QT学习笔记(六):Embedded Linux QT Display Management
来源:互联网 发布:大学搜题用什么软件 编辑:程序博客网 时间:2024/05/17 23:42
Qt for Embedded Linux Display Management
When rendering, the default behavior for each Qt for Embedded Linux client is to render its widgets into memory, while the server is responsible for putting the contents of the memory onto the screen. The server uses the screen driver to copy the content of the memory to the display.
The screen driver is loaded by the server application when it starts running, using Qt's plugin system.
Contents:
- Available Drivers
- Specifying a Driver
- Subdrivers and Multiple Drivers
Available Drivers
Qt for Embedded Linux provides drivers for the Linux framebuffer, the virtual framebuffer, transformed screens, VNC servers and multi screens. Run the configure script to list the available drivers:
./configure -help
In the default Qt configuration, only an unaccelerated Linux framebuffer driver (/dev/fb0) is enabled. The various drivers can be enabled and disabled using the configure script. For example:
./configure -qt-gfx-transformed
Custom screen drivers can be implemented by subclassing the QScreen class and creating a screen driver plugin (derived from theQScreenDriverPlugin class). The default implementation of the QScreenDriverFactory class will automatically detect the plugin, loading the driver into the server application at run-time.
Specifying a Driver
To specify which driver to use, set the QWS_DISPLAY environment variable. For example (if the current shell is bash, ksh, zsh or sh):
export QWS_DISPLAY="<driver>[:<driver specific options>]... [:<display num>]"
The valid values for the <driver> argument are LinuxFb, QVFb, VNC, Transformed, Multi and keys identifying custom drivers, and the <display num>argument is used to separate screens that are using the same screen driver and to enable multiple displays (see the Running Qt for Embedded Linux Applications documentation for more details). The driver specific options are described in the table below.
The QWS_DISPLAY environment variable can also be set using the -display option when running an application. For example:
myApplication -display "<driver>[:<driver specific options>]... [:<display num>]"
Subdrivers and Multiple Drivers
The VNC, Transformed and Multi screen drivers depend on subdrivers. The general syntax for specifying a driver is as follows:
export QWS_DISPLAY="<driver>[:<subdriver>][:<subdriver options>]... [ :<display num>]"
In the case of subdrivers, it is important to add a space between each subdriver and before the display number to separate the various drivers and displays. Note that Multi screen drivers can have several subdrivers. For example:
export QWS_DISPLAY="Multi: QVFb:0 QVFb:offset=640,0:1 :2"
Note also that the VNC screen driver defaults to a virtual screen driver if no subdriver is specified. In this case the VNC driver accepts a few additional (optional) arguments specifying the size and depth of the default virtual screen:
- size=<width x height>
- depth=<value>
- mmHeight=<physical height in millimeters>
- mmWidth=<physical width in millimeters>
Example running the VNC screen driver with a virtual screen of size 720x480 with 32 bits per pixel:
export QWS_DISPLAY="VNC:size=720x480:depth=32"
Example running the VNC screen driver on top of the Linux framebuffer driver:
export QWS_DISPLAY="VNC:LinuxFb"
In this last example, Qt is using two screen drivers simultaneously, displaying output on both the device's screen and across a network on VNC client displays.
- QT学习笔记(六):Embedded Linux QT Display Management
- Qt for Embedded Linux Display Management
- Qt for Embedded Linux Display Management
- Qt学习笔记(六) 事件处理
- Qt Quick学习笔记(六)
- Qt for Embedded Linux (嵌入式linuxQT)
- Qt-embedded-linux移植要点Qt
- qt-embedded-linux移植要点qt
- qt-embedded-linux移植要点qt
- qt-embedded-linux移植要点qt
- 【QT】Qt for Embedded Linux Architecture
- Qt-embedded-linux移植要点qt
- qt linux embedded x86 安装
- Qt/Embedded
- qt学习笔记(六)之简析对象树
- Qt学习笔记(六)项视图类
- Qt学习笔记外观篇(六):QLabel
- qt学习笔记(六)之简析对象树
- 05_家谱管理系统(小钱版)[数据结构][2012-02-03]
- 64位 win7访问TD
- 黑马程序员(C#1)之《小知识点》
- 谁来拯救云计算
- 一个Linux2.6版内核字符驱动的例子
- QT学习笔记(六):Embedded Linux QT Display Management
- Delete a service from the service list (windows)
- Linux清理Oracle日志巧用close_trace命令释放误删trace文件
- 字符串String类的完整实现 C++程序设计语言第11章
- 《C语言名题精选百则----7》
- 茶叶产业的前景
- python笔记
- 怎么样获取本机IP
- 黑马程序员(C#2)之《数据类型》