From 7da0279fd3b2785e8642f1ba462aa7c721b79058 Mon Sep 17 00:00:00 2001
From: ianhi <ianhuntisaak@gmail.com>
Date: Sat, 9 Jan 2021 00:41:16 -0500
Subject: [PATCH 1/8] Change styling of slider widgets

Goal is to add a clear handle for the user to grab and to provide visual feedback via color change of when the slider has been grabbed.

Simplify slider background rectangles

rename bkd -> track + change default color to lightgrey

lint

remove facecolor from snap demo example

Don't change handle color on grab.

correct errors in slider docstrings

Co-Authored-By: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com>
---
 examples/widgets/slider_demo.py      |   9 +-
 examples/widgets/slider_snap_demo.py |   7 +-
 lib/matplotlib/tests/test_widgets.py |   8 +-
 lib/matplotlib/widgets.py            | 148 +++++++++++++++++++++++----
 4 files changed, 137 insertions(+), 35 deletions(-)

diff --git a/examples/widgets/slider_demo.py b/examples/widgets/slider_demo.py
index aa33315d3db4..ffe66279a77b 100644
--- a/examples/widgets/slider_demo.py
+++ b/examples/widgets/slider_demo.py
@@ -32,14 +32,11 @@ def f(t, amplitude, frequency):
 line, = plt.plot(t, f(t, init_amplitude, init_frequency), lw=2)
 ax.set_xlabel('Time [s]')
 
-axcolor = 'lightgoldenrodyellow'
-ax.margins(x=0)
-
 # adjust the main plot to make room for the sliders
 plt.subplots_adjust(left=0.25, bottom=0.25)
 
 # Make a horizontal slider to control the frequency.
-axfreq = plt.axes([0.25, 0.1, 0.65, 0.03], facecolor=axcolor)
+axfreq = plt.axes([0.25, 0.1, 0.65, 0.03])
 freq_slider = Slider(
     ax=axfreq,
     label='Frequency [Hz]',
@@ -49,7 +46,7 @@ def f(t, amplitude, frequency):
 )
 
 # Make a vertically oriented slider to control the amplitude
-axamp = plt.axes([0.1, 0.25, 0.0225, 0.63], facecolor=axcolor)
+axamp = plt.axes([0.1, 0.25, 0.0225, 0.63])
 amp_slider = Slider(
     ax=axamp,
     label="Amplitude",
@@ -72,7 +69,7 @@ def update(val):
 
 # Create a `matplotlib.widgets.Button` to reset the sliders to initial values.
 resetax = plt.axes([0.8, 0.025, 0.1, 0.04])
-button = Button(resetax, 'Reset', color=axcolor, hovercolor='0.975')
+button = Button(resetax, 'Reset', hovercolor='0.975')
 
 
 def reset(event):
diff --git a/examples/widgets/slider_snap_demo.py b/examples/widgets/slider_snap_demo.py
index e985f84ca7ac..f02dd9a6b961 100644
--- a/examples/widgets/slider_snap_demo.py
+++ b/examples/widgets/slider_snap_demo.py
@@ -28,9 +28,8 @@
 plt.subplots_adjust(bottom=0.25)
 l, = plt.plot(t, s, lw=2)
 
-slider_bkd_color = 'lightgoldenrodyellow'
-ax_freq = plt.axes([0.25, 0.1, 0.65, 0.03], facecolor=slider_bkd_color)
-ax_amp = plt.axes([0.25, 0.15, 0.65, 0.03], facecolor=slider_bkd_color)
+ax_freq = plt.axes([0.25, 0.1, 0.65, 0.03])
+ax_amp = plt.axes([0.25, 0.15, 0.65, 0.03])
 
