PHPjpgraph的一点小提示（附安装方法），jpgraph安装方法_PHP教程

PHP jpgraph的一点小提示（附安装方法），jpgraph安装方法

　　PHP中的GD库本身是一套很强大的绘图库了，绘制的图像基本可以满足日常要求，但强大规强大，还是不够方便哈，因为强大方便的基于PHP的GD库的jpgraph也就诞生啦！

　　PHP默认是不启用GD库的，因为需要在php.ini的配置文件中将extension=php_gd2.dll注释打开。打开后你就可以画一些你想画的各种奇葩图案了。什么？不会画？那回去学基础！

　　今天看了一下某培训机构的视频，看了jpgraph报表这块儿，按照视频方法，在http://jpgraph.net/download/上下载了Version: 3.0.7版本，解压后在Examples目录下创建一个jpgraph目录，并将src目录下的除开Examples的所有文件剪切到Examples目录下刚创建的jpgraph目录内。然后把Examples拷贝到apache所配置的目录即可。

　　可是结果试了半天，老报错：

Warning: strftime(): It is not safe to rely on the system's timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone identifier. We selected the timezone 'UTC' for now, but please set date.timezone to select your timezone. in H:\TestFile\Examples\jpgraph\jpgraph.php on line 391

JpGraph Error: HTTP headers have already been sent.
Caused by output from file jpgraph.php at line 392.Explanation:
HTTP headers have already been sent back to the browser indicating the data as text before the library got a chance to send it's image HTTP header to this browser. This makes it impossible for the library to send back image data to the browser (since that would be interpretated as text by the browser and show up as junk text).

Most likely you have some text in your script before the call to Graph::Stroke(). If this texts gets sent back to the browser the browser will assume that all data is plain text. Look for any text, even spaces and newlines, that might have been sent back to the browser.

For example it is a common mistake to leave a blank line before the opening "".