Size level line markers to dpi aware font size

piker/ui/_graphics/_lines.py

@@ -18,6 +18,7 @@
 Lines for orders, alerts, L2.
 
 """
+from math import floor
 from typing import Tuple, Optional, List
 
 import pyqtgraph as pg
@@ -27,7 +28,7 @@ from PyQt5.QtCore import QPointF
 
 from .._annotate import mk_marker, qgo_draw_markers
 from .._label import Label, vbr_left, right_axis
-from .._style import hcolor
+from .._style import hcolor, _font
 
 
 # TODO: probably worth investigating if we can
@@ -628,11 +629,17 @@ def order_line(
     )
 
     if show_markers:
+        font_size = _font.font.pixelSize()
+
+        # scale marker size with dpi-aware font size
+        arrow_size = floor(1.375 * font_size)
+        alert_size = arrow_size * 0.666
+
         # add arrow marker on end of line nearest y-axis
         marker_style, marker_size = {
-            'buy': ('|<', 20),
-            'sell': ('>|', 20),
-            'alert': ('v', 12),
+            'buy': ('|<', arrow_size),
+            'sell': ('>|', arrow_size),
+            'alert': ('v', alert_size),
         }[action]
 
         # this fixes it the artifact issue! .. of course, bouding rect stuff
@@ -695,7 +702,7 @@ def order_line(
         rlabel = line.add_label(
             side='right',
             side_of_axis='left',
-            x_offset=3*marker_size + 5,
+            x_offset=4*marker_size,
             fmt_str=(
                 '{size:.{size_digits}f} '
             ),
@@ -739,14 +746,6 @@ def position_line(
         hide_xhair_on_hover=False,
         use_marker_margin=True,
     )
-    if size > 0:
-        arrow_path = mk_marker('|<')
-
-    elif size < 0:
-        arrow_path = mk_marker('>|')
-
-    line.add_marker(arrow_path)
-
     #  hide position marker when out of view (for now)
     vb = line.getViewBox()
 
@@ -775,6 +774,20 @@ def position_line(
     rlabel.render()
     rlabel.show()
 
+    # arrow marker
+    # scale marker size with dpi-aware font size
+    font_size = _font.font.pixelSize()
+
+    # scale marker size with dpi-aware font size
+    arrow_size = floor(1.375 * font_size)
+
+    if size > 0:
+        style = '|<'
+    elif size < 0:
+        style = '>|'
+
+    arrow_path = mk_marker(style, size=arrow_size)
+    line.add_marker(arrow_path)
     line.set_level(level)
 
     # sanity check