Make `ChartPlotWidget.default_view()` pin to L1

Instead of using a guess about how many x-indexes to reset the last
datum in-view to, calculate and shift the latest index such that it's
just before any L1 spread labels on the y-axis. This makes the view
placement "widget aware" and gives a much more cross-display UX.

Summary:
- add `ChartPlotWidget.pre_l1_x()` which returns a `tuple` of
  x view-coord points for the absolute x-pos and length of any L1
  line/labels
- make `.default_view()` only shift to see the xlast just outside
  the l1 but keep whatever view range xfirst as the first datum in view
- drop `LevelLine.right_point()` since this is now just a
  `.pre_l1_x()` call and can be retrieved from the line's internal chart
  ref
- drop `._style.bars_from/to_..` vars since we aren't using hard coded
  offsets any more

piker/ui/_anchors.py

@@ -25,7 +25,6 @@ from PyQt5.QtCore import QPointF
 from PyQt5.QtWidgets import QGraphicsPathItem
 
 if TYPE_CHECKING:
-    from ._axes import PriceAxis
     from ._chart import ChartPlotWidget
     from ._label import Label
 

piker/ui/_chart.py

@@ -25,7 +25,7 @@ from PyQt5 import QtCore, QtWidgets
 from PyQt5.QtCore import (
     Qt,
     QLineF,
-    QPointF,
+    # QPointF,
 )
 from PyQt5.QtWidgets import (
     QFrame,
@@ -56,8 +56,6 @@ from ._style import (
     CHART_MARGINS,
     _xaxis_at,
     _min_points_to_show,
-    _bars_from_right_in_follow_mode,
-    _bars_to_left_in_follow_mode,
 )
 from ..data.feed import Feed
 from ..data._source import Symbol
@@ -846,29 +844,62 @@ class ChartPlotWidget(pg.PlotWidget):
             QLineF(lbar, 0, rbar, 0)
         ).length()
 
-    def default_view(
+    def pre_l1_x(
         self,
-        index: int = -1,
+        view_coords: bool = False,
 
-    ) -> None:
+    ) -> tuple[float, float]:
+        '''
+        Return the scene x-coord for the value just before
+        the L1 labels on the y-axis as well as the length
+        of that L1 label from the y-axis.
+
+        '''
+        l1_len = self._max_l1_line_len
+        ryaxis = self.getAxis('right')
+        ryaxis_x = ryaxis.pos().x()
+        up_to_l1_sc = ryaxis_x - l1_len
+        if not view_coords:
+            return up_to_l1_sc, l1_len
+        else:
+            view = self.view
+            line = view.mapToView(
+                QLineF(up_to_l1_sc, 0, ryaxis_x, 0)
+            )
+            return line.x1(), line.length()
+
+    def default_view(self) -> None:
         '''
         Set the view box to the "default" startup view of the scene.
 
         '''
         try:
-            xlast = self._arrays[self.name][index]['index']
+            index = self._arrays[self.name]['index']
         except IndexError:
             log.warning(f'array for {self.name} not loaded yet?')
             return
 
-        begin = xlast - 1000
-        end = xlast + _bars_from_right_in_follow_mode
+        xfirst, xlast = index[0], index[-1]
+        view = self.view
+        vr = view.viewRange()
+        marker_pos, l1_len = self.pre_l1_x(view_coords=True)
+        end = xlast + l1_len
+        xl = vr[0][0]
+        begin = max(xl, xfirst)
+
+        # print(
+        #     f'view range: {vr}\n'
+        #     f'xlast: {xlast}\n'
+        #     f'marker pos: {marker_pos}\n'
+        #     f'l1 len: {l1_len}\n'
+        #     f'begin: {begin}\n'
+        #     f'end: {end}\n'
+        # )
 
         # remove any custom user yrange setttings
         if self._static_yrange == 'axis':
             self._static_yrange = None
 
