matplotlib · QuLogic · Feb 17, 2021 · Sep 4, 2020 · Sep 7, 2020 · Feb 12, 2021
diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
@@ -1584,6 +1584,12 @@ def _draw(renderer): raise Done(renderer)
             figure.canvas = orig_canvas
 
 
+def _no_output_draw(figure):
+    renderer = _get_renderer(figure)
+    with renderer._draw_disabled():
+        figure.draw(renderer)
+
+
 def _is_non_interactive_terminal_ipython(ip):
     """
     Return whether we are in a a terminal IPython, but non interactive.
@@ -1621,7 +1627,9 @@ def _check_savefig_extra_args(func=None, extra_kwargs=()):
     @functools.wraps(func)
     def wrapper(*args, **kwargs):
         name = 'savefig'  # Reasonable default guess.
-        public_api = re.compile(r'^savefig|print_[A-Za-z0-9]+$')
+        public_api = re.compile(
+            r'^savefig|print_[A-Za-z0-9]+|_no_output_draw$'
+        )
         seen_print_figure = False
         for frame, line in traceback.walk_stack(None):
             if frame is None:
@@ -1632,8 +1640,9 @@ def wrapper(*args, **kwargs):
                         frame.f_globals.get('__name__', '')):
                 if public_api.match(frame.f_code.co_name):
                     name = frame.f_code.co_name
-                    if name == 'print_figure':
+                    if name in ('print_figure', '_no_output_draw'):
                         seen_print_figure = True
+
             else:
                 break
 
@@ -2021,7 +2030,14 @@ def release_mouse(self, ax):
             self.mouse_grabber = None
 
     def draw(self, *args, **kwargs):
-        """Render the `.Figure`."""
+        """
+        Render the `.Figure`.
+
+        It is important that this method actually walk the artist tree
+        even if not output is produced because this will trigger
+        deferred work (like computing limits auto-limits and tick
+        values) that users may want access to before saving to disk.
+        """
 
     def draw_idle(self, *args, **kwargs):
         """

diff --git a/lib/matplotlib/backends/backend_pdf.py b/lib/matplotlib/backends/backend_pdf.py
@@ -28,7 +28,7 @@
 from matplotlib._pylab_helpers import Gcf
 from matplotlib.backend_bases import (
     _Backend, _check_savefig_extra_args, FigureCanvasBase, FigureManagerBase,
-    GraphicsContextBase, RendererBase)
+    GraphicsContextBase, RendererBase, _no_output_draw)
 from matplotlib.backends.backend_mixed import MixedModeRenderer
 from matplotlib.figure import Figure
 from matplotlib.font_manager import findfont, get_font
@@ -2730,6 +2730,10 @@ def print_pdf(self, filename, *,
             else:            # we opened the file above; now finish it off
                 file.close()
 
+    def draw(self):
+        _no_output_draw(self.figure)
+        return super().draw()
+
 
 FigureManagerPdf = FigureManagerBase
 

diff --git a/lib/matplotlib/backends/backend_pgf.py b/lib/matplotlib/backends/backend_pgf.py
@@ -19,7 +19,8 @@
 from matplotlib import _api, cbook, font_manager as fm
 from matplotlib.backend_bases import (
     _Backend, _check_savefig_extra_args, FigureCanvasBase, FigureManagerBase,
-    GraphicsContextBase, RendererBase)
+    GraphicsContextBase, RendererBase, _no_output_draw
+)
 from matplotlib.backends.backend_mixed import MixedModeRenderer
 from matplotlib.backends.backend_pdf import (
     _create_pdf_info_dict, _datetime_to_pdf)
@@ -906,6 +907,10 @@ def print_png(self, fname_or_fh, *args, **kwargs):
     def get_renderer(self):
         return RendererPgf(self.figure, None)
 
+    def draw(self):
+        _no_output_draw(self.figure)
+        return super().draw()
+
 
 FigureManagerPgf = FigureManagerBase
 

diff --git a/lib/matplotlib/backends/backend_ps.py b/lib/matplotlib/backends/backend_ps.py
@@ -23,7 +23,7 @@
 from matplotlib.afm import AFM
 from matplotlib.backend_bases import (
     _Backend, _check_savefig_extra_args, FigureCanvasBase, FigureManagerBase,
-    GraphicsContextBase, RendererBase)
+    GraphicsContextBase, RendererBase, _no_output_draw)
 from matplotlib.cbook import is_writable_file_like, file_requires_unicode
 from matplotlib.font_manager import get_font
 from matplotlib.ft2font import LOAD_NO_HINTING, LOAD_NO_SCALE
@@ -1129,6 +1129,10 @@ def _print_figure_tex(
 
