PHP image cropping and thumbnail usage examples explained

This time I will bring you phppicturescropping and thumbnailsUsageExplanation, phppicture cropping and thumbnail usageNotes What are they? The following is a practical case. Let’s take a look.

In phpprogramming, we often encounter situations where images are too large and have inconsistent specifications. The display control needs to be completed by JavaScript, which is used on mobile devices. When uploading, the display effect is not good and the traffic is huge. The pictures in the existing picture library need to be processed once to generate thumbnails suitable for mobile devices. The original work done by JS on the client side is transferred to the server side and centralized using PHP's GD library. deal with.

Requirements, image source and required size:

$src_img = "wallpaper.jpg"; 
$dst_w = 300; 
$dst_h = 200;

Crop the image to ensure that the image area is maximized and scaled to the specified size.

I initially used the imagecopyresized method to reduce the image proportionally. After actual operation, I found that the image was very dry after being reduced. Then switch to the imagecopyresampled (Let me tell you here, there are many reprints of this article on the Internet, but they all write imagecopyresampled as imagecopysampled, which makes it unusable, so I reposted this) method. This method will resample the image and reduce the size of the image. The image is smoothed to greatly improve the clarity.

<?php 
list($src_w,$src_h)=getimagesize($src_img); // 获取原图尺寸 
$dst_scale = $dst_h/$dst_w; //目标图像长宽比 
$src_scale = $src_h/$src_w; // 原图长宽比 
if($src_scale>=$dst_scale) 
{ 
// 过高 
$w = intval($src_w); 
$h = intval($dst_scale*$w); 
$x = 0; 
$y = ($src_h - $h)/3; 
} 
else 
{ 
// 过宽 
$h = intval($src_h); 
$w = intval($h/$dst_scale); 
$x = ($src_w - $w)/2; 
$y = 0; 
} 
// 剪裁 
$source=imagecreatefromjpeg($src_img); 
$croped=imagecreatetruecolor($w, $h); 
imagecopy($croped,$source,0,0,$x,$y,$src_w,$src_h); 
// 缩放 
$scale = $dst_w/$w; 
$target = imagecreatetruecolor($dst_w, $dst_h); 
$final_w = intval($w*$scale); 
$final_h = intval($h*$scale); 
imagecopyresampled($target,$croped,0,0,0,0,$final_w,$final_h,$w,$h); 
// 保存 
$timestamp = time(); 
imagejpeg($target, "$timestamp.jpg"); 
imagedestroy($target); 
?>

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the php Chinese website!

Recommended reading:

PHP crops the image without affecting its shape

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