTextNode(text));
                elements[j].appendChild(span);
            }
        }
    }
 
    if(hideFlicker)
        setStyleSheetState('hide-flicker',false);
}
 
function addLoadHandler(handler)
{
    if(window.addEventListener)
    {
        window.addEventListener("load",handler,false);
    }
    else if(window.attachEvent)
    {
        window.attachEvent("onload",handler);
    }
    else if(window.onload)
    {
        var oldHandler = window.onload;
        window.onload = function piggyback()
        {
            oldHandler();
            handler();
        };
    }
    else
    {
        window.onload = handler;
    }
}
 
function setStyleSheetState(id,enabled) 
{
    var sheet = document.getElementById(id);
    if(sheet)
        sheet.disabled = (!enabled);
}
 
function extractText(element)
{
    if(typeof element == "string")
        return element;
    else if(typeof element == "undefined")
        return element;
    else if(element.innerText)
        return element.innerText;
 
    var text = "";
    var kids = element.childNodes;
    for(var i=0;i<kids.length;i++)
    {
        if(kids[i].nodeType == 1)
        text += extractText(kids[i]);
        else if(kids[i].nodeType == 3)
        text += kids[i].nodeValue;
    }
 
    return text;
}
 
/*
    Finds elements on page that match a given CSS selector rule. Some
    complicated rules are not compatible.
    Based on Simon Willison's excellent "getElementsBySelector" function.
    Original code (with comments and description):
        http://simon.incutio.com/archive/2003/03/25/getElementsBySelector
*/
function getElementsBySelector(selector)
{
    var tokens = selector.split(' ');
    var currentContext = new Array(document);
    for(var i=0;i<tokens.length;i++)
    {
        token = tokens[i].replace(/^\s+/,'').replace(/\s+$/,'');
        if(token.indexOf('#') > -1)
        {
            var bits = token.split('#');
            var tagName = bits[0];
            var id = bits[1];
            var element = document.getElementById(id);
            if(tagName && element.nodeName.toLowerCase() != tagName)
                return new Array();
            currentContext = new Array(element);
            continue;
        }
 
        if(token.indexOf('.') > -1)
        {
            var bits = token.split('.');
            var tagName = bits[0];
            var className = bits[1];
            if(!tagName)
                tagName = '*';
 
            var found = new Array;
            var foundCount = 0;
            for(var h=0;h<currentContext.length;h++)
            {
                var elements;
                if(tagName == '*')
                    elements = currentContext[h].all ? currentContext[h].all : currentContext[h].getElementsByTagName('*');
                else
                    elements = currentContext[h].getElementsByTagName(tagName);
 
                for(var j=0;j<elements.length;j++)
                    found[foundCount++] = elements[j];
            }
 
            currentContext = new Array;
            var currentContextIndex = 0;
            for(var k=0;k<found.length;k++)
            {
                if(found[k].className && found[k].className.match(new RegExp('\\b'+className+'\\b')))
                    currentContext[currentContextIndex++] = found[k];
            }
 
            continue;
        }
 
        if(token.match(/^(\w*)\[(\w+)([=~\|\^\$\*]?)=?"?([^\]"]*)"?\]$/))
        {
            var tagName = RegExp.$1;
            var attrName = RegExp.$2;
            var attrOperator = RegExp.$3;
            var attrValue = RegExp.$4;
            if(!tagName)
                tagName = '*';
 
            var found = new Array;
            var foundCount = 0;
            for(var h=0;h<currentContext.length;h++)
            {
                var elements;
                if(tagName == '*')
                    elements = currentContext[h].all ? currentContext[h].all : currentContext[h].getElementsByTagName('*');
                else
                    elements = currentContext[h].getElementsByTagName(tagName);
 
                for(var j=0;j<elements.length;j++)
                    found[foundCount++] = elements[j];
            }
 
            currentContext = new Array;
            var currentContextIndex = 0;
            var checkFunction;
            switch(attrOperator)
            {
                case '=':
                    checkFunction = function(e) { return (e.getAttribute(attrName) == attrValue); };
                    break;
                case '~':
                    checkFunction = function(e) { return (e.getAttribute(attrName).match(new RegExp('\\b'+attrValue+'\\b'))); };
                    break;
                case '|':
                    checkFunction = function(e) { return (e.getAttribute(attrName).match(new RegExp('^'+attrValue+'-?'))); };
                    break;
                case '^':
                    checkFunction = function(e) { return (e.getAttribute(attrName).indexOf(attrValue) == 0); };
                    break;
                case '$':
                    checkFunction = function(e) { return (e.getAttribute(attrName).lastIndexOf(attrValue) == e.getAttribute(attrName).length - attrValue.length); };
                    break;
                case '*':
                    checkFunction = function(e) { return (e.getAttribute(attrName).indexOf(attrValue) > -1); };
                    break;
                default :
                    checkFunction = function(e) { return e.getAttribute(attrName); };
            }
 
            currentContext = new Array;
            var currentContextIndex = 0;
            for(var k=0;k<found.length;k++)
            {
                if(checkFunction(found[k]))
                    currentContext[currentContextIndex++] = found[k];
            }
 
            continue;
        }
 
        tagName = token;
        var found = new Array;
        var foundCount = 0;
        for(var h=0;h<currentContext.length;h++)
        {
            var elements = currentContext[h].getElementsByTagName(tagName);
            for(var j=0;j<elements.length; j++)
                found[foundCount++] = elements[j];
        }
 
        currentContext = found;
    }
 
    return currentContext;
}
 
 
}// end of scope, execute code
if(document.createElement && document.getElementsByTagName && !navigator.userAgent.match(/opera\/?6/i))
    com_stewartspeak_replacement();
 
 

[hsriat]

I could not see any "pixel ate" happening. Even it does happen, I believe it would be a error in your algorithm.

PS: I am inferring "pixel ate" as what happens to the videos being shown on the national TV channels when there's some inappropriate content/scene.