             _move_path_to_path_or_stream(tmpfile, outfile)
 
+    def draw(self):
+        _no_output_draw(self.figure)
+        return super().draw()
+
 
 def convert_psfrags(tmpfile, psfrags, font_preamble, custom_preamble,
                     paper_width, paper_height, orientation):

diff --git a/lib/matplotlib/backends/backend_svg.py b/lib/matplotlib/backends/backend_svg.py
@@ -17,7 +17,7 @@
 from matplotlib import _api, cbook
 from matplotlib.backend_bases import (
      _Backend, _check_savefig_extra_args, FigureCanvasBase, FigureManagerBase,
-     RendererBase)
+     RendererBase, _no_output_draw)
 from matplotlib.backends.backend_mixed import MixedModeRenderer
 from matplotlib.colors import rgb2hex
 from matplotlib.dates import UTC
@@ -1363,6 +1363,10 @@ def _print_svg(self, filename, fh, *, dpi=None, bbox_inches_restore=None,
     def get_default_filetype(self):
         return 'svg'
 
+    def draw(self):
+        _no_output_draw(self.figure)
+        return super().draw()
+
 
 FigureManagerSVG = FigureManagerBase
 

diff --git a/lib/matplotlib/backends/backend_template.py b/lib/matplotlib/backends/backend_template.py
@@ -191,7 +191,14 @@ class methods button_press_event, button_release_event,
     """
 
     def draw(self):
-        """Draw the figure using the renderer."""
+        """
+        Draw the figure using the renderer.
+
+        It is important that this method actually walk the artist tree
+        even if not output is produced because this will trigger
+        deferred work (like computing limits auto-limits and tick
+        values) that users may want access to before saving to disk.
+        """
         renderer = RendererTemplate(self.figure.dpi)
         self.figure.draw(renderer)
 

diff --git a/lib/matplotlib/testing/__init__.py b/lib/matplotlib/testing/__init__.py
@@ -4,6 +4,9 @@
 
 import locale
 import logging
+import subprocess
+from pathlib import Path
+from tempfile import TemporaryDirectory
 
 import matplotlib as mpl
 from matplotlib import _api
@@ -44,3 +47,31 @@ def setup():
     # are not necessarily the default values as specified in rcsetup.py.
     set_font_settings_for_testing()
     set_reproducibility_for_testing()
+
+
+def check_for_pgf(texsystem):
+    """
+    Check if a given TeX system + pgf is available
+
+    Parameters
+    ----------
+    texsystem : str
+        The executable name to check
+    """
+    with TemporaryDirectory() as tmpdir:
+        tex_path = Path(tmpdir, "test.tex")
+        tex_path.write_text(r"""
+            \documentclass{minimal}
+            \usepackage{pgf}
+            \begin{document}
+            \typeout{pgfversion=\pgfversion}
+            \makeatletter
+            \@@end
+        """)
+        try:
+            subprocess.check_call(
+                [texsystem, "-halt-on-error", str(tex_path)], cwd=tmpdir,
+                stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
+        except (OSError, subprocess.CalledProcessError):
+            return False
+        return True
diff --git a/lib/matplotlib/tests/test_backend_bases.py b/lib/matplotlib/tests/test_backend_bases.py
@@ -1,5 +1,6 @@
 import re
 
+from matplotlib.testing import check_for_pgf
 from matplotlib.backend_bases import (
     FigureCanvasBase, LocationEvent, MouseButton, MouseEvent,
     NavigationToolbar2, RendererBase)
@@ -13,6 +14,9 @@
 import numpy as np
 import pytest
 
