所以我知道之前已经问过这个问题，但是我很难理解如何实现防止图像失去透明背景的方法。
我的脚本允许我设置一种创建缩略图的方法，并调整上传的图像大小。
以下是我的代码，有人可以帮帮我吗？谢谢，麻烦您了！ ：）
调整功能：
function normal_resize_image($source, $destination, $image_type, $max_size, $image_width, $image_height, $quality){
if($image_width <= 0 || $image_height <= 0){return false;} //return false if nothing to resize
//do not resize if image is smaller than max size
if($image_width <= $max_size && $image_height <= $max_size){
if(save_image($source, $destination, $image_type, $quality)){
return true;
}
}
//Construct a proportional size of new image
$image_scale = min($max_size/$image_width, $max_size/$image_height);
$new_width = ceil($image_scale * $image_width);
$new_height = ceil($image_scale * $image_height);
$new_canvas = imagecreatetruecolor( $new_width, $new_height ); //Create a new true color image
//Copy and resize part of an image with resampling
if(imagecopyresampled($new_canvas, $source, 0, 0, 0, 0, $new_width, $new_height, $image_width, $image_height)){
save_image($new_canvas, $destination, $image_type, $quality); //save resized image
}
return true;
}
function thumb_resize_image($source, $destination, $image_type, $max_size, $image_width, $image_height, $quality){
if($image_width <= 0 || $image_height <= 0){return false;} //return false if nothing to resize
//do not resize if image is smaller than max size
if($image_width <= $max_size && $image_height <= $max_size){
if(save_image($source, $destination, $image_type, $quality)){
return true;
}
}
//Construct a proportional size of new image
$image_scale = min($max_size/$image_width, $max_size/$image_height);
$new_width = ceil($image_scale * $image_width);
$new_height = ceil($image_scale * $image_height);
$new_canvas = imagecreatetruecolor( $new_width, $new_height ); //Create a new true color image
//Copy and resize part of an image with resampling
if(imagecopyresampled($new_canvas, $source, 0, 0, 0, 0, $new_width, $new_height, $image_width, $image_height)){
save_image($new_canvas, $destination, $image_type, $quality); //save resized image
}
return true;
}
##### This function corps image to create exact square, no matter what its original size! ######
function crop_image_square($source, $destination, $image_type, $square_size, $image_width, $image_height, $quality){
if($image_width <= 0 || $image_height <= 0){return false;} //return false if nothing to resize
if( $image_width > $image_height )
{
$y_offset = 0;
$x_offset = ($image_width - $image_height) / 2;
$s_size = $image_width - ($x_offset * 2);
}else{
$x_offset = 0;
$y_offset = ($image_height - $image_width) / 2;
$s_size = $image_height - ($y_offset * 2);
}
$new_canvas = imagecreatetruecolor( $square_size, $square_size); //Create a new true color image
//Copy and resize part of an image with resampling
if(imagecopyresampled($new_canvas, $source, 0, 0, $x_offset, $y_offset, $square_size, $square_size, $s_size, $s_size)){
save_image($new_canvas, $destination, $image_type, $quality);
}
return true;
}
##### Saves image resource to file #####
function save_image($source, $destination, $image_type, $quality){
switch(strtolower($image_type)){//determine mime type
case 'image/png':
imagepng($source, $destination); return true; //save png file
break;
case 'image/gif':
imagegif($source, $destination); return true; //save gif file
break;
case 'image/jpeg': case 'image/pjpeg':
imagejpeg($source, $destination, $quality); return true; //save jpeg file
break;
default: return false;
}
}
以下是上传代码：
$sm_square_size = 300; //will ! be cropped
$md_square_size = 600; //will ! be cropped
$max_image_size = 1200; //Maximum image size (height and width)
$lg_prefix = "_lg"; //Large thumb Prefix
$md_prefix = "_md"; //Medium thumb Prefix
$sm_prefix = "_sm"; //Small thumb Prefix
$destination_folder = 'images/post_images/'; //upload directory ends with / (slash)
$jpeg_quality = 90; //jpeg quality
$image_name = $_FILES['image_file']['name']; //file name
//IF IMAGE UPLOADED
if($image_name != "") {
$image_size = $_FILES['image_file']['size']; //file size
$image_temp = $_FILES['image_file']['tmp_name']; //file temp
$image_size_info = getimagesize($image_temp); //get image size
if($image_size_info){
$image_width = $image_size_info[0]; //image width
$image_height = $image_size_info[1]; //image height
$image_type = $image_size_info['mime']; //image type
