'Image Overlay' script?

[goghost]

I've seen this in a few different places already, so I know it can be done, but not only am I confused as to HOW to do it, but I can't even think of what to call it to search for it :/

 

Basic idea - PHP places one image (defined by the user using a dropbox) in a 'field'. Based on more input by the user, it will place another image over it, creating a third image. It can layer endless amounts of images.

 

For example: Let's say this is one image: (x's are black pixels and -'s are white ones)

x---x-xx

--x-xx-x

-x-x-x-x

 

And that this is another one:

-xxx-x--

xx-x--x-

x-x-x-x-

 

And when you 'overlay' them you get:

 

xxxxxxxx

xxxxxxxx

xxxxxxxx

 

Or

--------

--------

--------

 

Depending on what you specify.

 

 

If you want working examples, ask me, I can get you some. If you know what I mean, though, please help!

 

Thanks,

Ghost //

[zq29]

This should be possible using something like imagecopymerge(), although it is probably worth checking out all of the GD Functions. If you need to use something a little more flexible / advanced, take a look at ImageMagick.

[printf]

If you want preserve transparent than you will have to read pixel by pixel if using the GD library. If you are using ImageMagick then that wouldn't be needed. Here is a quick GD example. It should be self explanatory. Example images also attached.

 

<?php

/* return image resource from a existing image file */

// $e = extension type ( 'gif', 'jpg', 'jpeg', 'png' );

// $p = path to image file ( 'x:/path/image.png' );

// return = resource

function imageFile ( $e, $p )
{
switch ( $e )
{
	case 'gif' :
	return imagecreatefromgif ( $p );
	break;
	case 'jpg' :
	case 'jpeg' :
	return imagecreatefromjpeg ( $p );
	break;
	case 'png' :
	return imagecreatefrompng ( $p );
	break;
}
}

/* return a (new) image resource */

// $s = size array returned from imageSize ();

// $t = true color image, default = true

// return = resource

function imageResource ( $s, $t = true )
{
switch ( $t )
{
	case false :
	return imagecreate ( $s['w'], $s['h'] );
	break;
	case true :
	return imagecreatetruecolor ( $s['w'], $s['h'] );
	break;
}
}

/* return a image resource size */

// $r = image resource

// return = size array ( 'w' => INT, 'h' => INT );

function imageSize ( $r )
{
return array ( 'w' => imagesx ( $r ), 'h' => imagesy ( $r ) );
}

/* save a image resource to a file */

function imageSave ( $e, $f, $r )
{
switch ( $e )
{
	case 'gif' :
	imagegif ( $r, $f );
	break;
	case 'jpg' :
	case 'jpeg' :
	imagejpeg ( $r, $f, 100 );
	break;
	case 'png' :
	imagepng ( $r, $f );
	break;
}
}

$background = true; // false would make overlay transparent

$extension  = 'jpg'; // out image file type

$bgc = array ( 0, 0, 64 ); // dark blue

// original image

$oi = 'f:/www/docs/0.png';

// mask image

$mi = 'f:/www/docs/1.png';

// final image

$fi = 'f:/www/docs/2.jpg';

// original image resource

$oir = imageFile ( 'png', $oi );

// mask image resource

$mir = imageFile ( 'png', $mi );

// original image size

$ois = imageSize ( $oir );

// mask image size

$mis = imageSize ( $mir );

// final image resource

$fir = imageResource ( $ois );

imagealphablending ( $fir, false );

imagesavealpha ( $fir, true );

imagecopyresampled ( $fir, $mir, 0, 0, 0, 0, $ois['w'], $ois['h'], $mis['w'], $mis['h'] );

imagedestroy ( $mir );

for ( $i = 0; $i < $ois['w']; $i++ )
{
for ( $j = 0; $j < $ois['h']; $j++ )
{
	if ( ( $alpha = ( imagecolorat ( $fir, $i, $j ) & 0x7F000000 ) >> 24 ) != 127 )
	{
		$b = imagecolorat ( $oir, $i, $j );

		imagesetpixel  ( $fir, $i, $j, imagecolorallocatealpha ( $fir, ( $b >> 16 ) & 0xFF, ( $b >> 8 ) & 0xFF, $b & 0xFF, $alpha ) );
	}
}
}

imagedestroy ( $oir );

if ( $background === true || $extension == 'jpg' )
{
$tir = imageResource ( $ois );

imagefilledrectangle ( $tir, 0, 0, $ois['w'], $ois['h'], imagecolorallocatealpha ( $tir, $bgc[0], $bgc[1], $bgc[2], 0 ) );

imagecopy ( $tir, $fir, 0, 0, 0, 0, $ois['w'], $ois['h'] );

imagedestroy ( $fir );

imageSave ( $extension, $fi, $tir );

imagedestroy ( $tir );
}
else
{
imageSave ( $extension, $fi, $fir );

imagedestroy ( $fir );
}

?>

 

 

 

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