Extract and fork `pyqtgraph` upstream submissions

Fork out our patch set submitted to upstream in multiple PRs (since they
aren't moving and/or aren't a priority to core) which can be seen in
full from the following diff:
https://github.com/pyqtgraph/pyqtgraph/compare/master...pikers:pyqtgraph:graphics_pin

Move these type extensions into the internal `.ui._pg_overrides` module.

The changes are related to both `pyqtgraph.PlotItem` and `.AxisItem` and
were driven for our need for multi-view overlays (overlaid charts with
optionally synced axis and interaction controls) as documented in the PR
to upstream: https://github.com/pyqtgraph/pyqtgraph/pull/2162

More specifically,
- wrt to `AxisItem` we added lru caching of tick values as per:
  https://github.com/pyqtgraph/pyqtgraph/pull/2160.
- wrt to `PlotItem` we adjusted some of the axis management code, namely
  adding a standalone `.removeAxis()` and modifying the `.setAxisItems()` logic
  to use it in: https://github.com/pyqtgraph/pyqtgraph/pull/2162
  as well as some tweaks to `.updateGrid()` to loop through all possible
  axes when grid setting.

piker/ui/_pg_overrides.py

@@ -15,11 +15,16 @@
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
 """
-Customization of ``pyqtgraph`` core routines to speed up our use mostly
+Customization of ``pyqtgraph`` core routines and various types normally
-based on not requiring "scentific precision" for pixel perfect view
+for speedups.
-transforms.
+
+Generally, our does not require "scentific precision" for pixel perfect
+view transforms.
 