} else {
die("Make sure image file is valid!");
}
//switch statement below checks allowed image type
//as well as creates new image from given file
switch($image_type){
case 'image/png':
$image_res = imagecreatefrompng($image_temp); break;
case 'image/gif':
$image_res = imagecreatefromgif($image_temp); break;
case 'image/jpeg': case 'image/pjpeg':
$image_res = imagecreatefromjpeg($image_temp); break;
default:
$image_res = false;
}
if($image_res){
//Get file extension and name to construct new file name
$image_info = pathinfo($image_name);
$image_extension = strtolower($image_info["extension"]); //image extension
$image_name_only = strtolower($image_info["filename"]);//file name only, no extension
$dateRec = date('d-M-Y-h-i-s');
//create a random name for new image (Eg: fileName_293749.jpg) ;
$new_file_name = $dateRec. '_' . rand(0, 9999999999);
//folder path to save resized images and thumbnails
$thumb_save_folder = $destination_folder.$new_file_name.$sm_prefix.'.'.$image_extension;
$medium_save_folder = $destination_folder.$new_file_name.$md_prefix.'.'.$image_extension;
$large_save_folder = $destination_folder.$new_file_name.$lg_prefix.'.'.$image_extension;
//call normal_resize_image() function to proportionally resize image
if(normal_resize_image($image_res, $large_save_folder, $image_type, $max_image_size, $image_width, $image_height, $jpeg_quality)) {
//call crop_image_square() function to create square thumbnails
if(!thumb_resize_image($image_res, $thumb_save_folder, $image_type, $sm_square_size, $image_width, $image_height, $jpeg_quality))
{ die('Error Creating thumbnail'); }
if(!thumb_resize_image($image_res, $medium_save_folder, $image_type, $md_square_size, $image_width, $image_height, $jpeg_quality))
{ die('Error Creating thumbnail'); }
$post_img_lg_New = $new_file_name.$lg_prefix.'.'.$image_extension;
$post_img_md_New = $new_file_name.$md_prefix.'.'.$image_extension;
$post_img_sm_New = $new_file_name.$sm_prefix.'.'.$image_extension;
$stmt = $mysqli->prepare('UPDATE HERE');
$stmt->bind_param('is', $results);
$stmt->execute();
$stmt->close();
}
}
//IF NO IMAGE UPLOADED
}
答案 0 :(得分：1)
在这里查看我的答案：
Trouble keeping transparency with upload script
我也在以下位置发布了答案：
function resizeImage($source, $destination, $image_type, $max_size, $image_width, $image_height, $quality) {
//RETURN FALSE IF NOTHING TO RESIZE
if($image_width <= 0 || $image_height <= 0){return false;}
//CHECK IF SMALLER THAN THE MAX SIZES
if($image_width <= $max_size && $image_height <= $max_size) { //IF SMALLER THAN MAX SIZES
$new_width = $image_width;
$new_height = $image_height;
} else { //ELSE CONSTRUCT PROPORTIONAL SIZE OF NEW IMAGE
$image_scale = min($max_size/$image_width, $max_size/$image_height);
$new_width = ceil($image_scale * $image_width);
$new_height = ceil($image_scale * $image_height);
}
$new_canvas = imagecreatetruecolor($new_width, $new_height);
$black = imagecolorallocate($new_canvas, 0, 0, 0);
imagecolortransparent($new_canvas, $black);
imagealphablending($new_canvas,false);
imagesavealpha($new_canvas, true);
if(imagecopyresampled($new_canvas, $source, 0, 0, 0, 0, $new_width, $new_height, $image_width, $image_height)){
$this->save_image($new_canvas, $destination, $image_type, $quality);
}
return true;
}
//Resize Image Normal
function normal_resize_image($source, $destination, $image_type, $max_size, $image_width, $image_height, $quality) {
//RETURN FALSE IF NOTHING TO RESIZE
if($image_width <= 0 || $image_height <= 0){return false;}
//CHECK IF SMALLER THAN THE MAX SIZES
if($image_width <= $max_size && $image_height <= $max_size) { //IF SMALLER THAN MAX SIZES
$new_width = $image_width;
$new_height = $image_height;
} else { //ELSE CONSTRUCT PROPORTIONAL SIZE OF NEW IMAGE
$image_scale = min($max_size/$image_width, $max_size/$image_height);
$new_width = ceil($image_scale * $image_width);
$new_height = ceil($image_scale * $image_height);
}
$new_canvas = imagecreatetruecolor($new_width, $new_height);
$black = imagecolorallocate($new_canvas, 0, 0, 0);
imagecolortransparent($new_canvas, $black);
imagealphablending($new_canvas,false);
imagesavealpha($new_canvas, true);
if(imagecopyresampled($new_canvas, $source, 0, 0, 0, 0, $new_width, $new_height, $image_width, $image_height)){
$this->save_image($new_canvas, $destination, $image_type, $quality);
}
return true;
}