PHP 中的 ImageMagick 水印 - 如何使用原始图像大小的百分比而不是水印图像大小的百分比来缩放水印？

Question

So I took ImageMagick Watermark in PHP code as available in www.rainbodesign.com and adjusted it so that it fits my needs: adding an overlay watermark image on the bottom right corner of the original image. This link triggers the conversion mywebsite.com/watermark.php?src=filepath-to-image and returns the new watermarked image. Here's the full code:

    <?php
// ImageMagick Watermark in PHP
// Copyright 2010-2011 by Richard L. Trethewey rick@rainbo.net
// http://www.rainbodesign.com/pub/watermark/
// 10/28/11 RLT
// If you use this script, I'd appreciate a link!  Thanks!

// 05/16/11 Updated to support text rotation, top/bottom/center
// 05/28/11 Updated to sanitize inputs
// 10/25/11 Added 'auto' color, inspired by Mikko's Blog http://valokuva.org/?p=59
//          RGB to HSL code by EasyRGB.com and http://serennu.com/colour/rgbtohsl.php

// 11/10/20 Deleted all references to text overlay and its settings
//          Added bottomright support

// Constants
$bContent = "Content-type: image/bmp";   // for BMP files
$jContent = "Content-type: image/jpeg";  // for JPEG files
$gContent = "Content-type: image/gif";   // for GIF files
$pContent = "Content-type: image/png";   // for PNG files
$tContent = "Content-type: image/tiff";  // for TIFF files
$old_image = '';    // Default base image filepath.

// User Settings and Defaults
$wm_image = 'images/watermark.png';     // Default watermark image file (include a path/URL, if necessary)
$wm_type = 'img';               // Set to 'msg' for text watermark.  Set to 'img' for image watermark.
$position = 'bottomright';   // Default watermark position - bottom left corner
$wm_opacity = 80;   // Default watermark image overlay opacity
$wm_rotate = 0;     // Default watermark image overlay rotation (in degrees)
// $gravity = 'SouthWest'; // Default watermark Imagemagick gravity - bottom left corner
$padding = 0;       // Default padding in pixels for watermark positioning.  Both top/bottom and left/right.

// Handle Query String option parameters
// src
 if (isset($_GET['src'])) { $old_image = $_GET['src']; }

// Block script hacking.
 $matches = array();
  if (preg_match('/([;\n\r])/i', $old_image, $matches)) { die; }

  switch(strtolower($position)) {
   case('bottom'):
    $gravity = 'SouthWest';
    break;
   case('bottomcenter'):
    $gravity = 'South';
    break;
   case('bottomright'):
      $gravity = 'SouthEast';
    break;
   case('top'):
    $gravity = 'NorthWest';
    break;
   case('topcenter'):
    $gravity = 'North';
    break;
   case('center'):
    $gravity = 'Center';
    break;
 } // end switch($position)

$dot = strrpos($old_image, '.');    // Set image type based on file name extension.  I know. Sorry, but it's fastest.
$extension = substr($old_image, $dot);
  switch($extension) {
   case('.jpg'):
   case('.jpeg'):
   $theContent = $jContent;
   $theWMType = 'jpg:-';
   break;
   case('.gif'):
   $theContent = $gContent;
   $theWMType = 'gif:-';
   break;
   case('.png'):
   $theContent = $pContent;
   $theWMType = 'png:-';
   break;
   case('.bmp'):
   $theContent = $bContent;
   $theWMType = 'bmp:-';
   break;
   case('.tif'):
   $theContent = $tContent;
   $theWMType = 'tif:-';
   break;
 } // end switch($extension)

// Image Overlay Watermark
 if ($wm_type == 'img') {
  $wmCmd = "convert $wm_image -background transparent -rotate $wm_rotate";
  $wmCmd .= " -scale 35%";
  $wmCmd .= " miff:- |";
  $wmCmd .= " composite -gravity $gravity -geometry +0+0 -blend " . $wm_opacity . "%";
  $wmCmd .= "  - $old_image $theWMType";
  } // endif $wm_type == 'img'

$test = 0; // set to 1 to view ImageMagick command being executed
 if ($test) {
 header('Content-type: text/plain');
 echo("$wmCmd\n");
 die;
}

  header($theContent);
  passthru($wmCmd);  // use passthru() to output binary data

exit;

?>

With this code I managed to add a watermark overlay image to the original images. But I need the watermak image to be 35% of original image size, not 35% of watermark image size! (Of course, with the watermark image mantaining it's aspect ratio)

// Image Overlay Watermark
 if ($wm_type == 'img') {
  $wmCmd = "convert $wm_image -background transparent -rotate $wm_rotate";
  $wmCmd .= " -scale 35%"; // here is where I need the magic to happen!
  $wmCmd .= " miff:- |";
  $wmCmd .= " composite -gravity $gravity -geometry +0+0 -blend " . $wm_opacity . "%";
  $wmCmd .= "  - $old_image $theWMType";
  } // endif $wm_type == 'img'

Does anybody know how to achieve this? Thanks in advance!! <3

Answer 1

I would get the size of the original with getimagesize() ( I know that is a GD command ) and use the width from that to resize the watermark.

$size = getimagesize($old_image);
$watermakSize = $size[0]*.3; ( you can work out what 35% is )

$wmCmd .= " -resize {$watermakSize}x"; // here is where I need the magic to happen!

There are other ways but this is a simple one.

It is always good to mention what version of Imagemagick you are using.