+needs_xelatex = pytest.mark.skipif(not check_for_pgf('xelatex'),
+                                   reason='xelatex + pgf is required')
+
 
 def test_uses_per_path():
     id = transforms.Affine2D()
@@ -187,3 +191,38 @@ def test_toolbar_zoompan():
     assert ax.get_navigate_mode() == "ZOOM"
     ax.figure.canvas.manager.toolmanager.trigger_tool('pan')
     assert ax.get_navigate_mode() == "PAN"
+
+
+@pytest.mark.parametrize(
+    "backend", ['svg', 'ps', 'pdf', pytest.param('pgf', marks=needs_xelatex)]
+)
+def test_draw(backend):
+    from matplotlib.figure import Figure
+    from matplotlib.backends.backend_agg import FigureCanvas
+    test_backend = pytest.importorskip(
+        f'matplotlib.backends.backend_{backend}'
+    )
+    TestCanvas = test_backend.FigureCanvas
+    fig_test = Figure(constrained_layout=True)
+    TestCanvas(fig_test)
+    axes_test = fig_test.subplots(2, 2)
+
+    # defaults to FigureCanvasBase
+    fig_agg = Figure(constrained_layout=True)
+    # put a backends.backend_agg.FigureCanvas on it
+    FigureCanvas(fig_agg)
+    axes_agg = fig_agg.subplots(2, 2)
+
+    init_pos = [ax.get_position() for ax in axes_test.ravel()]
+
+    fig_test.canvas.draw()
+    fig_agg.canvas.draw()
+
+    layed_out_pos_test = [ax.get_position() for ax in axes_test.ravel()]
+    layed_out_pos_agg = [ax.get_position() for ax in axes_agg.ravel()]
+
+    for init, placed in zip(init_pos, layed_out_pos_test):
+        assert not np.allclose(init, placed, atol=0.005)
+
+    for ref, test in zip(layed_out_pos_agg, layed_out_pos_test):
+        np.testing.assert_allclose(ref, test, atol=0.005)
diff --git a/lib/matplotlib/tests/test_backend_pgf.py b/lib/matplotlib/tests/test_backend_pgf.py
@@ -1,16 +1,15 @@
 import datetime
 from io import BytesIO
 import os
-from pathlib import Path
 import shutil
 import subprocess
-from tempfile import TemporaryDirectory
 
 import numpy as np
 import pytest
 
 import matplotlib as mpl
 import matplotlib.pyplot as plt
+from matplotlib.testing import check_for_pgf
 from matplotlib.testing.compare import compare_images, ImageComparisonFailure
 from matplotlib.backends.backend_pgf import PdfPages, common_texification
 from matplotlib.testing.decorators import (_image_directories,
@@ -19,32 +18,11 @@
 
 baseline_dir, result_dir = _image_directories(lambda: 'dummy func')
 
-
-def check_for(texsystem):
-    with TemporaryDirectory() as tmpdir:
-        tex_path = Path(tmpdir, "test.tex")
-        tex_path.write_text(r"""
-            \documentclass{minimal}
-            \usepackage{pgf}
-            \begin{document}
-            \typeout{pgfversion=\pgfversion}
-            \makeatletter
-            \@@end
-        """)
-        try:
-            subprocess.check_call(
-                [texsystem, "-halt-on-error", str(tex_path)], cwd=tmpdir,
-                stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)
-        except (OSError, subprocess.CalledProcessError):
-            return False
-        return True
-
-
-needs_xelatex = pytest.mark.skipif(not check_for('xelatex'),
+needs_xelatex = pytest.mark.skipif(not check_for_pgf('xelatex'),
                                    reason='xelatex + pgf is required')
-needs_pdflatex = pytest.mark.skipif(not check_for('pdflatex'),
+needs_pdflatex = pytest.mark.skipif(not check_for_pgf('pdflatex'),
                                     reason='pdflatex + pgf is required')
-needs_lualatex = pytest.mark.skipif(not check_for('lualatex'),
+needs_lualatex = pytest.mark.skipif(not check_for_pgf('lualatex'),
                                     reason='lualatex + pgf is required')
 needs_ghostscript = pytest.mark.skipif(
     "eps" not in mpl.testing.compare.converter,
@@ -341,7 +319,7 @@ def test_unknown_font(caplog):
 @pytest.mark.parametrize("texsystem", ("pdflatex", "xelatex", "lualatex"))
 @pytest.mark.backend("pgf")
 def test_minus_signs_with_tex(fig_test, fig_ref, texsystem):
-    if not check_for(texsystem):
+    if not check_for_pgf(texsystem):
         pytest.skip(texsystem + ' + pgf is required')
     mpl.rcParams["pgf.texsystem"] = texsystem
     fig_test.text(.5, .5, "$-1$")