PHP - Create thumbnail maintaining aspect ratio & remove blank portion? - php

Question

I am using a function from this question
PHP - Create Thumbnail & maintaining aspect ratio
The code is as below,
define('THUMBNAIL_IMAGE_MAX_WIDTH', 150);
define('THUMBNAIL_IMAGE_MAX_HEIGHT', 150);
function generate_image_thumbnail($source_image_path, $thumbnail_image_path)
{
list($source_image_width, $source_image_height, $source_image_type) = getimagesize($source_image_path);
switch ($source_image_type) {
case IMAGETYPE_GIF:
$source_gd_image = imagecreatefromgif($source_image_path);
break;
case IMAGETYPE_JPEG:
$source_gd_image = imagecreatefromjpeg($source_image_path);
break;
case IMAGETYPE_PNG:
$source_gd_image = imagecreatefrompng($source_image_path);
break;
}
if ($source_gd_image === false) {
return false;
}
$source_aspect_ratio = $source_image_width / $source_image_height;
$thumbnail_aspect_ratio = THUMBNAIL_IMAGE_MAX_WIDTH / THUMBNAIL_IMAGE_MAX_HEIGHT;
if ($source_image_width <= THUMBNAIL_IMAGE_MAX_WIDTH && $source_image_height <= THUMBNAIL_IMAGE_MAX_HEIGHT) {
$thumbnail_image_width = $source_image_width;
$thumbnail_image_height = $source_image_height;
} elseif ($thumbnail_aspect_ratio > $source_aspect_ratio) {
$thumbnail_image_width = (int) (THUMBNAIL_IMAGE_MAX_HEIGHT * $source_aspect_ratio);
$thumbnail_image_height = THUMBNAIL_IMAGE_MAX_HEIGHT;
} else {
$thumbnail_image_width = THUMBNAIL_IMAGE_MAX_WIDTH;
$thumbnail_image_height = (int) (THUMBNAIL_IMAGE_MAX_WIDTH / $source_aspect_ratio);
}
$thumbnail_gd_image = imagecreatetruecolor($thumbnail_image_width, $thumbnail_image_height);
imagecopyresampled($thumbnail_gd_image, $source_gd_image, 0, 0, 0, 0, $thumbnail_image_width, $thumbnail_image_height, $source_image_width, $source_image_height);
$img_disp = imagecreatetruecolor(THUMBNAIL_IMAGE_MAX_WIDTH,THUMBNAIL_IMAGE_MAX_HEIGHT);
$backcolor = imagecolorallocate($img_disp,0,0,0);
imagefill($img_disp,0,0,$backcolor);
imagecopy($img_disp, $thumbnail_gd_image, (imagesx($img_disp)/2)-(imagesx($thumbnail_gd_image)/2), (imagesy($img_disp)/2)-(imagesy($thumbnail_gd_image)/2), 0, 0, imagesx($thumbnail_gd_image), imagesy($thumbnail_gd_image));
imagejpeg($img_disp, $thumbnail_image_path, 90);
imagedestroy($source_gd_image);
imagedestroy($thumbnail_gd_image);
imagedestroy($img_disp);
return true;
}
It works well and will create thumbnail like this
I notice that the function will fill unused portion with black color
imagefill($img_disp,0,0,$backcolor);
How could I remove the black portion instead? I don't need fix width or height.

Answer 1

Maybe the easiest way is to preserve the aspect ratio.
// RESIZE AN IMAGE PROPORTIONALLY AND CROP TO THE CENTER
function resize_and_crop($original_image_url, $thumb_image_url, $thumb_w, $thumb_h, $quality=75)
{
// ACQUIRE THE ORIGINAL IMAGE: http://php.net/manual/en/function.imagecreatefromjpeg.php
$original = imagecreatefromjpeg($original_image_url);
if (!$original) return FALSE;
// GET ORIGINAL IMAGE DIMENSIONS
list($original_w, $original_h) = getimagesize($original_image_url);
// RESIZE IMAGE AND PRESERVE PROPORTIONS
$thumb_w_resize = $thumb_w;
$thumb_h_resize = $thumb_h;
if ($original_w > $original_h)
{
$thumb_h_ratio = $thumb_h / $original_h;
$thumb_w_resize = (int)round($original_w * $thumb_h_ratio);
}
else
{
$thumb_w_ratio = $thumb_w / $original_w;
$thumb_h_resize = (int)round($original_h * $thumb_w_ratio);
}
if ($thumb_w_resize < $thumb_w)
{
$thumb_h_ratio = $thumb_w / $thumb_w_resize;
$thumb_h_resize = (int)round($thumb_h * $thumb_h_ratio);
$thumb_w_resize = $thumb_w;
}
// CREATE THE PROPORTIONAL IMAGE RESOURCE
$thumb = imagecreatetruecolor($thumb_w_resize, $thumb_h_resize);
if (!imagecopyresampled($thumb, $original, 0,0,0,0, $thumb_w_resize, $thumb_h_resize, $original_w, $original_h)) return FALSE;
// ACTIVATE THIS TO STORE THE INTERMEDIATE IMAGE
// imagejpeg($thumb, 'thumbs/temp_' . $thumb_w_resize . 'x' . $thumb_h_resize . '.jpg', 100);
// CREATE THE CENTERED CROPPED IMAGE TO THE SPECIFIED DIMENSIONS
$final = imagecreatetruecolor($thumb_w, $thumb_h);
$thumb_w_offset = 0;
$thumb_h_offset = 0;
if ($thumb_w < $thumb_w_resize)
{
$thumb_w_offset = (int)round(($thumb_w_resize - $thumb_w) / 2);
}
else
{
$thumb_h_offset = (int)round(($thumb_h_resize - $thumb_h) / 2);
}
if (!imagecopy($final, $thumb, 0,0, $thumb_w_offset, $thumb_h_offset, $thumb_w_resize, $thumb_h_resize)) return FALSE;
// STORE THE FINAL IMAGE - WILL OVERWRITE $thumb_image_url
if (!imagejpeg($final, $thumb_image_url, $quality)) return FALSE;
return TRUE;
}
// USE CASE
echo '<a target="_blank" href="images/image_600x374.jpg">Original 600x374</a><br/>';
resize_and_crop('images/image_600x374.jpg', 'thumbs/temp_100x100.jpg', 100, 100);
echo '<a target="_blank" href="thumbs/temp_100x100.jpg">100x100</a><br/>';
resize_and_crop('images/image_600x374.jpg', 'thumbs/temp_200x100.jpg', 200, 100);
echo '<a target="_blank" href="thumbs/temp_200x100.jpg">200x100</a><br/>';
resize_and_crop('images/image_600x374.jpg', 'thumbs/temp_200x300.jpg', 200, 300);
echo '<a target="_blank" href="thumbs/temp_200x300.jpg">200x300</a><br/>';