Class GraphicsContextWx

lib/matplotlib/backends/backend_wx.py:284–390

The graphics context provides the color, line styles, etc. This class stores a reference to a wxMemoryDC, and a wxGraphicsContext that draws to it. Creating a wxGraphicsContext seems to be fairly heavy, so these objects are cached based on the bitmap object that is passed in.

class GraphicsContextWx(GraphicsContextBase):
    """
    The graphics context provides the color, line styles, etc.

    This class stores a reference to a wxMemoryDC, and a
    wxGraphicsContext that draws to it.  Creating a wxGraphicsContext
    seems to be fairly heavy, so these objects are cached based on the
    bitmap object that is passed in.

    The base GraphicsContext stores colors as an RGB tuple on the unit
    interval, e.g., (0.5, 0.0, 1.0).  wxPython uses an int interval, but
    since wxPython colour management is rather simple, I have not chosen
    to implement a separate colour manager class.
    """
    _capd = {'butt': wx.CAP_BUTT,
             'projecting': wx.CAP_PROJECTING,
             'round': wx.CAP_ROUND}

    _joind = {'bevel': wx.JOIN_BEVEL,
              'miter': wx.JOIN_MITER,
              'round': wx.JOIN_ROUND}

    _cache = weakref.WeakKeyDictionary()

    def __init__(self, bitmap, renderer):
        super().__init__()
        # assert self.Ok(), "wxMemoryDC not OK to use"
        _log.debug("%s - __init__(): %s", type(self), bitmap)

        dc, gfx_ctx = self._cache.get(bitmap, (None, None))
        if dc is None:
            dc = wx.MemoryDC(bitmap)
            gfx_ctx = wx.GraphicsContext.Create(dc)
            gfx_ctx._lastcliprect = None
            self._cache[bitmap] = dc, gfx_ctx

        self.bitmap = bitmap
        self.dc = dc
        self.gfx_ctx = gfx_ctx
        self._pen = wx.Pen('BLACK', 1, wx.SOLID)
        gfx_ctx.SetPen(self._pen)
        self.renderer = renderer

    def select(self):
        """Select the current bitmap into this wxDC instance."""
        if sys.platform == 'win32':
            self.dc.SelectObject(self.bitmap)
            self.IsSelected = True

    def unselect(self):
        """Select a Null bitmap into this wxDC instance."""
        if sys.platform == 'win32':
            self.dc.SelectObject(wx.NullBitmap)
            self.IsSelected = False

    def set_foreground(self, fg, isRGBA=None):
        # docstring inherited
        # Implementation note: wxPython has a separate concept of pen and