用GD库生成高质量的缩略图片

最新推荐文章于 2021-04-01 03:43:35 发布

转载最新推荐文章于 2021-04-01 03:43:35 发布 · 492 阅读

php 专栏收录该内容

27 篇文章

订阅专栏

本文介绍了一种使用PHP进行图片上传的方法，并实现了自动调整大小的功能以确保图片符合指定尺寸要求。该脚本能够处理JPEG、PNG和GIF格式的图片文件。

    <?  
      
    $FILENAME="image_name";  
      
    // 生成图片的宽度  
    $RESIZEWIDTH=400;  
      
    // 生成图片的高度  
    $RESIZEHEIGHT=400;  
      
      
    function ResizeImage($im,$maxwidth,$maxheight,$name){  
        $width = imagesx($im);  
        $height = imagesy($im);  
        if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){  
            if($maxwidth && $width > $maxwidth){  
                $widthratio = $maxwidth/$width;  
                $RESIZEWIDTH=true;  
            }  
            if($maxheight && $height > $maxheight){  
                $heightratio = $maxheight/$height;  
                $RESIZEHEIGHT=true;  
            }  
            if($RESIZEWIDTH && $RESIZEHEIGHT){  
                if($widthratio < $heightratio){  
                    $ratio = $widthratio;  
                }else{  
                    $ratio = $heightratio;  
                }  
            }elseif($RESIZEWIDTH){  
                $ratio = $widthratio;  
            }elseif($RESIZEHEIGHT){  
                $ratio = $heightratio;  
            }  
            $newwidth = $width * $ratio;  
            $newheight = $height * $ratio;  
            if(function_exists("imagecopyresampled")){  
                  $newim = imagecreatetruecolor($newwidth, $newheight);  
                  imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);  
            }else{  
                $newim = imagecreate($newwidth, $newheight);  
                  imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);  
            }  
            ImageJpeg ($newim,$name . ".jpg");  
            ImageDestroy ($newim);  
        }else{  
            ImageJpeg ($im,$name . ".jpg");  
        }  
    }  
      
      
    if($_FILES['image']['size']){  
        if($_FILES['image']['type'] == "image/pjpeg"){  
            $im = imagecreatefromjpeg($_FILES['image']['tmp_name']);  
        }elseif($_FILES['image']['type'] == "image/x-png"){  
            $im = imagecreatefrompng($_FILES['image']['tmp_name']);  
        }elseif($_FILES['image']['type'] == "image/gif"){  
            $im = imagecreatefromgif($_FILES['image']['tmp_name']);  
        }  
        if($im){  
            if(file_exists("$FILENAME.jpg")){  
                unlink("$FILENAME.jpg");  
            }  
            ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME);  
            ImageDestroy ($im);  
        }  
    }  
      
    ?>  
      
    <img src="<? echo($FILENAME.".jpg?reload=".rand(0,999999)); ?>"><br/><br/>  
      
    <form enctype="multipart/form-data" method="post">  
    <br/>  
    <input type="file" name="image" size="50" value="浏览"><p>  
    <input type="submit" value="上传图片">  
    </form>   
      
    </body>  
    </html>