Applies To: ReportListener Object.
The OutputPage method is unusual because, depending on the current ListenerType value, a ReportListener either triggers this method to signal you that a page is ready or expects you to trigger the calls yourself, to request the pages you want.
Understanding OutputPage's Two Processing Modes
In the first processing mode, the ReportListener acts in a style appropriate to printers and other output devices that handle output one page at a time. If necessary, these devices place incoming pages in a spool or queue until they are ready to handle more pages. This type of page-processing is forward-only; you cannot ask for any specific page a single time, after the ReportListener has begun rendering subsequent pages.
In the second processing mode, the ReportListener prepares all pages at once, effectively providing a queue of all pages until the device is ready to request them. You cannot request any pages until all pages are prepared. However, this type of page-processing results in a cached, or scrollable, collection of pages, as required by previewing devices; once the pages are prepared, you can request them in any order, and, you can request them multiple times.
Error-handling for OutputPage Parameters
The parameter list to OutputPage is complex and some parameters have multiple uses. For this reason, it may be difficult to interpret the errors you receive when you use the parameters incorrectly.
The following are the error messages you can expect if you send the ReportListener unexpected or inappropriate values when using this method.
| Error message and number | Conditions triggering this error |
| Must specify additional parameters (Error 94) | Triggered if you do not include all three required parameters (nPageNo, eDevice, nDeviceType). |
| Function argument value, type, or count is invalid (Error 11) | Triggered if nDeviceType receives an unrecognized value. |
| DataType property for field 'eDevice' is invalid (Error 1544) | Triggered if the eDevice argument’s data type does not match the requirements for a valid value in nDeviceType. For example, you might receive this value if nDeviceType is 0 or 1 and eDevice is not a valid handle, or if nDeviceType is one of the filename types but eDevice is not a string representing a valid filename. |
| Error writing to file 'filename' (Error 1105) | Triggered if nDeviceType is one of the filename types and eDevice appears valid but the file cannot be created. For example, the user might not have permissions to create a file in the specified directory. |
| Output page 'pageno' is not available (Error 2194) | Triggered if nPageNo is not appropriate to the current rendered pages, or if the ListenerType value is not properly set to one of the values (0, 1, 2, or 3) in which the ReportListener renders pages. |
For more information about Visual FoxPro error messages, see Error Messages Listed Numerically. For more information about what to do when errors occur when you process reports, see Handling Errors During Report Runs.
.gif) Caution |
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| In addition to the error messages above, which you may see if you invoke OutputPage with incorrect parameters, be aware that OutputPage needs resources available to the report even when you call it after the report run concludes. For example, if image file used in a report is built into your calling application, a call to OutputPage from a PreviewContainer needs access to that image file. Although no error message is generated, your report output will not be complete if you unload the application from which the REPORT FORM or LABEL command was issued. |