Close issue https://github.com/Phyks/replot/issues/2

This commit adds padding around the graph, depending on the used
linewidth, to close issue https://github.com/Phyks/replot/issues/2.

replot/figure.py

@@ -536,10 +536,46 @@ class Figure():
             self.legend,
             lambda: self._legend(axis, overload_legend=True)
         )
-        # Set xrange
+        # Set xrange / yrange
         render_helpers.set_axis_property(group_, axis.set_xlim, self.xrange)
-        # Set yrange
         render_helpers.set_axis_property(group_, axis.set_ylim, self.yrange)
+        # Note: Extend axes limits to have the full plot, even with large
+        # linewidths. This is necessary as we do not clip lines.
+        maximum_linewidth = max(
+            max([plt[1].get("lw", 0) for plt in self.plots[group_]]),
+            max([plt[1].get("linewidth", 0) for plt in self.plots[group_]])
+        )
+        if maximum_linewidth > 0:
+            # Only extend axes limits if linewidths is larger than the default
+            # one.
+            ticks_position = {  # Dump ticks position to restore them afterwards
+                "x": (axis.xaxis.get_majorticklocs(),
+                      axis.xaxis.get_minorticklocs()),
+                "y": (axis.yaxis.get_majorticklocs(),
+                      axis.yaxis.get_minorticklocs())
+            }
+            # Set xrange
+            extra_xrange = render_helpers.data_units_from_points(
+                maximum_linewidth,
+                axis,
+                reference="x")
+            xrange = (axis.get_xlim()[0] - extra_xrange / 2,
+                      axis.get_xlim()[1] + extra_xrange / 2)
+            render_helpers.set_axis_property(group_, axis.set_xlim, xrange)
+            # Set yrange
+            extra_yrange = render_helpers.data_units_from_points(
+                maximum_linewidth,
+                axis,
+                reference="y")
+            yrange = (axis.get_ylim()[0] - extra_yrange / 2,
+                      axis.get_ylim()[1] + extra_yrange / 2)
+            render_helpers.set_axis_property(group_, axis.set_ylim, yrange)
+            # Restore ticks
+            axis.xaxis.set_ticks(ticks_position["x"][0], minor=False)
+            axis.xaxis.set_ticks(ticks_position["x"][1], minor=True)
+            axis.yaxis.set_ticks(ticks_position["y"][0], minor=False)
+            axis.yaxis.set_ticks(ticks_position["y"][1], minor=True)
+
 
     def _render_gif_animation(self, figure, axes):
         """

replot/helpers/render.py

@@ -1,6 +1,7 @@
 """
 Various helper functions for plotting.
 """
+import numpy as np
 
 
 def set_axis_property(group_, setter, value, default_setter=None):
@@ -26,3 +27,72 @@ def set_axis_property(group_, setter, value, default_setter=None):
     else:
         if value is not None:
             setter(value)
+
+
+def linewidth_from_data_units(linewidth, axis, reference='y'):
+    """
+    Convert a linewidth in data units to linewidth in points.
+
+    Parameters
+    ----------
+    linewidth: float
+        Linewidth in data units of the respective reference-axis
+    axis: matplotlib axis
+        The axis which is used to extract the relevant transformation
+        data (data limits and size must not change afterwards)
+    reference: string
+        The axis that is taken as a reference for the data width.
+        Possible values: 'x' and 'y'. Defaults to 'y'.
+
+    Returns
+    -------
+    linewidth: float
+        Linewidth in points
+
+    From https://stackoverflow.com/questions/19394505/matplotlib-expand-the-line-with-specified-width-in-data-unit.
+    """
+    fig = axis.get_figure()
+    if reference == 'x':
+        length = fig.bbox_inches.width * axis.get_position().width
+        value_range = np.diff(axis.get_xlim())
+    elif reference == 'y':
+        length = fig.bbox_inches.height * axis.get_position().height
+        value_range = np.diff(axis.get_ylim())
+    # Convert length to points
+    length *= 72  # Inches to points is a fixed conversion in matplotlib
+    # Scale linewidth to value range
+    return linewidth * (length / value_range)
+
+
+def data_units_from_points(points, axis, reference='y'):
+    """
+    Convert points to data units on the given axis.
+
+    Parameters
+    ----------
+    points: float
+        Value in points to convert.
+    axis: matplotlib axis
+        The axis which is used to extract the relevant transformation
+        data (data limits and size must not change afterwards)
+    reference: string
+        The axis that is taken as a reference for the data width.
+        Possible values: 'x' and 'y'. Defaults to 'y'.
+
+    Returns
+    -------
+    points: float
+        Converted value.
+    """
+    fig = axis.get_figure()
+
+    if reference == 'x':
+        length = fig.bbox_inches.width * axis.get_position().width
+        value_range = np.diff(axis.get_xlim())
+    elif reference == 'y':
+        length = fig.bbox_inches.height * axis.get_position().height
+        value_range = np.diff(axis.get_ylim())
+    # Convert length to points
+    length *= 72  # Inches to points is a fixed conversion in matplotlib
+    # Scale linewidth to value range
+    return points / (length / value_range)