Disable draw_foo methods on renderer used to estimate tight extents.

anntzer · anntzer · commit cd519f8afa05 · 2020-03-13T23:02:59.000+01:00
For the pgf backend, in particular draw_image() cannot succeed because
that needs actual filesystem access (to set up \includegraphics).
diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
@@ -1489,10 +1489,15 @@ def __init__(self, name, canvas, key, x=0, y=0, guiEvent=None):
         self.key = key
 
 
-def _get_renderer(figure, print_method):
+def _get_renderer(figure, print_method, *, draw_disabled=False):
     """
     Get the renderer that would be used to save a `~.Figure`, and cache it on
     the figure.
+
+    If *draw_disabled* is True, additionally replace draw_foo methods on
+    *renderer* by no-ops.  This is used by the tight-bbox-saving renderer,
+    which needs to walk through the artist tree to compute the tight-bbox, but
+    for which the output file may be closed early.
     """
     # This is implemented by triggering a draw, then immediately jumping out of
     # Figure.draw() by raising an exception.
@@ -1506,8 +1511,14 @@ def _draw(renderer): raise Done(renderer)
         try:
             print_method(io.BytesIO())
         except Done as exc:
-            figure._cachedRenderer, = exc.args
-            return figure._cachedRenderer
+            renderer, = figure._cachedRenderer, = exc.args
+
+    if draw_disabled:
+        for meth_name in dir(RendererBase):
+            if meth_name.startswith("draw_"):
+                setattr(renderer, meth_name, lambda *args, **kwargs: None)
+
+    return renderer
 
 
 def _is_non_interactive_terminal_ipython(ip):
@@ -2058,7 +2069,8 @@ def print_figure(self, filename, dpi=None, facecolor=None, edgecolor=None,
                     renderer = _get_renderer(
                         self.figure,
                         functools.partial(
-                            print_method, dpi=dpi, orientation=orientation))
+                            print_method, dpi=dpi, orientation=orientation),
+                        draw_disabled=True)
                     self.figure.draw(renderer)
                     bbox_artists = kwargs.pop("bbox_extra_artists", None)
                     bbox_inches = self.figure.get_tightbbox(
diff --git a/lib/matplotlib/tests/test_backend_pgf.py b/lib/matplotlib/tests/test_backend_pgf.py
@@ -291,3 +291,11 @@ def test_tex_restart_after_error():
     fig = plt.figure()  # start from scratch
     fig.suptitle(r"this is ok")
     fig.savefig(BytesIO(), format="pgf")
+
+
+@needs_xelatex
+def test_bbox_inches_tight(tmpdir):
+    fig, ax = plt.subplots()
+    ax.imshow([[0, 1], [2, 3]])
+    fig.savefig(os.path.join(tmpdir, "test.pdf"), backend="pgf",
+                bbox_inches="tight")
