Crop and scale PHP Images

The image size is too large and its specifications are not uniform. The display control needs to be completed by JavaScript. When used on mobile devices, the display effect is poor and the traffic is huge. You need to process the image of the existing image library once, generate thumbnails that meet the requirements of mobile devices, and transfer the work done by the original client JS to the server using the php gd library for centralized processing.

Image Source and required size:

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

Crop the image to maximize the display of the image area and scale proportionally to the specified size.

At first, the imagecopyresized method was used for image proportional reduction. After the actual operation, it was found that the dry points were very serious after the image was reduced. Then use the imagecopysampled method. This method will re-sample the image and perform smooth processing on the reduced image to greatly improve the definition.

<? Phplist ($ src_w, $ src_h) = getimagesize ($ src_img); // obtain the source image size $ dst_scale = $ dst_h/$ dst_w; // target image Aspect Ratio $ src_scale = $ src_h/$ src_w; // source image aspect ratio if ($ src_scale> = $ dst_scale) {// too high $ w = intval ($ src_w ); $ h = intval ($ dst_scale * $ w); $ x = 0; $ y = ($ src_h-$ h)/3 ;} else {// too wide $ h = intval ($ src_h); $ w = intval ($ h/$ dst_scale); $ x = ($ src_w-$ w)/2; $ y = 0;} // crop $ source = imagecreatefromjpeg ($ src_img); $ croped = imagecreatetruecolor ($ w, $ H); imagecopy ($ croped, $ source, 0,0, $ x, $ y, $ src_w, $ src_h); // scale $ scale = $ dst_w/$ w; $ target = imagecreatetruecolor ($ dst_w, $ dst_h); $ final_w = intval ($ w * $ scale); $ final_h = intval ($ h * $ scale ); imagecopysampled ($ target, $ croped, 0, 0, 0, $ final_w, $ final_h, $ w, $ h); // save $ timestamp = time (); imagejpeg ($ target, "condition"); imagedestroy ($ target);?>