matplotlib · jakelevi1996 · Sep 27, 2024 · Sep 27, 2024 · Sep 27, 2024 · Sep 27, 2024
diff --git a/lib/matplotlib/_constrained_layout.py b/lib/matplotlib/_constrained_layout.py
@@ -226,19 +226,12 @@ def make_layoutgrids_gs(layoutgrids, gs):
        if parentgs not in layoutgrids:
            layoutgrids = make_layoutgrids_gs(layoutgrids, parentgs)
        subspeclb = layoutgrids[parentgs]
-        # gridspecfromsubplotspec need an outer container:
-        # get a unique representation:
-        rep = (gs, 'top')
-        if rep not in layoutgrids:
-            layoutgrids[rep] = mlayoutgrid.LayoutGrid(
-                parent=subspeclb,
-                name='top',
-                nrows=1, ncols=1,
-                parent_pos=(subplot_spec.rowspan, subplot_spec.colspan))
        layoutgrids[gs] = mlayoutgrid.LayoutGrid(
-                parent=layoutgrids[rep],
+                parent=subspeclb,
+                parent_flush=True,
                name='gridspec',
                nrows=gs._nrows, ncols=gs._ncols,
+                parent_pos=(subplot_spec.rowspan, subplot_spec.colspan),
                width_ratios=gs.get_width_ratios(),
                height_ratios=gs.get_height_ratios())
    return layoutgrids
@@ -434,6 +427,14 @@ def make_layout_margins(layoutgrids, fig, renderer, *, w_pad=0, h_pad=0,
                if (cbp_rspan.start == ss.rowspan.start and
                        cbbbox.y1 > bbox.y1):
                    margin['top'] += cbbbox.y1 - bbox.y1
+
+        if layoutgrids[gs].parent_flush:
+            inner_lb = layoutgrids[gs]
+            parent_ss = gs._subplot_spec
+            parent_gs = parent_ss.get_gridspec()
+            parent_lb = layoutgrids[parent_gs]
+            match_nested_margins(inner_lb, parent_lb, parent_ss)
+
        # pass the new margins down to the layout grid for the solution...
        layoutgrids[gs].edit_outer_margin_mins(margin, ss)

@@ -457,6 +458,24 @@ def make_layout_margins(layoutgrids, fig, renderer, *, w_pad=0, h_pad=0,
                layoutgrids[fig].edit_margin_min('left', w)


+def match_nested_margins(inner_lb, parent_lb, parent_ss):
+    def _match(loc, inner_cell, parent_cell):
+        inner_size = inner_lb.get_margins(loc, inner_cell)
+        parent_size = parent_lb.get_margins(loc, parent_cell)
+        size = max(parent_size, inner_size)
+        inner_lb.edit_margin_min(loc, size, inner_cell)
+        parent_lb.edit_margin_min(loc, size, parent_cell)
+
+    _match('left',      0, parent_ss.colspan.start)
+    _match('leftcb',    0, parent_ss.colspan.start)
+    _match('right',    -1, parent_ss.colspan.stop - 1)
+    _match('rightcb',  -1, parent_ss.colspan.stop - 1)
+    _match('top',       0, parent_ss.rowspan.start)
+    _match('topcb',     0, parent_ss.rowspan.start)
+    _match('bottom',   -1, parent_ss.rowspan.stop - 1)
+    _match('bottomcb', -1, parent_ss.rowspan.stop - 1)
+
+
 def make_margin_suptitles(layoutgrids, fig, renderer, *, w_pad=0, h_pad=0):
    # Figure out how large the suptitle is and make the
    # top level figure margin larger.

diff --git a/lib/matplotlib/_layoutgrid.py b/lib/matplotlib/_layoutgrid.py
@@ -34,12 +34,13 @@ class LayoutGrid:
    """

    def __init__(self, parent=None, parent_pos=(0, 0),
-                 parent_inner=False, name='', ncols=1, nrows=1,
+                 parent_inner=False, parent_flush=False, name='', ncols=1, nrows=1,
                 h_pad=None, w_pad=None, width_ratios=None,
                 height_ratios=None):
        Variable = kiwi.Variable
        self.parent_pos = parent_pos
        self.parent_inner = parent_inner
+        self.parent_flush = parent_flush
        self.name = name + seq_id()
        if isinstance(parent, LayoutGrid):
            self.name = f'{parent.name}.{self.name}'
@@ -202,6 +203,35 @@ def parent_constraints(self, parent):
                  # from top to bottom
                  self.tops[0] == top,
                  self.bottoms[-1] == bottom]
+            if self.parent_flush:
+                left_outer = (parent.lefts[cols[0]] +
+                              parent.margins['left'][cols[0]] +
+                              parent.margins['leftcb'][cols[0]])
+                right_outer = (parent.rights[cols[-1]] -
+                               parent.margins['right'][cols[-1]] -
+                               parent.margins['rightcb'][cols[-1]])
+                top_outer = (parent.tops[rows[0]] -
+                             parent.margins['top'][rows[0]] -
+                             parent.margins['topcb'][rows[0]])
+                bottom_outer = (parent.bottoms[rows[-1]] +
+                                parent.margins['bottom'][rows[-1]] +
+                                parent.margins['bottomcb'][rows[-1]])
+                left_inner = (self.lefts[0] +
+                              self.margins['left'][0] +
+                              self.margins['leftcb'][0])
+                right_inner = (self.rights[-1] -
+                               self.margins['right'][-1] -
+                               self.margins['rightcb'][-1])
+                top_inner = (self.tops[0] -
+                             self.margins['top'][0] -
+                             self.margins['topcb'][0])
+                bottom_inner = (self.bottoms[-1] +
+                                self.margins['bottom'][-1] +
+                                self.margins['bottomcb'][-1])
+                hc += [left_outer == left_inner,
+                       right_outer == right_inner,
+                       top_outer == top_inner,
+                       bottom_outer == bottom_inner]
        for c in hc:
            self.solver.addConstraint(c | 'required')


