软硬件环境

• ubuntu
• notify-osd
• libnotify-bin

概述

D-Bus是一种消息总线系统，它为应用程序之间互相调用提供了更为简单的方法。本文中实现的桌面通知就是基于D-Bus机制。桌面通知在ubuntu系统的早期版本中就有应用，如常见的音量调节、thunderbird的来信通知、QQ消息通知等都是如此。

先给一张系统架构图，方便理解。

为简单起见，在这里称请求方为Client，响应请求的为Server。

Server

sudo apt-get source notify-osd    
cd notify-osd-0.9.24    
vi notify-osd/src/default.c
 
#define DEFAULT_DESKTOP_BOTTOM_GAP 6.0f
#define DEFAULT_BUBBLE_WIDTH 24.0f
#define DEFAULT_BUBBLE_MIN_HEIGHT 5.0f
#define DEFAULT_BUBBLE_MAX_HEIGHT 12.2f
#define DEFAULT_BUBBLE_VERT_GAP 0.5f
#define DEFAULT_BUBBLE_HORZ_GAP 0.5f
#define DEFAULT_BUBBLE_SHADOW_SIZE 0.7f
#define DEFAULT_BUBBLE_SHADOW_COLOR "#000000"
#define DEFAULT_BUBBLE_BG_COLOR "#131313"
#define DEFAULT_BUBBLE_BG_OPACITY "#cc"
#define DEFAULT_BUBBLE_HOVER_OPACITY "#66"
#define DEFAULT_BUBBLE_CORNER_RADIUS 0.375f
#define DEFAULT_CONTENT_SHADOW_SIZE 0.125f
#define DEFAULT_CONTENT_SHADOW_COLOR "#000000"
#define DEFAULT_MARGIN_SIZE 1.0f
#define DEFAULT_ICON_SIZE 3.0f
#define DEFAULT_GAUGE_SIZE 0.625f
#define DEFAULT_GAUGE_OUTLINE_WIDTH 0.125f
#define DEFAULT_TEXT_FONT_FACE "Sans"
#define DEFAULT_TEXT_TITLE_COLOR "#ffffff"
#define DEFAULT_TEXT_TITLE_WEIGHT TEXT_WEIGHT_BOLD
#define DEFAULT_TEXT_TITLE_SIZE 1.0f
#define DEFAULT_TEXT_BODY_COLOR "#eaeaea"
#define DEFAULT_TEXT_BODY_WEIGHT TEXT_WEIGHT_NORMAL
#define DEFAULT_TEXT_BODY_SIZE 0.9f
#define DEFAULT_PIXELS_PER_EM 10.0f
#define DEFAULT_SYSTEM_FONT_SIZE 10.0f
#define DEFAULT_SCREEN_DPI 96.0f
#define DEFAULT_GRAVITY GRAVITY_NORTH_EAST

Note

DEFAULT_GRAVITY可以取如下3个值
* GRAVITY_NONE: the behavIoUr in Jaunty. A notification will always go into the top right corner.    
 
* GRAVITY_EAST: the behavIoUr NotifyOsd has been having for about a week in Karmic's development cycle,with the notifications centered vertically on the screen.    
 
* GRAVITY_NORTH_EAST: the Karmic behavIoUr. Works like GRAVITY_NONE but does not put asynchronous notifications on top of the screen,even if there is no synchronous notification being displayed.
 
./configure    
make    
make install(if you need)

Client

sudo apt-get install libnotify-bin

Have a test

1. 启动server

   notify-osd/src/notify-osd

2. 修改文字显示大小
   将 DEFAULT_TEXT_TITLE_SIZE 改为4.0f

3. Client发送请求

   notify-send “djstava” “I Love It”

桌面通知的python实现

1. 安装pynotify模块
   http://www.galago-project.org/downloads.php下载notify-python-0.1.1.tar.gz，解压然后进行安装三部曲./configure、make、sudo make install

2. 模块的使用

   try:
   import pynotify
   if pynotify.init(‘Fist Test’):
   n = pynotify.Notification(‘Title’,’message’)
   n.show()
   else:
   print ‘Pynotify module not initialized’
   except:
   print ‘Pynotify module not installed’
   ​
   可以像下面一样来设置消息的紧急级别

   n.set_urgency(pynotify.URGENCY_LOW)    
   n.set_urgency(pynotify.URGENCY_NORMAL)    
   n.set_urgency(pynotify.URGENCY_CRITICAL)

   关闭消息通知操作

   n.close()

参考资料

1、http://kobesearch.cpan.org/htdocs/Desktop-Notify/Desktop/Notify.pm.html
2、http://www.galago-project.org/specs/notification/0.9/index.html
3、https://wiki.ubuntu.com/NotifyOSD
4、http://doc.trolltech.com/4.2/intro-to-dbus.html
5、http://www.freedesktop.org/wiki/Software/dbus