[webkit-dev] Printing a WebView in ObjectiveC command-line application fails in OS X 10.5

Plessl Christian christian at plesslweb.ch
Tue Dec 4 10:53:06 PST 2007

I'm developing an open-source command line tool named wkpdf (http://wkpdf.plesslweb.ch 
) that uses WebKit to generate a PDF for a URL. Due to some unknown  
changes, wkpdf is not compatible with the recently released Mac OS X  
10.5 (Leopard).

When running wkpdf, NSView is raising the following assertion, when  
the WebView is printed:

    wkpdf --source http://wkpdf.plesslweb.ch --output wkpdf.pdf
    2007-12-04 19:24:45.585 wkpdf[1902:10b] *** Assertion failure in - 
[WebHTMLView lockFocusIfCanDraw],
    2007-12-04 19:24:45.586 wkpdf[1902:10b] lockFocus sent to a view  
which is not in a window

The same problem was also mentioned by Scott Garner on the cocoa-dev  
mailinglist (http://www.cocoabuilder.com/archive/message/cocoa/2007/11/2/192061 
) for his Automator action that converts URLs to PDFs.

I couldn't find a solution in Apple's documentation or on the web. I  
suppose the problem is related to the fact, that wkpdf doesn't have a  
user interface, i.e. the WebView is not visible. Here are some code  
snippets, the full source code can be browsed at http://wkpdf.plesslweb.ch/browser/trunk

The WebView is created like this:

    WebView * webView = [[WebView alloc]  
    [webView setFrameLoadDelegate: controller];
    NSURLRequest * request = ...
    [[webView mainFrame] loadRequest:request];

And later printed in the didFinishLoadForFrame callback:

    (void)webView:(WebView *)sender didFinishLoadForFrame:(WebFrame  
    NSView *viewToPrint = [[[sender mainFrame] frameView] documentView];
    printOp = [NSPrintOperation printOperationWithView:viewToPrint
    [printOp setShowPanels:NO];
    [printOp runOperation];

The assertion is caused by [printOp runOperation].

Does anyone have an idea how to solve this problem? Is this the  
appropriate mailing list for this question, or would cocoa-dev be more  

Best regards,

More information about the webkit-dev mailing list