-        view = self.view
         view.setXRange(
             min=begin,
             max=end,
@@ -1228,7 +1259,6 @@ class ChartPlotWidget(pg.PlotWidget):
         ifirst = array[0]['index']
         # slice data by offset from the first index
         # available in the passed datum set.
-        start = lbar - ifirst
         return array[lbar - ifirst:(rbar - ifirst) + 1]
 
     def maxmin(

piker/ui/_lines.py

@@ -20,7 +20,7 @@ Lines for orders, alerts, L2.
 """
 from functools import partial
 from math import floor
-from typing import Tuple, Optional, List, Callable
+from typing import Optional, Callable
 
 import pyqtgraph as pg
 from pyqtgraph import Point, functions as fn
@@ -32,7 +32,6 @@ from ._anchors import (
     marker_right_points,
     vbr_left,
     right_axis,
-    # pp_tight_and_right,  # wanna keep it straight in the long run
     gpath_pin,
 )
 from ..calc import humanize
@@ -104,8 +103,8 @@ class LevelLine(pg.InfiniteLine):
 
         # list of labels anchored at one of the 2 line endpoints
         # inside the viewbox
-        self._labels: List[Label] = []
-        self._markers: List[(int, Label)] = []
+        self._labels: list[Label] = []
+        self._markers: list[(int, Label)] = []
 
         # whenever this line is moved trigger label updates
         self.sigPositionChanged.connect(self.on_pos_change)
@@ -124,7 +123,7 @@ class LevelLine(pg.InfiniteLine):
         self._y_incr_mult = 1 / chart.linked.symbol.tick_size
         self._right_end_sc: float = 0
 
-    def txt_offsets(self) -> Tuple[int, int]:
+    def txt_offsets(self) -> tuple[int, int]:
         return 0, 0
 
     @property
@@ -315,17 +314,6 @@ class LevelLine(pg.InfiniteLine):
         # TODO: enter labels edit mode
         print(f'double click {ev}')
 
-    def right_point(
-        self,
-    ) -> float:
-
-        chart = self._chart
-        l1_len = chart._max_l1_line_len
-        ryaxis = chart.getAxis('right')
-        up_to_l1_sc = ryaxis.pos().x() - l1_len
-
-        return up_to_l1_sc
-
     def paint(
         self,
 
@@ -422,23 +410,23 @@ class LevelLine(pg.InfiniteLine):
 
     ) -> QtWidgets.QGraphicsPathItem:
 
+        self._marker = path
+        self._marker.setPen(self.currentPen)
+        self._marker.setBrush(fn.mkBrush(self.currentPen.color()))
         # add path to scene
         self.getViewBox().scene().addItem(path)
 
-        self._marker = path
-
-        rsc = self.right_point()
-
-        self._marker.setPen(self.currentPen)
-        self._marker.setBrush(fn.mkBrush(self.currentPen.color()))
+        # place to just-left of L1 labels
+        rsc = self._chart.pre_l1_x()[0]
         path.setPos(QPointF(rsc, self.scene_y()))
 
         return path
 
     def hoverEvent(self, ev):
-        """Mouse hover callback.
+        '''
+        Mouse hover callback.
 
-        """
+        '''
         cur = self._chart.linked.cursor
 
         # hovered
@@ -614,7 +602,8 @@ def order_line(
     **line_kwargs,
 
 ) -> LevelLine:
-    '''Convenience routine to add a line graphic representing an order
+    '''
+    Convenience routine to add a line graphic representing an order
     execution submitted to the EMS via the chart's "order mode".
 
     '''
@@ -689,7 +678,6 @@ def order_line(
 
             return f'{account}: '
 
-
         label.fields = {
             'size': size,
             'size_digits': 0,

piker/ui/_style.py

@@ -14,9 +14,10 @@
 # You should have received a copy of the GNU Affero General Public License
 # along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
-"""
+'''
 Qt UI styling.
-"""
+
+'''
 from typing import Optional, Dict
 import math
 
@@ -202,8 +203,6 @@ _xaxis_at = 'bottom'
 # charting config
 CHART_MARGINS = (0, 0, 2, 2)
 _min_points_to_show = 6
-_bars_to_left_in_follow_mode = int(61*6)
-_bars_from_right_in_follow_mode = round(0.16 * _bars_to_left_in_follow_mode)
 _tina_mode = False