我用过一些php实现的图片大小调整(image resize)函数，但是都不是很完美，有的图片在调整之后完全变形，还有的无缘无故多了一些线条，有的在颜色亮度上也差强人意。今天我重新找了下，又有了一些收获。
if(isset($_FILES['manager_photo']) && !empty($_FILES['manager_photo']['name']))
{
$photo_name=$manager_name."-".$_FILES["manager_photo"]["name"];
$tmpname = $_FILES['manager_photo']['tmp_name'];
$file_ext= substr($photo_name, strripos($photo_name, '.'));
$dir = "./manager_photos/";
// finally resize
@img_resize( $tmpname , 90 , $dir , $photo_name, 1);
}
function img_resize( $tmpname, $size, $save_dir, $save_name, $maxisheight = 0 )
{
$save_dir .= ( substr($save_dir,-1) != "/") ? "/" : "";
$gis = getimagesize($tmpname);
$type = $gis[2];
switch($type)
{
case "1": $imorig = imagecreatefromgif($tmpname); break;
case "2": $imorig = imagecreatefromjpeg($tmpname);break;
case "3": $imorig = imagecreatefrompng($tmpname); break;
default: $imorig = imagecreatefromjpeg($tmpname);
}
$x = imagesx($imorig);
$y = imagesy($imorig);
$woh = (!$maxisheight)? $gis[0] : $gis[1] ;
if($woh <= $size)
{
$aw = $x;
$ah = $y;
}
else
{
if(!$maxisheight){
$aw = $size;
$ah = $size * $y / $x;
} else {
$aw = $size * $x / $y;
$ah = $size;
}
}
$im = imagecreatetruecolor($aw,$ah);
if (imagecopyresampled($im,$imorig , 0,0,0,0,$aw,$ah,$x,$y))
if (imagejpeg($im, $save_dir.$save_name))
return true;
else
return false;
}//img_resize用ImageMagick来实现
有人提到用ImageMagick来实现，它里面有很多选项，我们可以用很少的代码就能实现图片调整。值得研究下。
$image = new Imagick($src); $image->resizeImage($width,$height,Imagick::FILTER_LANCZOS,1); $image->cropImage($width_2, $height_2, $x, $y); $image->setCompression(Imagick::COMPRESSION_JPEG); $image->setImageCompressionQuality(82); $image->writeImage($dest); $image->destroy();
用php_class_upload实现
如果如上介绍不适合你，你不单能图片上传和图片调整，还可以切、割、加水印、旋转、翻转等等。
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其他实现代码参考
此代码可以返回图片以及正确的名称，但是只能是黑色的？
function resize($originalImage){
list($width, $height) = getimagesize($originalImage);
$newName=basename($originalImage);
$imageResized = imagecreatetruecolor(128, 128);
$imageTmp = imagecreatefromjpeg($originalImage);
imagecopyresampled($imageResized, $imageTmp, 0, 0, 0, 0, 128, 128, $width, $height);
imagejpeg($imageResized, "resizedImg/$newName",100);
imageDestroy($imageResized);
}代码改善后，看看如下代码，可以设置颜色。
function resizeImage($file){
define ('MAX_WIDTH', 1500);//max image width
define ('MAX_HEIGHT', 1500);//max image height
define ('MAX_FILE_SIZE', 10485760);
//iamge save path
$path = 'storeResize/';
//size of the resize image
$new_width = 128;
$new_height = 128;
//name of the new image
$nameOfFile = 'resize_'.$new_width.'x'.$new_height.'_'.basename($file['name']);
$image_type = $file['type'];
$image_size = $file['size'];
$image_error = $file['error'];
$image_file = $file['tmp_name'];
$image_name = $file['name'];
$image_info = getimagesize($image_file);
//check image type
if ($image_info['mime'] == 'image/jpeg' or $image_info['mime'] == 'image/jpg'){
}
else if ($image_info['mime'] == 'image/png'){
}
else if ($image_info['mime'] == 'image/gif'){
}
else{
//set error invalid file type
}
if ($image_error){
//set error image upload error
}
if ( $image_size > MAX_FILE_SIZE ){
//set error image size invalid
}
switch ($image_info['mime']) {
case 'image/jpg': //This isn't a valid mime type so we should probably remove it
case 'image/jpeg':
$image = imagecreatefromjpeg ($image_file);
break;
case 'image/png':
$image = imagecreatefrompng ($image_file);
break;
case 'image/gif':
$image = imagecreatefromgif ($image_file);
break;
}
if ($new_width == 0 && $new_height == 0) {
$new_width = 100;
$new_height = 100;
}
