On Friday 30 November 2007 08:23:28 pm bsnipes wrote:
> Absolutely. The first thing that comes to my mind is an example of the
> relationship between the Form, dPanel and Sizers when starting a project
> and then adding extra sizers and controls to a form. Just a simple program
> to browse directories and list the files in a list box might cover the
> basics of what a newbie needs.
> I have no problem with using the Wiki for the examples as opposed to
> distributing the examples. Thanks for the offer of apps.
>
> Thanks,
> Brian
Sounds fine. But I have a little twist. Instead of me just building the form
let's keep a running dialog via this email list of the steps to get it done.
That way others can help and put their .02 in too . And at the end I'll
gather the messages and put them on the wiki. You are expected to ask
questions and make suggestions. Let's get started.
A Dabo form. The word "form" brings up a little history. Dabo's two primary
authors (Ed and Paul) come from the windows world and are long time Visual
Fox Pro programmers. In the VFP world a form is a window, a frame, a
window-object, a widget in other languages. But the concept is simple:
It is any rectangular area displayed on a video monitor with a common set of
properties. Such as borders, resizing, menu bar, Titles, etc... The most
important property is it has a painting and coordinate system for placing
other objects within the "client area". Bottom line it is a window that
you have seen on every computer that you use to close, expand and interact
with daily. It is a python object. In fact everything in python (and
therefore Dabo) is an object.
A dPanel is a container (a Dabo/python object). It is used to define an area
within the client area of a form (window). Within the context of Dabo it
actually does more. It mains the tab order of the controls within the panel.
It contains it's own coordinate system (normally you would use sizers) for
controls such as buttons, text boxes. Simple but very important.
Sizers! Sizers! Sizers! What can I say.
Sizers are a layout mechanism, a layout manager, a set of rules to describe
the layout, a means to allow resizing of objects. They are sort of a
container - in that they contain the controls you need layed out. Not much
really. But for some reason it becomes a stumbling block for many
programmers coming from the windows world were placement of controls is
fixed. I know it was hard for me (I'm a VFP guy too). But there is plenty
of help on the web. In fact check the Dabo wiki for more information on how
to use sizers.
We have several types of sizers. A vertical box, a horizontal box, and grid
sizer. Recall I said that sizers are a set of rules. Well this is how I
think of the rules. A vertical sizer expands or resizes in the horizontal.
A horizontal sizer expands or resizes in the vertical. A grid sizer is a
speadsheet where I set the column size and the number of columns a control
can span. This of course is way to simple of an explanation but it works for
me.
So what is the relationship of form, dPanel and sizers? Well, a form can
contain a panel and a sizer determines how controls (including panels) are
layouted within a form.
So let do a little coding by starting out with a form.
import dabo
dabo.ui.loadUI('wx')
class MainForm(dabo.ui.dForm):
def afterInit(self):
self.Caption = "File Tutorial"
# I have added a sizer to show you how to create and call the layout
# but at this point it is not strictly needed.
self.Sizer = vs=dabo.ui.dSizer("vertical")
self.layout()
if __name__ == "__main__":
app = dabo.dApp()
app.BasePrefKey = "fileTutor"
app.setAppInfo("appName", "File Tutorial ")
# The app starts by running "MainForm"
app.MainFormClass = MainForm
#you have to start the event loop
app.start()
Run the above code and you will get a simple form with a title and the
built-in Dabo menu.
Ok lets add a little more to display a panel
immediately after
self.Sizer =vs= dabo.ui.dSizer("vertical")
add
vs.append(dabo.ui.dPanel(self,BackColor = "green))
Run again.
This should give you a little green box in the upper left hand corner.
Ok now let's expand the panel to fill the form in several steps by adding
paramenters to the vs.append method. Just add a ',1'.
.
vs.append(dabo.ui.dPanel(self,BackColor = "green),1)
Run it again - what happened?.
Now add one more parameter so it reads
vs.append(dabo.ui.dPanel(self,BackColor = "green),1,'x')
At this point I will stop and ask you to tell me (and others on the list)
what is happening. Your clue is we are adding a container/control/object to
a sizer using the the append method (function).
--
John Fabiani
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