Drop legacy step path gen, always slice full data

Mostly just dropping old commented code for "step mode" format
generation. Always slice the tail part of the input data and move to the
new `ms_threshold` in the `pg` profiler'

piker/ui/_curve.py

@@ -272,8 +272,6 @@ class FastAppendCurve(pg.GraphicsObject):
         x = (x + np.array([-0.5, 0, 0, 0.5])).flatten()
         y = y.flatten()
 
-        # presumably?
-        self._in_ds = True
         return x, y
 
     def update_from_array(
@@ -305,7 +303,7 @@ class FastAppendCurve(pg.GraphicsObject):
         profiler = profiler or pg.debug.Profiler(
             msg=f'FastAppendCurve.update_from_array(): `{self._name}`',
             disabled=not pg_profile_enabled(),
-            gt=ms_slower_then,
+            ms_threshold=ms_slower_then,
         )
         flip_cache = False
 
@@ -342,6 +340,10 @@ class FastAppendCurve(pg.GraphicsObject):
         showing_src_data = self._in_ds
         # should_redraw = False
 
+        # by default we only pull data up to the last (current) index
+        x_out_full = x_out = x[:slice_to_head]
+        y_out_full = y_out = y[:slice_to_head]
+
         # if a view range is passed, plan to draw the
         # source ouput that's "in view" of the chart.
         if (
@@ -358,7 +360,7 @@ class FastAppendCurve(pg.GraphicsObject):
             vl, vr = view_range
 
             # last_ivr = self._x_iv_range
-            # ix_iv, iy_iv = self._x_iv_range = (x_iv[0], x_iv[-1])
+           # ix_iv, iy_iv = self._x_iv_range = (x_iv[0], x_iv[-1])
 
             zoom_or_append = False
             last_vr = self._vr
@@ -414,16 +416,8 @@ class FastAppendCurve(pg.GraphicsObject):
             # self.disable_cache()
             # flip_cache = True
 
-        else:
+        if prepend_length > 0:
-            # if (
+            should_redraw = True
-            #     not view_range
-            #     or self._in_ds
-            # ):
-            # by default we only pull data up to the last (current) index
-            x_out, y_out = x[:slice_to_head], y[:slice_to_head]
-
-            if prepend_length > 0:
-                should_redraw = True
 
         # check for downsampling conditions
         if (
@@ -459,30 +453,10 @@ class FastAppendCurve(pg.GraphicsObject):
             or new_sample_rate
             or prepend_length > 0
         ):
-            # if (
-            #     not view_range
-            #     or self._in_ds
-            # ):
-            #     # by default we only pull data up to the last (current) index
-            #     x_out, y_out = x[:-1], y[:-1]
-
-            # step mode: draw flat top discrete "step"
-            # over the index space for each datum.
-            # if self._step_mode:
-            #     self.disable_cache()
-            #     flip_cache = True
-            #     x_out, y_out = step_path_arrays_from_1d(
-            #         x_out,
-            #         y_out,
-            #     )
-
-            #     # TODO: numba this bish
-            #     profiler('generated step arrays')
-
             if should_redraw:
                 if self.path:
-                    # print(f'CLEARING PATH {self._name}')
                     self.path.clear()
+                    profiler('cleared paths due to `should_redraw=True`')
 
                 if self.fast_path:
                     self.fast_path.clear()
@@ -556,23 +530,6 @@ class FastAppendCurve(pg.GraphicsObject):
             new_y = y[-append_length - 2:slice_to_head]
             profiler('sliced append path')
 
-            # if self._step_mode:
-            # #     new_x, new_y = step_path_arrays_from_1d(
-            # #         new_x,
-            # #         new_y,
-            # #     )
-            # #     # [1:] since we don't need the vertical line normally at
-            # #     # the beginning of the step curve taking the first (x,
-            # #     # y) poing down to the x-axis **because** this is an
-            # #     # appended path graphic.
-            # #     new_x = new_x[1:]
-            # #     new_y = new_y[1:]
-
-            #     self.disable_cache()
-            #     flip_cache = True
-
-            #     profiler('generated step data')
-
             profiler(
                 f'diffed array input, append_length={append_length}'
             )
@@ -812,7 +769,7 @@ class FastAppendCurve(pg.GraphicsObject):
         profiler = pg.debug.Profiler(
             msg=f'FastAppendCurve.paint(): `{self._name}`',
             disabled=not pg_profile_enabled(),
-            gt=ms_slower_then,
+            ms_threshold=ms_slower_then,
         )
         self.prepareGeometryChange()