// ensure size limits can not be abused
$new_width = min ($new_width, MAX_WIDTH);
$new_height = min ($new_height, MAX_HEIGHT);
//get original image h/w
$width = imagesx ($image);
$height = imagesy ($image);
//$align = 'b';
$zoom_crop = 1;
$origin_x = 0;
$origin_y = 0;
//TODO setting Memory
// generate new w/h if not provided
if ($new_width && !$new_height) {
$new_height = floor ($height * ($new_width / $width));
} else if ($new_height && !$new_width) {
$new_width = floor ($width * ($new_height / $height));
}
// scale down and add borders
if ($zoom_crop == 3) {
$final_height = $height * ($new_width / $width);
if ($final_height > $new_height) {
$new_width = $width * ($new_height / $height);
} else {
$new_height = $final_height;
}
}
// create a new true color image
$canvas = imagecreatetruecolor ($new_width, $new_height);
imagealphablending ($canvas, false);
if (strlen ($canvas_color) < 6) {
$canvas_color = 'ffffff';
}
$canvas_color_R = hexdec (substr ($canvas_color, 0, 2));
$canvas_color_G = hexdec (substr ($canvas_color, 2, 2));
$canvas_color_B = hexdec (substr ($canvas_color, 2, 2));
// Create a new transparent color for image
$color = imagecolorallocatealpha ($canvas, $canvas_color_R, $canvas_color_G,$canvas_color_B, 127);
// Completely fill the background of the new image with allocated color.
imagefill ($canvas, 0, 0, $color);
// scale down and add borders
if ($zoom_crop == 2) {
$final_height = $height * ($new_width / $width);
if ($final_height > $new_height) {
$origin_x = $new_width / 2;
$new_width = $width * ($new_height / $height);
$origin_x = round ($origin_x - ($new_width / 2));
} else {
$origin_y = $new_height / 2;
$new_height = $final_height;
$origin_y = round ($origin_y - ($new_height / 2));
}
}
// Restore transparency blending
imagesavealpha ($canvas, true);
if ($zoom_crop > 0) {
$src_x = $src_y = 0;
$src_w = $width;
$src_h = $height;
$cmp_x = $width / $new_width;
$cmp_y = $height / $new_height;
// calculate x or y coordinate and width or height of source
if ($cmp_x > $cmp_y) {
$src_w = round ($width / $cmp_x * $cmp_y);
$src_x = round (($width - ($width / $cmp_x * $cmp_y)) / 2);
} else if ($cmp_y > $cmp_x) {
$src_h = round ($height / $cmp_y * $cmp_x);
$src_y = round (($height - ($height / $cmp_y * $cmp_x)) / 2);
}
// positional cropping!
if ($align) {
if (strpos ($align, 't') !== false) {
$src_y = 0;
}
if (strpos ($align, 'b') !== false) {
$src_y = $height - $src_h;
}
if (strpos ($align, 'l') !== false) {
$src_x = 0;
}
if (strpos ($align, 'r') !== false) {
$src_x = $width - $src_w;
}
}
// positional cropping!
imagecopyresampled ($canvas, $image, $origin_x, $origin_y, $src_x, $src_y, $new_width, $new_height, $src_w, $src_h);
} else {
imagecopyresampled ($canvas, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
}
//Straight from Wordpress core code. Reduces filesize by up to 70% for PNG's
if ( (IMAGETYPE_PNG == $image_info[2] || IMAGETYPE_GIF == $image_info[2]) && function_exists('imageistruecolor') && !imageistruecolor( $image ) && imagecolortransparent( $image ) > 0 ){
imagetruecolortopalette( $canvas, false, imagecolorstotal( $image ) );
}
$quality = 100;
$nameOfFile = 'resize_'.$new_width.'x'.$new_height.'_'.basename($file['name']);
if (preg_match('/^image\/(?:jpg|jpeg)$/i', $image_info['mime'])){
imagejpeg($canvas, $path.$nameOfFile, $quality);
} else if (preg_match('/^image\/png$/i', $image_info['mime'])){
imagepng($canvas, $path.$nameOfFile, floor($quality * 0.09));
} else if (preg_match('/^image\/gif$/i', $image_info['mime'])){
imagegif($canvas, $path.$nameOfFile);
}
} 
