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Volume Number: | 9 | |
Issue Number: | 6 | |
Column Tag: | MacApp Workshop |
Related Info: Print Manager
TReportPrinter
A supplemental printing class for MacApp
By William L. Colsher, Minneapolis, Minnesota
Note: Source code files accompanying article are located on MacTech CD-ROM or source code disks.
About the author
William L. Colsher, 5400 3rd Avene South. Minneapolis, Minnesota 55419.
Background
MacApp is, without question, the most comprehensive commercially available class library for the Macintosh. And to a large extent it fulfills its rather ambitious goal of providing a complete Macintosh application framework. But no class designer can anticipate every use to which his work will be put. He must produce a set of general purpose classes that are easily subclassed to provide specific behavior yet still contain enough functionality to be worth using. Nowhere is this more evident than in MacApp’s printing architecture.
One of the fundamental assumptions built into MacApp is the relationship between a document (represented by a subclass of TFileBasedDocument) and the presentation of that document’s data (by the many subclasses of TView). Specifically, it is assumed that some combination of TView objects will be able to present the document’s data both on screen and when that data is printed. As a consequence, MacApp’s printing class TStdPrintHandler depends on a document’s TView objects to draw the data on the selected printer.
This is a reasonable and powerful assumption. It takes advantage of QuickDraw’s ability to draw in any GrafPort regardless of whether that GrafPort represents a window, a printer, a buffer in RAM, or something we haven’t yet imagined. It also greatly simplifies the creation of WYSIWYG style applications. For some documents this is ideal. To print one simply attaches a TStdPrintHandler or a subclass of it to the TView to be printed. This TView need not be the same view used to display the document on screen. Nevertheless, it must be a subclass of TView.
In many cases that assumption is perfectly valid. But for a large class of real-world applications, the TView/TStdPrintHandler approach is unnecessarily (even hopelessly) complex. These are the applications that must print reports. Boring though they may be to program, printed reports are the lifeblood of modern business. The problem with reports (from the standpoint of MacApp’s printing architecture) is that it is often impossible to predict their length or exact form without first processing all the data that is to be printed. While it is possible to create views “on the fly” to represent a printed report, it is often impractical. The process is complex and time consuming at best. The data must be processed at least twice (once to build the views, then again to print them). Unless they are very carefully designed, the TView subclasses will tend to multiply uncontrollably as reporting requirements change. And, perhaps most important from an object programming point of view, the data objects lose control of a very important piece of functionality: their own printing.
TReportPrinter attempts to provide an alternative to MacApp’s built in printing architecture that addresses just this problem. TReportPrinter’s goal is to encapsulate the Macintosh printing process in a way that makes it easy for an application to format and print text oriented reports. It effectively hides the often poorly understood mechanics of the Macintosh Printing Manager, leaving the well understood process of formatting report lines to the document and it’s data objects.
Overview of TReportPrinter
The structure of TReportPrinter corresponds quite closely to that of the traditional Macintosh “printing loop”. Its fields contain the various pointers required by the Printing Manager and its methods implement the many steps required to print the lines and pages of a report and to provide an adequate safety net should something go wrong. In addition there are methods that provide control of print characteristics (font, size, etc.), pagination, and the printing of headers and footers. The rest of this section explains the function of each field and method of TReportPrinter in some detail. They are documented in alphabetical order for easy reference, Their usage is documented in the next section: Using TReportPrinter.
Fields:
Boolean fAutoFormFeed - TRUE if TReportPrinter is to start a new page whenever fBottomOfPage will be passed by the next print operation.
short fBottomOfPage - Stores the highest location (in pixels) to be printed on a page. It may not be greater than the length of the page in pixels.
short fCurrentFace - Store the current font’s “face” (i.e. bold, italic, etc.).
CStr255 fCurrentFontName - Stores the name of the font currently used for printing. It is provided for the convenience of subclasses.
short fCurrentFontNumber - Stores the number of the current printing font.
short fCurrentPage - A convenience for subclasses that need to print page numbers.
short fCurrentSize - Stores the current font’s size.
short fLeftMargin - The left margin location in pixels, offset from zero.
long fMaxSpoolLines - The maximum number of lines that the Printing Manager can spool to disk. It is calculated in IReportPrinter().