 # define the values to use for snapping
 allowed_amplitudes = np.concatenate([np.linspace(.1, 5, 100), [6, 7, 8, 9]])
@@ -60,7 +59,7 @@ def update(val):
 samp.on_changed(update)
 
 ax_reset = plt.axes([0.8, 0.025, 0.1, 0.04])
-button = Button(ax_reset, 'Reset', color=slider_bkd_color, hovercolor='0.975')
+button = Button(ax_reset, 'Reset', hovercolor='0.975')
 
 
 def reset(event):
diff --git a/lib/matplotlib/tests/test_widgets.py b/lib/matplotlib/tests/test_widgets.py
index f2ac7749d6ea..6784ac2ab60e 100644
--- a/lib/matplotlib/tests/test_widgets.py
+++ b/lib/matplotlib/tests/test_widgets.py
@@ -332,7 +332,7 @@ def test_slider_horizontal_vertical():
     assert slider.val == 10
     # check the dimension of the slider patch in axes units
     box = slider.poly.get_extents().transformed(ax.transAxes.inverted())
-    assert_allclose(box.bounds, [0, 0, 10/24, 1])
+    assert_allclose(box.bounds, [0, .25, 10/24, .5])
 
     fig, ax = plt.subplots()
     slider = widgets.Slider(ax=ax, label='', valmin=0, valmax=24,
@@ -341,7 +341,7 @@ def test_slider_horizontal_vertical():
     assert slider.val == 10
     # check the dimension of the slider patch in axes units
     box = slider.poly.get_extents().transformed(ax.transAxes.inverted())
-    assert_allclose(box.bounds, [0, 0, 1, 10/24])
+    assert_allclose(box.bounds, [.25, 0, .5, 10/24])
 
 
 @pytest.mark.parametrize("orientation", ["horizontal", "vertical"])
@@ -358,7 +358,7 @@ def test_range_slider(orientation):
         valinit=[0.1, 0.34]
     )
     box = slider.poly.get_extents().transformed(ax.transAxes.inverted())
-    assert_allclose(box.get_points().flatten()[idx], [0.1, 0, 0.34, 1])
+    assert_allclose(box.get_points().flatten()[idx], [0.1, 0.25, 0.34, 0.75])
 
     # Check initial value is set correctly
     assert_allclose(slider.val, (0.1, 0.34))
@@ -366,7 +366,7 @@ def test_range_slider(orientation):
     slider.set_val((0.2, 0.6))
     assert_allclose(slider.val, (0.2, 0.6))
     box = slider.poly.get_extents().transformed(ax.transAxes.inverted())
-    assert_allclose(box.get_points().flatten()[idx], [0.2, 0, 0.6, 1])
+    assert_allclose(box.get_points().flatten()[idx], [0.2, .25, 0.6, .75])
 
     slider.set_val((0.2, 0.1))
     assert_allclose(slider.val, (0.1, 0.2))
diff --git a/lib/matplotlib/widgets.py b/lib/matplotlib/widgets.py
index 7d2243f6c553..5050f73c9df0 100644
--- a/lib/matplotlib/widgets.py
+++ b/lib/matplotlib/widgets.py
@@ -267,9 +267,9 @@ def __init__(self, ax, orientation, closedmin, closedmax,
         self._fmt.set_useOffset(False)  # No additive offset.
         self._fmt.set_useMathText(True)  # x sign before multiplicative offset.
 
-        ax.set_xticks([])
-        ax.set_yticks([])
+        ax.set_axis_off()
         ax.set_navigate(False)
+
         self.connect_event("button_press_event", self._update)
         self.connect_event("button_release_event", self._update)
         if dragging:
@@ -329,7 +329,9 @@ class Slider(SliderBase):
     def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
                  closedmin=True, closedmax=True, slidermin=None,
                  slidermax=None, dragging=True, valstep=None,
-                 orientation='horizontal', *, initcolor='r', **kwargs):
+                 orientation='horizontal', *, initcolor='r',
+                 track_color='lightgrey', handle_facecolor='white',
+                 handle_edgecolor='.75', handle_size=10, **kwargs):
         """
         Parameters
         ----------
@@ -380,6 +382,19 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
             The color of the line at the *valinit* position. Set to ``'none'``
             for no line.
 
