Add a celiagg kiva backend for Wx (#608)

enable/wx/celiagg.py

@@ -0,0 +1,52 @@
+# (C) Copyright 2005-2021 Enthought, Inc., Austin, TX
+# All rights reserved.
+#
+# This software is provided without warranty under the terms of the BSD
+# license included in LICENSE.txt and may be redistributed only under
+# the conditions described in the aforementioned license. The license
+# is also available online at http://www.enthought.com/licenses/BSD.txt
+#
+# Thanks for using Enthought open source!
+
+import numpy as np
+import wx
+
+from kiva.celiagg import CompiledPath, GraphicsContext  # noqa
+
+from .base_window import BaseWindow
+from .scrollbar import NativeScrollBar
+
+
+class Window(BaseWindow):
+    def _create_gc(self, size, pix_format="rgba32"):
+        gc = GraphicsContext(
+            (size[0] + 1, size[1] + 1),
+            pix_format=pix_format,
+            base_pixel_scale=self.base_pixel_scale,
+        )
+        gc.translate_ctm(0.5, 0.5)
+        return gc
+
+    def _window_paint(self, event):
+        if self.control is None:
+            event.Skip()
+            return
+
+        control = self.control
+        wdc = control._dc = wx.PaintDC(control)
+
+        bmp = wx.Bitmap.FromBufferRGBA(
+            self._gc.width(), self._gc.height(), np.ravel(self._gc.gc.array)
+        )
+        bmp.SetSize(control.GetSize())
+        wdc.DrawBitmap(bmp, 0, 0)
+
+        control._dc = None
+
+
+def font_metrics_provider():
+    from kiva.api import Font
+
+    gc = GraphicsContext((1, 1))
+    gc.set_font(Font())
+    return gc