PHP method to implement scaling of png images (supports transparent background)

The example in this article describes the method of scaling png images in PHP. Share it with everyone for your reference. The specific implementation method is as follows:

function smart_resize_image( $file, $width = 0, $height = 0, $proportional = false, $output = 'file', $delete_original = true, $use_linux_commands = false )
{
 if ( $height <= 0 && $width <= 0 ) {
 return false;
 }
 $info = getimagesize($file);
 $image = '';
 $final_width = 0;
 $final_height = 0;
 list ($width_old, $height_old) = $info;
 if ($proportional) {
 if ($width == 0) $factor = $height/$height_old;
 elseif ($height == 0) $factor = $width /$width_old;
 else $factor = min ($width / $width_old, $height / $height_old);
 $final_width = round ($width_old * $factor);
 $final_height = round ($height_old * $factor);
 }
 else {
 $final_width = ( $width <= 0 ) ? $width_old : $width;
 $final_height = ( $height <= 0 ) ? $height_old : $height;
 }
 switch ($info [2] ) {
 case IMAGETYPE_GIF:
 $image = imagecreatefromgif($file);
 break;
 case IMAGETYPE_JPEG:
 $image = imagecreatefromjpeg($file);
 break;
 case IMAGETYPE_PNG:
 $image = imagecreatefrompng($ file);
 break;
 default:
 return false;
 }
 $image_resized = imagecreatetruecolor( $final_width, $final_height );
 if ( ($info[2] == IMAGETYPE_GIF) || ($info[2] = = IMAGETYPE_PNG) ) {
 $trnprt_indx = imagecolortransparent($image);
 // If we have a specific transparent color
 if ($trnprt_indx >= 0) {
 // Get the original image's transparent color's RGB values
 $trnprt_color = imagecolorsforindex($image, $trnprt_indx);
 // Allocate the same color in the new image resource
 $trnprt_indx = imagecolorallocate($image_resized, $trnprt_color['red'], $trnprt_color['green'], $trnprt_color[ 'blue']);
 // Completely fill the background of the new image with allocated color.
 imagefill($image_resized, 0, 0, $trnprt_indx);
 // Set the background color for new image to transparent
 imagecolortransparent( $image_resized, $trnprt_indx);
 }
 // Always make a transparent background color for PNGs that don't have one allocated already
 elseif ($info[2] == IMAGETYPE_PNG) {
 // Turn off transparency blending (temporarily )
 imagealphablending($image_resized, false);
 // Create a new transparent color for image
 $color = imagecolorallocatealpha($image_resized, 0, 0, 0, 127);
 // Completely fill the background of the new image with allocated color.
 imagefill($image_resized, 0, 0, $color);
 // Restore transparency blending
 imagesavealpha($image_resized, true);
 }
 }
 imagecopyresampled($image_resized, $image, 0, 0, 0 , 0, $final_width, $final_height, $width_old, $height_old);
 if ( $delete_original ) {
 if ( $use_linux_commands )
 exec('rm '.$file);
 else
 @unlink($file);
 }
 switch ( strtolower($output) ) {
 case 'browser':
 $mime = image_type_to_mime_type($info[2]);
 header("Content-type: $mime");
 $output = NULL;
 break;
 case 'file':
 $output = $file;
 break;
 case 'return':
 return $image_resized;
 break;
 default:
 break;
 }
 switch ($info[2] ) {
 case IMAGETYPE_GIF:
 imagegif($image_resized, $output);
 break;
 case IMAGETYPE_JPEG:
 imagejpeg($image_resized, $output);
 break;
 case IMAGETYPE_PNG:
 imagepng($image_resized, $output);
 break;
 default:
 return false;
 }
 return true;
}

I hope this article will be helpful to everyone’s PHP programming design.

PHP, png