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/...lotlib/tests/baseline_images/test_constrainedlayout/constrained_layout11rat.png b/...lotlib/tests/baseline_images/test_constrainedlayout/constrained_layout11rat.png
diff --git a/...matplotlib/tests/baseline_images/test_constrainedlayout/constrained_layout6.png b/...matplotlib/tests/baseline_images/test_constrainedlayout/constrained_layout6.png
diff --git a/...ib/tests/baseline_images/test_constrainedlayout/plot_nested_grid_alignment1.png b/...ib/tests/baseline_images/test_constrainedlayout/plot_nested_grid_alignment1.png
diff --git a/...ib/tests/baseline_images/test_constrainedlayout/plot_nested_grid_alignment2.png b/...ib/tests/baseline_images/test_constrainedlayout/plot_nested_grid_alignment2.png
diff --git a/...ib/tests/baseline_images/test_constrainedlayout/plot_nested_grid_alignment3.png b/...ib/tests/baseline_images/test_constrainedlayout/plot_nested_grid_alignment3.png
diff --git a/...ib/tests/baseline_images/test_constrainedlayout/plot_nested_grid_alignment4.png b/...ib/tests/baseline_images/test_constrainedlayout/plot_nested_grid_alignment4.png
diff --git a/...ib/tests/baseline_images/test_constrainedlayout/plot_nested_grid_alignment5.png b/...ib/tests/baseline_images/test_constrainedlayout/plot_nested_grid_alignment5.png
diff --git a/...ib/tests/baseline_images/test_constrainedlayout/plot_nested_grid_alignment6.png b/...ib/tests/baseline_images/test_constrainedlayout/plot_nested_grid_alignment6.png
diff --git a/lib/matplotlib/tests/test_constrainedlayout.py b/lib/matplotlib/tests/test_constrainedlayout.py
@@ -719,3 +719,81 @@ def test_layout_leak():
    gc.collect()
    assert not any(isinstance(obj, mpl._layoutgrid.LayoutGrid)
                   for obj in gc.get_objects())
+
+
+def plot_nested_grid_alignment(top, middle, bottom_axes, bottom):
+    def add_subplots(axis, nx, ny):
+        axis.clear()
+        axis.get_xaxis().set_visible(False)
+        axis.get_yaxis().set_visible(False)
+        subplot_spec = axis.get_subplotspec()
+        subgrid_spec = subplot_spec.subgridspec(nx, ny)
+        axis_list = subgrid_spec.subplots().flatten().tolist()
+        for a in axis_list:
+            show_random_image(a)
+
+        return axis_list
+
+    def show_random_image(axis):
+        z = np.linspace(0, 1, 30).reshape(10, 3)
+        axis.pcolormesh(z, cmap="plasma")
+
+    fig = plt.figure(figsize=[20, 12], layout="constrained")
+    fig.get_layout_engine().set(w_pad=0.2, h_pad=0.2)
+
+    axes = fig.subplots(2, 2, width_ratios=[1, 2]).flatten().tolist()
+    for a in axes:
+        show_random_image(a)
+    show_random_image(axes[0])
+    if top:
+        axes[0].set_title("title", fontsize=50)
+        axes[0].set_xlabel("xlabel", fontsize=50)
+        axes[0].get_xaxis().set_tick_params(labelsize=50)
+        axes[-1].set_ylabel("ylabel", fontsize=50)
+        axes[-1].get_yaxis().set_tick_params(labelsize=50)
+        axes[0].get_xaxis().set_visible(False)
+    axes = add_subplots(axes[1], 2, 2)
+    if middle:
+        axes[-1].set_title("title", fontsize=50)
+        axes[0].set_title("title", fontsize=50)
+        axes[0].set_ylabel("ylabel", fontsize=50)
+        axes[0].get_yaxis().set_tick_params(labelsize=30)
+        axes[1].set_ylabel("ylabel", fontsize=50)
+        axes[1].get_yaxis().set_tick_params(labelsize=30)
+        axes[-1].get_xaxis().set_tick_params(labelsize=50)
+        axes[-1].set_xlabel("xlabel", fontsize=50)
+    if bottom_axes:
+        axes = add_subplots(axes[2], 2, 3)
+        if bottom:
+            axes[3].set_ylabel("ylabel", fontsize=50)
+            axes[3].get_yaxis().set_tick_params(labelsize=50)
+
+
+@image_comparison(['plot_nested_grid_alignment1.png'])
+def test_nested_grid_alignment1():
+    plot_nested_grid_alignment(False, False, False, False)
+
+
+@image_comparison(['plot_nested_grid_alignment2.png'])
+def test_nested_grid_alignment2():
+    plot_nested_grid_alignment(True, False, False, False)
+
+
+@image_comparison(['plot_nested_grid_alignment3.png'])
+def test_nested_grid_alignment3():
+    plot_nested_grid_alignment(False, True, False, False)
+
+
+@image_comparison(['plot_nested_grid_alignment4.png'])
+def test_nested_grid_alignment4():
+    plot_nested_grid_alignment(True, False, True, False)
+
+
+@image_comparison(['plot_nested_grid_alignment5.png'])
+def test_nested_grid_alignment5():
+    plot_nested_grid_alignment(False, True, True, False)
+
+
+@image_comparison(['plot_nested_grid_alignment6.png'])
+def test_nested_grid_alignment6():
+    plot_nested_grid_alignment(False, False, True, True)