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Add blitting to Slider widgets #23439

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Add blitting to Slider widgets #23439

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107 changes: 87 additions & 20 deletions lib/matplotlib/widgets.py
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Original file line number Diff line number Diff line change
Expand Up @@ -232,7 +232,7 @@ class SliderBase(AxesWidget):
For the slider to remain responsive you must maintain a reference to it.
"""
def __init__(self, ax, orientation, closedmin, closedmax,
valmin, valmax, valfmt, dragging, valstep):
valmin, valmax, valfmt, dragging, valstep, useblit):
if ax.name == '3d':
raise ValueError('Sliders cannot be added to 3D Axes')

Expand Down Expand Up @@ -265,6 +265,11 @@ def __init__(self, ax, orientation, closedmin, closedmax,
ax.set_axis_off()
ax.set_navigate(False)

self._useblit = useblit and self.canvas.supports_blit
if self._useblit:
self._background = None
self.connect_event("draw_event", self._clear)

self.connect_event("button_press_event", self._update)
self.connect_event("button_release_event", self._update)
if dragging:
Expand Down Expand Up @@ -301,6 +306,18 @@ def reset(self):
if np.any(self.val != self.valinit):
self.set_val(self.valinit)

def _blit_draw(self, artists):
if not self.drawon:
return
if not self._useblit or self._background is None:
self.ax.figure.canvas.draw_idle()
return

self.canvas.restore_region(self._background)
for a in artists:
self.ax.draw_artist(a)
self.canvas.blit(self.ax.get_tightbbox())


class Slider(SliderBase):
"""
Expand All @@ -320,7 +337,8 @@ 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_style=None, **kwargs):
track_color='lightgrey', handle_style=None, useblit=False,
**kwargs):
"""
Parameters
----------
Expand Down Expand Up @@ -390,6 +408,13 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
`~.Line2D` constructor. e.g. ``handle_style = {'style'='x'}`` will
result in ``markerstyle = 'x'``.

useblit : bool, default: False
Use blitting for faster drawing if supported by the backend.
See the tutorial :doc:`/tutorials/advanced/blitting` for details.

If you enable blitting, you should set *valfmt* to a fixed-width
format, or there may be artifacts if the text changes width.

Notes
-----
Additional kwargs are passed on to ``self.poly`` which is the
Expand All @@ -398,7 +423,7 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
``edgecolor``, ``alpha``, etc.).
"""
super().__init__(ax, orientation, closedmin, closedmax,
valmin, valmax, valfmt, dragging, valstep)
valmin, valmax, valfmt, dragging, valstep, useblit)

if slidermin is not None and not hasattr(slidermin, 'val'):
raise ValueError(
Expand All @@ -419,6 +444,7 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
marker_props = {
f'marker{k}': v for k, v in {**defaults, **handle_style}.items()
}
animated_style = {'animated': True} if self._useblit else {}

if orientation == 'vertical':
self.track = Rectangle(
Expand All @@ -427,11 +453,14 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
facecolor=track_color
)
ax.add_patch(self.track)
self.poly = ax.axhspan(valmin, valinit, .25, .75, **kwargs)
self.poly = ax.axhspan(valmin, valinit, .25, .75, **animated_style,
**kwargs)
# Drawing a longer line and clipping it to the track avoids
# pixelation-related asymmetries.
self.hline = ax.axhline(valinit, 0, 1, color=initcolor, lw=1,
clip_path=TransformedPatchPath(self.track))
self._line = self.hline = ax.axhline(
valinit, 0, 1, color=initcolor, lw=1,
clip_path=TransformedPatchPath(self.track),
**animated_style)
handleXY = [[0.5], [valinit]]
else:
self.track = Rectangle(
Expand All @@ -440,15 +469,19 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
facecolor=track_color
)
ax.add_patch(self.track)
self.poly = ax.axvspan(valmin, valinit, .25, .75, **kwargs)
self.vline = ax.axvline(valinit, 0, 1, color=initcolor, lw=1,
clip_path=TransformedPatchPath(self.track))
self.poly = ax.axvspan(valmin, valinit, .25, .75, **animated_style,
**kwargs)
self._line = self.vline = ax.axvline(
valinit, 0, 1, color=initcolor, lw=1,
clip_path=TransformedPatchPath(self.track),
**animated_style)
handleXY = [[valinit], [0.5]]
self._handle, = ax.plot(
*handleXY,
"o",
**marker_props,
clip_on=False
clip_on=False,
**animated_style
)

