这个水印功能可以改进吗(PHP) [英] Can this watermark function be improve (PHP)

问题描述

下面是我为我的php照片上传脚本制作的水印功能.我很好奇是否有更好的方法来检查文件类型，注意我必须使用那部分代码 2 次

Below is a watermark function I made for my php photo upload script. I am curious if there is a better way of doing the parts that check for the file type, notice I had to use that part of code 2 times

<?PHP
function watermark($source_file,$source_width,$source_height,$image_type) {
    //first image below will be large then small in 1line if/else
    $watermarksize = ($source_width > 300) ? '../images/fpwatermark.gif' : '../images/fpwatermark.gif';
    //now add the watermark to the image.
    $watermark = imagecreatefromgif($watermarksize);
    switch ($image_type) {
        case 'gif':
            $image = imagecreatefromgif($source_file);
            break;
        case 'jpg':
            $image = imagecreatefromjpeg($source_file);
            break;
        case 'png':
            $image = imagecreatefrompng($source_file);
            break;
        default:
            $image = imagecreatefromjpeg($source_file);
            break;
    }
    //get the dimensions of the watermark
    list($water_width, $water_height) = getimagesize($watermarksize);
    // Water mark process
    $x = $source_width - $water_width - 8; //horizontal position
    $y = $source_height - $water_height - 8; //vertical positon
    // imagesy($image) can be the source images width
    imagecopymerge($image, $watermark, $x, $y, 0, 0, $water_width, $water_height, 65);
    switch ($image_type) {
        case 'gif':
            imagegif($image, $source_file, 90);
            break;
        case 'jpg':
            imagejpeg($image, $source_file, 90);
            break;
        case 'png':
            imagepng($image, $source_file, 90);
            break;
        default:
            imagejpeg($image, $source_file, 90);
            break;
    }
    imagedestroy($image);
    return $source_file;
}
?>

推荐答案

您可以使用动态函数调用，如下图所示.此代码与您的代码略有不同，因为它在提供无效图像类型时返回，而不是假定它是 jpeg.如果你坚持这种行为，它应该很容易改变，很难.

You could use dynamic function calls, as illustrated below. This code is subtly different from yours since it returns if an invalid image type is provided rather than assume that it's jpeg. If you insist on that behavior it should be easy enough to change, tough.

PHP 并不总是支持所有这些图像类型，因此您可能需要使用 function_exists() 在给他们打电话之前检查一下.调用不存在的函数是 PHP 中的致命错误.

It's not always the case that all these image types are supported by PHP so you might want to use function_exists() to check for that before calling them. Calling a non-existant function is a fatal error in PHP.

<?PHP
function watermark($source_file,$source_width,$source_height,$image_type) {
    $validTypes = array("gif" => "gif", "jpg" => "jpeg", "jpeg" => "jpeg", "png" => "png");
    if (!array_key_exists($image_type, $validTypes)) {
        trigger_error("Not a valid image type", E_USER_WARNING);
        return NULL;
    }

    $inFunc = "imagecreatefrom" . $validTypes[$image_type];
    $outFunc = "image" . $validTypes[$image_type];

    //first image below will be large then small in 1line if/else
    $watermarksize = ($source_width > 300) ? '../images/fpwatermark.gif' : '../images/fpwatermark.gif';
    //now add the watermark to the image.
    $watermark = imagecreatefromgif($watermarksize);

    // open the image using the assigned function
    $image = $inFunc($source_file);

    //get the dimensions of the watermark
    list($water_width, $water_height) = getimagesize($watermarksize);
    // Water mark process
    $x = $source_width - $water_width - 8; //horizontal position
    $y = $source_height - $water_height - 8; //vertical positon
    // imagesy($image) can be the source images width
    imagecopymerge($image, $watermark, $x, $y, 0, 0, $water_width, $water_height, 65);

    // save the image
    $outFunc($image, $source_file, 90);

    imagedestroy($image);
    return $source_file;
}

如果你安装了 exif 扩展，你可以使用 exif_imagetype() 自动检测图片类型.

If you have the exif extension installed you could use exif_imagetype() to automatically detect the type of the image.

另一个更优雅但也包含更多代码的选项是使用多态:

Another option that's a bit more elegant, but also contains more code is to use polymorfism:

<?php

interface Codec {
    public function open($file);
    public function save($img);
}

class JPEGCodec implements Codec {
    public function open($file) { return imagecreatefromjpeg($file); }
    public function save($img, $out_file) { imagejpeg($img, $out_file, 90); }
}

class PNGCodec implements Codec {
    public function open($file) { return imagecreatefrompng($file); }
    public function save($img, $out_file) { imagepng($img, $out_file, 9); }
}

class GIFCodec implements Codec {
    public function open($file) { return imagecreatefromgif($file); }
    public function save($img, $out_file) { imagegif($img, $out_file); }
}

class WatermarkException extends Exception {}

class Watermark
{
    private $_codecs = array();

    public function __construct()
    {
        $this->_codecs["jpg"] = $this->_codecs["jpeg"] = new JPEGCodec();
        $this->_codecs["png"] = new PNGCodec();
        $this->_codecs["gif"] = new GIFCodec();
    }

    function watermark($source_file,$source_width,$source_height,$image_type) {
        if (!array_key_exists($image_type, $this->_codecs)) {
            throw new WatermarkException("Not a valid image type");
        }

        $codec = $this->_codecs[$image_type];

        //first image below will be large then small in 1line if/else
        $watermarksize = ($source_width > 300) ? '../images/fpwatermark.gif' : '../images/fpwatermark.gif';
        //now add the watermark to the image.
        $watermark = imagecreatefromgif($watermarksize);

        // load image
        $image = $codec->open($source_file);

        //get the dimensions of the watermark
        list($water_width, $water_height) = getimagesize($watermarksize);
        // Water mark process
        $x = $source_width - $water_width - 8; //horizontal position
        $y = $source_height - $water_height - 8; //vertical positon
        // imagesy($image) can be the source images width
        imagecopymerge($image, $watermark, $x, $y, 0, 0, $water_width, $water_height, 65);

        // save image
        $codec->save($image, $source_file);

        imagedestroy($image);
        return $source_file;
    }
}

我知道您可能更喜欢第一个.:)

I realize that you'll probably prefer the first one. :)

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