Design a flow chart with moveable drawing object


I would greatly appreciated if you could share your ideas about writing the program as described in its specification below.

I just like to have some keys word, concepts that point me to the direction.  I was puzzling me is how to move the object around.

These are some of my initial ideas:
1) Draw object
2) When mouse click down , notify the location
3) if the location match the location of the drawing object
then, if mouse release, update the new location.
4) Draw the object at the new location and erase the old location.

Thank very much for your attention.


The aim is to build a system which allows the user to draw, and edit a graph
(such as a flowchart).  A graph consists of nodes and edges.  Each edge joins
two nodes.
Assume that edges are straight lines, and that the same two nodes cannot have
more than one edge joining them.  The basic operations are adding and deleting
adding and deleting edges, and moving nodes around.

Extras for nodes.  The user should have a choice of shape to represent a node:
e.g. a little circle, little square etc.  It should be possible to change the
shapes of existing
nodes.  Also each node can have a small text-label displayed underneath.  In
addition, it should be possible to attach a longer text comment to a node:
this will be too
small for direct display, but the user should have an option to display this
in a separate window or pop-up box.

Extras for edges.  Similar features as for nodes: small label displayed
half-way along the edge, longer text comment displayable on request.  Also
there should be a
choice of style for edges: plain line, line with arrow-head at one end, or at
both ends; of course it should be possible to change styles later.

Moving.  It should be possible to move a node around: if there are any edges
which have one end at that node, they should "follow" the node as it moves
(while their
other ends remain fixed).

Multi-selections and regions.  It should be possible to move several nodes at
once.  The nodes to be moved can be selected in two ways (aim to provide both
The first way is by multi-selection: select nodes by clicking (perhaps with
the shift-key down, to distinguish this from selecting single nodes); the
selected nodes should be
highlighted somehow; clicking on a selected node (still with shift down)
should unselect it.  The second way is by regions: use the mouse to drag out a
rectangular area:
nodes within this area are selected.  Whichever selection method has been
used, a subsequent move operation will apply to all the selected nodes.  Also,
other operations
should be applicable to selections: e.g. delete all selected nodes, or change
shape of all selected nodes to small square.

Modes.  This applies to the node-shapes and edge-shapes: the current mode
determines the shapes of nodes and edges which get created.  There should be a
facility to
change modes.

Shrink/grow.  Drag out a rectangular area.  Now drag out a second such area.
The first area gets "resized" to fit the second.  This means that all nodes in
the first area
get moved: this will, for example, bring them closer together if the second
area is smaller than the first.

Initial, minimal system.  The first stage can be produced jointly by the
group.  Extensions are to be added to it separately by individual group
members.  The first stage
should allow just creating nodes, and creating edges between nodes.  The other
features can be worked on separately:

deleting nodes
moving nodes
adding/deleting arrow-heads
load/save work from/to file
changing node-shapes
modes for current node/edge shape
small labels for nodes/edges
large text comments for nodes/edges
region selection
moving a multi-selection or region
other operations on multi-selection or region
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too much text for reading and 50 points ... :-) i don't think that anobody will be interested ... (sorry - but your problem is not in designeing - it's just hard work to implementat everything )

so goto your JDK directory (if you don't have one - download it from goto the demo/GraphLayout/ subdirectory - there is an example that maybe will be usefull for you - look at the working applets first ...
if you find this suggestion usefull, i can post it as an answer (so i'll get the points :)

hope this helps
oh, oh, oh - too much typos there ... :(

if you don't have this example, i can post it here or send it to you as e-mail attachment ... it's only 11K .java file ...
ninhAuthor Commented:
Hello heyhey,

That would be great.  Are you going to post the example in the jdk.. ?? Or is that a different example.

My email is

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hi ninh,
sorry - i don't have some other examples ...
but you can check this URL for a freeware program
hello, ninh
if the information I've posted here helped you, I can post an answer . ;-)
ninhAuthor Commented:
Hello Hey hey,

Thank you so much for your information.As a way to say thank you..more points.  However, the dead line to hand in the project is way way paaased.  

Oppp..This should be a very good example to see how it is implemented.  

Many thanks

ninhAuthor Commented:
One more thing, I have found a API package created from awt that is quite good since it allows object to be move.
Have you heard something called "subartic".  I have manage to download the software but I lost the book mark.  I will post it when I receive the CD from my office.

>> Thank you so much for your information.As a way to say thank you..more points.

So ...  I'm postinhg an answer.

P.S. I'm still interested in "subartic" URL.

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ninhAuthor Commented:
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