Php method of generating image thumbnail function based on GD library

This article mainly introduces PHP based on the implementation of the GD library image thumbnail function, involving PHP for picture attributes related operations skills, the need for friends can refer to the following

In this paper, we describe the generated image thumbnail function of PHP based on the GD library implementation. Share to everyone for your reference, as follows:

<?php/** * Generate thumbnail function (supports picture format: GIF, JPEG, PNG and BMP) * @author ruxing.li * @param string $src source picture path * @param int $width thumbnail width degree (equal to scale only when the height is specified) * @param int $width thumbnail height (equal to zoom only when width is specified) * @param string $filename save path (output to browser if not specified) * @return bool */fu Nction Mkthumbnail ($src, $width = null, $height = NULL, $filename = null) {if (!isset ($width) &&!isset ($height)  ) return false;  if (Isset ($width) && $width <= 0) return false;  if (Isset ($height) && $height <= 0) return false;  $size = getimagesize ($SRC);  if (! $size) return false;  List ($src _w, $src _h, $src _type) = $size;  $SRC _mime = $size [' MIME '];      Switch ($src _type) {Case 1: $img _type = ' gif ';    Break      Case 2: $img _type = ' jpeg ';    Break      Case 3: $img _type = ' png ';    Break      Case: $img _type = ' wbmp ';    Break  Default:return false;  if (!isset ($width)) $width = $src _w * ($height/$src _h); if (!isset ($height)) $height = $src _h * ($width/$src _w); $imagecreatefunc = ' Imagecreatefrom '.  $img _type;  $src _img = $imagecreatefunc ($SRC);  $dest _img = Imagecreatetruecolor ($width, $height);  Imagecopyresampled ($dest _img, $src _img, 0, 0, 0, 0, $width, $height, $src _w, $src _h); $imagefunc = ' image '.  $img _type;  if ($filename) {$imagefunc ($dest _img, $filename);    } else {header (' Content-type: '. $src _mime);  $imagefunc ($dest _img);  } Imagedestroy ($src _img);  Imagedestroy ($dest _img); return true;} $result = Mkthumbnail ('./img_3324.jpg ', 147, 147);

Note: Remember to open the support of GD library first

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