PHP cropping pictures into fixed size code method_PHP tutorial

When making a home page call image, sometimes it is necessary to obtain a fixed size image, because the image position of the home page is usually specified by the designer. If it is to call the latest released image, because it is not known what proportion of the image the customer will upload. , so sometimes there is no way to determine the proportion of the image. Front-end page writers usually use the method of fixing the height and width of the img element to control the image from overflowing. However, if the proportion of the image is not the required proportion, it will cause the image to be called Post-deformation greatly affects the beauty of the page. One solution is to scale it according to the proportion of the original image. The scaled image will inevitably have blank spaces, and the blank spaces are filled with color. In this way, although the image is not deformed, the There will be many problems. For example, if the user sends an image that is very tall but has an average width, and if it is compressed into a 1:1 image, then the image will basically not be visible after compression.
My solution here is to crop any image to a fixed size, the image will not be deformed, and the blank space will be stretched and filled. The image will always be filled with no blank space. Friends who have used bcastr should know that bcastr ensures that the image call will not be deformed. , for a fixed-size output image frame, the source image has the following situations:
1: The height and width of the image to be output are smaller than the height and width of the source image, written as judgment $new_width<$src_width && $new_height<$src_width
2: The height and width of the image to be output are larger than the height and width of the original image, written as judgment $new_width>$src_width && $new_height>$src_width
3: Exclude the first and second two types, that is, the situation of zooming in and zooming out at the same time plus the judgment of equal
For 1 and 2, the function processing codes are exactly the same, so they can be summarized into one processing statement

Give the php implementation code

/*
*Description: The function is to crop an image to an image of any size without deforming the image
* Parameter description: Enter the file name of the image to be processed, the save file name of the generated new image, the width of the generated new image, and the height of the generated new image
* written by smallchicken
* time 2008-12-18
*/
// Obtain an image of any size, stretch the missing parts, 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;
$ratio=1.0;
// The height and width of the generated image are smaller or larger than the original ones. The principle is to enlarge by a large ratio and reduce by a large ratio (the reduced ratio will be smaller)
if( ($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,$dst_file,100);
break;
default:
break;
}
} // end if 1
// 2 One side of the target image is larger than the original image, and one side is smaller than the original image. First enlarge the ordinary image, and then crop it
// =if( ($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 image in the middle, the height or width of the image 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
?>