Image Pixel Border - GD

[Local_Hero]

I've been searching and asking around with no success so any help or direction is appreciated!

I have a page that allows the user to specify a font, text, and size. Then the page displays it in a .png image for the font,text,and size they wanted. The image is transparent except for the text which is black. I want to be able to specify a border around the text.

Is there a way to tell PHP to look for transparent pixels and colored (black) pixels and create 2 border pixels (red for instance) on the transparent side? All that I am using is: ImageColorTransparent($image,$background_color); with the background_color being white.

[Local_Hero]

Thanks to Bokeh I've gotten a little further. He has suggested I check each pixel and see if it is different from the previous one. I'm really new to the GD library but I understand how he suggest to solve it. Here is some of the code that I came up with:

if($transparent_background)
    ImageColorTransparent($image,$background_color) ;

header('Content-type: ' . $mime_type) ;
ImagePNG($image) ;

$pxwidth = imagesx($image);
$pxheight = imagesy($image);
$previous_color = 0;

   for($yy = 0;$yy < $pxheight;++$yy){

       for($xx = 0;$xx < $pxwidth;++$xx){

           $current_color = ImageColorAt($image, $xx, $yy);

           if($current_color !== $previous_color && $xx < $pxwidth-1){
             #change $previous_color pixel to red???
           }
        }
   }

I think I got a start, but I've probably been staring at the same page for too long. I'm not sure exactally how I should change the previous transparent pixel 😕 Does anyone have any ideas to get me through the next step?
Thanks!

[Weedpacket]

Is [man]imagesetpixel[/man] what you're looking for?

[Local_Hero]

Yeah, I think so. I guess I'm not 100% sure I understand what I need to set the color (red for example). I tried:

if($transparent_background) 
    ImageColorTransparent($image,$background_color) ; 

header('Content-type: ' . $mime_type) ; 
ImagePNG($image) ; 

$pxwidth = imagesx($image); 
$pxheight = imagesy($image); 
$previous_color = 0; 

   for($yy = 0;$yy < $pxheight;++$yy){ 

       for($xx = 0;$xx < $pxwidth;++$xx){ 

           $current_color = ImageColorAt($image, $xx, $yy); 

           if($current_color !== $previous_color && $xx < $pxwidth-1){ 
             imagesetpixel ( $image, $xx, $yy, FF0);
           } 
        } 
   } 

It doesn't do anything, the image still gets created. I guess I didn't expect it to be that easy. My logic seems right I think. I check every x in each y row. If the first color isn't like the next, change it to red. But I know with PHP if one thing is out of place nothing happens. Any Ideas?

[Weedpacket]

You need to declare the colour ([man]imagecolorallocate[/man]), which is why that function is referred to on the [man]imagesetpixel[/man] page under "see also".

[Local_Hero]

Oh Yeah,
I added -
imagesetpixel ( $image, $xx, $yy, imagecolorallocate($previous_color, 255, 0, 0));
Which should make a red pixel, but doesn't. Something is missing and I can't find it. My page is located at: http://www.localheroclothing.com/images/jerseyfonts.php

The images call another script

<img src="http://www.localheroclothing.com/images/fontchange1.php?time='.microtime()'&text=<? echo($fonttext);?>&font=<? echo($fontype);?>&color=000&bg_color=EFEFEF&size=<? echo($fontsize);?>" 
   alt="localhero" width="140" height="34" class="<?php if( !$_POST['newfont'] || !$_POST['newtext']) echo('hideme');?>">

And the other script draws the font

<?php session_start(); 
/* 
    Dynamic Heading Generator 
    By Stewart Rosenberger 
    http://www.stewartspeak.com/headings/     

*/ 

$textcolor = $_SESSION['textcolor']; 
$backcolor = $_SESSION['backcolor']; 
define('FONTPATH', '/www/htdocs/images/fonts/'); 
$font_file = FONTPATH.$_GET['font']; 

$font_size  = $_GET['size']; 
$font_color =  $_GET['color']; 
$background_color =  $_GET['bg_color']; 
$transparent_background  = true ; 
$cache_images = false ; 
$cache_folder = '' ; 
$mime_type = 'image/png' ; 
$extension = '.png' ; 
$send_buffer_size = 4096 ; 

