matplotlib · QuLogic · Apr 30, 2020 · Apr 23, 2020 · tacaswell · Apr 28, 2020
diff --git a/doc/api/api_changes_3.3/behaviour.rst b/doc/api/api_changes_3.3/behaviour.rst
@@ -201,7 +201,6 @@ no longer accept the unsupported ``'best'`` location.  Previously, invalid Axes
 locations would use ``'best'`` and invalid Figure locations would used ``'upper
 right'``.
 
-
 Passing Line2D's *drawstyle* together with *linestyle* is removed
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
@@ -214,3 +213,18 @@ Upper case color strings
 
 Support for passing single-letter colors (one of "rgbcmykw") as UPPERCASE
 characters is removed; these colors are now case-sensitive (lowercase).
+
+tight/constrained_layout no longer worry about titles that are too wide
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+*tight_layout* and *constrained_layout* shrink axes to accommodate
+"decorations" on the axes.  However, if an xlabel or title is too long in the
+x direction, making the axes smaller in the x-direction doesn't help.  The
+behavior of both has been changed to ignore the width of the title and
+xlabel and the height of the ylabel in the layout logic.
+
+This also means there is a new keyword argument for `.axes.Axes.get_tightbbox`:
+``for_layout_only``, which defaults to *False*, but if *True* returns a
+bounding box using the rules above.  `.axis.Axis.get_tightbbox` gets an
+``ignore_label`` keyword argument, which is *None* by default, but which can
+also be 'x' or 'y'. 
diff --git a/lib/matplotlib/_constrained_layout.py b/lib/matplotlib/_constrained_layout.py
@@ -258,7 +258,11 @@ def _make_layout_margins(ax, renderer, h_pad, w_pad):
     fig = ax.figure
     invTransFig = fig.transFigure.inverted().transform_bbox
     pos = ax.get_position(original=True)
-    tightbbox = ax.get_tightbbox(renderer=renderer)
+    try:
+        tightbbox = ax.get_tightbbox(renderer=renderer, for_layout_only=True)
+    except TypeError:
+        tightbbox = ax.get_tightbbox(renderer=renderer)
+
     if tightbbox is None:
         bbox = pos
     else:

diff --git a/lib/matplotlib/axes/_base.py b/lib/matplotlib/axes/_base.py
@@ -4086,11 +4086,15 @@ def get_default_bbox_extra_artists(self):
             for _axis in self._get_axis_list():
                 artists.remove(_axis)
 
+        artists.remove(self.title)
+        artists.remove(self._left_title)
+        artists.remove(self._right_title)
+
         return [artist for artist in artists
                 if (artist.get_visible() and artist.get_in_layout())]
 
     def get_tightbbox(self, renderer, call_axes_locator=True,
-                      bbox_extra_artists=None):
+                      bbox_extra_artists=None, *, for_layout_only=False):
         """
         Return the tight bounding box of the axes, including axis and their
         decorators (xlabel, title, etc).
@@ -4116,6 +4120,10 @@ def get_tightbbox(self, renderer, call_axes_locator=True,
             caller is only interested in the relative size of the tightbbox
             compared to the axes bbox.
 
+        for_layout_only : default: False
+            The bounding box will *not* include the x-extent of the title and
+            the xlabel, or the y-extent of the ylabel.
+
         Returns
         -------
         `.BboxBase`
@@ -4141,22 +4149,37 @@ def get_tightbbox(self, renderer, call_axes_locator=True,
             self.apply_aspect()
 
         if self.axison:
-            bb_xaxis = self.xaxis.get_tightbbox(renderer)
+            igl = 'x' if for_layout_only else None
+            try:
+                bb_xaxis = self.xaxis.get_tightbbox(renderer, ignore_label=igl)
+            except TypeError:
+                # in case downstream library has redefined axis:
+                bb_xaxis = self.xaxis.get_tightbbox(renderer)
             if bb_xaxis:
                 bb.append(bb_xaxis)
 
-            bb_yaxis = self.yaxis.get_tightbbox(renderer)
+            igl = 'y' if for_layout_only else None
+            try:
+                bb_yaxis = self.yaxis.get_tightbbox(renderer, ignore_label=igl)
+            except TypeError:
+                # in case downstream library has redefined axis:
+                bb_xaxis = self.yaxis.get_tightbbox(renderer)
             if bb_yaxis:
                 bb.append(bb_yaxis)
-
         self._update_title_position(renderer)
-
         axbbox = self.get_window_extent(renderer)
         bb.append(axbbox)
 
         for title in [self.title, self._left_title, self._right_title]:
             if title.get_visible():
-                bb.append(title.get_window_extent(renderer))
+                bt = title.get_window_extent(renderer)
+                if for_layout_only and bt.width > 0:
+                    # make the title bbox 1 pixel wide so its width
+                    # is not accounted for in bbox calculations in
+                    # tight/constrained_layout
+                    bt.x0 = (bt.x0 + bt.x1) / 2 - 0.5
+                    bt.x1 = bt.x0 + 1.0
+                bb.append(bt)
 
         bbox_artists = bbox_extra_artists
         if bbox_artists is None:
@@ -4179,7 +4202,6 @@ def get_tightbbox(self, renderer, call_axes_locator=True,
                     and 0 < bbox.width < np.inf
                     and 0 < bbox.height < np.inf):
                 bb.append(bbox)
-
         return mtransforms.Bbox.union(
             [b for b in bb if b.width != 0 or b.height != 0])
 

diff --git a/lib/matplotlib/axis.py b/lib/matplotlib/axis.py
@@ -1079,10 +1079,15 @@ def _get_tick_bboxes(self, ticks, renderer):
                 [tick.label2.get_window_extent(renderer)
                  for tick in ticks if tick.label2.get_visible()])
 
