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"""
Helper module for the *bbox_inches* parameter in `.Figure.savefig`.
"""
from matplotlib.transforms import Bbox, TransformedBbox, Affine2D
def adjust_bbox(fig, bbox_inches, fixed_dpi=None):
"""
Temporarily adjust the figure so that only the specified area
(bbox_inches) is saved.
It modifies fig.bbox, fig.bbox_inches,
fig.transFigure._boxout, and fig.patch. While the figure size
changes, the scale of the original figure is conserved. A
function which restores the original values are returned.
"""
origBbox = fig.bbox
origBboxInches = fig.bbox_inches
_boxout = fig.transFigure._boxout
old_aspect = []
locator_list = []
sentinel = object()
for ax in fig.axes:
locator = ax.get_axes_locator()
if locator is not None:
ax.apply_aspect(locator(ax, None))
locator_list.append(locator)
current_pos = ax.get_position(original=False).frozen()
ax.set_axes_locator(lambda a, r, _pos=current_pos: _pos)
# override the method that enforces the aspect ratio on the Axes
if 'apply_aspect' in ax.__dict__:
old_aspect.append(ax.apply_aspect)
else:
old_aspect.append(sentinel)
ax.apply_aspect = lambda pos=None: None
def restore_bbox():
for ax, loc, aspect in zip(fig.axes, locator_list, old_aspect):
ax.set_axes_locator(loc)
if aspect is sentinel:
# delete our no-op function which un-hides the original method
del ax.apply_aspect
else:
ax.apply_aspect = aspect
fig.bbox = origBbox
fig.bbox_inches = origBboxInches
fig.transFigure._boxout = _boxout
fig.transFigure.invalidate()
fig.patch.set_bounds(0, 0, 1, 1)
if fixed_dpi is None:
fixed_dpi = fig.dpi
tr = Affine2D().scale(fixed_dpi)
dpi_scale = fixed_dpi / fig.dpi
fig.bbox_inches = Bbox.from_bounds(0, 0, *bbox_inches.size)
x0, y0 = tr.transform(bbox_inches.p0)
w1, h1 = fig.bbox.size * dpi_scale
fig.transFigure._boxout = Bbox.from_bounds(-x0, -y0, w1, h1)
fig.transFigure.invalidate()
fig.bbox = TransformedBbox(fig.bbox_inches, tr)
fig.patch.set_bounds(x0 / w1, y0 / h1,
fig.bbox.width / w1, fig.bbox.height / h1)
return restore_bbox
def process_figure_for_rasterizing(fig, bbox_inches_restore, fixed_dpi=None):
"""
A function that needs to be called when figure dpi changes during the
drawing (e.g., rasterizing). It recovers the bbox and re-adjust it with
the new dpi.
"""
bbox_inches, restore_bbox = bbox_inches_restore
restore_bbox()
r = adjust_bbox(fig, bbox_inches, fixed_dpi)
return bbox_inches, r
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