Printing Off-screen PDFViews

Question

I have a situation where I want to print a multi-page PDF. While I could use the PDFKit utility classes and/or quartz functions to get the information to manually write drawing/pagination code for a NSView subclass, I had thought that quicker alternative would be to create an off-screen PDFView and tell it to print itself. When I tried this solution, the print dialog didn't go away, all of the print settings controls on the right half of the print dialog disappeared, and the application froze.

I then wrote a tiny test application with the following method that illustrates the problem. When the test program is compiled without the USE_PDF_VIEW preprocessor macro defined, the blank view displays fine. If USE_PDF_VIEW is defined, the document doesn't print, most of the print dialog controls disappear, and the app freezes. While I have other ways of accomplishing my goal, I'm curious as to why this shortcut doesn't work. Is there something about Cocoa drawing I still don't understand? Am I banging into Apple Voodoo Magic(tm) behind the scenes that makes PDFView behave in a completely different way than other NSViews?

- (void)printMyStuff:(id)sender {

NSPrintInfo *currInfo = [NSPrintInfo sharedPrintInfo];

#ifdef USE_PDF_VIEW


    PDFView *pdfView = [[PDFView alloc] init];
    PDFDocument *pdfDoc = [[PDFDocument alloc] initWithURL:[NSURL fileURLWithPath:@"/Users/wls/Documents/my_document.pdf"]];
    [pdfView setDocument: pdfDoc];
    [pdfView printWithInfo:currInfo autoRotate:YES];


#else

    NSView *myView = [[NSView alloc] initWithFrame:NSMakeRect(0, 0, 500, 500)];
    NSPrintOperation *myop = [NSPrintOperation printOperationWithView:myView printInfo:currInfo];
    [myop runOperation];


#endif

}

Answer 1

PDFView is a subclass of NSView. The designated initializer for NSView is -initWithFrame: ... if you don't use -initWithFrame: strange things can happen. Since PDFView has no other designated initializers, -initWithFrame: is it. I'm guessing that's at least part of your problem.

Another part may be memory related. Are you using garbage collection or not? If you are, you're not keeping a reference to your PDFView anywhere, so may be getting deallocated. If you aren't using garbage collection, you're leaking your PDFView (also because you keep no reference to it, so you can release it when you're done). Same with your myView NSView instance ... you're leaking it if you're not using GC.