-    def get_tightbbox(self, renderer):
+    def get_tightbbox(self, renderer, *, ignore_label=None):
         """
         Return a bounding box that encloses the axis. It only accounts
         tick labels, axis label, and offsetText.
+
+        If ``ignore_label`` is 'x', then the width of the label is collapsed
+        to near zero.  If 'y', then the height is collapsed to near zero. This
+        is for tight/constrained_layout to be able to ignore too-long labels
+        when doing their layout.
         """
         if not self.get_visible():
             return
@@ -1100,11 +1105,24 @@ def get_tightbbox(self, renderer):
 
         bboxes = [
             *(a.get_window_extent(renderer)
-              for a in [self.label, self.offsetText]
+              for a in [self.offsetText]
               if a.get_visible()),
             *ticklabelBoxes,
             *ticklabelBoxes2,
         ]
+        # take care of label
+        if self.label.get_visible():
+            bb = self.label.get_window_extent(renderer)
+            # for constrained/tight_layout, we want to ignore the label's
+            # width because the adjustments they make can't be improved.
+            # this code collapses the relevant direction
+            if ignore_label == 'x' and bb.width > 0:
+                bb.x0 = (bb.x0 + bb.x1) / 2 - 0.5
+                bb.x1 = bb.x0 + 1.0
+            elif ignore_label == 'y' and bb.height > 0:
+                bb.y0 = (bb.y0 + bb.y1) / 2 - 0.5
+                bb.y1 = bb.y0 + 1.0
+            bboxes.append(bb)
         bboxes = [b for b in bboxes
                   if 0 < b.width < np.inf and 0 < b.height < np.inf]
         if bboxes:

diff --git a/...atplotlib/tests/baseline_images/test_constrainedlayout/constrained_layout11.png b/...atplotlib/tests/baseline_images/test_constrainedlayout/constrained_layout11.png
diff --git a/lib/matplotlib/tests/test_constrainedlayout.py b/lib/matplotlib/tests/test_constrainedlayout.py
@@ -176,7 +176,7 @@ def test_constrained_layout10():
 @image_comparison(['constrained_layout11.png'])
 def test_constrained_layout11():
     """Test for multiple nested gridspecs"""
-    fig = plt.figure(constrained_layout=True, figsize=(10, 3))
+    fig = plt.figure(constrained_layout=True, figsize=(13, 3))
     gs0 = gridspec.GridSpec(1, 2, figure=fig)
     gsl = gridspec.GridSpecFromSubplotSpec(1, 2, gs0[0])
     gsl0 = gridspec.GridSpecFromSubplotSpec(2, 2, gsl[1])

diff --git a/lib/matplotlib/tests/test_tightlayout.py b/lib/matplotlib/tests/test_tightlayout.py
@@ -258,29 +258,23 @@ def test_empty_layout():
 
 @pytest.mark.parametrize("label", ["xlabel", "ylabel"])
 def test_verybig_decorators(label):
-    """Test that warning emitted when xlabel/ylabel too big."""
+    """Test that no warning emitted when xlabel/ylabel too big."""
     fig, ax = plt.subplots(figsize=(3, 2))
     ax.set(**{label: 'a' * 100})
-    with pytest.warns(UserWarning):
-        fig.tight_layout()
 
 
 def test_big_decorators_horizontal():
-    """Test that warning emitted when xlabel too big."""
+    """Test that doesn't warn when xlabel too big."""
     fig, axs = plt.subplots(1, 2, figsize=(3, 2))
     axs[0].set_xlabel('a' * 30)
     axs[1].set_xlabel('b' * 30)
-    with pytest.warns(UserWarning):
-        fig.tight_layout()
 
 
 def test_big_decorators_vertical():
-    """Test that warning emitted when xlabel too big."""
+    """Test that doesn't warn when ylabel too big."""
     fig, axs = plt.subplots(2, 1, figsize=(3, 2))
     axs[0].set_ylabel('a' * 20)
     axs[1].set_ylabel('b' * 20)
-    with pytest.warns(UserWarning):
-        fig.tight_layout()
 
 
 def test_badsubplotgrid():

diff --git a/lib/matplotlib/tight_layout.py b/lib/matplotlib/tight_layout.py
@@ -77,8 +77,15 @@ def auto_adjust_subplotpars(
         if all(not ax.get_visible() for ax in subplots):
             continue
 
-        tight_bbox_raw = Bbox.union([
-            ax.get_tightbbox(renderer) for ax in subplots if ax.get_visible()])
+        bb = []
+        for ax in subplots:
+            if ax.get_visible():
+                try:
+                    bb += [ax.get_tightbbox(renderer, for_layout_only=True)]
+                except TypeError:
+                    bb += [ax.get_tightbbox(renderer)]
+
+        tight_bbox_raw = Bbox.union(bb)
         tight_bbox = TransformedBbox(tight_bbox_raw,
                                      fig.transFigure.inverted())