[MacRuby-devel] NSBitmapImageRep representationUsingType

Wed Aug 11 16:36:43 PDT 2010

Hi Kenny,

Could you try to extract the image scaling code (which seems to cause the crash if I read well) into a smaller program and see if you still have the problem?

A backtrace would be nice, otherwise. If your app crashes you might have a crash log in ~/Library/Logs/CrashReporter for it.

Laurent

On Aug 11, 2010, at 1:43 PM, Kenny Lovrin wrote:

> Sure, here's the parts that I think is of value:
> 
> Heres how my queue is defined:
> 
> class MetadataDownloader
> 
> 	@@queue = Dispatch::Queue.new("se.kennylovrin.test")
> 
> 	class << self
> 
> 		def fetch(id)
> 			downloader = new(id)
> 			@@queue.async do
> 				downloader.start
> 			end
> 		end
> 
> 	end
> 
> <more code here.....>
> end
> 
> I use this by looping an array of integers, calling MetadataDownloader.fetch(var), hoping it will instantiate a new downloader and start it in the queue. :)
> 
> Then, it does some work, connecting to some API's and downloading som data which contains a url to an image, that url is later passed into this instance method:
> 
> def save_poster(url)
> 		stamp = Time.now.to_i
> 		save_path = File.join CoreDataManager.instance.app_support_dir, "posters", "#{stamp}.jpg"
> 		save_path_small = File.join CoreDataManager.instance.app_support_dir, "posters", "#{stamp}_small.jpg"
> 		
> 		fm = NSFileManager.defaultManager
> 		unless fm.fileExistsAtPath save_path
> 			error = Pointer.new_with_type "@"
> 			unless fm.createDirectoryAtPath save_path.stringByDeletingLastPathComponent, withIntermediateDirectories:true, attributes:nil, error:error
> 				NSLog "Failed to create dir for poster"
> 				return nil
> 			end
> 			
> 			img_data = NSData.dataWithContentsOfURL NSURL.URLWithString(url)
> 			
> 			if img_data && fm.createFileAtPath(save_path, contents:img_data, attributes:nil)
> 				NSLog "Fullsize poster saved"
> 				jpeg_data = rescaled_image img_data
> 				unless jpeg_data && jpeg_data.writeToFile(save_path_small, atomically:true)
> 					NSLog "Failed to scale down poster at #{save_path_small}"
> 					return nil
> 				end
> 				NSLog "Small poster saved"
> 			else
> 				NSLog "Failed to save poster at #{save_path}"
> 				return nil
> 			end
> 			
> 			img_data = nil
> 		end
> 		
> 		save_path_small
> 	end
> 
> which uses this instance method to do the scaling (this seems to be where the problem is):
> 
> def rescaled_image(img_data)
> 		NSLog "Rescaling poster"
> 		NSLog "Calculating dimensions"
> 		img = CIImage.imageWithData img_data
> 		y_scale = 300 / img.extent.size.height
> 		x_scale = 200 / img.extent.size.width
> 		scale = [y_scale, x_scale].min
> 		
> 		NSLog "Setting up filter"
> 		scale_filter = CIFilter.filterWithName "CILanczosScaleTransform"
> 		scale_filter.setValue(NSNumber.numberWithFloat(scale), forKey:"inputScale")
> 		scale_filter.setValue(NSNumber.numberWithFloat(1.0), forKey:"inputAspectRatio")
> 		scale_filter.setValue(img, forKey:"inputImage")
> 		
> 		NSLog "Getting scaled image from filter"
> 		img = scale_filter.valueForKey "outputImage"
> 		
> 		NSLog "Create bitmap rep from image"
> 		rep = NSBitmapImageRep.alloc.initWithCIImage img
> 		NSLog "#{rep}"
> 		options = NSMutableDictionary.dictionaryWithObject NSNumber.numberWithFloat(0.85), forKey:NSImageCompressionFactor
> 		options.setValue(NSNumber.numberWithBool(true), forKey:NSImageProgressive)
> 		
> 		NSLog "Getting jpeg data from bitmap rep"
> 		jpeg_data = rep.representationUsingType NSJPEGFileType, properties:options
> 		
> 		NSLog "Rescale done, returning data"
> 		jpeg_data
> 	end
> 
> As I said, it crashes randomly, but always at the line where it's trying t get the jpeg representation.. I'm pretty new to Cocoa so I there might be something stupod going on here.. ;) Everything works as expected if I do not try to do the image scaling..
> 
> I think I am on MacRuby rev. 4407, but there is a risk I have done an update to rev 4407 but never built it.. I think that is what I have installed though.
> 
> What do I need to do to get a proper crash log? :)
> 
> Thanks a lot!
> Kenny
> 
> On 11 August 2010 22:28, Thibault Martin-Lagardette <thibault.ml at gmail.com> wrote:
> If it's small enough, and if you can, could you probably share the code with us? It might help us debug de problem.
> If you can't, we may need a little more than just that:
> - What version of MacRuby are you running?
> - Can you attach a crashlog?
> 
> The more info, the better :-)
> 
> --
> Thibault Martin-Lagardette
> 
> 
> 
> On Aug 11, 2010, at 12:55, Kenny Lovrin wrote:
> 
> > Hey guys
> >
> > I have a piece of code that runs in a background thread, and it crashes randomly. I can't see any structure to the crashing, other than it always seem to crash at the following line:
> >
> > jpeg_data = rep.representationUsingType NSJPEGFileType, properties:options
> >
> > Are there any known issues with this and macruby, or am I wrong somewhere else? I tried running it both on the main thread and also by using sync instead of async when i dispatch the thread to the queue, but it still crashes randomly.
> >
> > I'm not entierly sure how to debug this, all I get in the log is an EXC_BAD_ACCESS and then it stops in my editor at objc_msgSend.
> > Any ideas? :)
> >
> > PS. I need to rescale an image, if anyone know any other way that works in a background thread please share. :)
> >
> > Thanks!
> > Kenny
> > _______________________________________________
> > MacRuby-devel mailing list
> > MacRuby-devel at lists.macosforge.org
> > http://lists.macosforge.org/mailman/listinfo.cgi/macruby-devel
> 
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