After the film exited the lives of ordinary people, the classic process of filming-washing film-expanding photos gradually disappeared from us. Instead, there are a large number of digital camera user groups and a wide variety of storage media. Digital photo frames are the best way to play back these photos. As a core product for viewing digital photos, digital photo frames are catering to the needs of consumers.
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1 System Requirements Analysis
Many people don't understand where the charm of digital photo frames is. Digital photos taken nowadays have begun to show a growth in geometric progression. If you want to print these photos again, you will have to waste a lot of money. Traditional photo frames and photo albums can no longer bear the burden of preservation. The digital photo frame will completely liberate those digital photos that have been accumulated, so that every moment worth remembering in your life will no longer be buried in the hard disk. Digital photo frames can be used to beautify the home and create a refined living experience. Share happiness, show success; bring to parents, ease their thoughts; or bring them into the office to ease the pressure of work.
Compared with traditional photo frames, digital photo frames also have many advantages. The digital photo frame adopts the shape of an ordinary photo frame, and is more exquisite. It uses a liquid crystal display to display photos, and is equipped with a power supply, a storage medium, etc., so that multiple photos can be played on the display screen, and some digital photo frames also add MP3. Multimedia entertainment functions such as MP4 are more advantageous than the single function of ordinary photo frames.
As a consumer electronics product, digital photo frames must consider the following aspects:
1) User interface and interface are friendly and easy to operate. As a consumer electronics product, its customers are diversified, most of which are non-professional, even elderly or children. Whether the operation is user-friendly and succinct, it becomes an important factor for users to quickly accept products. .
2) System compatibility, digital photo frame should be able to identify and process the current digital camera capture image format, access to mainstream semiconductor storage peripherals.
3) Storage is reliable. As a storage device, it must pass strict functional tests to ensure that users do not lose information during use.
In view of this, the main functions of digital photo frame products should include the following aspects:
1) Supports mainstream semiconductor memory cards from which image files can be read.
2) Display multiple image files in full screen on the LCD screen to support various mainstream formats.
3) Display time and date
4) It can be operated by button or touch screen.
2 overall system design
The digital photo frame architecture design based on Linux using Qt supports embedded Linux system by using pure C++ language development, and uses Qt/Eembedded as GUI to provide powerful user interface. The purpose of designing in Linux user space is for system portability. .
The system architecture of this project consists of the following levels:
1) The underlying hardware. This design uses the A8 experimental box of Sunplus as Samsung S5PV210.
2) Driver
3) Operating system. A PC with an Ubuntu system or an Ubuntu virtual machine.
4) Qt application
The digital photo frame designed by this project mainly adopts Qt-based programming design, and it is made into a digital photo frame with the A8 experimental box. When the digital photo frame is initialized, it will scan all the supported image files in the specified directory. The user can turn forward or backward through the button, and can zoom in and out.
3 Realize the digital photo frame project process
First build the system, including the establishment of the Linux platform Linux virtual machine environment and the ARM platform Linux system. Implemented using Qt programming. There are two ways to develop a common Qt application:
The first is to write C++ code using a text editor, then generate the project and compile it from the command line;
The second is to write C++ code using QtCreator, install Qt Embedded SDK for Qt Creator, and then use Qt Creator to compile the program. Because Qt Creator has a good visual interface and it contains a very powerful C++ code editor, the second method is our first choice.
1) In Qt, click on the menu bar File/New File or Project and create a new file type Qt C++Project/Qt Gui Application. Enter the project name QtImage and save path in the next Qt Gui Applic ation dialog.
The digital photo album project created is shown in Figure 1.
The following is the main program of the digital photo frame, the main function is to display the widget control on the interface.
The Ui display interface is shown in Figure 2.
The picture is displayed as shown in Figure 3 by clicking the zoom out button in the upper left corner.
The next picture is displayed as shown in Figure 4 by clicking the page control button in the upper left corner.
2) Experiment box platform display
Software development for common embedded systems uses cross-compilation and debugging. The cross-compilation debugging environment is built on the host machine, and the corresponding development board becomes the target board. The A8 experiment box used by this project is Samsung S5PV210, which is the ARM A8 architecture processor. The GNU compiler provides such a function that you can choose to develop the required host and target machine to build the development environment when the compiler compiles. So the first step before the embedded development is to install a PC with the specified operating system as the host development machine. Embedded development usually requires the host to be configured with a network that supports NFS (used for mounts during cross-development). Then you need to establish a development environment for cross-compilation debugging on the host.
Next, compile the Qt application for the experiment box operation, first connect the serial port and network cable of the experiment box to the PC.
Execute Qt Creator's Build/Clean All, clean up the previously produced build files, and prevent errors in compiling the embedded version of the program. Click the icon shown in the lower left corner and the compile selection box will pop up. Click the drop-down list to the right of “Build†and select “Qt for A8 Release†among the four compilation types that pop up. Click the "Build AIl" button to start compiling the version of the experiment box run until the progress bar above the compile selection button turns green, indicating that the compilation is complete. And in the project's save directory, you can find a folder called "QtImage-build-desktop", as shown in Figure 5. The compiled executable is in this folder.
Copy the QtImage file in the QtImage-build-desktop folder to Windows, and download QtImage to the experiment box according to the method of downloading the program in the above; in the HyperTerminal, use chmod 777 QtImage to add executable permissions to QtImage, and Run it. The operation is shown in Figure 6.
The application can be operated using a touch screen on the experiment box.
4 Conclusion
With the rapid development of embedded systems, their applications have penetrated into every area of ​​people's lives. Large to the military field, small to children's toys, it is quietly changing people's production and lifestyle in different forms. It has become a hot spot in the computer field today, so the development and discussion of embedded systems is of great significance.
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