 """
+import functools
+from typing import Optional
+
 import pyqtgraph as pg
 
 
@@ -46,3 +51,268 @@ def _do_overrides() -> None:
     """
     # we don't care about potential fp issues inside Qt
     pg.functions.invertQTransform = invertQTransform
+    pg.PlotItem = PlotItem
+    pg.AxisItem = AxisItem
+
+
+# NOTE: the below customized type contains all our changes on a method
+# by method basis as per the diff:
+# https://github.com/pyqtgraph/pyqtgraph/commit/8e60bc14234b6bec1369ff4192dbfb82f8682920#diff-a2b5865955d2ba703dbc4c35ff01aa761aa28d2aeaac5e68d24e338bc82fb5b1R500
+
+class PlotItem(pg.PlotItem):
+    '''
+    Overrides for the core plot object mostly pertaining to overlayed
+    multi-view management as it relates to multi-axis managment.
+
+    '''
+    def __init__(
+        self,
+        parent=None,
+        name=None,
+        labels=None,
+        title=None,
+        viewBox=None,
+        axisItems=None,
+        default_axes=['left', 'bottom'],
+        enableMenu=True,
+        **kargs
+    ):
+        super().__init__(
+            parent=parent,
+            name=name,
+            labels=labels,
+            title=title,
+            viewBox=viewBox,
+            axisItems=axisItems,
+            # default_axes=default_axes,
+            enableMenu=enableMenu,
+            kargs=kargs,
+        )
+        # self.setAxisItems(
+        #     axisItems,
+        #     default_axes=default_axes,
+        # )
+
+    # NOTE: this is an entirely new method not in upstream.
+    def removeAxis(
+        self,
+        name: str,
+        unlink: bool = True,
+
+    ) -> Optional[pg.AxisItem]:
+        """
+        Remove an axis from the contained axis items
+        by ```name: str```.
+
+        This means the axis graphics object will be removed
+        from the ``.layout: QGraphicsGridLayout`` as well as unlinked
+        from the underlying associated ``ViewBox``.
+
+        If the ``unlink: bool`` is set to ``False`` then the axis will
+        stay linked to its view and will only be removed from the
+        layoutonly be removed from the layout.
+
+        If no axis with ``name: str`` is found then this is a noop.
+
+        Return the axis instance that was removed.
+
+        """
+        entry = self.axes.pop(name, None)
+
+        if not entry:
+            return
+
+        axis = entry['item']
+        self.layout.removeItem(axis)
+        axis.scene().removeItem(axis)
+        if unlink:
+            axis.unlinkFromView()
+
+        self.update()
+
+        return axis
+
+    # Why do we need to always have all axes created?
+    #
+    # I don't understand this at all.
+    #
+    # Everything seems to work if you just always apply the
+    # set passed to this method **EXCEPT** for some super weird reason
+    # the view box geometry still computes as though the space for the
+    # `'bottom'` axis is always there **UNLESS** you always add that
+    # axis but hide it?
+    #
+    # Why in tf would this be the case!?!?
+    def setAxisItems(
+        self,
+        # XXX: yeah yeah, i know we can't use type annots like this yet.
+        axisItems: Optional[dict[str, pg.AxisItem]] = None,
+        add_to_layout: bool = True,
+        default_axes: list[str] = ['left', 'bottom'],
+    ):
+        """
+        Override axis item setting to only
+
+        """
+        axisItems = axisItems or {}
+
+        # XXX: wth is is this even saying?!?
+        # Array containing visible axis items
+        # Also containing potentially hidden axes, but they are not
+        # touched so it does not matter
+        # visibleAxes = ['left', 'bottom']
+        # Note that it does not matter that this adds
+        # some values to visibleAxes a second time
+
+        # XXX: uhhh wat^ ..?
+
+        visibleAxes = list(default_axes) + list(axisItems.keys())
+
+        # TODO: we should probably invert the loop here to not loop the
+        # predefined "axis name set" and instead loop the `axisItems`
+        # input and lookup indices from a predefined map.
+        for name, pos in (
+            ('top', (1, 1)),
+            ('bottom', (3, 1)),
+            ('left', (2, 0)),
+            ('right', (2, 2))
+        ):
+            if (
+                name in self.axes and
+                name in axisItems
+            ):
+                # we already have an axis entry for this name
+                # so remove the existing entry.
+                self.removeAxis(name)
+
+            # elif name not in axisItems:
+            #     # this axis entry is not provided in this call
+            #     # so remove any old/existing entry.
+            #     self.removeAxis(name)
+
+            # Create new axis
+            if name in axisItems:
+                axis = axisItems[name]
+                if axis.scene() is not None:
+                    if (
+                        name not in self.axes
+                        or axis != self.axes[name]["item"]
+                    ):
+                        raise RuntimeError(
+                            "Can't add an axis to multiple plots. Shared axes"
+                            " can be achieved with multiple AxisItem instances"
+                            " and set[X/Y]Link.")
+
+            else:
+                # Set up new axis
+
+                # XXX: ok but why do we want to add axes for all entries
+                # if not desired by the user? The only reason I can see
+                # adding this is without it there's some weird
+                # ``ViewBox`` geometry bug.. where a gap for the
+                # 'bottom' axis is somehow left in?
+                axis = AxisItem(orientation=name, parent=self)
+
+            axis.linkToView(self.vb)
+
+            # XXX: shouldn't you already know the ``pos`` from the name?
+            # Oh right instead of a global map that would let you
+            # reasily look that up it's redefined over and over and over
+            # again in methods..
+            self.axes[name] = {'item': axis, 'pos': pos}
+
+            # NOTE: in the overlay case the axis may be added to some
+            # other layout and should not be added here.
+            if add_to_layout:
+                self.layout.addItem(axis, *pos)
+
+            # place axis above images at z=0, items that want to draw
+            # over the axes should be placed at z>=1:
+            axis.setZValue(0.5)
+            axis.setFlag(
+                axis.GraphicsItemFlag.ItemNegativeZStacksBehindParent
+            )
+            if name in visibleAxes:
+                self.showAxis(name, True)
+            else:
+                # why do we need to insert all axes to ``.axes`` and
+                # only hide the ones the user doesn't specify? It all
+                # seems to work fine without doing this except for this
+                # weird gap for the 'bottom' axis that always shows up
+                # in the view box geometry??
+                self.hideAxis(name)
+
+    def updateGrid(
+        self,
+        *args,
+    ):
+        alpha = self.ctrl.gridAlphaSlider.value()
+        x = alpha if self.ctrl.xGridCheck.isChecked() else False
+        y = alpha if self.ctrl.yGridCheck.isChecked() else False
+        for name, dim in (
+            ('top', x),
+            ('bottom', x),
+            ('left', y),
+            ('right', y)
+        ):
+            if name in self.axes:
+                self.getAxis(name).setGrid(dim)
+        # self.getAxis('bottom').setGrid(x)
+        # self.getAxis('left').setGrid(y)
+        # self.getAxis('right').setGrid(y)
+
+
+# NOTE: overrides to lru_cache the ``.tickStrings()`` output.
+class AxisItem(pg.AxisItem):
+
+    def __init__(
+        self,
+        orientation,
+        pen=None,
+        textPen=None,
+        linkView=None,
+        parent=None,
+        maxTickLength=-5,
+        showValues=True,
+        text='',
+        units='',
+        unitPrefix='',
+        lru_cache_tick_strings: bool = True,
+        **args,
+    ):
+        super().__init__(
+            orientation=orientation,
+            pen=pen,
+            textPen=textPen,
+            linkView=linkView,
+            maxTickLength=maxTickLength,
+            showValues=showValues,
+            text=text,
+            units=units,
+            unitPrefix=unitPrefix,
+            parent=parent,
+        )
+        if lru_cache_tick_strings:
+            self.tickStrings = functools.lru_cache(
+                maxsize=2**20
+            )(self.tickStrings)
+
+    def tickValues(
+        self,
+        minVal: float,
+        maxVal: float,
+        size: int,
+
+    ) -> list[tuple[float, tuple[str]]]:
+        '''
+        Repack tick values into tuples for lru caching.
+
+        '''
+        ticks = []
+        for scalar, values in super().tickValues(minVal, maxVal, size):
+            ticks.append((
+                scalar,
+                tuple(values),  # this
+            ))
+
+        return ticks