php – 使用透明度调整图像PNG

发布时间：2020-12-13 16:13:31 所属栏目：PHP教程来源：网络整理

导读：我想用透明plz帮助调整图像PNG的大小. 这是代码： function resize($width,$height) { $new_image = imagecreatetruecolor($width,$height); imagealphablending($new_image,false); imagesavealpha($new_image,true); $transparent = imagecolorallocatealp

我想用透明plz帮助调整图像PNG的大小.
这是代码：

function resize($width,$height) {

  $new_image = imagecreatetruecolor($width,$height);

  imagealphablending($new_image,false);
  imagesavealpha($new_image,true);
  $transparent = imagecolorallocatealpha($new_image,255,127);
  imagefilledrectangle($new_image,$width,$height,$transparent);

  imagecopyresampled($new_image,$this->image,$this->getWidth(),$this->getHeight());
  $this->image = $new_image;
}

解决方法

试试这个

更新

function createThumb($upfile,$dstfile,$max_width,$max_height){
       $size = getimagesize($upfile);
       $width = $size[0];
       $height = $size[1];
       $x_ratio = $max_width / $width;
       $y_ratio = $max_height / $height;
       if( ($width <= $max_width) && ($height <= $max_height)) {
               $tn_width = $width;
               $tn_height = $height;
       } elseif (($x_ratio * $height) < $max_height) {
               $tn_height = ceil($x_ratio * $height);
               $tn_width = $max_width;
       } else {
               $tn_width = ceil($y_ratio * $width);
               $tn_height = $max_height;
       }
       if($size['mime'] == "image/jpeg"){
               $src = ImageCreateFromJpeg($upfile);
               $dst = ImageCreateTrueColor($tn_width,$tn_height);
               imagecopyresampled($dst,$src,$tn_width,$tn_height,$height);
               imageinterlace( $dst,true);
               ImageJpeg($dst,100);
       } else if ($size['mime'] == "image/png"){
               $src = ImageCreateFrompng($upfile);

    // integer representation of the color black (rgb: 0,0)
    $background = imagecolorallocate($src,0);
    // removing the black from the placeholder
    imagecolortransparent($src,$background);

    // turning off alpha blending (to ensure alpha channel information 
    // is preserved,rather than removed (blending with the rest of the 
    // image in the form of black))
    imagealphablending($src,false);

    // turning on alpha channel information saving (to ensure the full range 
    // of transparency is preserved)
    imagesavealpha($src,true);
               $dst = ImageCreateTrueColor($tn_width,$height);
               Imagepng($dst,$dstfile);

       } else {

               $src = ImageCreateFromGif($upfile);
               $dst = ImageCreateTrueColor($tn_width,$height);
               imagegif($dst,$dstfile);
       }
    }

（编辑：李大同）

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