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Re: NSView drawing in tool

by Andreas Höschler :: Rate this Message:

Hi Fred,

>>> I have a tool (service) that is supposed to generate PNG images using
>>> NSView drawRect and
>>>
>>> NSBitmapImageRep *rep = [[NSBitmapImageRep alloc]
>>> initWithFocusedViewRect:[mapView bounds]];
>>>
>>> When running this tool and calling the above method (NSView, NSImage
>>> stuff,...) I get
>>>
>>> GSFontInfo.m:71 Assertion failed in GSFontEnumerator(class), method
>>> sharedEnumerator. Called with fontEnumeratorClass unset. The shared
>>> NSApplication instance must be created before methods that need the
>>> backend may be called.
>>>
>>> OK, I modified my main.m to call
>>>
>>> [NSApplication sharedApplication];
>>>
>>> before starting the event loop with [[NSRunLoop currentRunLoop] run],
>>> but this gives me
>>>
>>> /opt/GNUstep/Local/Tools/OSMMapServer: Uncaught exception
>>> WindowServerCommunication, reason: Unable to connect to X Server `'
>>>
>>> What am i missing?
>>
>> I tried to run my OSMMapServer. There I get
>>
>> 2009-06-22 23:58:50.268 OSMMapServer[3122] *** Assertion failure in
>> -[MapView lockFocus], AppKit.subproj/NSView.m:2343
>> lockFocus sent to a view whose window is deferred and does not yet
>> have
>> a corresponding platform window
>>
>> It seems I am on the wrong track with my approach!? Is there any
>> example
>> of a GNUstep tool that generates PNGs or TIFFs from a NSView after
>> drawing NSBezierPaths?
>> How is this done correctly? Hints are greatly appreciated!
>>
>
> Was this the result of running your code on MacOSX? You didn't say so,
> but the error message clearly isn't from GNUstep.

No this last output was from my attempt on MacOSX and can be rather
ignored since I have to get this to run on GNUstep. On GNUstep I get

Abort (core dumped)Tools/OSMMapServer: Uncaught exception
WindowServerCommunication, reason: Unable to connect to X Server `'

> Why do you insist on your code being a tool? Wouldn't an application be
> a better fit?

No, definitely not. The tool is a service running in the background
(managed by cron), responding to XML requests from client apps. In this
special case the purpose of the service is to generate images (map
tiles) (PNG or TIPP) according to a given XML request. The service has
the logic to generate the images and the connection to the database
holding the data, not the client apps.

> On MacOSX you could try to work with an NSImage instead of an NSView.
> You can just draw on that instead of drawing to the view. On GNUstep
> this is currently not fully supported. Any help to improve that would
> be
> highly appreciated

I just realized that the tool works as expected on GNUstep when being
logged in on the console of the machine supposed to run the service.
However, in production this service is supposed to be started by cron
with noone being logged in!? Any idea how to get around the

Abort (core dumped)Tools/OSMMapServer: Uncaught exception
WindowServerCommunication, reason: Unable to connect to X Server `'

problem then?

Thanks a lot!

Regards,

Andreas

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