+        track_color : color, default: 'lightgrey'
+            The color of the background track. The track is accessible for
+            further styling via the *track* attribute.
+
+        handle_facecolor : color, default: 'white'
+            The facecolor of the circular slider handle.
+
+        handle_edgecolor : color, default: '.75'
+            The edgecolor of the circle slider handle.
+
+        handle_size : int, default: 10
+            The size of the circular slider handle in points.
+
         Notes
         -----
         Additional kwargs are passed on to ``self.poly`` which is the
@@ -404,11 +419,33 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
         self.val = valinit
         self.valinit = valinit
         if orientation == 'vertical':
-            self.poly = ax.axhspan(valmin, valinit, 0, 1, **kwargs)
-            self.hline = ax.axhline(valinit, 0, 1, color=initcolor, lw=1)
+            self.track = Rectangle(
+                (.25, 0), .5, 1,
+                transform=ax.transAxes,
+                facecolor=track_color
+            )
+            ax.add_patch(self.track)
+            self.poly = ax.axhspan(valmin, valinit, .25, .75, **kwargs)
+            self.hline = ax.axhline(valinit, .25, .75, color=initcolor, lw=1)
+            handleXY = [[0.5], [valinit]]
         else:
-            self.poly = ax.axvspan(valmin, valinit, 0, 1, **kwargs)
-            self.vline = ax.axvline(valinit, 0, 1, color=initcolor, lw=1)
+            self.track = Rectangle(
+                (0, .25), 1, .5,
+                transform=ax.transAxes,
+                facecolor=track_color
+            )
+            ax.add_patch(self.track)
+            self.poly = ax.axvspan(valmin, valinit, .25, .75, **kwargs)
+            self.vline = ax.axvline(valinit, .25, .75, color=initcolor, lw=1)
+            handleXY = [[valinit], [0.5]]
+        self._handle, = ax.plot(
+            *handleXY,
+            "o",
+            markersize=handle_size,
+            markeredgecolor=handle_edgecolor,
+            markerfacecolor=handle_facecolor,
+            clip_on=False
+        )
 
         if orientation == 'vertical':
             self.label = ax.text(0.5, 1.02, label, transform=ax.transAxes,
@@ -499,11 +536,13 @@ def set_val(self, val):
         """
         xy = self.poly.xy
         if self.orientation == 'vertical':
-            xy[1] = 0, val
-            xy[2] = 1, val
+            xy[1] = .25, val
+            xy[2] = .75, val
+            self._handle.set_ydata([val])
         else:
-            xy[2] = val, 1
-            xy[3] = val, 0
+            xy[2] = val, .75
+            xy[3] = val, .25
+            self._handle.set_xdata([val])
         self.poly.xy = xy
         self.valtext.set_text(self._format(val))
         if self.drawon:
@@ -558,6 +597,10 @@ def __init__(
         dragging=True,
         valstep=None,
         orientation="horizontal",
+        track_color='lightgrey',
+        handle_facecolor='white',
+        handle_edgecolor='.75',
+        handle_size=10,
         **kwargs,
     ):
         """
@@ -598,6 +641,19 @@ def __init__(
         orientation : {'horizontal', 'vertical'}, default: 'horizontal'
             The orientation of the slider.
 
+        track_color : color, default: 'lightgrey'
+            The color of the background track. The track is accessible for
+            further styling via the *track* attribute.
+
+        handle_facecolor : color, default: 'white'
+            The facecolor of the circular slider handle.
+
+        handle_edgecolor : color, default: '.75'
+            The edgecolor of the circular slider handles.
+
+        handle_size : int, default: 10
+            The size of the circular slider handles in points.
+
         Notes
         -----
         Additional kwargs are passed on to ``self.poly`` which is the
@@ -620,9 +676,43 @@ def __init__(
         self.val = valinit
         self.valinit = valinit
         if orientation == "vertical":
+            self.track = Rectangle(
+                (.25, 0), .5, 2,
+                transform=ax.transAxes,
+                facecolor=track_color
+            )
+            ax.add_patch(self.track)
             self.poly = ax.axhspan(valinit[0], valinit[1], 0, 1, **kwargs)
+            handleXY_1 = [.5, valinit[0]]
+            handleXY_2 = [.5, valinit[1]]
         else:
+            self.track = Rectangle(
+                (0, .25), 1, .5,
+                transform=ax.transAxes,
+                facecolor=track_color
+            )
+            ax.add_patch(self.track)
             self.poly = ax.axvspan(valinit[0], valinit[1], 0, 1, **kwargs)
+            handleXY_1 = [valinit[0], .5]
+            handleXY_2 = [valinit[1], .5]
+        self._handles = [
+            ax.plot(
+                *handleXY_1,
+                "o",
+                markersize=handle_size,
+                markeredgecolor=handle_edgecolor,
+                markerfacecolor=handle_facecolor,
+                clip_on=False
+            )[0],
+            ax.plot(
+                *handleXY_2,
+                "o",
+                markersize=handle_size,
+                markeredgecolor=handle_edgecolor,
+                markerfacecolor=handle_facecolor,
+                clip_on=False
+            )[0]
+        ]
 
