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解析php中两种缩放图片的函数,为图片添加水印

Jun 06, 2016 pm 08:31 PM
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本篇文章是对php中两种缩放图片的函数,为图片添加水印的方法进行了详细的分析介绍,需要的朋友参考下

有两种改变图像大小的方法.
(1):ImageCopyResized() 函数在所有GD版本中有效,但其缩放图像的算法比较粗糙.
(2):ImageCopyResampled(),其像素插值算法得到的图像边缘比较平滑.质量较好(但该函数的速度比 ImageCopyResized() 慢).
两个函数的参数是一样的.如下:
ImageCopyResampled(dest,src,dx,dy,sx,sy,dw,dh,sw,sh);
ImageCopyResized(dest,src,dx,dy,sx,sy,dw,dh,sw,sh);
它们两个都是从原图像(source)中抓取特定位置(sx,sy)复制图像qu区域到目标t 图像(destination)的特定位置(dx,dy)。另外dw,dh指定复制的图像区域在目标图像上的大小,sw,香港服务器,sh指定从原图像复制的图像区域 的大小。如果有ps经验的话,就相当于在原图像选择一块区域,剪切移动到目的图像上,同时有拉伸或缩小的操作。
例一:
(本例子是将图片按原大小的4/1的大小显示)

复制代码 代码如下:


// 指定文件路径和缩放比例
$filename = 'test.jpg';
$percent = 0.5;
// 指定头文件Content typezhi值
header('Content-type: image/jpeg');
// 获取图片的宽高
list($width, $height) = getimagesize($filename);
$newwidth = $width * $percent;
$newheight = $height * $percent;
// 创建一个图片。接收参数分别为宽高,返回生成的资源句柄
$thumb = imagecreatetruecolor($newwidth, $newheight);
//获取源文件资源句柄。接收参数为图片路径,返回句柄
$source = imagecreatefromjpeg($filename);
// 将源文件剪切全部域并缩小放到目标图片上。前两个为资源句柄
imagecopyresampled($thumb, $source, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
// 输出给浏览器
imagejpeg($thumb);
?>


推荐一个简单实用的缩放图片工具 SimpleImage,香港服务器租用,参考
使用方法:

复制代码 代码如下:


include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->resize(250,400);
$image->save('picture2.jpg');?>
设定宽度,等比例缩放
include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->resizeToWidth(250);
$image->save('picture2.jpg');?>
设定高度,等比例缩放
include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->resizeToHeight(500);
$image->save('picture2.jpg');
$image->resizeToHeight(200);
$image->save('picture3.jpg');?>
按比例,缩放至50%
include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->scale(50);
$image->save('picture2.jpg');?>
缩放后直接输出到屏幕
header('Content-Type: image/jpeg');
include('SimpleImage.php');
$image = new SimpleImage();
$image->load('picture.jpg');
$image->resizeToWidth(150);
$image->output();?>


SimpleImage.php 源码请轻点文章开头链接,到那下载
--------------------------------------------------------------------------------
为图片加上水印

复制代码 代码如下:


$source=imagecreatefromjpeg('E:/image/guide_pic.jpg');
$thumb=imagecreatefromjpeg('E:/image/l.JPG');
//取得图片的宽度,高度,类型
list($width,$height,$mine)=getimagesize('E:/image/guide_pic.jpg');
imagecopymerge ($source,$thumb,$width-124,$height-150,0,0,88,73,70);
//生成图片
imagejpeg($source,'E:/image/logo.jpg');
?>


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