[MacRuby-devel] NSBitmapImageRep representationUsingType
Thibault Martin-Lagardette
thibault.ml at gmail.com
Wed Aug 11 18:11:47 PDT 2010
Also, that's just a side note, but since you're using MacRuby, I think you should try to take advantage of the ruby syntax.
For example:
options = NSMutableDictionary.dictionaryWithObject NSNumber.numberWithFloat(0.85), forKey:NSImageCompressionFactor
would become:
options = {NSImageCompressionFactor => 0.85}
I think it makes the code much more readable.
--
Thibault Martin-Lagardette
On Aug 11, 2010, at 16:36, Laurent Sansonetti wrote:
> 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
>> > _______________________________________________
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>> > MacRuby-devel at lists.macosforge.org
>> > http://lists.macosforge.org/mailman/listinfo.cgi/macruby-devel
>>
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