Re: making a clock face

Adding another note or two:

1) take a look at the wxPython wiki, specifically the pages on drawing.

2) if you want your clock to resize itself with the window automatically,
you can use a wx.lib.float_canvas to handle all the scaling for you. And
the Paint events, etc :-)

The demo provides a toolbar that lets you pan and zoom around, but if you
simply don't use that part, you get a auto-scaling static drawing.

tHere are lots of demos for ut here:

https://github.com/PythonCHB/wxPythonDemos

That being said, if you like the provided analog clock, you're probably
best off simply adapting that.

-CHB





On Fri, Nov 27, 2020 at 11:40 AM Tim Roberts <[email protected]> wrote:

> On Nov 27, 2020, at 3:32 AM, Nathan smith <[email protected]> wrote:
>
>
> I have a follow up question though regarding the drawing of a clock.
>
> Unfortunately, the time being displayed may not always be the time of the
> system itself, and from what I have read the wx.AnalogClock does not
> support time being passed to it?
>
>
> Correct.  Remember, you have the complete source code.  As published, it
> pulls the current time at the beginning of the “draw” function that handles
> painting.    However, because Python is such a magical language, you are
> free to derive your own class from it that pulls the time from a member
> variable, which you can supply.
>
>
> On the subject of drawing though I wanted to ask, I've had limited
> exposure to the wx.PaintDC and only been drawing to a frame rather than a
> panel.
>
> So drawing to a panel should work as well?
>
>
> You can draw to any window.  Neither a frame nor a panel has any content
> of its own, so you don’t have to worry about sharing the space.
>
>
> Finally if I did something like:
>
> self.dc = wx.PaintDC(panel)
>
>
> No.  You only do this inside the EVT_PAINT handler.  You can’t cache it.
> One of the responsibilities of a “paint” handler is to tell the system “OK,
> I’ve finished”, so the system knows that any dirty regions have been
> repainted.  The PaintDC handles that little bit of overhead on your behalf
> in its destructor.  If you don’t do that, when your paint handler returns,
> the system thinks there are still dirty regions that need to be repainted,
> and it will trigger another EVT_PAINT.
>
> If you need to draw on your panel outside of a paint handler, you’d use
> wx.ClientDC.
>
>
> hbox1 = wx.BoxSizer(wx.HORIZONTAL)
> hbox1.Add(self.dc, 1, wx.EXPAND|wx.ALIGN_LEFT|wx.ALL,5)
>
>
> No.  A DC is not a window.  A DC merely stores the current set of things
> you can draw with: fonts, colors, brushes, pens, bitmaps, and so on.  The
> only things you can add to a sizer are windows.  You’d add the panel to the
> sizer.  Or, if the panel is the only thing in the frame, you don’t need the
> sizer — the panel will automatically expand to fill the frame.
>
>
> Later if I did self.dc.Clear() And drew something else using that same
> self.dc instance, it woudl draw it in the space given to it by the sizer
> hbox1, is that right?
>
>
> Nope.  A sizer is not a window — you cannot draw on a sizer.  You can draw
> on a panel, using a DC, and the sizer merely manages the size of the panel.
>
>
> I realise to you these questions probably seem obvious and you're
> wondering why I ask such simple things, but I'm trying to get the theory
> straight in my mind before I put pen to paper or, in this case, brush to
> panel :)
>
>
> Have you read through the wxWidgets documentation on windows, sizers, and
> DCs?  You’re confusing some pretty fundamental topics here.  Those guys
> went to all the trouble of writing it, hoping people would read it.  There
> are some great wxPython tutorials explaining the basics, and there’s also
> Robin’s excellent book on wxPython.
>
>
> In my application for drawing that I have been working on I am using size
> calculations to work out where the middle of the screen is for my central
> point and just working around that.
> Would that still work with inclusion of the sizers?
>
>
> When you say “screen”, do you mean “window”?  All you have to do is keep
> track of which window you’re drawing into.  If you want to find the center
> of your panel, then that’s what you do:
>     size = sell.clockPanel.GetClientSize()
>     # Center is at size.x // 2 and size.y // 2
> And if you’re using a DC for the panel, then the upper left is at (0,0)
> and you just start drawing.
> —
> Tim Roberts, [email protected]
> Providenza & Boekelheide, Inc.
>
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