Implementing custom NSView in Cocoa on OS X
I am creating a Cocoa application wherein one view will contain the "hex dump" of the currently loaded document. Up until this point, I ha开发者_如何学运维ve been using a bog-standard (and very unappealing) NSTextField
, but I am now looking for something more powerful.
I am a great fan of 0xED.app
and would love to replicate its main "hex dump" view. How would I go about doing this?
I'm not necessarily after the eye-candy, but the ability to select a range of bytes without also selecting the offset or text columns. I am a loss as to where I would even begin to implement this effectively. Surely this is not drawn upon a blank canvas?
To get started and see how things basically work:
- Subclass NSView.
- Add an instance variable to hold your NSData.
- Override drawRect:
- Iterate your NSData
- Use methods from NSString drawing AppKit additions to draw the bytes.
This approach will be slow for a large amount of data, but will give you a good handle on implementing a NSView subclass. After that, you'll want to improve the drawing performance by implementing something better than repeated calls to draw strings one at a time. You'll also want to implement overrides of methods like mouseDown: and keyDown: to handle input from the user to allow things like selecting a range of bytes.
That should get you started, once you have that going, I'd suggest asking follow up questions.
My guess is that it's probably accomplished using a NSTableView or subclass of it.
It might be a little tricky to get the correct text selection accomplished this way, but it's probably possible.
If you want to take a look at how a Cocoa interface is built you can use NibToXibConverter.
- Download 0xED, right click on 0xED.app and select "Show Package Contents". Extract the Contents/Resources/English.lproj folder.
- Run NibToXibConverter, browse to the folder extracted above, and put a tick next to "Decompile NIBs".
- Select the "Convert" button and it will convert the NIBs to XIBs
Double click a XIB to open it in XCode and you can see how they are constructed
- You will note that in the case of 0xED he is using a custom class (most likely a subclass of UIView with custom drawing as Jon Hess suggests).
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