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PHP实例制作水印图片

Jun 23, 2016 pm 01:49 PM
phpmakepictureExamplewatermark

目前QQ空间和新浪微博等社交软件中,分享的图片大多都是添加水印的。添加水印之后的照片也就变得独一无二了,好像就是添加了一个专属的个人签名。可以很好的防止别人盗用你的照片,也能够让别人一看水印就能在上面得到一些关于照片的信息。今天写了一个给图片添加水印的函数,和大家分享一下。有了这个函数,给照片添加水印就显的方便多了。其实原理很简单,原图是一张图片,水印其实也是一张图片,只不过有的水印是白色或透明色背景,然后两张图片进行合成,就成了水印图片。

1.制作水印图片所需php函数

(1)getimagesize();

(2)imagecreatefromgif();imagecreatefromjpeg();imagecreatefrompng;

(3)imagecogy();

(4)imagegif();imagejpeg();imagepng();

具体函数如何使用,我就不细讲了,大家可以参考php参考手册

2.代码分享

<?phpfunction watermark($maxfile,$minfile){	//获取大小图信息	$maxarr=getimagesize($maxfile);	$minarr=getimagesize($minfile);	$max_width=$maxarr[0];	$max_height=$maxarr[1];	$max_format=$maxarr[2];	$max_mime=$maxarr['mime'];		$min_width=$minarr[0];	$min_height=$minarr[1];	$min_format=$minarr[2];	//$min_mime=$minarr['mime'];                //判断大小图格式	switch($max_format){		case 1:			$max_createimg="imagecreatefromgif";			$max_outimg="imagegif";			break;		case 2:			$max_createimg="imagecreatefromjpeg";			$max_outimg="imagejpeg";			break;		case 3:			$max_createimg="imagecreatefrompng";			$max_outimg="imagepng";			break;	}	switch($min_format){		case 1:			$min_createimg="imagecreatefromgif";			break;		case 2:			$min_createimg="imagecreatefromjpeg";			break;		case 3:			$min_createimg="imagecreatefrompng";			break;	}	//创建大小图资源	$maxim=$max_createimg($maxfile);	$minim=$min_createimg($minfile);		//两张图的尺寸差	$D_value_x=$max_width-$min_width;	$D_value_y=$max_height-$min_height;		//添加水印	imagecopy($maxim,$minim,$D_value_x,$D_value_y,0,0,$min_width,$min_height);		//保存水印图片	header("content-type:{$max_mime}");	$max_outimg($maxim,"watermark.jpg");}watermark("picture/apple.jpg","picture/copypic.jpg");?>

3.说几点代码中可能不太好理解的地方

(1)因为不同格式的图片所需要的函数后缀是不一样的,所以必须在使用函数创建资源和保存水印图片前进行判断图片格式。

(2)计算两个图片的尺寸差,是为了将小图很好的添加到大图的右下角(大多水印都是添加到右下角的吧)。

4.整体可以优化的地方

(1)两个switch总觉得有点多了。如果放到if语句或者for循环中,肯定能整合一下。好饿,所以以后在优化这个问题(明显是给自己找借口)。

(2)我用的水印直接是另一张尺寸较小的图片。然而实际的水印大多是一行字,一个网址,一个时间等。可以用做制作验证码的方法,制作水印。然后将水印所需要的文字作为函数的参数,就可以在一张图片中添加自己想要的水印,同时水印的生成也不需要去找图片,完全自动生成。


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