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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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