         if orientation == "vertical":
             self.label = ax.text(
@@ -661,6 +751,7 @@ def __init__(
                 horizontalalignment="left",
             )
 
+        self._active_handle = None
         self.set_val(valinit)
 
     def _min_in_bounds(self, min):
@@ -698,6 +789,8 @@ def _update_val_from_pos(self, pos):
         else:
             val = self._max_in_bounds(pos)
             self.set_max(val)
+        if self._active_handle:
+            self._active_handle.set_xdata([val])
 
     def _update(self, event):
         """Update the slider position."""
@@ -716,7 +809,20 @@ def _update(self, event):
         ):
             self.drag_active = False
             event.canvas.release_mouse(self.ax)
+            self._active_handle = None
             return
+
+        # determine which handle was grabbed
+        handle = self._handles[
+            np.argmin(
+                np.abs([h.get_xdata()[0] - event.xdata for h in self._handles])
+            )
+        ]
+        # these checks ensure smooth behavior if the handles swap which one
+        # has a higher value. i.e. if one is dragged over and past the other.
+        if handle is not self._active_handle:
+            self._active_handle = handle
+
         if self.orientation == "vertical":
             self._update_val_from_pos(event.ydata)
         else:
@@ -773,17 +879,17 @@ def set_val(self, val):
         val[1] = self._max_in_bounds(val[1])
         xy = self.poly.xy
         if self.orientation == "vertical":
-            xy[0] = 0, val[0]
-            xy[1] = 0, val[1]
-            xy[2] = 1, val[1]
-            xy[3] = 1, val[0]
-            xy[4] = 0, val[0]
+            xy[0] = .25, val[0]
+            xy[1] = .25, val[1]
+            xy[2] = .75, val[1]
+            xy[3] = .75, val[0]
+            xy[4] = .25, val[0]
         else:
-            xy[0] = val[0], 0
-            xy[1] = val[0], 1
-            xy[2] = val[1], 1
-            xy[3] = val[1], 0
-            xy[4] = val[0], 0
+            xy[0] = val[0], .25
+            xy[1] = val[0], .75
+            xy[2] = val[1], .75
+            xy[3] = val[1], .25
+            xy[4] = val[0], .25
         self.poly.xy = xy
         self.valtext.set_text(self._format(val))
         if self.drawon:

From 61304ad1216d3fb5b59dae94dda1f6b4e826b235 Mon Sep 17 00:00:00 2001
From: Ian Hunt-Isaak <ianhuntisaak@gmail.com>
Date: Tue, 12 Jan 2021 17:49:44 -0500
Subject: [PATCH 2/8] correctly specify the type of the slider `poly` attribute

