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Chapter 2 SCREEN MANAGEMENT INTRINSICS This chapter provides comprehensive information about the Hi-Li intrinsics. If you have never used the screen management facility, read this chapter before you begin using Hi-Li intrinsics to code your application. The topics in this chapter include: * The basic structure of Hi-Li intrinsics and how they are used * The way Hi-Li uses the Application-ready Buffer (ARB) * The languages that Hi-Li supports * The data types and structures that Hi-Li uses * The rules for using Hi-Li Hi-Li Intrinsics The HP screen management facility comprises three core intrinsics, HPDSEND, HPDREAD, and HPDPROMPT. They provide the basic functions needed for the exchange of data between the terminal and your application. These core intrinsics are supported by the HPDOPENFORMS, HPDCLOSEFORMS, HPDENABLETERM, and HPDDISABLETERM intrinsics. They perform housekeeping functions such as opening and closing forms files. The remaining intrinsics perform more specialized functions that your application may require, such as configuring parts of the execution environment. Figure 2-1 shows the relationships among the intrinsics.Figure 2-1. Core and Supporting Intrinsics Core Intrinsics. These intrinsics provide basic functionality. HPDSEND Passes application data to the operator's device and arranges it according to a scheme identified or provided by the application. HPDREAD Collects data from the operator's device and returns it to the application. HPDPROMPT Lets the application focus the operator's attention by altering and highlighting data when it is displayed at the terminal. Supporting Intrinsics. These intrinsics provide supportive and specialized capabilities. Supportive Capabilities: HPDOPENFORMS These intrinsics perform the housekeeping HPDCLOSEFORMS duties of opening and closing forms, and HPDENABLETERM enabling and disabling the terminal. HPDDISENABLETERM Specialized Capabilities: HPDGETENV HPDSETENV These intrinsics let you see and set the values for options in the execution environment. Use them when your application requires a special configuration. HPDPRINTFORM Lets you obtain a printed copy of a form with its data. HPDGETDESIGN Lets you retrieve design information to facilitate documenting your application. HP32424 Lets you identify the current version of the Hi-Li software. The Hi-Li intrinsics and their parameters are described in detail in Chapter 3. The Hi-Li Model Hi-Li is designed to control the transfer of data between the terminal and an application with an interactive user interface. The data is transferred as a block, rather than item by item. The sequence is as follows. The HPDSEND intrinsic sets up the form and displays it according to instructions specified in the application. The instructions cover such things as the initialization of field displays, key label display, and the display of application messages in the message window. The HPDREAD intrinsic reads and collects the information that the operator supplies on the form. If any errors are detected, the HPDPROMPT intrinsic is called to alert the operator to the error by highlighting particular fields and/or displaying messages. The supporting intrinsics enable the core intrinsics to transfer data by performing the basic housekeeping tasks of enabling the terminal and opening the forms file, and then disabling the terminal and closing the forms file when the application is finished.Figure 2-2. The Hi-Li Model Hi-Li and the Application-ready Buffer (ARB) A data buffer is passed by the application to HPDSEND, HPDREAD, and HPDPRINTFORM. You can specify the instructions for how you want data moved between this buffer and the form in one of two ways. In the first way, you code your application to specify how you want the contents of the data buffer handled by including a 'data description' parameter. This is the direct method of transferring data, and Hi-Li supports five such methods. In the second way, you code your application to specify that you want the contents of the data buffer handled according to specifications in the forms file. This is the indirect method, which takes advantage of the Application-ready Buffer (ARB). Each of these six methods is discussed in detail in Chapter 4. The Application-ready Buffer. The purpose of the ARB is to represent data as the application expects to use it, and not necessarily as it appears on the screen. For example, a given application may have one arrangement of fields on the screen that corresponds to data entry needs, and a different internal arrangement that corresponds to file storage layout. In addition, some of the