How to add a watermark to a GD image resource - php

Question

I am using php GD image for the image upload but I want to add watermark to resized image. I found some code to add a watermark but I couldn't make it work. I need some hints.
function resizeImage($CurWidth, $CurHeight, $MaxSize, $DestFolder, $SrcImage, $Quality, $ImageType)
{
//Check Image size is not 0
if ($CurWidth <= 0 || $CurHeight <= 0) {
return false;
}
//Construct a proportional size of new image
$ImageScale = min($MaxSize / $CurWidth, $MaxSize / $CurWidth);
$NewWidth = ceil($ImageScale * $CurWidth);
$NewHeight = ceil($ImageScale * $CurHeight);
$NewCanves = imagecreatetruecolor($NewWidth, $NewHeight);
$watermark_png_file = 'watermark.png';
//calculate center position of watermark image
$watermark_left = ($NewWidth / 2) - (300 / 2); //watermark left
$watermark_bottom = ($NewHeight / 2) - (100 / 2); //watermark bottom
$watermark = imagecreatefrompng($watermark_png_file); //watermark image
//use PHP imagecopy() to merge two images.
imagecopy($NewCanves, $watermark, $watermark_left, $watermark_bottom, 0, 0, 300, 100); //merge image
// Resize Image
if (imagecopyresampled($NewCanves, $SrcImage, 0, 0, 0, 0, $NewWidth, $NewHeight, $CurWidth, $CurHeight))
{
switch (strtolower($ImageType))
{
case 'image/png':
imagepng($NewCanves, $DestFolder);
break;
case 'image/gif':
imagegif($NewCanves, $DestFolder);
break;
case 'image/jpeg':
case 'image/pjpeg':
imagejpeg($NewCanves, $DestFolder, $Quality);
break;
default:
return false;
}
//Destroy image, frees memory
if (is_resource($NewCanves)) imagedestroy($NewCanves);
return true;
}
}
I have tried this code but it doesn't work:
function generate_watermarked_image($ImageType, $CurWidth, $CurHeight, $paddingFromBottomRight = 0)
{
$watermarkFileLocation = 'logo.png';
$watermarkImage = imagecreatefrompng($watermarkFileLocation);
$watermarkWidth = imagesx($watermarkImage);
$watermarkHeight = imagesy($watermarkImage);
$originalImage = imagecreatefromstring($ImageType);
$destX = $CurWidth - $watermarkWidth - $paddingFromBottomRight;
$destY = $CurHeight - $watermarkHeight - $paddingFromBottomRight;
// creating a cut resource
$cut = imagecreatetruecolor($watermarkWidth, $watermarkHeight);
// copying that section of the background to the cut
imagecopy($cut, $originalImage, 0, 0, $destX, $destY, $watermarkWidth, $watermarkHeight);
// placing the watermark now
imagecopy($cut, $watermarkImage, 0, 0, 0, 0, $watermarkWidth, $watermarkHeight);
// merging both of the images
imagecopymerge($originalImage, $cut, $destX, $destY, 0, 0, $watermarkWidth, $watermarkHeight, 100);
}