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20 years ago
I needed to draw a "pointer" image over a map, but had some problems with png image transparency.
So I created a png image with white background (not transparent) and merged it on my map, after defining white color as transparent:

<?php

$src_file = 'source.jpg';
list($src_w, $src_h, $src_t, $src_a) = getimagesize($src_file);

$ptr_file = 'pointer.png'; // must have no transparency, but white background
list($ptr_w, $ptr_h, $ptr_t, $ptr_a) = getimagesize($ptr_file);

// destination image dimensions:
$dst_w = 400;
$dst_h = 200;

// pointer position:
$ptr_x = 195;
$ptr_y = 70;

$srcImage = imageCreateFromJpeg($src_file) or die ('failed imageCreateFromJpg'); 
$dstImage = imageCreateTrueColor($dst_w, $dst_h) or die ('failed imageCreateTrueColor'); 

imageCopyResampled($dstImage, $srcImage, 0, 0, 0, 0, $dst_w, $dst_h, $src_w, $src_h) or die ('failed imageCopyResampled'); 

$ptrImage = imageCreateFromPng($ptr_file) or die ('failed imageCreateFromPng'); 

$ptr_white = imageColorAllocate($ptrImage,255,255,255);
imageColorTransparent($ptrImage,$ptr_white);

imageCopyMerge($dstImage, $ptrImage, $ptr_x, $ptr_y, 0, 0, $ptr_w, $ptr_h, 100) or die ('failed imageCopyMerge');

imageJpeg($dstImage,'',100) or die ('failed imageJpeg');

imageDestroy($srcImage) or die ('failed imageDestroy(1)');
imageDestroy($dstImage) or die ('failed imageDestroy(2)');
imageDestroy($ptrImage) or die ('failed imageDestroy(3)');

?>
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