我在 SO 上发现了很多关于此的问题，但似乎没有一个可以解决我的问题。
我需要调整图像大小并将它们保存到特定目录。我下面的课程完全按照我的需要工作，但透明图像除外。透明图像在应该透明的地方变黑。
SimpleImage的修改类
<?php
/**
* Class ImageResize
*/
class ImageResize {
/**
* Image
* @var resource
*/
var $image;
/**
* Image type
* @var int
*/
var $image_type;
/**
* Loads the image file
* @param $filename
*/
function load($filename) {
$image_info = getimagesize($filename);
$this->image_type = $image_info[2];
unset($image_info);
if ($this->image_type == IMAGETYPE_JPEG) {
$this->image = imagecreatefromjpeg($filename);
} elseif ($this->image_type == IMAGETYPE_GIF) {
$this->image = imagecreatefromgif($filename);
} elseif ($this->image_type == IMAGETYPE_PNG) {
$this->image = imagecreatefrompng($filename);
}
}
/**
* Saves the image file
* @param $filename
* @param int $image_type
* @param int $compression
* @param null $permissions
*/
function save($filename, $image_type = IMAGETYPE_JPEG, $compression = 75, $permissions = NULL) {
if ($image_type == IMAGETYPE_JPEG) {
imagejpeg($this->image, $filename, $compression);
} elseif ($image_type == IMAGETYPE_GIF) {
imagegif($this->image, $filename);
} elseif ($image_type == IMAGETYPE_PNG) {
imagepng($this->image, $filename);
}
if ($permissions != NULL) {
chmod($filename, $permissions);
}
}
/**
* Outputs the image file
* @param int $image_type
*/
function output($image_type = IMAGETYPE_JPEG) {
if ($image_type == IMAGETYPE_JPEG) {
imagejpeg($this->image);
} elseif ($image_type == IMAGETYPE_GIF) {
imagegif($this->image);
} elseif ($image_type == IMAGETYPE_PNG) {
imagepng($this->image);
}
}
/**
* Gets the image width
* @return int
*/
function getWidth() {
return imagesx($this->image);
}
/**
* Gets the image height
* @return int
*/
function getHeight() {
return imagesy($this->image);
}
/**
* Resize the image to a specified height
* @param $height
*/
function resizeToHeight($height) {
$ratio = $height / $this->getHeight();
$width = $this->getWidth() * $ratio;
$this->resize($width, $height);
unset($ratio, $width);
}
/**
* Resize the image to a specified width
* @param $width
*/
function resizeToWidth($width) {
$actualWidth = $this->getWidth();
if ($width < $actualWidth) {
$ratio = $width / $actualWidth;
$height = $this->getheight() * $ratio;
$this->resize($width, $height);
}
unset($actualWidth, $ratio, $height);
}
/**
* Scales the image
* @param $scale
*/
function scale($scale) {
$width = $this->getWidth() * $scale / 100;
$height = $this->getheight() * $scale / 100;
$this->resize($width, $height);
unset($width, $height);
}
/**
* Resize the image
* @param $width
* @param $height
*/
function resize($width, $height) {
$new_image = imagecreatetruecolor($width, $height);
imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());
$this->image = $new_image;
unset($new_image);
}
}
我已经尝试了这些修复，正如我在整个 SO 和强大的 Google 中发现的那样：
注意：这些修复程序已添加到resize方法中。
第一次修复：
function resize($width, $height) {
$new_image = imagecreatetruecolor($width, $height);
// Attempt fix transparency
if ($this->image_type == IMAGETYPE_PNG || $this->image_type == IMAGETYPE_GIF) {
// Even tried with 255, 255, 255 for white and still no good
imagecolortransparent($new_image, imagecolorallocatealpha($new_image, 0, 0, 0, 127));
imagealphablending($new_image, false);
imagesavealpha($new_image, true);
}
imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());
$this->image = $new_image;
unset($new_image);
}
第一个修复不会将黑色变为白色，并且会使图像质量非常低。所以这似乎不能正常工作。
第二个修复：
function resize($width, $height) {
$new_image = imagecreatetruecolor($width, $height);
if ($this->image_type == IMAGETYPE_PNG || $this->image_type == IMAGETYPE_GIF) {
$colourBlack = imagecolorallocate($new_image, 0, 0, 0);
imagecolortransparent($new_image, $colourBlack);
}
imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());
$this->image = $new_image;
unset($new_image);
}
第二个修复似乎也没有修复黑色背景，质量也不算太差，但可能会更好。
第三次修复：
function resize($width, $height) {
$new_image = imagecreatetruecolor($width, $height);
if ($this->image_type == IMAGETYPE_PNG || $this->image_type == IMAGETYPE_GIF) {
imagefill($new_image, 0, 0, imagecolorallocatealpha($new_image, 255, 255, 255, 127)); // Works but horrible quality
}
imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());
$this->image = $new_image;
unset($new_image);
}
第三个修复实际上用白色代替了透明度，但质量太差了，我不能使用它。
我的问题：
我希望我错过了一些东西，但如果没有，有没有办法做到这一点？我不想使用timThumb, phpThumb, 或class.upload.php脚本。主要是因为我正在使用的系统以及方式timthumb和phpthumb工作方式并不理想。更改所有使用它的class.upload.php脚本会做太多的工作......（我被抛弃的旧系统......）
感谢您的任何帮助，您可以提供！:)
编辑：
通过这样做，我终于能够使 png 透明度起作用（在此处找到答案）：
function resize($width, $height) {
$new_image = imagecreatetruecolor($width, $height);
/* Check if this image is PNG or GIF, then set if Transparent*/
if(($this->image_type == IMAGETYPE_GIF) || ($this->image_type==IMAGETYPE_PNG)){
imagealphablending($new_image, false);
imagesavealpha($new_image,true);
$transparent = imagecolorallocatealpha($new_image, 255, 255, 255, 127);
imagefilledrectangle($new_image, 0, 0, $width, $height, $transparent);
}
imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());
$this->image = $new_image;
unset($new_image);
}
我仍然需要弄清楚如何为 gif 进行此修复