operating system:
1. Storage mode: In the WinCE operating system, its data content is stored in memory. There is also different storage methods in memory, some of which is still sustainable after power failure, and the operating system comes with the application and installation of the installation disk generated by the EVB packaging tool. The other part is RAM. After power failure, the content is lost, usually the database is stored in this section, so it is important to note that the database or other useful files are often backed up to the PC.
The directory on the PDA is also a tree, it has only one root node, because there is no "drive letter" concept, the root directory is a slash (/), the subdirectories under the same are the same.
One point to remind everyone to pay attention to the capacity of storage, using the first impression of the order of the orders that the PC may have the stored order is G, but the M digitial level on the PDA, such as Symbol 2700 storage capacity is 16m, newer The model 2800 is only 32M, and the applications and data files are stored in space stored in this area.
2. Communication with the PC: You can modify, delete, paste, copy, etc. on the PDA, but you cannot transfer files to your PC. To back up the data to your PC, you have to understand how PDA communicates with PC, and complete the communication, you need to install a named ActiveSync Synchronization (SYNCHRONIZATION). You can modify, delete, paste, copy, etc. on the PDA, but you cannot transfer files to your PC. After the synchronization program is processed, an icon will appear in the taskbar. It is scheduled to query the COM port. When the PDA is connected to the PC, click the synchronization program icon and select Explorer, there will be the same interface with the Windows operating system. The files on the PDA are displayed in the tree structure, but in this interface we can only delete, copy, paste, and view file properties, and cannot run executable or view file content directly.
To manually complete the movement of the PDA and PC files, you can drag and drop files directly, or copy it first, both of which are two-way, that is, can be from the PDA to the PDA.
The synchronization program can automatically handle the consistency of the two files, my habits are not using automatic synchronization, and the synchronization needs to be verified after each PDA is connected to the PC, and the speed is slow.
3. File format: Why can't you run PDA executables directly or view the contents of the file on the PDA? The reason is that the file storage format and PDA on the PC are different. Take the Access library file as an example, which will be significantly larger from the PC to the PDA. It is relatively small for the format of plain text. Whenever the file moves in two different operating platforms, the synchronization program performs conversion of data format in the background.
4.WINCE operation:
Take Symbol2700 as an example, it is a liquid crystal display. The following is a numeric keypad, and the main operation is done by a touch screen and a soft keyboard on the screen. The soft keyboard is at the bottom of the screen, and it is minimized. After clicking, the layout is substantially the same as the ordinary PC keyboard, you can use a pen to select a number or letter, you can also implement a number, the handwritten input of the letter, but the identification rate is not high. The input on the PDA is often switching the keyboard and the keyboard is small, it is not convenient to choose, so it should minimize the user's input, especially the input of the letter.
Delete, copy, paste and other operations cannot be done with the keyboard. There is no way to support the right click in this area, so you can pop up the files when you operate, you want to use the stylus for file operations. The PC's right-click menu is operated.
5. Operating system:
Symbol2700 / 2800 operating system is Windows CE 3.0, Microsoft divides the entire CE 3.0 product line into three: PocketPC (mainly used in palm), Handheld PC (used for similar notebooks with terminals , The volume is much larger, the built-in keyboard and a PCMCIA expansion slot, etc.) and the Mobile Phone (smart phone system), three products use the Windows CE 3.x operating system. Symbol's 2700/2800 Series PDA is part of PocketPC. The operating system widely applied to the PDA also has an old Palm OS, and its operating system is DR-DOS. The main development tools on the PALM system are one of Code Warrior - C . Code Warrior supports the application of the graphical interface, but the development process is more cumbersome, first draws the interface with the graphical interface tool, then enter the code in the code editing tool, but cannot view the interface in the code input tool, which is convenient for the operation. Sex and Wince visual development platform cannot be synonymous.
Difference to VB:
EVB is self-disciplined or the RAD environment is absent from VB, so more is the same point as VB, and the following mainly describe the different points to pay attention to during the development process.
grammar:
Wince is Microsoft used to challenge the Palm operating system. It adheres to Microsoft's consistent style. It is to start to push the market when the technology has not completed maturity. EVB is also inevitably infected with immature. The most obvious is not coordinated between grammar and development environment.
EVB's syntax has a small part of the Wince, but basically can be seen as a subset of VB, most of which is the original VB. The problem we have to pay is: EVB development environment also has smart tips in Visual Studio, automatically listing function parameters, automatically completes keywords, but some syntax will appear smart tips when entering the code window, and actual EVB does not support, When running, you will be prompted to "find the keyword". For example: String, Space and other functions have the above problems. So can't believe in the development environment, don't think that there is a smart prompt in the development environment, it must be the correct syntax.
In addition, the definition of type (TYPE) is not supported.
Engineering Type:
There are two main types, one is the form of a form, which is the same as the normal standard EXE in VB, and the other is called Formless engineering, that is, the project is only code, which does not contain a form, similar to the MAIN function in VB. Started project.
The EVB application is generated after compiling is the .vb file, is not .exe file, on the PDA.vb file is associated with the EVB interpretation PVBLoad.exe, which is loaded and explained.
Form mechanism:
The mechanism of the form in EVB has many different VBs, and only part of it is listed here.
Load Event: The form will only be once in the application, and EVB has no unload method. That is to say, only the Form_Load event is triggered when the first display is displayed, and then the form will only be hidden (.hide), and the form unload, the form is not removed from the memory (End) will only clear it from memory. . The starting of the form is in the form of initialization, etc., which cannot be written to the Form_Load event like VB.
Size: The form can specify its size when designing, but how the specified size is displayed regardless of the design when it is designed.
Event: Wince's form does not have ControlBox, instead of a round OK button in the upper right corner, the corresponding event of this button is form_okclick (??), you must write code in the process to implement Forms and other functions . Control:
The control in the EVB is less than VB, and it will be cumbersome when used.
For example, a menu, you have to use the control in EVB, not as convenient in VB. The menu entry is added and the code corresponding to each entry must be done manually.
If you want to implement the code bar code function on different models such as Symbol 2700/2800, you must install the controls corresponding to the model. The control appearance and text box (TextBox) can complete the function of the text box. When the cursor is in this control, press the scan button on the PDA to scan the barcode, if the scan is successful, accompanied by "" sound barcode Displayed in this control.
API call:
First, the API under the WinCE operating system is mainly in a dynamic link library named Coredll.dll;
Second, the previous syntax section refers to the EVB does not support the TYPE structure, and a special process is required when the parameter of the referenced API is a TYPE structure. The specific processing method is to transfer the struct type in the parameter to the type length of each member to pass them into a hexadecimal string to the API, and the same reason If the API returns is the Type structure, then it is also sixteen The form of a string is reflected, and if you want to get the desired result, "translation" has to be reversed to obtain the final result.
Installer production:
The installation of the EVB application also has a setup wizard. Follow the prompts to generate the installation package, the difference is that the program is working in two parts when installing, and a part is running the installer on the PC, and the other is, when installed After running to a certain step, it will prompt the user to continue to install on the PDA. In the installation process, PC and PDAs are to process in the coupling state.
