PHP tutorial: Crop any image to a fixed size_PHP tutorial

Agni Website Building Academy (Bkjia.Com) PHP document: To make a homepage call image, sometimes it is necessary to obtain a fixed size image, because the image position of the homepage is usually specified by the designer If you are calling the latest release image, because you don’t know what proportion of the image the customer will upload, 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 achieve this. Control the image from overflowing, but if the proportion of the image is not the required proportion, it will cause the image to be deformed after being called, which greatly affects the beauty of the page. One solution is to scale according to the proportion of the original image, and the scaled image It is inevitable that there will be blank spaces, and the blank spaces should be filled with color. Although the image will not be deformed, there will be many problems. For example, if the user sends an image with a high image but an average width, if it is compressed into a 1:1 image, Then after compression, the image will basically not be visible.

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 guarantees image calling. Without deformation, for a fixed-size output image frame, the source image has the following situations:

1: The aspect ratio of the image to be output is smaller than the height and width of the source image, written as $new_width<$src_width && $new_height<$src_width
2: The aspect ratio of the image to be output is smaller than the original image Both height and width are large, written as judgment $new_width>$src_width && $new_height>$src_width
3: Exclude the first and second two types, that is, the case of enlarging while reducing, plus the judgment of equal
For 1, 2. The function processing code is exactly the same, so it can be summarized into one processing statement

The following is the code implemented by PHP:

以下为引用的内容：
/*
* 说明：函数功能是把一个图像裁剪为任意大小的图像，图像不变形

* 参数说明：输入 需要处理图片的 文件名，生成新图片的保存文件名，生成新图片的宽，生成新图片的高
* written by smallchicken
* time 2008-12-18
*/
// 获得任意大小图像，不足地方拉伸，不产生变形，不留下空白

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();
}
// 图像类型
$type=exif_imagetype($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;
$ratio=1.0;
// 生成的图像的高宽比原来的都小，或都大 ，原则是 取大比例放大，取大比例缩小（缩小的比例就比较小了）
if( ($ratio_w < 1 && $ratio_h < 1) || ($ratio_w > 1 && $ratio_h > 1))
{
if($ratio_w < $ratio_h)
{
$ratio = $ratio_h ; // 情况一，宽度的比例比高度方向的小，按照高度的比例标准来裁剪或放大
}else {
$ratio = $ratio_w ;
}
// 定义一个中间的临时图像，该图像的宽高比 正好满足目标要求
$inter_w=(int)($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,$inter_h);
// 生成一个以最大边长度为大小的是目标图像$ratio比例的临时图像
// 定义一个新的图像
$new_img=imagecreatetruecolor($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, $dst_file,100); // 存储图像
break;
case IMAGETYPE_PNG :
imagepng($new_img,$dst_file,100);
break;
case IMAGETYPE_GIF :
imagegif($new_img,$dst_file,100);
break;
default:
break;
}
} // end if 1
// 2 目标图像 的一个边大于原图，一个边小于原图 ，先放大平普图像，然后裁剪
// =if( ($ratio_w < 1 && $ratio_h > 1) || ($ratio_w >1 && $ratio_h <1) )
else{
$ratio=$ratio_h>$ratio_w? $ratio_h : $ratio_w; //取比例大的那个值
// 定义一个中间的大图像，该图像的高或宽和目标图像相等，然后对原图放大
$inter_w=(int)($w * $ratio);
$inter_h=(int) ($h * $ratio);
$inter_img=imagecreatetruecolor($inter_w , $inter_h);
//将原图缩放比例后裁剪
imagecopyresampled($inter_img,$src_img,0,0,0,0,$inter_w,$inter_h,$w,$h);
// 定义一个新的图像
$new_img=imagecreatetruecolor($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, $dst_file,100); // 存储图像
break;
case IMAGETYPE_PNG :
imagepng($new_img,$dst_file,100);
break;
case IMAGETYPE_GIF :
imagegif($new_img,$dst_file,100);
break;
default:
break;
}
}// if3
}// end function
?>

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