---
 lib/matplotlib/widgets.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/matplotlib/widgets.py b/lib/matplotlib/widgets.py
index 5050f73c9df0..1a8d3de88798 100644
--- a/lib/matplotlib/widgets.py
+++ b/lib/matplotlib/widgets.py
@@ -398,8 +398,8 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
         Notes
         -----
         Additional kwargs are passed on to ``self.poly`` which is the
-        `~matplotlib.patches.Rectangle` that draws the slider knob.  See the
-        `.Rectangle` documentation for valid property names (``facecolor``,
+        `~matplotlib.patches.Polygon` that draws the slider knob.  See the
+        `.Polygon` documentation for valid property names (``facecolor``,
         ``edgecolor``, ``alpha``, etc.).
         """
         super().__init__(ax, orientation, closedmin, closedmax,
@@ -657,8 +657,8 @@ def __init__(
         Notes
         -----
         Additional kwargs are passed on to ``self.poly`` which is the
-        `~matplotlib.patches.Rectangle` that draws the slider knob.  See the
-        `.Rectangle` documentation for valid property names (``facecolor``,
+        `~matplotlib.patches.Polygon` that draws the slider knob.  See the
+        `.Polygon` documentation for valid property names (``facecolor``,
         ``edgecolor``, ``alpha``, etc.).
         """
         super().__init__(ax, orientation, closedmin, closedmax,

From 776af75fde690e05a3faece29a32f92de4e332ee Mon Sep 17 00:00:00 2001
From: Ian Hunt-Isaak <ianhuntisaak@gmail.com>
Date: Fri, 22 Jan 2021 23:41:19 -0500
Subject: [PATCH 3/8] Consolidate slider handle styling kwargs

Co-Authored-By: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com>
---
 lib/matplotlib/widgets.py | 69 +++++++++++++++++++++++----------------
 1 file changed, 41 insertions(+), 28 deletions(-)

diff --git a/lib/matplotlib/widgets.py b/lib/matplotlib/widgets.py
index 1a8d3de88798..c8d26b6b653b 100644
--- a/lib/matplotlib/widgets.py
+++ b/lib/matplotlib/widgets.py
@@ -330,8 +330,7 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
                  closedmin=True, closedmax=True, slidermin=None,
                  slidermax=None, dragging=True, valstep=None,
                  orientation='horizontal', *, initcolor='r',
-                 track_color='lightgrey', handle_facecolor='white',
-                 handle_edgecolor='.75', handle_size=10, **kwargs):
+                 track_color='lightgrey', handle_style=None, **kwargs):
         """
         Parameters
         ----------
@@ -386,14 +385,16 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
             The color of the background track. The track is accessible for
             further styling via the *track* attribute.
 
-        handle_facecolor : color, default: 'white'
-            The facecolor of the circular slider handle.
+        handle_style : dict
+            Properties of the slider handle. Supported values are
 
-        handle_edgecolor : color, default: '.75'
-            The edgecolor of the circle slider handle.
-
-        handle_size : int, default: 10
-            The size of the circular slider handle in points.
+            ========= ===== ======= ========================================
+            Key       Value Default Description
+            ========= ===== ======= ========================================
+            facecolor color 'white' The facecolor of the slider handle.
+            edgecolor color '.75'   The edgecolor of the slider handle.
+            size      int   10      The size of the slider handle in points.
+            ========= ===== ======= ========================================
 
         Notes
         -----
@@ -418,6 +419,15 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
             valinit = valmin
         self.val = valinit
         self.valinit = valinit
+
+        marker_props = {}
+        defaults = {'facecolor':'white', 'edgecolor':'.75', 'size':10}
+        if handle_style is not None:
+            for k in ['facecolor', 'edgecolor', 'size']:
+                marker_props[f'marker{k}'] = handle_style.get(k, defaults[k])
+        else:
+            marker_props = {f'marker{k}': v for k, v in defaults.items()}
+
         if orientation == 'vertical':
             self.track = Rectangle(
                 (.25, 0), .5, 1,
@@ -441,9 +451,7 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
         self._handle, = ax.plot(
             *handleXY,
             "o",
-            markersize=handle_size,
-            markeredgecolor=handle_edgecolor,
-            markerfacecolor=handle_facecolor,
+            **marker_props,
             clip_on=False
         )
 
@@ -598,9 +606,7 @@ def __init__(
         valstep=None,
         orientation="horizontal",
         track_color='lightgrey',
-        handle_facecolor='white',
-        handle_edgecolor='.75',
-        handle_size=10,
+        handle_style=None,
         **kwargs,
     ):
         """
@@ -645,14 +651,16 @@ def __init__(
             The color of the background track. The track is accessible for
             further styling via the *track* attribute.
 
