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Mac Forum / Programming / Mac Programming / January 2006TIFF Image To Pre-Existing NSBitmapImageRep?
I have a TIFF image in my nib file's Images tab, and I can acquire that image and "composite" it into an NSImage object. But what I really want to do is copy it into an NSBitmapImageRep that I have pre-created and defined to my own specifications. This seems to be impossible, because you can draw the TIFF only to the current drawing context, which is chosen with lockFocus, and lockFocus works only on NSViews and NSImages, not on NSImageReps. I can, of course, use addRepresentation to make my NSBitmapImageRep a representation in an NSImage, and then draw into that NSImage, right? But it doesn't work -- what happens is that lockFocus creates *another* representation for the NSImage, and the TIFF-drawing takes place there, not in the NSBitmapImageRep that you wanted it to use. (This seems to happen even if you use lockFocusOnRepresentation and specify the pre-existing NSBitmapImageRep.) In summary: How do we get a TIFF image from the nib file to an existing (pre-defined) NSBitmapImageRep? Please reply to this posting only if you have a specific answer to my specific question. I wouldn't be posting it here if I hadn't already spent several hours searching the internet, reading Apple's documentation, and experimenting with these objects in an attempt to figure it out. Thanks in advance, Darel > I have a TIFF image in my nib file's Images tab, and I can acquire that > image and "composite" it into an NSImage object. But what I really [quoted text clipped - 14 lines] > In summary: How do we get a TIFF image from the nib file to an > existing (pre-defined) NSBitmapImageRep? I think you're going to have to do the copying of the data yourself. NSImage will not draw into an NSBitmapImageRep. It's relatively trivial to get a *new* NSBitmapImageRep from an arbitrary NSImage, but for whatever reason you don't want that. If you load an NSImage with your TIFF, resize it to fit your existing NSBitmapImageRep, and then pull a new NSBitmapImageRep out of it, it should be relatively trivial to write a blitter that will copy the pixel data out of the new one and into your existing one.  SignatureMichael Ash Rogue Amoeba Software Thanks, Michael -- I was afraid that might be the case. Basically I want to be able to specify the exact structure of the NSBitmapImageRep (planes, bits-per-plane, etc.) so I can manipulate its contents with my own graphics functions. Your suggestion that I get a new NSBitmapImageRep from an NSImage would be perfect if I can be guaranteed that it will produce the same kind of NSBitmapImageRep each time... is that controllable when getting a new NSBitmapImageRep from an NSImage? Your wisdom is appreciated -- please forget my earlier feistiness in another thread! :D Darel > I think you're going to have to do the copying of the data yourself. > NSImage will not draw into an NSBitmapImageRep. It's relatively trivial to [quoted text clipped - 5 lines] > should be relatively trivial to write a blitter that will copy the pixel > data out of the new one and into your existing one. > Thanks, Michael -- I was afraid that might be the case. Basically I > want to be able to specify the exact structure of the NSBitmapImageRep [quoted text clipped - 4 lines] > time... is that controllable when getting a new NSBitmapImageRep from > an NSImage? For some reason, this question really got me curious, but I couldn't find anything. I even wrote up a bunch of stuff about how I can't find anything but you could probably get away with assuming X, or trying Y. Then I found the answer. Actually, I did this *twice*, each time finding a better answer. I think I'm done now. So here you go: NSGraphicsContext has a graphicsContextWithBitmapImageRep: method. It has a restriction that it only works with single-plane data, but this should be no great problem. Once you create that, you should be able to start drawing into it by using the +setCurrentContext: method of the class (disclaimer: I've never tried this), then draw your image. Actually, you probably want to do a saveGraphicsState first, then a restoreGraphicsState after. And whew, there you go. I hope you'll report back on how it works, since this is something untried for me. > Your wisdom is appreciated -- please forget my earlier feistiness in > another thread! :D Don't worry about it. Bygones, right? SignatureMichael Ash Rogue Amoeba Software Michael, Bygones! Probably more my fault than yours. Thanks very much for that technique -- I read it several days ago but am just replying now. I also tried your method of reading the file in as pure data and copying it to my NSBitmapImageRep with a loop. That worked too, but it took me a few tries before I figured out how to read the uncompressed 24-bit BMP format I'm now using. My maiden Cocoa project is coming along well, but there's still a lot of work to do -- it's pretty heavy on custom graphic manipulation, which is why I needed to control the imagerep so tightly. Also had to research spline curves for part of it; that's interesting. Wikipedia does a good job of explaining it. Just saw something interesting on DaringFireball that your company is hiring? Telecommuters at that? But it'll be a while before I can even apply -- my Cocoa experience is just beginning. I'll keep you posted! Regards, Darel Finley <DarelRex@gmail.com> [snip] > Thanks very much for that technique -- I read it several days ago but > am just replying now. I guess that means it worked? I'm glad to hear it. There's no reason it shouldn't, but I don't trust untested stuff. > I also tried your method of reading the file in > as pure data and copying it to my NSBitmapImageRep with a loop. That > worked too, but it took me a few tries before I figured out how to read > the uncompressed 24-bit BMP format I'm now using. That's not actually what I originally suggested, but that's ok. I was suggesting that you read it using NSBitmapImageRep, but make assumptions about the resulting pixel format. I've written code like this before and it was pretty easy, but making assumptions like that is a bad thing to do. Until I researched my second answer, I didn't even know there was a general way to do it "right". > My maiden Cocoa project is coming along well, but there's still a lot > of work to do -- it's pretty heavy on custom graphic manipulation, > which is why I needed to control the imagerep so tightly. Also had to > research spline curves for part of it; that's interesting. Wikipedia > does a good job of explaining it. I hope you've checked out CoreImage. With a decent graphics card you can get some amazing speed out of it, and using the straightforward kernel language it's very customizable. It's not really oriented toward stuff like spline curves though, so it might not be useful to you. > Just saw something interesting on DaringFireball that your company is > hiring? Telecommuters at that? But it'll be a while before I can even > apply -- my Cocoa experience is just beginning. It's always the same story, too many projects and not enough people. Since it's been brought up, if anybody else is following along and interested, there's more information here: http://www.rogueamoeba.com/company/jobs/ SignatureMichael Ash Rogue Amoeba Software |
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