On 1 Jul 2008, at 04:23, Matt Orr wrote:
Hi guys!
I am very new to Cocoa, but not new to UNIX development. GUI
programming is
new to me, and I am tackling it heavily ;)
I have a little assignment at work to create a simple application
which
charts a bunch of processes, much like OmniGraffle (
http://www.omnigroup.com/applications/omnigraffle/). I was wondering
how
such graphing was implemented, and more importantly, where to read.
I went
through the 3rd edition of Cocoa Programming for Mac OS X, but I
still dont
have any ideas on how to start implementing such a beast.
Can you please point me to potential topics and aspects of Cocoa I
should
research? I have played a little bit with quartz, but it seems too
complicated (or is it?) of a solution for the simple thing I am
trying to
achieve.
Any input is much appreciated!
Hi,
First, I totally recommend looking at DrawKit, which is a brilliant
framework for interactive graphics.
I wish it had been around when I started writing SQLEditor.
Another thing to look at is the Apple Sketch example.
It might also be worth looking at whether you can use Graphviz code
and display the result in a window as an image of some kind.
I have some thoughts, which may or may not prove useful:
Conceptually you have an application that might consist of a document
window with a view that is a subclass of NSView in it.
That view draws shapes (like rectangles and circles) and joins them
together with lines.
You can implement the drawRect: method of your subclass and draw the
objects there, which is fairly easy to do. (http://developer.apple.com/documentation/Cocoa/Conceptual/CocoaDrawingGuide
)
If you just want to display the diagram and you don't need any
interaction with your objects you could probably stop there.
Allowing interaction with the objects makes everything more complicated.
If you have interaction you will want to allow dragging (detect
whether the mouse click is in the drag region of an object and move it
with the mouse)
and resizing (detect if the mouse is in the resize handle and then
resize the object)
NSView (via its superclass NSResponder) has mouseDown: and mouseUp:
methods that may help here. There are also methods for detecting mouse
dragging.
The way that I structured my app was to have a canvas class (a
subclass of NSView) and then "object views" which are drawn into the
canvas,
an object view knows how to draw itself into a suitable canvas object
and the canvas object asks each object that is visible to draw itself
when it gets a drawRect message.
If you have connectable objects you also need a mechanism to notify
connectors that the objects they connect between have moved, so the
connectors can update.
An easy way of doing this is just to store pointers to the connected
objects and send them messages directly, but notifications might work
as well.
If you want to write code, the sketch sample may give some more examples
hope the project goes well!
Angus
--
Angus Hardie
[EMAIL PROTECTED]
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