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Mac Forum / Programming / Mac Programming / December 2005NSWindow -- Where To Put Content-Drawing Code?
I'm very new to Cocoa and Xcode, so this is a pretty basic question, but I've searched the web and Apple's built-in documentation for several hours now with no luck. When a window redraws, I want to execute the following code to draw its content region: [imageRep draw]; Wow, what could be simpler? But where do I put that code (or any other drawing code I might later write) so that it is executed when my window is refreshed? I have read about delegation and notification, and get nothing but confused. Everything I try generates unhelpful compile errors. I tried looking in the AppKit examples, but couldn't find any that answered this question. As an experiment, I hooked up a button in another window to an IBAction that did this: NSView *myView=[imageWindow contentView]; [myView lockFocus]; [imageRep draw]; [myView unlockFocus]; That works! -- but only when I click the button. And when imageWindow is miniaturized into the dock and then restored, my image is gone, of course. All I need is a simple code example that illustrates where my "draw" command needs to reside in my project so that it gets executed every time my window is drawing its content area. Thanks much, and please CC your reply to <DarelRex@gmail.com> if you don't mind. I'll check back at this newsgroup periodically. Darel > I'm very new to Cocoa and Xcode, so this is a pretty basic question, > but I've searched the web and Apple's built-in documentation for > several hours now with no luck. You don't draw into windows or views like that. You subclass NSView and do all your drawing in its drawRect: method. If you already have an NSImage (or NSImageRep which you can easily wrap in an NSImage), you'd probably want to just use an NSImageView and let it take care of drawing your image, though. Cheers, -- Uli Kusterer http://www.zathras.de Uli, Thanks for the quick reply, but I really need a code sample. I've read about NSViews, subclassing, etc., and I'm just banging my head into the wall trying to get it to work. (Vague compile errors about things being undefined or improperly used.) Do you know where I can find a simple, little code example of the technique you are describing? I'm finding that Apple's built-in documentation is woefully lacking of any code samples at all, except for their Examples/AppKit projects. In the meantime, I will read-up on NSImageView -- I think that's one object I didn't know about, and have not yet looked at. Darel > > I'm very new to Cocoa and Xcode, so this is a pretty basic question, > > but I've searched the web and Apple's built-in documentation for [quoted text clipped - 9 lines] > -- Uli Kusterer > http://www.zathras.de Uli, IT WORKED! You're a genius. I made a borderless NSImageView in my window, made it the same size as the window, and then put in code to hook it up to a new NSImage object that I connect to my imagerep. And bingo, I don't even have to draw the content at all -- it's just there all the time. Thank you very much, now I'm back in action writing my app. Darel > Do you know where I can find a > simple, little code example of the technique you are describing? I'm > finding that Apple's built-in documentation is woefully lacking of any > code samples at all, except for their Examples/AppKit projects. If you don't have it already, try to get Aaron Hillegass' book on Cocoa programming (the first one (2nd edition), not the new 'advanced' one). It covers all the structural basics of Cocoa programming as a nice walkthrough-style tutorial. Apple's Currency Converter and Moon Travel Tutorial never helped me understand anything, but after Hillegass it was crystal-clear. Once you know what he tells you, it gets a lot easier to understand how the reference docs are structured. Cheers, -- Uli http://www.zathras.de > I'm very new to Cocoa and Xcode, so this is a pretty basic question, > but I've searched the web and Apple's built-in documentation for [quoted text clipped - 27 lines] > command needs to reside in my project so that it gets executed every > time my window is drawing its content area. I would highly recommend that you check out a Cocoa tutorial. There's a good list here, although others probably know better places to find them than I do: http://www.cocoadev.com/index.pl?CocoaTutorials You may prefer dead-tree material, and there's a good list here: http://www.cocoadev.com/index.pl?CocoaBooks I know that it's tempting to ignore the holistic view and jump right in, and try to find specific help with specific problems, but it doesn't really work that way. For large APIs in general, and Cocoa in particular, you need a certain base. That is to say, before you can do anything, you have to know a fair chunk of everything. Rather than concentrating on this single problem, following a tutorial or book that's oriented towards beginners will help you along the path to knowing a fair chunk of everything in a relatively painless fashion. If you really insist on going directly into this one thing, check out the docs. Aside from the API references that cover "what does X do?", Apple has a lot of excellent conceptual documentation that covers questions like "how do I do X?" Your particular question is covered here: http://developer.apple.com/documentation/Cocoa/Conceptual/DrawViews/index.html?h ttp://developer.apple.com/documentation/Cocoa/Conceptual/DrawViews/Tasks/Drawing InViews.html Using Google with "site:apple.com" is usually helpful for finding these things. I found that page by searching for "cocoa drawing site:apple.com". And finally, to cut to the punch line a bit, you would subclass NSView and override drawRect:.  