-        handle_facecolor : color, default: 'white'
-            The facecolor of the circular slider handle.
+        handle_style : dict
+            Properties of the slider handles. Supported values are
 
-        handle_edgecolor : color, default: '.75'
-            The edgecolor of the circular slider handles.
-
-        handle_size : int, default: 10
-            The size of the circular slider handles in points.
+            ========= ===== ======= =========================================
+            Key       Value Default Description
+            ========= ===== ======= =========================================
+            facecolor color 'white' The facecolor of the slider handles.
+            edgecolor color '.75'   The edgecolor of the slider handles.
+            size      int   10      The size of the slider handles in points.
+            ========= ===== ======= =========================================
 
         Notes
         -----
@@ -675,6 +683,15 @@ def __init__(
             valinit = self._value_in_bounds(valinit)
         self.val = valinit
         self.valinit = valinit
+
+        marker_props = {}
+        defaults = {'facecolor':'white', 'edgecolor':'.75', 'size':10}
+        if handle_style is not None:
+            for k in ['facecolor', 'edgecolor', 'size']:
+                marker_props[f'marker{k}'] = handle_style.get(k, defaults[k])
+        else:
+            marker_props = {f'marker{k}': v for k, v in defaults.items()}
+
         if orientation == "vertical":
             self.track = Rectangle(
                 (.25, 0), .5, 2,
@@ -699,17 +716,13 @@ def __init__(
             ax.plot(
                 *handleXY_1,
                 "o",
-                markersize=handle_size,
-                markeredgecolor=handle_edgecolor,
-                markerfacecolor=handle_facecolor,
+                **marker_props,
                 clip_on=False
             )[0],
             ax.plot(
                 *handleXY_2,
                 "o",
-                markersize=handle_size,
-                markeredgecolor=handle_edgecolor,
-                markerfacecolor=handle_facecolor,
+                **marker_props,
                 clip_on=False
             )[0]
         ]

From 2f153b84cc510818943e574a380b17f6dc9f9584 Mon Sep 17 00:00:00 2001
From: Ian Hunt-Isaak <ianhuntisaak@gmail.com>
Date: Mon, 15 Feb 2021 19:20:13 -0500
Subject: [PATCH 4/8] promote all keys to marker{key}

Co-authored-by: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com>
---
 lib/matplotlib/widgets.py | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/lib/matplotlib/widgets.py b/lib/matplotlib/widgets.py
index c8d26b6b653b..275c4c01fec4 100644
--- a/lib/matplotlib/widgets.py
+++ b/lib/matplotlib/widgets.py
@@ -420,13 +420,8 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
         self.val = valinit
         self.valinit = valinit
 
-        marker_props = {}
         defaults = {'facecolor':'white', 'edgecolor':'.75', 'size':10}
-        if handle_style is not None:
-            for k in ['facecolor', 'edgecolor', 'size']:
-                marker_props[f'marker{k}'] = handle_style.get(k, defaults[k])
-        else:
-            marker_props = {f'marker{k}': v for k, v in defaults.items()}
+        marker_props = {f'marker{k}': v for k, v in {**defaults, **handle_style}}
 
         if orientation == 'vertical':
             self.track = Rectangle(

From 1e3f6526d0f4868affe2a53cac7fb94d1acd0778 Mon Sep 17 00:00:00 2001
From: ianhi <ianhuntisaak@gmail.com>
Date: Mon, 15 Feb 2021 19:26:47 -0500
Subject: [PATCH 5/8] expand doc string for handle_style

---
 lib/matplotlib/widgets.py | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/lib/matplotlib/widgets.py b/lib/matplotlib/widgets.py
index 275c4c01fec4..6c909533bd52 100644
--- a/lib/matplotlib/widgets.py
+++ b/lib/matplotlib/widgets.py
@@ -386,7 +386,7 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
             further styling via the *track* attribute.
 
