我有透明的图像,我想覆盖整个图像,以赋予它更大的效果.在此代码中,它会裁剪现有图像.它合并了两个,但最后的顶部没有显示alpha.我怎样才能解决这个问题？

<?
    $dst_x = 0;   // X-coordinate of destination point. 
    $dst_y = 0;   // Y --coordinate of destination point. 
    $src_x = 163; // Crop Start X posITion in original image
    $src_y = 0;   // Crop Srart Y position in original image
    $dst_w = 469; // Thumb width
    $dst_h = 296; // Thumb height
    $src_w = 469; // $src_x + $dst_w Crop end X position in original image
    $src_h = 296; // $src_y + $dst_h Crop end Y position in original image

    // Creating an image with true colors having thumb dimensions.( to merge with the original image )
    $dst_image = imagecreatetruecolor($dst_w,$dst_h);
    // Get original image
    $src_image = imagecreatefromjPEg("http://www.ucatholic.COM/wp-content/uploads/2012/10/Sallixtus-631x295.jpg");
    // Cropping 
    imagecopyresampled($dst_image,$src_image,$dst_x,$dst_y,$src_x,$src_y,$dst_w,$dst_h,$src_w,$src_h);
    // Saving 
    imagejpeg($dst_image,"images/crop.jpg");

    $src = imagecreateFrompng('http://www.EdVizenor.com/images/saintCover.png');

    /// THIS LINE NOT WORKING - -   // Copy and merge
    imagecopymerge($dst_image,$src,469,296,100);

    header('Content-type: image/png');
    imagegif($dst_image);
    ?>

imagecopy($dst_image,296);