Re: Drawing: The Right place to keep bounds
Re: Drawing: The Right place to keep bounds
- Subject: Re: Drawing: The Right place to keep bounds
- From: Paul Bruneau <email@hidden>
- Date: Wed, 25 Nov 2009 11:23:02 -0500
OK, I see what you are saying, and to that I respond, why does every
example that I have ever found of how to draw objects in a custom view
happen to be a drawing program? :)
And I'm not sure I buy what you are saying, because, just like I
mentioned for the Sketch example, what does his program do when the
user makes a new window with the same view in it and that view has a
different zoom factor, or is scrolled to a different position?
My question remains: where should I keep this information? Surely
people draw objects in apps other than drawing programs that are
limited to a single view.
I do thank you for your response!
On Nov 25, 2009, at 11:00 AM, David Hirsch wrote:
I think you are missing the point of the quote, which is that
drawing programs are an exception to the typical rule that view data
must be strictly separated from the model ("However, in this
case"). When the model data is all about visual information
(drawing), then you have no choice but to violate the rule.
On Nov 25, 2009, at 7:27 AM, Paul Bruneau wrote:
I am also pretty sure that Cocoa Design Patterns does it wrong
because it admits such:
The model in this example is deliberately kept simple to preserve
the focus on the Controller
subsystem. In most applications, properties like rectangles and
colors are user interface concerns that
don’t belong in the Model subsystem. However, in this case,
MYShapeDraw is a drawing program.
This seems like a common problem that I have had with various Cocoa
information over the years. Everything is kept simple for the sake
of the example, and I am left clueless about the correct way to do
it (or I am too dumb to see it). In the quote above, I have learned
that the rectangles don't belong in the Model subsystem. OK that's
a good start! Now, where do they belong?
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