TReportStatusWindow fMyStatusWindow - Reference to the modal status window TReportPrinter creates when starting a report. This window is responsible for intercepting Cmd-. It may display any status message.
long fPrintedLines - The number of lines that have been printed. Used with fMaxSpoolLines to determine when to close the Printing Manager “document” and start a new one.
TPPrPort fPrintingPort - Pointer to the Printing Manager TPPrPort being used for printing.
Boolean fPrintManagerIsOpen - There are two methods where TReportPrinter might open the Printing Manager with a call to PrOpen(). However, it is important to do this only once. It is set to TRUE when PrOpen() is called.
THPrint fPrintRecord - Handle to the Printing Manager “print record” currently in use.
CStr255 fReportTitle - Displayed in the status window, this field is usually the parent document’s name. It does not have to be however. It also may be a convenience when printing headers or footers.
Boolean fUserAborted - Set to TRUE if a user hits Cmd-.
Methods:
pascal void DoClosePage(void) - DoClosePage() encapsulates PrClosePage(). Rarely called by the user of TReportPrinter.
pascal void DoFormFeed(void) - DoFormFeed() calls PrintFooter(), advances to the top of the next page (by calling DoClosePage() and DoOpenPage()) and then calls PrintHeader().
pascal Boolean DoOpenPage(void) - DoOpenPage() encapsulates PrOpenPage(). Rarely called by the user of TReportPrinter. (Call DoFormFeed() instead.)
pascal void DoPrClose(void) - Calls PrClose(), sets fPrintManagerIsOpen to false, frees the print record and closes the status window if it exists. Not normally called by the user of the class.
pascal void DoPrOpen(void) - Calls PrOpen() and allocates a print record if necessary. Sets fPrintManagerIsOpen to true. Not normally called by the user of the class.
pascal void EndReport(void) - Call EndReport() when your printing is finished. It closes the current page and print document, then calls the appropriate Print Manager routines to “print” your report.
pascal void Free(void) - Call this method from you document’s Free() method.
pascal unsigned long GetFreeSpaceOnDisk(int theVolume) - Used internally to determine how large a document we can “spool”.
pascal Boolean HandlePageSetup(void) - Call HandlePageSetup() in response to a cPageSetup command in your document’s DoMenuCommand() method.
pascal void IReportPrinter(CStr255 theFont, short theFace, short theSize, short leftMargin, short bottomOfPage, Boolean autoFormFeed);
IReportPrinter() sets the initial parameters for printing. Notice that the font to be used is specified by its name. theFace and theSize are specified as you would for QuickDraw. The two margin arguments are specified in pixels. If autoFormFeed is true, TReportPrinter will advance to the next page whenever a “line feed” operation would cause the next line to print beyond bottomOfPage
pascal Boolean PrintALine(CStr255 theLine, Boolean doLineFeed);
PrintALine() prints the contents of theLine. If doLineFeed is true, it also advances the cursor to the logical next line.
pascal void PrintFooter(void) - Override this method to print your page footer.
pascal void PrintHeader(void) - Override this method to print your page header.
pascal void SetDocumentName(Str255 docName) - Used to tell TReportPrinter the name of the document being printed. TReportPrinter passes this information on to the status window.
pascal void SetFace(short theFace);
pascal void SetFont(CStr255 theFont);
pascal void SetSize(short theSize);
These three methods set the face, font, and size that will be used for printing. These methods must be called after a DoOpenPage() to work correctly.
pascal Boolean StartReport(CmdNumber aCmdNumber) - StartReport() opens the print manager, calls PRJobDialog() and instantiates the status window. It also verifies that the bottom margin does not exceed the size of the paper. (If it does, the bottom margin is set to the bottom of the printing GrafPort.)
pascal void UserAbort(void) - Called by the status window if the user hits Cmd-.
pascal void VerticalTab(short pixels) - Advances the cursor down the current page by pixels. It will cross page boundaries in the obvious way.
