PHP - How do I convert a rectangle image to a square image?

Question

How do I change a rectangular image to a square-shaped avatar in php, such that no matter what is the resolution of the uploaded image, it is able to resize to a centralized 42 x 42 pixel avatar. This is the php code I am using. Anyone can advise.

<?php 
//Name you want to save your file as
$save = 'myfile1.jpg';

$file = 'original1.jpg'; 
echo "Creating file: $save"; 
$size = 0.45; 
header('Content-type: image/jpeg') ; 
list($width, $height) = getimagesize($file) ; 
$modwidth = $width * $size; 
$modheight = $height * $size; 
$tn = imagecreatetruecolor($modwidth, $modheight) ; 
$image = imagecreatefromjpeg($file) ; 
imagecopyresampled($tn, $image, 0, 0, 0, 0, $modwidth, $modheight, $width, $height) ; 

// Here we are saving the .jpg, you can make this gif or png if you want
//the file name is set above, and the quality is set to 100%
imagejpeg($tn, $save, 100) ; 
?> 

Answer 1

First you need to be tell where is the central square in a rectangle with dimensions $x and $y.

// horizontal rectangle
if ($x > $y) {
    $square = $y;              // $square: square side length
    $offsetX = ($x - $y) / 2;  // x offset based on the rectangle
    $offsetY = 0;              // y offset based on the rectangle
}
// vertical rectangle
elseif ($y > $x) {
    $square = $x;
    $offsetX = 0;
    $offsetY = ($y - $x) / 2;
}
// it's already a square
else {
    $square = $x;
    $offsetX = $offsetY = 0;
}

Now we can build a square from it, just need to resize it to 42x42. Something like this should work:

list($x, $y) = getimagesize($file);

// code snippet from above goes here
// so we get the square side and the offsets

$endSize = 42;
$tn = imagecreatetruecolor($endSize, $endSize);
imagecopyresampled($tn, $image, 0, 0, $offsetX, $offsetY, $endSize, $endSize, $square, $square);

---

So, if we have a rectangular image 100x80, the code will figure out that the big square size is 80, x offset is 10, y offset is 0. Roughly, it looks like this:

    100
-----------
|         |
|         | 80
|         |
-----------

     |
     V

    80
 ---------               42
 |       |             -----
 |       | 80   --->   |   | 42
 |       |             -----
 ---------

After we crop the big square from the original rectangle, we just shrink it to the end size, which is 42 in your case.

---

Just tested and works perfectly, make sure you remove the echo line if you plan to output the image into the browser (combined with the header).

Answer 2

I don't know if someone was looking for this, but I needed to have a 600 x 600 squared image.

The source could be any rectangular image and I needed to mantain proportion of the original image and center the original rectangular image in a 600 x 600 squared white image.

Here it is

• src_file: URL of Source Image
• destination_file: Path where the destination file will be saved.
• square_dimensions (pixels). I needed 600, but could be any value.

• jpeg_quality: Quality (0, 100) . I used default 90

  function square_thumbnail_with_proportion($src_file,$destination_file,$square_dimensions,$jpeg_quality=90)
  {
      // Step one: Rezise with proportion the src_file *** I found this in many places.
  
      $src_img=imagecreatefromjpeg($src_file);
  
      $old_x=imageSX($src_img);
      $old_y=imageSY($src_img);
  
      $ratio1=$old_x/$square_dimensions;
      $ratio2=$old_y/$square_dimensions;
  
      if($ratio1>$ratio2)
      {
          $thumb_w=$square_dimensions;
          $thumb_h=$old_y/$ratio1;
      }
      else    
      {
          $thumb_h=$square_dimensions;
          $thumb_w=$old_x/$ratio2;
      }
  
      // we create a new image with the new dimmensions
      $smaller_image_with_proportions=ImageCreateTrueColor($thumb_w,$thumb_h);
  
      // resize the big image to the new created one
      imagecopyresampled($smaller_image_with_proportions,$src_img,0,0,0,0,$thumb_w,$thumb_h,$old_x,$old_y); 
  
      // *** End of Step one ***
  
      // Step Two (this is new): "Copy and Paste" the $smaller_image_with_proportions in the center of a white image of the desired square dimensions
  
      // Create image of $square_dimensions x $square_dimensions in white color (white background)
      $final_image = imagecreatetruecolor($square_dimensions, $square_dimensions);
      $bg = imagecolorallocate ( $final_image, 255, 255, 255 );
      imagefilledrectangle($final_image,0,0,$square_dimensions,$square_dimensions,$bg);
  
      // need to center the small image in the squared new white image
      if($thumb_w>$thumb_h)
      {
          // more width than height we have to center height
          $dst_x=0;
          $dst_y=($square_dimensions-$thumb_h)/2;
      }
      elseif($thumb_h>$thumb_w)
      {
          // more height than width we have to center width
          $dst_x=($square_dimensions-$thumb_w)/2;
          $dst_y=0;
  
      }
      else
      {
          $dst_x=0;
          $dst_y=0;
      }
  
      $src_x=0; // we copy the src image complete
      $src_y=0; // we copy the src image complete
  
      $src_w=$thumb_w; // we copy the src image complete
      $src_h=$thumb_h; // we copy the src image complete
  
      $pct=100; // 100% over the white color ... here you can use transparency. 100 is no transparency.
  
      imagecopymerge($final_image,$smaller_image_with_proportions,$dst_x,$dst_y,$src_x,$src_y,$src_w,$src_h,$pct);
  
      imagejpeg($final_image,$destination_file,$jpeg_quality);
  
      // destroy aux images (free memory)
      imagedestroy($src_img); 
      imagedestroy($smaller_image_with_proportions);
      imagedestroy($final_image);
  }