Re: Some advice creating a graph class
From: River Ross (river.ross_at_sbcglobal.net)
Date: 02/20/05
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Date: Sun, 20 Feb 2005 21:30:15 GMT
Consider using a 3rd party control, there are many out there. Supposedly
here's a free one:
http://www.codeproject.com/miscctrl/graph2d.asp
My first year on the job as a professional programmer I needed a graph for
an app and coded it myself. Although this was a good way to experience GDI
I know now it was probably not the wisest decision. It wound up being much
more effort than I had initially thought. Unless you just want to be
entertained and your company doesn't mind you wasting an extra month or two
of labor its a wiser business decision to go with a 3rd party control.
"rs" <removethis4spam.rastacey@nl.rogers.com> wrote in message
news:caydnVBkA_vlaYXfRVn-2g@rogers.com...
> Thanks. I didn't realize I could use the dc in the view without passing it
> in as a parameter.
>
> "Edward H. Fabrega" <spiritualfields@wavecable.com> wrote in message
> news:PYednVSm3qMrcoXfRVn-vg@wavecable.com...
>>
>> "rs" <removethis4spam.rastacey@nl.rogers.com> wrote in message
>> news:B_udnaD6CuV5LYXfRVn-iA@rogers.com...
>> >I am developing a program to draw a graph of database data using the
>> >OnPaint
>> > function in the View class.
>> > In the CView class I am grabbing the device context and then passing it
> to
>> > a
>> > function where I draw the actual graph by creating pens & brushes and
>> > using
>> > moveto/lineto functions etc.
>> >
>> > void CBView::OnPaint()
>> > {
>> > CPaintDC dc(this); // device context for painting
>> > DrawGraph(&dc);
>> > }
>> >
>> > This is working well but becoming quite large as a function and would
>> > think
>> > it is time to create a class to encapsulate the graph function.
>> > This seemed pretty straight forward until I started and realized it's
> not
>> > all that straight forward.
>> >
>> > Questions like what base class should this be derived from? How should
> the
>> > parameters be passed? etc.
>> >
>> > Any ideas, or tutorials or examples would be appreciated.
>> >
>> > Thanks.
>> >
>> >
>> >
>>
>> Take a look at this. Are you trying to draw a grid like this?
>>
>> http://members.aol.com/spiritualfields/main_screenshot.htm
>>
>> That screen shot is of a CView drawn to reperesent a database. All of the
>> drawing takes place in the view. There is no way of keeping your OnPaint
>> small. It is a monumental task to draw and then populate the cells.
>> Especially if the "cell"s are really rectangles that you keep track of as
>> you draw the grid. If your only problem is that the function is big then
> you
>> have no problem. If you get more specific as to functionality, i.e. "how
> do
>> I keep track of the data?" "How do I scroll the window so that different
>> parts of the database are visible?" "How do I keep the column headers
> from
>> scrolling vertically" How do I keep the row headers from scrolling
>> horizontally?" How do I write into the cells from the database?" then I
>> might be able to help you, at least with the building of the grid. If you
>> are also building your database, then I might be able to help you there,
> as
>> well. Joe Newcomer's advice about letting OnPaint (I use OnDraw) worry
> about
>> drawing the grid is a good one, as it makes no sense to farm out painting
>> functionalilty to a function other than the one designed for painting.
>>
>> Ed
>>
>>
>>
>
>
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