Using TReportPrinter
Incorporating TReportPrinter into your program is a straightforward task. The first step is to create an instance of TReportPrinter and initialize it. This is typically done in your document’s initialization method and requires only two lines (all these examples are from the demonstration program available on the source code disk):
/* 1 */ fMyReportPrinter= new TReportPrinter; fMyReportPrinter->IReportPrinter(“\pmonaco”,// Font normal, // Face 9, // Size 36, // Left margin 648, // Bottom Margin false); // no auto-FF
Of course you will also have to respond to menu commands. In your document’s DoMenuCommand( ) method, the following lines handle all that is necessary:
/* 2 */ case cPageSetup: fMyReportPrinter->HandlePageSetup(); break; case cPrint: GetInspectorName(docName); // get this document’s name fMyReportPrinter->SetDocumentName(docName); if(fMyReportPrinter->StartReport(aCmdNumber)) { fMyReportPrinter->PrintHeader(); // Your code to feed lines to the report printer goes here fMyReportPrinter->EndReport(); } break;
Except in very simple cases (such as the demo program that accompanies this article) it is probably preferable to create and post a command to handle the cPrint case. This better fits the object way of life by isolating your printing code from parts of the program that really have no business knowing about printing. It will also make it easier to create new “reporting” objects as your users’ needs change.
Some Interesting Things To Note
Because TReportPrinter is designed to print reports (not documents) it cannot be used to handle things like the “Print Documents” Apple Event without considerable re-writing. This is a fairly straightforward task and while it would be interesting (and perhaps even useful) to complete, I have a full time job and a family to attend to. Therefore, it is left as an exercise for the interested reader. A couple of hints are in order however. First, since TReportPrinter makes many calls to gApplication->PollEvent( ) it will be necessary to change the global event mask to ignore Apple Events. This is because two Apple Events are sent when a user Prints from the finder: the Print Document event with its list of documents to be printed and a Quit event. Rather obnoxiously (but necessarily) it sends them “back to back”. So... if your application continues to process Apple Events while the Finder is printing, it will quit in the middle of printing the first document.
The second hint involves handling multiple print jobs. TReportPrinter assumes that it will be printing one report at a time and that a user will select “Page Setup” if necessary. When Finder Printing, one normally provides the “Page Setup” and “Print” dialogs only once, preserving a copy of the print record (a THPrint named fPrintRecord in TReportPrinter) for use in each subsequent print job. I would be very interested in hearing from anyone who manages these modifications. Although I don’t have a use for the class today, one never knows what’s just around the corner.
Users of other application frameworks and class libraries have probably noted that TReportPrinter is descended from TObject, MacApp’s base class. There is actually nothing in TReportPrinter that requires this. Converting it for use with another system should involve little more than changing the base class, replacing calls to PollEvent( ) with their equivalent, and modifying the way a user abort is handled to fit the library being used. TReportPrinter also makes fairly extensive use of MacApp’s error handling mechanism and that code too would have to be changed.
Finally, although TReportPrinter has been used quite heavily in a couple of commercial applications, it has been slightly modified for this article. And, while I have tested it, that is no reason to assume that it is completely bug free. If you do encounter bugs, I’ll be interested to hear from you. The best way to contact me is writing the address at the beginning of this article. I can also be contacted on AppleLink at SKAMP.
