Shulou(Shulou.com)06/01 Report--

This article introduces you to several commonly used embedded Linux GUI and what its characteristics are, the content is very detailed, interested friends can refer to, I hope to help you.

With the rapid development of Internet and network and gradually into people's homes, consumer electronics, computer, communication (3C) integration trend is increasingly obvious, embedded systems have become a hot spot of research and application. Embedded real-time Linux operating system is widely adopted because of its low price, powerful function and easy portability. It has become an emerging force. Of course, people with vision have already seen the development and prospect of it. Nowadays, with the rapid popularity of WAP mobile phones, PDAs, set-top boxes, and DVD/VCD players, users put forward higher requirements for the GUI of these handheld devices, hoping to see the gorgeous and beautiful GUI that only PCs have. GUI has become a bridge between man and machine, embedded systems require more and more GUI, and all of these require a lightweight, less resource, high performance, reliable, configurable and beautiful GUI support. Java technology is a great technology for servers, personal computers, and embedded systems. Because of its cross-platform characteristics. Java has been very successful on servers and desktops. On the GUI side, however, Java has very limited features to build graphical user interfaces. The idea is to use platform-independent Java APIs packaged into different operating systems to develop native graphical user interfaces, known as abstract window tools (AWT). Only common widgets such as file fields, text fields, selection boxes, radio buttons, list boxes, and buttons are supported by AWT, and graphics and image features support is very limited, that is, only enough to build simple applets. Recognizing the need for more advanced graphical user interface components and graphics capabilities, Sun developed Swing, Java 2D, Java3D, input/output of images, and Java Advanced Graphics (JAI). Swing is the standard API(Application Programming Interface) used to build Java graphical interfaces, and some AWT classes are based on Swing. It has a complete set of components from buttons to file fields, tables, trees and file editors. These components do not depend on parts native to the operating system, but are drawn using primitive graphics such as lines, rectangles, and text. This painting represents a sensory plug-in that mimics native sensory. SWT is based on Java development, its design concept is to maximize the operating system graphics components API, that is, as long as the operating system provides the corresponding graphics components, then SWT simply uses JNI technology to call them, only those components that are not provided in the operating system, SWT will do a simulation implementation. SWT also provides direct access to the operating system's native GUI, so SWT-based Java applications have native GUI and can be integrated with other native applications and components. Using SWT development kit, the advantages of Jaya language such as simplicity, cross-platform and reliability are gradually merged into the application development of graphical interface. Another door to success for the Java language is opening up. 2.1 SWT+GtkFB graphics system architecture SWT is at the top of the architecture, it and Java AwT and Swing belong to the high-level library needed to design graphical interfaces. SWT also addresses some of AWT's and Swing's problems, and has evolved into an operating system-independent library of graphical components. Appropriate simulation is used in the generation of components, the original operating system is used in the basic components, and simulation technology is used for more complex components. SWT-based Java applications have native graphical user interfaces and can be integrated with native applications and widgets.

Pango is a full-featured framework for the layout and display of internationalized text. Pango can handle text arranged in directions other than left-to-right, and can easily manage complex languages, even letters that take different forms depending on the context of use. For example, it supports bidirectional text, allowing users to mix left-to-right text with right-to-left text, and plug-ins for determining the shape of complex texts such as Arabic and Tamil. Pango is not only international, but the Pango library handles the display of antialiased font text well with Xft and XRender support. 2.1.3 Working Principle of GtkFB When an application is connected to GtkFB, gtk_init() will be called, as shown in Figure 3. At this time, GtkFB starts Linux Framebiffer, sets resolution and color number, and then opens peripherals such as keyboard and mouse (PDA open button and touch screen). Then go to a specific directory to read fonts, and finally initialize window and event management. GtkFB can support framebuffer with 8, 16, 24 and 32bpp. 2.2 SWT+GtkFB graphics system advantages Because GtkFB runs directly on FrameBufer, skipping X system, this saves X Server resources, which makes memory consumption and running speed significantly improved. In addition, JNI technology makes the program running speed and event response higher, and can meet the real-time application occasions with strict time requirements. SWT stability, the key is derived from SWT design concept. SWT maximizes the graphical component API of the operating system, that is, as long as the operating system provides the corresponding graphical components, SWT only uses JNI technology to call them, and only those components that are not provided in the operating system, SWT will do a simulation implementation itself. It can be seen that the stability of SWT performance depends largely on the stability of graphics components of the corresponding operating system. SWT's API is identical to the desktop version, so code can be easily ported and shared between desktop and embedded devices. SWT uses LGPL license, users can freely or even encourage to modify the source code to better meet the needs of users, it is easy to reduce the specific SWT+GtkFB according to the needs of users, according to LGPL license, users need to publish the modified source code, but users do not have to publish the source code of self-contained applications. SWT is based on Java language development, with platform independence, object-oriented, portable, security and other characteristics of Java language. Users can easily develop widgets that meet their needs based on the widgets provided by SWT, and it is easy to use these widgets to build applications. 3.1 The next step is to create SWT and GTK directories in/home/XXX/and set up environment variables. 3.2 Compile and install Gtk+2.0tar zxvf glib-2.0.6.tar.gz -C $GTK_HOME/src./ configure --prefix=$GTK_HOMEmake inSTalltar zxvf atk-1.0.1.tar.gz -C $GTK_HOME/src。/ configure --prefix=$GTK_HOMEmake install steps similar to atk installation. Embedded Linux GUI can be used in many fields, such as home appliance market, commercial market, industrial and automation market, defense market, communication market, etc. For example, in the communications market, mobile phones, video phones, set-top boxes, etc. may become the operating platform for embedded Linu.x, and a user-friendly user interface is a key factor in winning consumers. Therefore embedded Linux graphics system will play a more important role. If you have learned embeddings by this time, you will be very lucky. But you want to learn really can not find the direction of no resources, you can also private me. I believe I can also provide you with a lot of help.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.