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Fix wxcairo byteorder. - #10429
Fix wxcairo byteorder.#10429tacaswell merged 3 commits into
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I can only try this next weekend. If the bitmap has the right size already, I would suggest to re-use the buffer of the bitmap. |
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It's really not that hard to do it in python, see e.g. also https://github.com/matplotlib/matplotlib/pull/10436/files#diff-8b813556cc81b4a1a066f8d62e6519aeR28 which is perhaps an even better way to do this (and if both PRs come in I'll factor that out in a common function). I'm not too worried about inefficiency of the numpy version (pure C may be slightly more efficient but that's true for everything using numpy and this specific part is no worse than a bunch of other places where we use numpy). cairo can render to a user-supplied buffer (https://pycairo.readthedocs.io/en/latest/reference/surfaces.html#cairo.ImageSurface.create_for_data) but I'm not sure whether wx can expose access to the bitmap buffer? Note also that the cairo buffer requires specific data alignment (although the doc is not totally clear on whether alignment is only required for performance or also just for correctness). In any case I'd say the current cairo backend is so unefficient that an extra buffer copy is the last of my worries. |
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It seems that wx.Bitmap does not expose the memory buffer, even though that would be an obvious feature. But there's this method which could be used if the size did not change: https://wxpython.org/Phoenix/docs/html/wx.Bitmap.html#wx.Bitmap.CopyFromBuffer Maybe one of the formats does already the required reordering:
In that case, BitmapFromBuffer could be replaced by: if not self.bitmap or size_changed:
self.bitmap = wx.Bitmap(width, height, 32)
self.bitmap.CopyFromBuffer(buf, wx.BitmapBufferFormat_...)
That's a bit inefficient as the Bitmap's memory will be initialized, but most of the time it saves allocation/deallocation. |
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The seemingly normal diff --git a/lib/matplotlib/backends/backend_wxcairo.py b/lib/matplotlib/backends/backend_wxcairo.py
index 71a6831c7..84b82e64c 100644
--- a/lib/matplotlib/backends/backend_wxcairo.py
+++ b/lib/matplotlib/backends/backend_wxcairo.py
@@ -36,6 +36,7 @@ class FigureCanvasWxCairo(_FigureCanvasWxBase, FigureCanvasCairo):
_FigureCanvasWxBase.__init__(self, parent, id, figure)
FigureCanvasCairo.__init__(self, figure)
self._renderer = RendererCairo(self.figure.dpi)
+ self.bitmap = wxc.EmptyBitmap(0, 0)
def draw(self, drawDC=None):
width = int(self.figure.bbox.width)
@@ -44,13 +45,11 @@ class FigureCanvasWxCairo(_FigureCanvasWxBase, FigureCanvasCairo):
self._renderer.set_ctx_from_surface(surface)
self._renderer.set_width_height(width, height)
self.figure.draw(self._renderer)
- buf = np.frombuffer(surface.get_data(), dtype="uint8").reshape((height, width, 4))
- if sys.byteorder == "little":
- b, g, r, a = np.rollaxis(buf, -1)
- else:
- a, r, g, b = np.rollaxis(buf, -1)
- rgba8888 = np.dstack([r, g, b, a])
- self.bitmap = wxc.BitmapFromBuffer(width, height, rgba8888)
+ if ((width, height)
+ != (self.bitmap.GetWidth(), self.bitmap.GetHeight())):
+ self.bitmap = wxc.EmptyBitmap(width, height)
+ self.bitmap.CopyFromBuffer(
+ surface.get_data(), wx.BitmapBufferFormat_ARGB32)
self._isDrawn = True
self.gui_repaint(drawDC=drawDC, origin='WXCairo')
gives me (py2.7 wx 3.0.2.0; don't have phoenix installed now) File "matplotlib/pyplot.py", line 253, in show
return _show(*args, **kw)
File "matplotlib/backend_bases.py", line 192, in show
manager.show()
File "matplotlib/backends/backend_wx.py", line 1298, in show
self.canvas.draw()
File "matplotlib/backends/backend_wxcairo.py", line 53, in draw
surface.get_data(), wx.BitmapBufferFormat_ARGB32)
File "/usr/lib/python2.7/site-packages/wx-3.0-gtk3/wx/_gdi.py", line 814, in CopyFromBuffer
return _gdi_.Bitmap_CopyFromBuffer(*args, **kwargs)
RuntimeError: Failed to gain raw access to bitmap data.
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It might actually be trivial: there's wx.lib.wxcairo.BitmapFromImageSurface. def draw(self, drawDC=None):
import wx.lib.wxcairo as wxcairo
width = int(self.figure.bbox.width)
height = int(self.figure.bbox.height)
surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, width, height)
self._renderer.set_ctx_from_surface(surface)
self._renderer.set_width_height(width, height)
self.figure.draw(self._renderer)
self.bitmap = wxcairo.BitmapFromImageSurface(surface)
self._isDrawn = True
self.gui_repaint(drawDC=drawDC, origin='WXCairo')
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I can't easily test on Windows. Looks like you have access to a wider range of setups than I do, so feel free to push a better solution to this PR or open another one. |
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OK, the version with wx.lib.wxcairo.BitmapFromImageSurface is working on Ubuntu with 4.0.1 and 3.0.2 as well. Also it has been in the old and new wxPython demos. So it should work everywhere. |
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Backport PR #10429 on branch v2.2.x
PR Summary
I'm still not sure what I'm supposed to do with premultiplication (https://wxpython.org/Phoenix/docs/html/wx.Bitmap.html#wx.Bitmap.FromBufferRGBA is not very clear...) but at least this should get the byteorders correct).
See #10395 (comment).
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