         handle_style : dict
-            Properties of the slider handle. Supported values are
+            Properties of the slider handle. Default values are
 
             ========= ===== ======= ========================================
             Key       Value Default Description
@@ -396,6 +396,10 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
             size      int   10      The size of the slider handle in points.
             ========= ===== ======= ========================================
 
+            Other values will be transformed as marker{foo} and passed to the
+            `~.Line2D` constructor. e.g. ``handle_style = {'style'='x'}`` will
+            result in ``markerstyle = 'x'``.
+
         Notes
         -----
         Additional kwargs are passed on to ``self.poly`` which is the
@@ -420,8 +424,10 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
         self.val = valinit
         self.valinit = valinit
 
-        defaults = {'facecolor':'white', 'edgecolor':'.75', 'size':10}
-        marker_props = {f'marker{k}': v for k, v in {**defaults, **handle_style}}
+        defaults = {'facecolor': 'white', 'edgecolor': '.75', 'size': 10}
+        marker_props = {
+            f'marker{k}': v for k, v in {**defaults, **handle_style}
+        }
 
         if orientation == 'vertical':
             self.track = Rectangle(
@@ -647,7 +653,7 @@ def __init__(
             further styling via the *track* attribute.
 
         handle_style : dict
-            Properties of the slider handles. Supported values are
+            Properties of the slider handles. Default values are
 
             ========= ===== ======= =========================================
             Key       Value Default Description
@@ -657,6 +663,10 @@ def __init__(
             size      int   10      The size of the slider handles in points.
             ========= ===== ======= =========================================
 
+            Other values will be transformed as marker{foo} and passed to the
+            `~.Line2D` constructor. e.g. ``handle_style = {'style'='x'}`` will
+            result in ``markerstyle = 'x'``.
+
         Notes
         -----
         Additional kwargs are passed on to ``self.poly`` which is the
@@ -679,13 +689,10 @@ def __init__(
         self.val = valinit
         self.valinit = valinit
 
-        marker_props = {}
-        defaults = {'facecolor':'white', 'edgecolor':'.75', 'size':10}
-        if handle_style is not None:
-            for k in ['facecolor', 'edgecolor', 'size']:
-                marker_props[f'marker{k}'] = handle_style.get(k, defaults[k])
-        else:
-            marker_props = {f'marker{k}': v for k, v in defaults.items()}
+        defaults = {'facecolor': 'white', 'edgecolor': '.75', 'size': 10}
+        marker_props = {
+            f'marker{k}': v for k, v in {**defaults, **handle_style}
+        }
 
         if orientation == "vertical":
             self.track = Rectangle(

From e160db4d3b58f124f26711bed68c06a30a676084 Mon Sep 17 00:00:00 2001
From: ianhi <ianhuntisaak@gmail.com>
Date: Mon, 15 Feb 2021 20:24:00 -0500
Subject: [PATCH 6/8] fix errors in processing handle style

---
 lib/matplotlib/widgets.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lib/matplotlib/widgets.py b/lib/matplotlib/widgets.py
index 6c909533bd52..1d4350f5b24c 100644
--- a/lib/matplotlib/widgets.py
+++ b/lib/matplotlib/widgets.py
@@ -425,8 +425,9 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
         self.valinit = valinit
 
         defaults = {'facecolor': 'white', 'edgecolor': '.75', 'size': 10}
+        handle_style = {} if handle_style is None else handle_style
         marker_props = {
-            f'marker{k}': v for k, v in {**defaults, **handle_style}
+            f'marker{k}': v for k, v in {**defaults, **handle_style}.items()
         }
 
         if orientation == 'vertical':
@@ -690,8 +691,9 @@ def __init__(
         self.valinit = valinit
 
         defaults = {'facecolor': 'white', 'edgecolor': '.75', 'size': 10}
+        handle_style = {} if handle_style is None else handle_style
         marker_props = {
-            f'marker{k}': v for k, v in {**defaults, **handle_style}
+            f'marker{k}': v for k, v in {**defaults, **handle_style}.items()
         }
 
         if orientation == "vertical":

