php修改图片尺寸

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png图片

function imageResizer($url, $width, $height) {$image = imagecreatefrompng($url);$width_orig = imagesx($image);  $height_orig = imagesy($image); $ratio_orig = $width_orig/$height_orig;if ($width/$height > $ratio_orig) {$width = floor($height*$ratio_orig);} else {$height = floor($width/$ratio_orig);}$image_p = @imagecreate($width, $height)or die("Cannot Initialize new GD image stream");$alpha = imagecolorallocatealpha($image_p, 0, 0, 0, 127);//为一幅图像分配颜色 + alpha//int imagecolorallocatealpha ( resource $image , int $red , int $green , int $blue , int $alpha )//imagecolorallocatealpha() 的行为和 imagecolorallocate() 相同，但多了一个额外的透明度参数 alpha，其值从 0 到 127。0 表示完全不透明，127 表示完全透明。如果分配失败则返回 FALSE。imagefill($image_p, 0, 0, $alpha);$aa=imagecopyresampled($image_p, $image, 0, 0, 0, 0, $width, $height, $width_orig, $height_orig);imagesavealpha($image_p, true);header('Content-type: image/png');imagepng($image_p,"2.png");//输出到图片文件2.png}imageResizer("1.png", 100, 20);

JPEG图片

function imageResizer($url, $width, $height) {list($width_orig, $height_orig) = getimagesize($url);$ratio_orig = $width_orig/$height_orig;if ($width/$height > $ratio_orig) {$width = $height*$ratio_orig;} else {$height = $width/$ratio_orig;}// 重新取样$image_p = imagecreatetruecolor($width, $height);$image = imagecreatefromjpeg($url);imagecopyresampled($image_p, $image, 0, 0, 0, 0, $width, $height, $width_orig, $height_orig);// 输出header('Content-type: image/jpeg');imagejpeg($image_p, "2.jpg", 100);}imageResizer("1.jpg", 100, 200);

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