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Void MyPrintout::GetPageInfo(int *minPage, int *maxPage, Typically, your OnPreparePrinting function will calculate the values returned by GetPageInfo and will look something like this: However, the printout will stop printing if HasPage returns false. The default values for minPage and maxPage are 1 and 32,000, respectively. The first two integers represent the range supported by this printout object for the current document, and the second two integers represent a user selection (not currently used by wxWidgets). GetPageInfo should be overridden to return minPage, maxPage, pageFrom, and pageTo. You will need to provide at least GetPageInfo, HasPage, and OnPrintPage, but you can override any of the other methods below as well. When creating a printout object, the application can pass an optional title that will appear in the print manager under some operating systems. Figure 5-9 shows the print preview window, with a control bar along the top providing page navigation, printing, and zoom control.ДЇigure 5-9 Print preview window More on wxPrintout Closing the frame automatically destroys the two printout objects.

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When the preview frame is initialized, it disables all other top-level windows in order to avoid actions that might cause the document to be edited after the print or preview process has started. WxPreviewFrame *frame = new wxPreviewFrame(preview, this, WxMessageBox(wxT('There was a problem previewing. Perhaps your current printer is not set correctly?'), WxPrintPreview *preview = new wxPrintPreview( Void MyFrame::OnPreview(wxCommandEvent& event) Then pass the preview object to wxPreviewFrame, call the frame's Initialize function, and show the frame. You can also pass a wxPrintDialogData object so that the preview picks up settings that the user chose earlier. To preview the document, create a wxPrintPreview object, passing two printout objects to it: one for the preview and one to use for printing if the user requests it.

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(In a real application, g_printDialogData would probably be a data member of your application class.) See Chapter 8, 'Using Standard Dialogs,' for more about print and page dialogs and how to use them. You can pass a pointer to this data to wxPrinter to be used in the print dialog, and then if printing is successful, copy the settings back from wxPrinter to your global object, as in the previous example. It's a good idea to keep a global wxPrintDialogData object in your application to store the last settings selected by the user. The wxPrintDialogData class stores data related to the print dialog, such as the pages the user selected for printing and the number of copies to be printed. (*g_printDialogData) = printer.GetPrintDialogData() Д«ecause the Print function returns only after all pages have been rendered and sent to the printer, the printout object can be created on the stack. WxMessageBox(wxT('You cancelled printing'), WxMessageBox(wxT('There was a problem printing. Perhaps your current printer is not set correctly?'), wxT('Printing'), wxOK) If (wxPrinter::GetLastError() = wxPRINTER_ERROR) If (!printer.Print(this, &printout, true))

Void MyFrame::OnPrint(wxCommandEvent& event) A global object storing print settings To start printing, a wxPrintout object is passed to a wxPrinter object, and Print is called to kick off the printing process, showing a print dialog before printing the pages specified by the layout object and the user. The same printout class can be used for both printing and preview. The wxWidgets printing framework will show the print dialog, create the printer device context, and call appropriate wxPrintout functions when appropriate. The main task for the developer is to derive a new class from wxPrintout, overriding functions that specify how to print a page ( OnPrintPage), how many pages there are ( GetPageInfo), document setup ( OnPreparePrinting), and so on. However, a more flexible method is to use the wxWidgets printing framework to 'drive' printing. Learn More о”ЂBuy Using the Printing FrameworkДЄs we've seen, wxPrinterDC can be created and used directly. Cross-Platform GUI Programming with wxWidgets

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