PNG透明度调整大小与SimpleImage.php类

Question

我使用SimpleImage.php类的修改版本：http://www.white-hat-web-design.co.uk/articles/php-image-resizing.php

的编辑我就phpfreaks发现（http://www.phpfreaks.com/forums/index.php?topic=301811.0），但是当我使用的PNG被调整，但透明度是黑色的。

我打这个电话，如：

$max_width = 200; // set a max width 
$max_height = 150; // set a max height 
if($imgW > $imgH){ // width is greater 
     // resize to width up to max 
     if($imgW > $max_width) $image->resizeToWidth($max_width); 
} 
else { // height is greater 
     // resize to height up to max 
     if($imgH > $max_height) $image->resizeToHeight($max_height); 
} 

$image->save($_SERVER['DOCUMENT_ROOT']."/path/" . $new_filename); 

我不知道缺少了什么。任何帮助表示赞赏...

class SimpleImage { 
    var $image; 
    var $image_type; 

    function load($filename) { 
     $image_info = getimagesize($filename); 
     $this->image_type = $image_info[2]; 
     if($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); 
     } 
    } 
    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); 
     } 
    } 

    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) { 
      imageAlphaBlending($this->image, true); 
      imageSaveAlpha($this->image, true); 
      imagepng($this->image); 
     } 
    } 

    function getWidth() { 
     return imagesx($this->image); 
    } 
    function getHeight() { 
     return imagesy($this->image); 
    } 
    function resizeToHeight($height) { 
     $ratio = $height/$this->getHeight(); 
     $width = $this->getWidth() * $ratio; 
     $this->resize($width,$height); 
    } 
    function resizeToWidth($width) { 
     $ratio = $width/$this->getWidth(); 
     $height = $this->getheight() * $ratio; 
     $this->resize($width,$height); 
    } 
    function scale($scale) { 
     $width = $this->getWidth() * $scale/100; 
     $height = $this->getheight() * $scale/100; 
     $this->resize($width,$height); 
    } 
    function resize($width,$height) { 

     // ADDED CODE IS HERE - NOT SURE WHY IT DOESN'T WORK FOR PNG 

     // Setup new image 
     $new_image = imagecreatetruecolor($width, $height); 
     // These parameters are required for handling PNG files. 
     imagealphablending($new_image, false); 
     imagesavealpha($new_image,true); 
     $transparent = imagecolorallocatealpha($new_image, 255, 255, 255, 127); 
     imagefilledrectangle($new_image, 0, 0, $width, $height, $transparent); 
     // Resize image 
     imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight()); 
     $this->image = $new_image; 
    } 
} 

Answer 1

现在有透明度工作PNG，但不是gif。下面是编辑的特定功能的情况下，它会帮助别人：

保存功能：

function save($filename, $image_type=IMAGETYPE_JPEG, $compression=75, $permissions=null) { 

    // do this or they'll all go to jpeg 
    $image_type=$this->image_type; 

    if($image_type == IMAGETYPE_JPEG) { 
    imagejpeg($this->image,$filename,$compression); 
    } elseif($image_type == IMAGETYPE_GIF) { 
    imagegif($this->image,$filename); 
    } elseif($image_type == IMAGETYPE_PNG) { 
    // need this for transparent png to work   
    imagealphablending($this->image, false); 
    imagesavealpha($this->image,true); 
    imagepng($this->image,$filename); 
    } 
    if($permissions != null) { 
    chmod($filename,$permissions); 
    } 

}

大小功能

function resize($width,$height,$forcesize='n') { 

    /* optional. if file is smaller, do not resize. */ 
    if ($forcesize == 'n') { 
     if ($width > $this->getWidth() && $height > $this->getHeight()){ 
      $width = $this->getWidth(); 
      $height = $this->getHeight(); 
     } 
    } 

    $new_image = imagecreatetruecolor($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; 

}

Answer 2

我没有玩GD很长一段时间我自己（我喜欢ImageMagick的），但你可以尝试复制前还设置阿尔法源图像：

... 
// ADDED CODE IS HERE .. 
imagealphablending($this->image, true); 
... 

HTH。

Answer 3

的功能imagecreatetruecolor()不适用于GIF。使用imagecreate方法代替：

if($this->image_type == IMAGETYPE_GIF){ 
    $new_image = imagecreate($Width, $Height); // for gif files 
} else{ 
    $new_image = imagecreatetruecolor($Width, $Height); // for all other files 
} 

Answer 4

我做了同样在本https://stackoverflow.com/a/6401135/262462但编辑的这部分

function save($filename, $image_type=IMAGETYPE_JPEG, $compression=75, $permissions=null) { 

// do this or they'll all go to jpeg 
$image_type=$this->image_type; 

这个

function save($filename, $image_type="original", $compression=75, $permissions=null) { 

    if ($image_type=="original") 
     $image_type=$this->image_type;