Listing: TReportPrinter.h #ifndef __REPORTPRINTER__ #define __REPORTPRINTER__ 1 #include <Printing.h> const short kStatusWindowView = 2000; const IDTypekDocumentNameID = ‘VW08’; class TReportStatusWindow; class TReportPrinter: public TObject { private: BooleanfPrintManagerIsOpen; public: CStr255fCurrentFontName; short fCurrentFontNumber; long fMaxSpoolLines; long fPrintedLines; short fCurrentFace; short fCurrentSize; short fLeftMargin; short fBottomOfPage; BooleanfAutoFormFeed; BooleanfUserAborted; TPPrPort fPrintingPort; // a pointer THPrintfPrintRecord;// a handle TReportStatusWindow *fMyStatusWindow; short fCurrentPage; CStr255fReportTitle; virtual pascal void IReportPrinter(CStr255 theFont, short theFace, short theSize, short leftMargin, short bottomOfPage, Boolean autoFormFeed); virtual pascal void DoPrOpen(void); virtual pascal void DoPrClose(void); virtual pascal void SetFont(CStr255 theFont); virtual pascal void SetFace(short theFace); virtual pascal void SetSize(short theSize); virtual pascal Boolean StartReport(CommandNumber aCmdNumber); virtual pascal Boolean PrintALine(const CStr255 theLine, Boolean doLineFeed); virtual pascal void DoFormFeed(void); virtual pascal Boolean DoOpenPage(void); virtual pascal void DoClosePage(void); virtual pascal void VerticalTab(short pixels); virtual pascal void EndReport(void); virtual pascal Boolean HandlePageSetup(void); virtual pascal void PrintHeader(void); virtual pascal void PrintFooter(void); virtual pascal void Free(void); virtual pascal unsigned long GetFreeSpaceOnDisk(int theVolume); virtual pascal void UserAbort(void); virtual pascal void SetDocumentName(CStr255 docName); }; class TReportStatusWindow: public TWindow { public: virtual pascal void IReportStatusWindow(TReportPrinter *myPrinter); virtual pascal void DoCommandKeyEvent(TToolboxEvent* event); virtual pascal void SetMessage(CStr255 theMessage); private: TReportPrinter *fMyPrinter; }; #endif
Listing: TReportPrinter.cp #include <MacApp.h> #include <Fonts.h> #include “TReportPrinter.h” //•••••• TReportPrinter •••••• #pragma segment PrintInit pascal void TReportPrinter::IReportPrinter(CStr255 theFont, short theFace, short theSize, short leftMargin, short bottomOfPage, Boolean autoFormFeed) { short theFontNumber; fPrintRecord = nil; fPrintingPort = nil; fMyStatusWindow = nil; // true if we handle formfeeds fAutoFormFeed = autoFormFeed; // initialize the font/face/size fields fCurrentFontName = theFont; GetFNum(theFont, theFontNumber); fCurrentFontNumber = theFontNumber; fCurrentFace = theFace; fCurrentSize = theSize; fBottomOfPage = bottomOfPage; fLeftMargin = leftMargin; fUserAborted = false; fMyStatusWindow = nil; fPrintedLines = nil; fCurrentPage = nil; fPrintManagerIsOpen = false; // GetFreeSpaceOnDisk returns a value in multiples of 1024. // We can only use half the space since the print manager // spool file and a background print file of the same size // might exist at the same time. Then, If we have 80 // character lines, we’ll get about 12 of them // per 1024 bytes. short theVol; // get default volume ref. number OSErr err = GetVol(0,theVol); long maxSpoolLines = (GetFreeSpaceOnDisk(theVol) / 2) * 12; fMaxSpoolLines = maxSpoolLines; } #pragma segment PrintOpen pascal void TReportPrinter::DoPrOpen(void) { FailInfo fi; THPrintaPrintRecord = nil; VOLATILE(aPrintRecord); if(fi.Try()) { if(!fPrintManagerIsOpen) { // open only if necessary PrOpen(); // Allocate and initialize a print record if necessary if(fPrintRecord == nil) { aPrintRecord = (THPrint)NewHandle(sizeof(TPrint)); PrintDefault(aPrintRecord);// Set “standard” values fPrintRecord = aPrintRecord; } fPrintManagerIsOpen = true; } fi.Success(); } else { fPrintManagerIsOpen = false; if(fPrintRecord) { DisposeHandle((Handle)fPrintRecord); fPrintRecord = nil; } PrClose(); fi.ReSignal(); } } #pragma segment PrintOpen pascal void TReportPrinter::SetDocumentName(CStr255 theDoc) { fReportTitle = theDoc; } #pragma segment PrintMain pascal