screen data, always in character format, may need to be converted and stored in non-character formats for subsequent processing. Finally, the application's internal buffer may contain data fields that are not for display on the operator's terminal, such as dataset search items (keys) or system checksums. You can use the ARB to accomplish the data remapping, type conversions, and masking required by your application, instead of having to write application code for these purposes. Use the ARB menus in FORMSPEC/V to specify the necessary data manipulations. Whether or not you choose to use the ARB method for managing data transfers between your application and its associated forms depends on the specific requirements of your application. For complete information about the Application-ready Buffer, see the HP Forms Management (VPLUS/V) Reference Manual (Part No. 32209-90001). Data Types Table 2-1 shows the data types and structures that are used in Hi-Li intrinsics. Table 2-1. Data Types and Structures ------------------------------------------------------------------------------------------------- | | | | | | FORMSPEC | COBOL | Pascal | FORTRAN | | | | | | ------------------------------------------------------------------------------------------------- | | | | | | CHAR | X | Packed array | CHAR *_ | | | | CHAR [.._] | | | | | | | | YYDDMM | X(6) | as above | CHAR *6xx | | | | | | | ZONEn | 9(_).n | --- | --- | | | | | | | PACKn | 9(_)Vn COMP-3 | --- | --- | | | | | | | SPACKn | S9(-)Vn COMP-3 | --- | --- | | | | | | | REAL | --- | REAL | REAL | | | | | | | LONG | --- | LONG | Double | | | | | Precision | | | | | | | INT | S9(4) COMP | Subrange | Integer **2 | | | | -32768..32767 | | | | | | | | DINT | S9(9) COMP | Integer | Integer **4 | | | | | | ------------------------------------------------------------------------------------------------- Note: [n] represents the number of decimal digits How Hi-Li Intrinsic Parameters Operate The Hi-Li intrinsics act as a link between the application and the forms created with FORMSPEC/V. Table 2-2 shows how the information flow is controlled by various parameters as they are passed between Hi-Li and the application. Table 2-2. Information Flow --------------------------------------------------------------------------------------------- | | | | Data | How it is Processed | | | | --------------------------------------------------------------------------------------------- | | | | Communications | - Set up by the application | | (GLOBALPAK | - Formatted by open/enable | | | - Passed between intrinsics | | | | --------------------------------------------------------------------------------------------- | | | | Status | - Passed back from each intrinsic | | | to the application | | | | --------------------------------------------------------------------------------------------- | | | | Processing Instructions | - Passed to each intrinsic | | (SENDPAK, READPAK, PROMPTPAK, | by the application | | DATADESCPT, LABELDESCRPT, | | | READITEMS, | | | CURSORPOSITION) | | | | | --------------------------------------------------------------------------------------------- | | | | User Interface Specifications | - Passed to HPDSEND and HPDPROMPT | | (FORMPAK) | by the application | | (FIELDLIST for HPDPROMPT) | | | | | --------------------------------------------------------------------------------------------- | | | | User Message | - Passed to HPDSEND and HPDPROMPT | | (MSG) | by the application | | | | --------------------------------------------------------------------------------------------- | | | | Data | - Passed to HPDSEND by | | (DATABUF) | the application | | | | | | - Passed from HPDREAD to the application | | | | --------------------------------------------------------------------------------------------- | | | | Key Labels | - Passed to HPDSEND and HPDPROMPT | | (LABELBUF) | by the application | | | | --------------------------------------------------------------------------------------------- | | | | Edit Report | Passed from HPDREAD to | | (FIELDLIST from HPDREAD) | the application | | | | --------------------------------------------------------------------------------------------- Abbreviated Parameters. Each intrinsic has multiple parameters. Certain parameters can be collapsed so that they pass only one part, or pass a null value if they are not necessary to your application. This allows you to build in the feature set you currently need without having to enter "dummy" information you do not want to include. If you decide to use additional features at a later time, you can simply activate and/or expand the necessary parameter; you do not have to add an additional