Float values no longer accepted in wxPython-4.1.2a1.dev5259?

#1

Hi,

I installed wxPython-4.1.2a1.dev5259+d3bdb143-cp310-cp310-win_amd64.whl wheel file. I have python 3.10.1 64 bit and Windows 11.

Now I get lots of errors like this:

TypeError: DC.DrawLine(): arguments did not match any overloaded call:
overload 1: argument 1 has unexpected type ‘float’

In wxpython 4.1.1, it accepted float values, but now it asks for integer values only. What is wrong?

Float conversion differences between python 3.9 and 3.10
#2

You’re using Python 3.10 right? That’s a Python 3.10 change, not a change in wxPython. Methods that accept integers will no longer silently accept and truncate floats.

1 Like
#3

Why on earth would someone introduce a change like that? That’s the most ridiculous thing I’ve ever heard.

#4

Why does DC.DrawLine(), wx.Rect, wx.Pen etc require integer-type arguments in the first place? Why didn’t they made those arguments floats?

#5

Because wx.DCs use integer coordinates. In the wx.DC view of the world there is nothing between pixel (3,1) and (4,1) for example. If you need floating point sub-pixel precision then wx.GraphicsContext is available.

The details for the change in Python are here:Issue 37999: No longer use implicit convertion to int with loss - Python tracker A little searching will probably turn up more discussion about it.

2 Likes
#6

So, even though I pass a floating point argument to wx.DC, it converts it to an integer?

Does wx.DrawLine(3.8 is converted to wx.DrawLine(3 ?

How about wx.Font, it also doesn’t accept float values anymore. What happens to wx.Font(11.7 in python 3.9, is it converted to wx.Font(11 ?

#7 
import wx

app = wx.App()

font = wx.Font(11.7, wx.ROMAN, wx.NORMAL, wx.NORMAL)

print("Point size =", font.GetPointSize())

Even with Python 3.8 this gives a DeprecationWarning and, yes the point size is truncated:

richardt@Pavilion ~/.../hci/wxpython/fonts $ python3.8 font_size.py 
font_size.py:5: DeprecationWarning: an integer is required (got type float).  Implicit conversion to integers using __int__ is deprecated, and may be removed in a future version of Python.
  font = wx.Font(11.7, wx.ROMAN, wx.NORMAL, wx.NORMAL)
Point size = 11
1 Like
#8

I don’t understand, I use wx.PaintDC. Does it mean that I use wx.DC? How can I make my app use wx.GraphicsContext?

My code:

self.dc = wx.PaintDC(self)
self.Bind(wx.EVT_PAINT, self.onPaint)

Thus every time the panel is refreshed, everything is redrawn. Do I use wx.DC here? How can I make my app use wx.GraphicsContext?

#9

Out of interest I had a look at drawing text in a wxGraphicsContext. Previously I have used the following to create a GraphicsContext from a DC:

    gcdc = wx.GCDC(dc)
    gc = gcdc.GetGraphicsContext()

But the documentation for GraphicsContext says you can also do:

gc = wx.GraphicsContext.Create(dc)

The GraphicsContext.CreateFont() method takes a float for the sizeInPixels arg, whereas the wx.Font() constructor takes an int for the pointSize arg. So the sizes will be different.

However, since wxPython version 4.1/wxWidgets-3.1.2, wx.Font has a SetFractionalPointSize() method which does take a float as the pointSize arg.

The following code experiments with these ideas:

import wx

class TestPanel(wx.Panel):
    def __init__(self, *args, **kw):
        wx.Panel.__init__(self, *args, **kw)
        self.Bind(wx.EVT_PAINT, self.OnPaint)


    def Draw(self, dc):
        dc.SetBackground(wx.Brush("sky blue"))
        dc.Clear()
        # gcdc = wx.GCDC(dc)
        # gc = gcdc.GetGraphicsContext()
        gc = wx.GraphicsContext.Create(dc)

        gc_font = gc.CreateFont(11.7, facename='')
        gc.SetFont(gc_font)
        gc.DrawText("gc.DrawText()", 20, 20)

        wx_font = wx.Font(11, wx.FONTFAMILY_DEFAULT, wx.NORMAL, wx.NORMAL)
        dc.SetFont(wx_font)
        dc.DrawText("dc.DrawText()", 20, 60)

        wx_font.SetFractionalPointSize(11.7)
        dc.SetFont(wx_font)
        dc.DrawText("dc.DrawText()", 20, 80)

        wx_font.SetFractionalPointSize(12.0)
        dc.SetFont(wx_font)
        dc.DrawText("dc.DrawText()", 20, 100)


    def OnPaint(self, evt):
        dc = wx.PaintDC(self)
        self.Draw(dc)


if __name__ == '__main__':
    app = wx.App()
    frame = wx.Frame(None, title="Graphics Context Test", size=(300, 200))
    pnl = TestPanel(frame)
    frame.Show()
    app.MainLoop()

Tested on Python 3.8.10 + wxPython 4.1.1 gtk3 (phoenix) wxWidgets 3.1.5 + Linux Mint 20.2

#10

Thanks but, when you do

wx.GraphicsContext doesn’t have methods like SetTextForeground, which PaintDC have. How to solve this?

#11

The only way I have found to do this is to create a wx.Font, set its fractional point size and then pass it with a colour to the GraphicsContext’s overloaded SetFont() method:

        wx_font = wx.Font(11, wx.FONTFAMILY_DEFAULT, wx.NORMAL, wx.NORMAL)
        wx_font.SetFractionalPointSize(11.7)
        gc.SetFont(wx_font, wx.RED)
        gc.DrawText("gc.DrawText()", 20, 80)

However, that may defeat the point of using a GraphicsContext in the first place.

1 Like