php图片加水印_ATHER Shu(A.S)的Blog

/**
 * PNG ALPHA CHANNEL SUPPORT for imagecopymerge();
 * This is a function like imagecopymerge but it handle alpha channel well!!!
 **/
function imagecopymerge_alpha($dst_im, $src_im, $dst_x, $dst_y, $src_x, $src_y, $src_w, $src_h, $pct){
  $opacity=$pct;
  // getting the watermark width
  $w = imagesx($src_im);
  // getting the watermark height
  $h = imagesy($src_im);
  
  // creating a cut resource
  $cut = imagecreatetruecolor($src_w, $src_h);
  // copying that section of the background to the cut
  imagecopy($cut, $dst_im, 0, 0, $dst_x, $dst_y, $src_w, $src_h);
  // inverting the opacity
  $opacity = $opacity;
  
  // placing the watermark now
  imagecopy($cut, $src_im, 0, 0, $src_x, $src_y, $src_w, $src_h);
  imagecopymerge($dst_im, $cut, $dst_x, $dst_y, $src_x, $src_y, $src_w, $src_h, $opacity);