// check for GD support 
if(!function_exists('ImageCreate')) 
    fatal_error('Error: Server does not support PHP image generation') ; 

// clean up text 
if(empty($_GET['text'])) 
    fatal_error('Error: No text specified.') ; 

$text = $_GET['text'] ; 
if(get_magic_quotes_gpc()) 
    $text = stripslashes($text) ; 
$text = javascript_to_html($text) ; 

// 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) ; 

   $pxwidth = imagesx($image); 
   $pxheight = imagesy($image); 
   $previous_color = 0; 

   for($yy = 0;$yy < $pxheight;++$yy){ 

       for($xx = 0;$xx < $pxwidth;++$xx){ 

           $current_color = ImageColorAt($image, $xx, $yy); 

           if($current_color !== $previous_color && $xx < $pxwidth-1){ 
  imagesetpixel ( $image, $xx, $yy, imagecolorallocate($previous_color, 255, 0, 0));

           } 
                     } 

   } 

// save copy of image for cache 
#if($cache_images) 
#{ 
#    @ImagePNG($image,$cache_filename) ; 
#} 
# 
ImageDestroy($image) ; 
exit ; 


/* 
    try to determine the "dip" (pixels dropped below baseline) of this 
    font for this size. 
*/ 
function get_dip($font,$size) 
{ 
    $test_chars = 'abcdefghijklmnopqrstuvwxyz' . 
                  'ABCDEFGHIJKLMNOPQRSTUVWXYZ' . 
                  '1234567890' . 
                  '!@#$%^&*()\'"\\/;.,`~<>[]{}-+_-=' ; 
    $box = @ImageTTFBBox($size,0,$font,$test_chars) ; 
    return $box[3] ; 
} 


/* 
    attempt to create an image containing the error message given. 
    if this works, the image is sent to the browser. if not, an error 
    is logged, and passed back to the browser as a 500 code instead. 
*/ 
function fatal_error($message) 
{ 
    // send an image 
    if(function_exists('ImageCreate')) 
    { 
        $width = ImageFontWidth(5) * strlen($message) + 10 ; 
        $height = ImageFontHeight(5) + 10 ; 
        if($image = ImageCreate($width,$height)) 
        { 
            $background = ImageColorAllocate($image,255,255,255) ; 
            $text_color = ImageColorAllocate($image,0,0,0) ; 
            ImageString($image,5,5,5,$message,$text_color) ;     

            header('Content-type: image/png') ; 
            ImagePNG($image) ; 
            ImageDestroy($image) ; 
            exit ; 
        } 
    } 

// send 500 code 
header("HTTP/1.0 500 Internal Server Error") ; 
print($message) ; 
exit ; 
} 


/* 
    decode an HTML hex-code into an array of R,G, and B values. 
    accepts these formats: (case insensitive) #ffffff, ffffff, #fff, fff 
*/     

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 ; 
} 


/* 
    convert embedded, javascript unicode characters into embedded HTML 
    entities. (e.g. '%u2018' => '‘'). returns the converted string. 
*/ 
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 ; 
} 

?> 

I know it's a lot to look at but it's layed out pretty straight forward. :bemused:

[Weedpacket]

The main thing I see is that you never change the value of $previous_color after you've set it. The other thing is that in [man]imagecolorallocate[/man], the first argument is supposed to be the image you're allocating the colour to (and it would make sense to only do it once per colour).
So

$current_color = ImageColorAt($image, $xx, $yy); 

would need to be

$previous_color = $current_color;
$current_color = ImageColorAt($image, $xx, $yy); 

And

imagesetpixel ( $image, $xx, $yy, imagecolorallocate($previous_color, 255, 0, 0));

would need to be

imagesetpixel ( $image, $xx, $yy, $red);

, where $red is defined earlier (in the same place and in the same way as you're allocating those other colours) as:

$red = imagecolorallocate($image, 255, 0, 0);

Whether that's all that needs to change I don't know, but it will get you closer.

[Local_Hero]

Thanks a lot for explaining. I'll work on those fixes and see what I get. Thanks again!