From a7c4df6a4304cf71514858cd5f998e66588d8b7c Mon Sep 17 00:00:00 2001
From: Ian Hunt-Isaak <ianhuntisaak@gmail.com>
Date: Sun, 7 Mar 2021 22:38:44 -0500
Subject: [PATCH 7/8] tune slider initline parameters to minimize asymmetry

Co-Authored-By: Tim Hoffmann <2836374+timhoffm@users.noreply.github.com>
---
 lib/matplotlib/widgets.py | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/lib/matplotlib/widgets.py b/lib/matplotlib/widgets.py
index 1d4350f5b24c..09573e45950e 100644
--- a/lib/matplotlib/widgets.py
+++ b/lib/matplotlib/widgets.py
@@ -438,7 +438,7 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
             )
             ax.add_patch(self.track)
             self.poly = ax.axhspan(valmin, valinit, .25, .75, **kwargs)
-            self.hline = ax.axhline(valinit, .25, .75, color=initcolor, lw=1)
+            self.hline = ax.axhline(valinit, .15, .85, color=initcolor, lw=1)
             handleXY = [[0.5], [valinit]]
         else:
             self.track = Rectangle(
@@ -448,7 +448,12 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
             )
             ax.add_patch(self.track)
             self.poly = ax.axvspan(valmin, valinit, .25, .75, **kwargs)
-            self.vline = ax.axvline(valinit, .25, .75, color=initcolor, lw=1)
+            # These asymmetric limits (.2, .9) minimize the asymmetry
+            # above and below the *poly* when rendered to pixels.
+            # This seems to be different for Horizontal and Vertical lines.
+            # For discussion see:
+            # https://github.com/matplotlib/matplotlib/pull/19265
+            self.vline = ax.axvline(valinit, .2, .9, color=initcolor, lw=1)
             handleXY = [[valinit], [0.5]]
         self._handle, = ax.plot(
             *handleXY,

From f5dcedd2e989fac1fbc7ab54d313f8698c5717c9 Mon Sep 17 00:00:00 2001
From: Ian Hunt-Isaak <ianhuntisaak@gmail.com>
Date: Wed, 23 Jun 2021 17:17:38 -0400
Subject: [PATCH 8/8] Add whats new for new slider styles

---
 doc/users/next_whats_new/slider_styling.rst | 42 +++++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 doc/users/next_whats_new/slider_styling.rst

diff --git a/doc/users/next_whats_new/slider_styling.rst b/doc/users/next_whats_new/slider_styling.rst
new file mode 100644
index 000000000000..f007954b4806
--- /dev/null
+++ b/doc/users/next_whats_new/slider_styling.rst
@@ -0,0 +1,42 @@
+Updated the appearance of Slider widgets
+----------------------------------------
+
+The appearance of `~.Slider` and `~.RangeSlider` widgets
+were updated and given new styling parameters for the
+added handles.
+
+.. plot::
+
+    import matplotlib.pyplot as plt
+    from matplotlib.widgets import Slider
+
+    plt.figure(figsize=(4, 2))
+    ax_old = plt.axes([0.2, 0.65, 0.65, 0.1])
+    ax_new = plt.axes([0.2, 0.25, 0.65, 0.1])
+    Slider(ax_new, "New", 0, 1)
+
+    ax = ax_old
+    valmin = 0
+    valinit = 0.5
+    ax.set_xlim([0, 1])
+    ax_old.axvspan(valmin, valinit, 0, 1)
+    ax.axvline(valinit, 0, 1, color="r", lw=1)
+    ax.set_xticks([])
+    ax.set_yticks([])
+    ax.text(
+        -0.02,
+        0.5,
+        "Old",
+        transform=ax.transAxes,
+        verticalalignment="center",
+        horizontalalignment="right",
+    )
+
+    ax.text(
+        1.02,
+        0.5,
+        "0.5",
+        transform=ax.transAxes,
+        verticalalignment="center",
+        horizontalalignment="left",
+    )