void TReportPrinter::Free(void) { if(fPrintRecord) { DisposeHandle((Handle)fPrintRecord); fPrintRecord = nil; } // fPrintingPort should have been freed and set to 0 by the // PrCloseDoc call in EndReport(). But just to be on // the safe side... if(fPrintingPort) { PrCloseDoc(fPrintingPort); fPrintingPort = nil; } if(IsObject(fMyStatusWindow)) fMyStatusWindow->Close(); inherited::Free(); } #pragma segment PrintMain pascal Boolean TReportPrinter::HandlePageSetup(void) { //Note: The TReportPrinter MUST be initialized before // allowing a call to this method. Booleanrc = false; DoPrOpen();// open the print manager if necessary if(fPrintRecord) { rc = PrStlDialog(fPrintRecord); } return rc; } #pragma segment PrintOpen pascal Boolean TReportPrinter::StartReport( CommandNumber/* aCmdNumber*/) { // display the Job Dialog and if it returns true, open the // print port and then open the first page. FailInfo fiWindow, fiPrint; Boolean doIt = false; TReportStatusWindow *aStatusWindow = nil; TPPrPort aPrintingPort = nil; VOLATILE(aStatusWindow); if(fiPrint.Try()) { DoPrOpen();// open the print manager if necessary fCurrentPage = 0; fPrintedLines = 0; fUserAborted = false; doIt = PrJobDialog(fPrintRecord); if(doIt && PrError() == noErr) { // first we try to open the print document aPrintingPort = PrOpenDoc(fPrintRecord, 0, 0); fPrintingPort = aPrintingPort; if(PrError() == noErr) { if(fiWindow.Try()) { aStatusWindow = (TReportStatusWindow *) gViewServer->NewTemplateWindow (kStatusWindowView, 0); aStatusWindow->IReportStatusWindow(this); aStatusWindow->Open(); fMyStatusWindow = aStatusWindow; fiWindow.Success(); } else { fMyStatusWindow = nil; fiWindow.ReSignal(); } // let everybody else update, etc. gApplication->PollEvent(false); if(DoOpenPage()) {// try to start a page doIt = true; // everything worked! // verify that the bottom margin does not excede // the capabilities of the printer if(fBottomOfPage > ((GrafPtr)fPrintingPort)->portRect.bottom) fBottomOfPage = ((GrafPtr)fPrintingPort)->portRect.bottom; } else { // PrOpenPage failed doIt = false; } } else { // PrOpenDoc failed... PrCloseDoc(fPrintingPort); // frees fPrintingPort fPrintingPort = nil; doIt = false; } } else { // PrJobDialog() failed or the user hit cancel doIt = false; } if (!doIt) // finish cleaning up after any failures DoPrClose(); fiPrint.Success(); } else { fiPrint.ReSignal(); } return doIt; } #pragma segment PrintMain pascal void TReportPrinter::DoPrClose(void) { PrClose(); // close the print manager (TN 161) fPrintManagerIsOpen = false; if(fPrintRecord) {// and dispose of the print record DisposeHandle((Handle)fPrintRecord); fPrintRecord = nil; } if(IsObject(fMyStatusWindow)) // has free on closing checked in viewedit fMyStatusWindow->Close(); fMyStatusWindow = nil; } #pragma segment PrintMain pascal void TReportPrinter::EndReport(void) { // Note: This is the simplest possible way to // wrap up a print job. TPrStatusstatus; PrClosePage(fPrintingPort); // ensure current page is closed PrCloseDoc(fPrintingPort); // frees fPrintingPort fPrintingPort = nil; if ((**fPrintRecord).prJob.bJDocLoop == bSpoolLoop && PrError() == noErr) { // let everybody else update, etc. gApplication->PollEvent(false); PrPicFile(fPrintRecord,0,0,0,status); } DoPrClose(); } #pragma segment PrintImage pascal Boolean TReportPrinter::DoOpenPage(void) { // Notes: PrOpenPage completely resets the printing // grafport so it is necessary to set the font, face, // and size every time we do this. fCurrentPage++; fMyStatusWindow->SetMessage(fReportTitle); // let everybody else update, etc. gApplication->PollEvent(false); PrOpenPage(fPrintingPort, 0); if(PrError() == noErr) { TextFont(fCurrentFontNumber); TextFace(fCurrentFace); TextSize(fCurrentSize); return true; } else { PrClosePage(fPrintingPort);// match the cPrOpenPage PrCloseDoc(fPrintingPort); // frees fPrintingPort fPrintingPort = nil; return false; } } #pragma segment PrintImage pascal void TReportPrinter::DoClosePage(void) { TPPrPort aPrintingPort = nil; FailInfo fi; VOLATILE(aPrintingPort); PrClosePage(fPrintingPort);// end the page if(fPrintedLines > fMaxSpoolLines) { EndReport(); // print what we have if(fi.Try()) { // start a new one aPrintingPort = PrOpenDoc(fPrintRecord, 0, 0); fPrintingPort = aPrintingPort; fi.Success(); } else { fPrintingPort = nil; fi.ReSignal(); } } // let everybody else update, etc. gApplication->PollEvent(false); } // Note: The next three methods must be called AFTER // DoOpenPage() to have the desired effect. #pragma segment PrintImage pascal void TReportPrinter::SetFont(CStr255 theFont) { short theFontNumber; fCurrentFontName = theFont; GetFNum(theFont, theFontNumber); fCurrentFontNumber = theFontNumber; // actually set the font in the grafport TextFont(fCurrentFontNumber); } #pragma segment PrintImage pascal void TReportPrinter::SetFace(short theFace) { fCurrentFace = theFace; TextFace(fCurrentFace); } #pragma segment PrintImage pascal void TReportPrinter::SetSize(short theSize) { fCurrentSize = theSize; TextSize(fCurrentSize); } #pragma segment PrintImage pascal void TReportPrinter::DoFormFeed(void) { PrintFooter(); DoClosePage(); DoOpenPage(); PrintHeader(); } #pragma segment PrintImage pascal void TReportPrinter::PrintHeader(void) { FontInfo theInfo; // basic operation only - override for custom header GetFontInfo(theInfo); MoveTo(fLeftMargin, theInfo.ascent + theInfo.descent + theInfo.leading); // don’t forget to increment fPrintedLines } #pragma segment PrintImage pascal void TReportPrinter::PrintFooter(void) { // Override for custom Footer // don’t forget to increment fPrintedLines } #pragma segment PrintImage pascal Boolean TReportPrinter::PrintALine( const CStr255 theLine, Boolean doLineFeed) { // Note: LineFeeds are done based on the font metrics. // For other size linefeeds use VerticalTab(); CPoint theSpot; FontInfo theInfo; GrafPtrsavedPort; if(fUserAborted) { PrSetError(iPrAbort); // let the print manager know EndReport(); return false; } DrawString(theLine); if(doLineFeed) { fPrintedLines++; GetPen(theSpot); GetFontInfo(theInfo); short verticalPosition = theSpot.v + theInfo.ascent + theInfo.descent + theInfo.leading; MoveTo(fLeftMargin, verticalPosition); if(verticalPosition >= fBottomOfPage && fAutoFormFeed) { DoFormFeed(); } GetPort(savedPort); // let everybody else update, etc. gApplication->PollEvent(false); SetPort(savedPort); // make sure we’re in the right place } return true; } #pragma segment PrintImage pascal void TReportPrinter::VerticalTab(short pixels) { CPoint theSpot; GetPen(theSpot); theSpot.v+=pixels; if(theSpot.v >= fBottomOfPage) { DoFormFeed(); } else MoveTo(theSpot.h, theSpot.v); } #pragma segment PrintInit pascal unsigned long TReportPrinter::GetFreeSpaceOnDisk( int theVolume) { HVolumeParam HPB; OSErr err; unsigned long pfreeBytes; HPB.ioNamePtr = 0L; HPB.ioVRefNum = theVolume; HPB.ioVolIndex = 0; err = PBHGetVInfo((HParamBlockRec *)&HPB,false); if (err == noErr) pfreeBytes = (unsigned long int)HPB.ioVFrBlk * HPB.ioVAlBlkSiz / 1024; else pfreeBytes = 0L; return(pfreeBytes); } #pragma segment PrintImage pascal void TReportPrinter::UserAbort(void) { // so we’ll fall out of the print loop fUserAborted = true; // window’s been freed so forget about it fMyStatusWindow = nil; } //•••••• TReportStatusWindow •••••• #pragma segment PrintImage pascal void TReportStatusWindow::IReportStatusWindow( TReportPrinter *aPrinter) { fMyPrinter = aPrinter; } #pragma segment PrintImage pascal void TReportStatusWindow::DoCommandKeyEvent( TToolboxEvent* event) { if(event->fCharacter == ‘.’) { // tell the ReportPrinter to bail out fMyPrinter->UserAbort(); this->Close(); } else inherited::DoCommandKeyEvent(event); } #pragma segment PrintImage pascal void TReportStatusWindow::SetMessage( CStr255 theMessage) { FailInfo fi; if(fi.Try()) { TStaticText *theText = (TStaticText *) FindSubView(kDocumentNameID); theText->SetText(theMessage, true); fi.Success(); } else { fi.ReSignal(); } }
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