intrinsic call. The chnglisttype subparameter of the FORMPAK parameter (HPDSEND intrinsic) provides an example of how this works. The chnglisttype parameter allows you to indicate whether you want the HPDSEND intrinsic to apply change specifications supplied by the application to fields on a given form. If you assign chnglisttype a value of zero (to indicate that the change list is empty), the following five subparameters that detail these change specifications are ignored by Hi-Li. For example: changlisttype = 0 then: listcount chngentry fieldident chngtype chngspec are ignored and never referenced by Hi-Li. Therefore, the FORMPAK parameter can be abbreviated by specifying a changlisttype value of zero. See the HPDSEND intrinsic in Chapter 3 for a complete discussion of the chnglisttype parameter and its subparameters. Supported Languages Hi-Li intrinsics can be used with COBOL, FORTRAN, and Pascal. The call formats for each of these languages are listed in Table 2-3. Table 2-3. Language Call Formats --------------------------------------------------------------------------------------------- | | | | Language | Intrinsic Call Format | | | | --------------------------------------------------------------------------------------------- | | | | COBOL | CALL "intrinsicname" USING parameter1 | | | parameter2 | | | parameter3 | | | . | | | . | | | . | | | | | | parametern. | | | | --------------------------------------------------------------------------------------------- | | | | FORTRAN | CALL intrinsicname (parameter1, parameter2,.|.) | | | --------------------------------------------------------------------------------------------- | | | | Pascal | intrinsicname (parameter1, parameter2,...); | | | | --------------------------------------------------------------------------------------------- To ensure consistency among calls from different programming languages, the following rules apply to all parameters: * Parameters are passed by reference. This means that a literal value cannot be used as a parameter. * No condition codes are returned. The status of the call is returned in a status word included as part of the RETURNPAK parameter. * Return type intrinsics are not allowed. Any values returned by the intrinsic are sent as passed parameters. Hi-Li Dependencies and Rules The following is a list of rules and dependencies that must be followed and observed when you use the Hi-Li intrinsics. 1. A forms file must be open before you can print the form. 2. A forms file must be open and your terminal must be enabled before you can use the HPDSEND, HPDREAD, and HPDPROMPT intrinsics. 3. The HPDGETENV and HPDSETENV intrinsics have guidelines you must follow that depend on the value you give the MODE parameter. See the HPDGETENV and HPDSETENV intrinsics in Chapter 3 for information about these guidelines. 4. The HPDGETDESIGN intrinsic is not compatible with any of the other Hi-Li intrinsics. This is because the other intrinsics depend on the form referenced by the HPDSEND intrinsic. This form and the form referenced by HPDGETDESIGN may be different. Because of this, you must define a separate GLOBALPAK parameter that you use only with HPDGETDESIGN; you cannot call this intrinsic using the GLOBALPAK parameter that you pass to the other intrinsics. 5. You cannot call tHE HPDREAD and HPDPROMPT intrinsics directly following a call to HPDENABLETERM. This is because Hi-Li expects to see the HPDSEND intrinsic that sets up the form. To call HPDREAD or HPDPROMPT in this case, call HPDSEND first. 6. The following read sequences are allowed: a. A read call following a send and/or a prompt. b. A read call followed by a second read call with the 'doreread' option. 7. You cannot call HPDREAD or HPDPROMPT directly follow ing a call to HPDPRINTFORM. This is because HPDREAD and HPDPROMPT use the form referenced by the previous HPDSEND intrinsic. Only one Hi-Li storage area is allocated for form information. When HPDSEND is called, it sets up this storage area with certain values. When HPDPRINTFORM is called, it resets these values. Therefore, to call HPDREAD or HPDPROMPT after making an HPDPRINTFORM call, call HPDSEND. 8. You cannot mix Hi-Li calls with VPLUS/V calls. 9. A forms file must be opened before you can use the HPDCLOSEFORMS intrinsic to close it. 10. The terminal must be enabled before you can use the HPDDDISABLETERM intrinsic to release it. 11. Consecutive forms file opens are not allowed. Always close the open forms file before opening another. 12. Consecutive terminal enables are not allowed. Always disable the enabled terminal before enabling a second one.
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