SignatureMichael Ash Rogue Amoeba Software Michael, Maybe you should ask before jumping to conclusions. I did the CurrencyConverter tutorial on Apple's Cocoa website before I even started my own project. Unfortunately, the tutorial doesn't cover much except the most general use of Xcode, Interface Builder, and the MVC organization method (which I am using). The rest of Apple's documentation seems to be a huge object-library reference with no code samples. Since Uli answered my question, my project is coming along very nicely. Darel <DarelRex@gmail.com> > > I'm very new to Cocoa and Xcode, so this is a pretty basic question, > > but I've searched the web and Apple's built-in documentation for [quoted text clipped - 59 lines] > And finally, to cut to the punch line a bit, you would subclass NSView and > override drawRect:. > Maybe you should ask before jumping to conclusions. I did the > CurrencyConverter tutorial on Apple's Cocoa website before I even [quoted text clipped - 3 lines] > documentation seems to be a huge object-library reference with no code > samples. There is a lot of example code on the Apple Developer Connection web site and in /Developer/Examples on your Mac when you have the Xcode Tools installed. -- Chris > Michael, > [quoted text clipped - 5 lines] > documentation seems to be a huge object-library reference with no code > samples. Darel, Maybe you should actually read Michael's suggestion all the way through (to where he gave you the explicit answer to your question and suggestions as to how to find answers to future questions) or at least up to the handy links before deciding that he wasn't going to be helpful. You might then have realized that he had jumped to one conclusion and it was correct. The fact that you asked the question you did was an excellent indication that you hadn't gone through any relevant tutorial. Your follow-up here indicates that you've done one, and that one happens to be so contrived as to be pretty much useless (as you've discovered). Greg > > And finally, to cut to the punch line a bit, you would subclass NSView and > > override drawRect:. SignatureGoal 2005: Convincing James Hetfield to cover the Strawberry Shortcake "Are You Berry Berry Happy?" song. > Michael, > [quoted text clipped - 3 lines] > except the most general use of Xcode, Interface Builder, and the MVC > organization method (which I am using). I'm sorry, which conclusion did I jump to? I never said you didn't do a tutorial, I merely recommended that you try one. The fact that you've tried exactly *one* tutorial which is extremely small and does not, in fact, provide anything like the holistic view I was advocating doesn't change anything there. > The rest of Apple's > documentation seems to be a huge object-library reference with no code > samples. This would be why I introduced you to the conceputal docs. Apple also has a truly enormous library of sample code, both on your hard drive as others have pointed out, and on their web site. SignatureMichael Ash Rogue Amoeba Software No wonder the Mac hasn't risen above 5% market share in 20+ years... ask a simple, specific question and get extremely verbose criticisms that your whole approach is wrong. That'll win converts! Thanks againk, Uli, for your concise and very helpful reply -- you stand as a model to others. > No wonder the Mac hasn't risen above 5% market share in 20+ years... > ask a simple, specific question and get extremely verbose criticisms > that your whole approach is wrong. That'll win converts! It wasn't criticism, it was advice. If you can't tell the difference, you may wish to avoid posting to these sorts of forums. I made the assumption, based on the fact that you posted to a forum full of human beings with "help" in the name, that you were looking for help, not robotic answers. As such, I provided the help I felt was appropriate. You certainly don't have to like it, I'm not egotistical enough to think that my advice is always worth reading, but does it really merit complaining because you got a verbose response with lots of pointers to various forms of help? If you want robotic answers, stick to Google and noninteractive web sites. SignatureMichael Ash Rogue Amoeba Software Michael Ash said: >If you want robotic answers, stick to Google and noninteractive web sites. Believe me, I tried both of those quite a lot before posting my question to this group. Maybe I overreacted a bit to your first post on this thread, and for that I apologize. But I went to a lot of trouble to formulate my question in a way that would project that I had tried both research and experimentation, and was at a dead end. If a specific answer to a specific question is "robotic," then yes, I was looking for a "robotic" answer, and it was very frustrating to get a reply that leads off with links to very general Cocoa reading material, and tells me I'm not taking the "holistic view." I don't post a question here unless I feel I'm seriously stuck, and then I try to describe my problem as specifically as possible, to maximize the probability that a repsonder will get me unstuck. Most of the problems I have encountered in my recent attempts to learn Cocoa have been solved by my own research and experimentation, and you didn't hear about them here. Thanks, Darel > No wonder the Mac hasn't risen above 5% market share in 20+ years... (Actually, a major element of that is that fact that market share is a measure of the relative sales volume per quarter and that favors equipment with a shorter service life.) > ask a simple, specific question and get extremely verbose criticisms > that your whole approach is wrong. Your approach _was_ wrong. And you got a good, complete answer which you didn't read all the way through. You did not get criticism, or anything resembling it, until you decided that you wanted to play victim. G SignatureGoal 2005: Convincing James Hetfield to cover the Strawberry Shortcake "Are You Berry Berry Happy?" song. |
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