PHP crop picture into fixed size code method_PHP tutorial

/*
* Description: The function is to crop an image into an image of any size without deformation of the image
* Parameter description: Enter the file that needs to be processed. Name, generate the save file name of the new image, generate the width of the new image, generate the height of the new image
* written by smallchicken
* time 2008-12-18
*/
// Get any Large or small images, stretched where necessary, no deformation, no blank space
function my_image_resize($src_file, $dst_file , $new_width , $new_height) {
if($new_width <1 || $new_height < ;1) {
echo "params width or height error !";
exit();
}
if(!file_exists($src_file)) {
echo $src_file . " is not exists !";
exit();
}
// Image type
$type=exif_imagetype($src_file);
$support_type=array(IMAGETYPE_JPEG, IMAGETYPE_PNG, IMAGETYPE_GIF);
if(!in_array($type, $support_type,true)) {
echo "this type of image does not support! only support jpg , gif or png";
exit();
}
//Load image
switch($type) {
case IMAGETYPE_JPEG :
$src_img=imagecreatefromjpeg($src_file);
break;
case IMAGETYPE_PNG :
$ src_img=imagecreatefrompng($src_file);
break;
case IMAGETYPE_GIF :
$src_img=imagecreatefromgif($src_file);
break;
default:
echo "Load image error! ";
exit();
}
$w=imagesx($src_img);
$h=imagesy($src_img);
$ratio_w=1.0 * $new_width / $w ;
$ratio_h=1.0 * $new_height / $h;
$ratio=1.0;
// The height and width of the generated image are smaller or larger than the original ones. The principle is to enlarge at a larger ratio , reduce by a large ratio (the reduction ratio is relatively small)
if( ($ratio_w < 1 && $ratio_h < 1) || ($ratio_w > 1 && $ratio_h > 1)) {
if($ratio_w < $ratio_h) {
$ratio = $ratio_h ; // Case 1, the width ratio is smaller than the height direction, crop or enlarge according to the height ratio standard
}else {
$ratio = $ratio_w ;
}
// Define an intermediate temporary image whose aspect ratio exactly meets the target requirements
$inter_w=(int)($new_width / $ratio );
$inter_h=(int) ($new_height / $ratio);
$inter_img=imagecreatetruecolor($inter_w , $inter_h);
imagecopy($inter_img, $src_img, 0,0,0 ,0,$inter_w,$inter_h);
// Generate a temporary image with the maximum side length as the target image $ratio ratio
// Define a new image
$new_img=imagecreatetruecolor ($new_width,$new_height);
imagecopyresampled($new_img,$inter_img,0,0,0,0,$new_width,$new_height,$inter_w,$inter_h);
switch($type) {
case IMAGETYPE_JPEG :
imagejpeg($new_img, $dst_file,100); // Store image
break;
case IMAGETYPE_PNG :
imagepng($new_img,$dst_file,100);
break;
case IMAGETYPE_GIF :
imagegif($new_img,$dst_file,100);
break;
default:
break;
}
} // end if 1
// 2 One side of the target image is larger than the original image, and one side is smaller than the original image. First enlarge the plain image, and then crop it
// =if( ($ratio_w < 1 && $ratio_h > 1 ) || ($ratio_w >1 && $ratio_h <1) )
else{
$ratio=$ratio_h>$ratio_w? $ratio_h : $ratio_w; //Take the value with the larger ratio
//Define a large intermediate image whose height or width is equal to the target image, and then enlarge the original image
$inter_w=(int)($w * $ratio);
$inter_h=( int) ($h * $ratio);
$inter_img=imagecreatetruecolor($inter_w , $inter_h);
//Crop the original image after scaling
imagecopyresampled($inter_img,$src_img,0, 0,0,0,$inter_w,$inter_h,$w,$h);
//Define a new image
$new_img=imagecreatetruecolor($new_width,$new_height);
imagecopy($ new_img, $inter_img, 0,0,0,0,$new_width,$new_height);
switch($type) {
case IMAGETYPE_JPEG :
imagejpeg($new_img, $dst_file,100); / / Store image
break;
case IMAGETYPE_PNG :
imagepng($new_img,$dst_file,100);
break;
case IMAGETYPE_GIF :
imagegif($new_img,$dst_file, 100);
break;
default:
break;
}
}// if3
}// end function
?>