if orientation == 'vertical':
Expand All @@ -459,7 +492,8 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
self.valtext = ax.text(0.5, -0.02, self._format(valinit),
transform=ax.transAxes,
verticalalignment='top',
horizontalalignment='center')
horizontalalignment='center',
**animated_style)
else:
self.label = ax.text(-0.02, 0.5, label, transform=ax.transAxes,
verticalalignment='center',
Expand All @@ -468,10 +502,22 @@ def __init__(self, ax, label, valmin, valmax, valinit=0.5, valfmt=None,
self.valtext = ax.text(1.02, 0.5, self._format(valinit),
transform=ax.transAxes,
verticalalignment='center',
horizontalalignment='left')
horizontalalignment='left',
**animated_style)

self.set_val(valinit)

def _clear(self, event):
"""Internal event handler to refresh the blitting background."""
if self.ignore(event):
return
area = self.ax.get_tightbbox()
self._background = self.canvas.copy_from_bbox(area)
artists = [self.poly, self._line, self.valtext, self._handle]
for a in artists:
self.ax.draw_artist(a)
self.canvas.blit(self.ax.get_tightbbox())

def _value_in_bounds(self, val):
"""Makes sure *val* is with given bounds."""
val = self._stepped_value(val)
Expand Down Expand Up @@ -549,8 +595,7 @@ def set_val(self, val):
self._handle.set_xdata([val])
self.poly.xy = xy
self.valtext.set_text(self._format(val))
if self.drawon:
self.ax.figure.canvas.draw_idle()
self._blit_draw([self.poly, self._line, self.valtext, self._handle])
self.val = val
if self.eventson:
self._observers.process('changed', val)
Expand Down Expand Up @@ -603,6 +648,7 @@ def __init__(
orientation="horizontal",
track_color='lightgrey',
handle_style=None,
useblit=False,
**kwargs,
):
"""
Expand Down Expand Up @@ -662,6 +708,13 @@ def __init__(
`~.Line2D` constructor. e.g. ``handle_style = {'style'='x'}`` will
result in ``markerstyle = 'x'``.

useblit : bool, default: False
Use blitting for faster drawing if supported by the backend.
See the tutorial :doc:`/tutorials/advanced/blitting` for details.

If you enable blitting, you should set *valfmt* to a fixed-width
format, or there may be artifacts if the text changes width.

Notes
-----
Additional kwargs are passed on to ``self.poly`` which is the
Expand All @@ -670,7 +723,7 @@ def __init__(
``edgecolor``, ``alpha``, etc.).
"""
super().__init__(ax, orientation, closedmin, closedmax,
valmin, valmax, valfmt, dragging, valstep)
valmin, valmax, valfmt, dragging, valstep, useblit)

# Set a value to allow _value_in_bounds() to work.
self.val = [valmin, valmax]
Expand All @@ -689,6 +742,7 @@ def __init__(
marker_props = {
f'marker{k}': v for k, v in {**defaults, **handle_style}.items()
}
animated_style = {'animated': True} if self._useblit else {}

if orientation == "vertical":
self.track = Rectangle(
Expand All @@ -710,7 +764,7 @@ def __init__(
poly_transform = self.ax.get_xaxis_transform(which="grid")
handleXY_1 = [valinit[0], .5]
handleXY_2 = [valinit[1], .5]
self.poly = Polygon(np.zeros([5, 2]), **kwargs)
self.poly = Polygon(np.zeros([5, 2]), **animated_style, **kwargs)
self._update_selection_poly(*valinit)
self.poly.set_transform(poly_transform)
self.poly.get_path()._interpolation_steps = 100
Expand All @@ -721,13 +775,15 @@ def __init__(
*handleXY_1,
"o",
**marker_props,
clip_on=False
clip_on=False,
**animated_style
)[0],
ax.plot(
*handleXY_2,
"o",
**marker_props,
clip_on=False
clip_on=False,
**animated_style
)[0]
]

Expand All @@ -748,6 +804,7 @@ def __init__(
transform=ax.transAxes,
verticalalignment="top",
horizontalalignment="center",
**animated_style
)
else:
self.label = ax.text(
Expand All @@ -766,11 +823,22 @@ def __init__(
transform=ax.transAxes,
verticalalignment="center",
horizontalalignment="left",
**animated_style
)

self._active_handle = None
self.set_val(valinit)

def _clear(self, event):
"""Internal event handler to refresh the blitting background."""
if self.ignore(event):
return
artists = [self.poly, self.valtext, *self._handles]
self._background = self.canvas.copy_from_bbox(self.ax.get_tightbbox())
for a in artists:
self.ax.draw_artist(a)
self.canvas.blit(self.ax.get_tightbbox())

def _update_selection_poly(self, vmin, vmax):
"""
Update the vertices of the *self.poly* slider in-place
Expand Down Expand Up @@ -931,8 +999,7 @@ def set_val(self, val):

self.valtext.set_text(self._format((vmin, vmax)))

if self.drawon:
self.ax.figure.canvas.draw_idle()
self._blit_draw([self.poly, self.valtext, *self._handles])
self.val = (vmin, vmax)
if self.eventson:
self._observers.process("changed", (vmin, vmax))
Expand Down