#1141: GLWindow.OnPaint() broken on Windows
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Reporter: glynn | Owner: grass-dev@…
Type: defect | Status: new
Priority: normal | Milestone: 6.4.0
Component: wxGUI | Version: unspecified
Keywords: nviz | Platform: MSWindows XP
Cpu: All |
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GLWindow.!OnPaint() (in nviz_mapdisp.py) calls:
{{{
dc = wx.PaintDC(self)
}}}
On Windows, wx.PaintDC() can only be called in an EVT_PAINT handler, but
GLWindow.!OnPaint() is called from at least two other places:
GLWindow.!OnMouseAction() (nviz_mapdisp.py:226) and
!MapFrame.!AddToolbar() (mapdisp.py:417). The latter causes an exception
when switching to "3D View":
{{{
Traceback (most recent call last):
File "C:\msys\1.0\home\glynn\src\grass-7.0\dist.i686-pc-
mingw32\etc\gui\wxpython\gui_modules\toolbars.py", line 322, in
OnSelectTool
self.parent.AddToolbar("nviz")
File "C:\msys\1.0\home\glynn\src\grass-7.0\dist.i686-pc-
mingw32\etc\gui\wxpython\gui_modules\mapdisp.py", line 417, in AddToolbar
self.MapWindow3D.OnPaint(None) # -> LoadData
File "C:\msys\1.0\home\glynn\src\grass-7.0\dist.i686-pc-
mingw32\etc\gui\wxpython\gui_modules\nviz_mapdisp.py", line 163, in
OnPaint
dc = wx.PaintDC(self)
File "C:\Program Files\Python26\lib\site-packages\wx-2.8-msw-
unicode\wx\_gdi.py", line 4804, in __init__
_gdi_.PaintDC_swiginit(self,_gdi_.new_PaintDC(*args, **kwargs))
wx._core.PyAssertionError: C++ assertion "wxAssertFailure" failed at
..\..\src\msw\dcclient.cpp(219) in wxPaintDC::wxPaintDC(): wxPaintDC may
be created only in EVT_PAINT handler!
}}}
I note that the created DC isn't actually used, so I'm assuming this it's
being created to keep Windows happy (if you don't create a PaintDC,
Windows won't "validate" the rectangle and will just keep send PAINT
messages).
I'm also assuming that !OnPaint() is being called to ensure that the state
gets fully initialised. If you just want to force a redraw, you would
normally do so asynchronously using wx.Window.Refresh(). But that won't
work if you're counting on !OnPaint() having been called before
proceeding.
I think that !OnPaint() should probably be split into e.g. !OnPaint() and
!DoPaint(), with the latter doing most of the work while the former simply
creates the PaintDC then calls !DoPaint(). Making this change eliminates
the above exception, although the wxGUI crashes shortly afterwards (in
Gs_loadmap_as_short(), AFAICT).
PS: I set the "component" field to wxGUI; is NVIZ for the !Tcl/Tk NVIZ or
for either version?
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Ticket URL: <http://trac.osgeo.org/grass/ticket/1141>
GRASS GIS <http://grass.osgeo.org>
