fix(studio): 统一 Box/Mini 箭头网格与强度着色

shared/src/orisys_app_shared/acquisition/arrows.py

@@ -23,7 +23,7 @@ FLOW_IDLE_HEX = "#8A93A6"
 #: BGR grey used for depth samples that carry no value.
 NO_DEPTH_BGR = (0x8A, 0x8A, 0x8A)
 
-#: The fixed flow-magnitude colour range, in **uv pixels of displacement**.
+#: Finger's fixed flow-magnitude colour range, in **uv pixels of displacement**.
 #:
 #: The colour of an arrow is a statement about its magnitude, so it has to be the same
 #: statement from one frame to the next: a per-frame range makes the same magnitude a
@@ -34,6 +34,8 @@ NO_DEPTH_BGR = (0x8A, 0x8A, 0x8A)
 #: where the arrow itself does. A pane that offers the operator a colour range owns this
 #: value and passes it as ``magnitude_range`` to :func:`draw_arrow_display`.
 FLOW_MAGNITUDE_RANGE: tuple[float, float] = (0.0, 2.0)
+#: Box/Mini use a 2 px activation floor, so their fixed range extends to 8 px.
+BOX_FLOW_MAGNITUDE_RANGE: tuple[float, float] = (0.0, 8.0)
 
 #: Whether an inactive sample is drawn as a quiet dot. **On**, which is the decided
 #: display behaviour: a sample below the display threshold is a statement about the
@@ -498,8 +500,10 @@ def draw_arrow_display(
     finger style falls back to the finger defaults and box style to :func:`sdk_box_policy`.
 
     ``magnitude_range`` fixes the colour scale, in the same unit as ``flow_on_px``
-    (uv pixels of displacement); the default is :data:`FLOW_MAGNITUDE_RANGE` and a
-    settings model that owns the range passes its own here. ``per_frame_colour`` opts
+    (uv pixels of displacement). The default is :data:`FLOW_MAGNITUDE_RANGE` for
+    finger and :data:`BOX_FLOW_MAGNITUDE_RANGE` for box/mini; their different
+    sampling floors need different fixed ranges to retain intensity contrast.
+    A settings model that owns the range passes its own here. ``per_frame_colour`` opts
     back in to normalising every frame against its own maximum, which makes one
     magnitude a different colour from one frame to the next.
 
@@ -570,7 +574,11 @@ def draw_arrow_display(
                 policy=selected,
                 colormap=colormap,
                 below_threshold_color=tuple(draw_kw["below_threshold_color"]),
-                magnitude_range=magnitude_range,
+                magnitude_range=(
+                    magnitude_range
+                    if magnitude_range is not None
+                    else FLOW_MAGNITUDE_RANGE if finger else BOX_FLOW_MAGNITUDE_RANGE
+                ),
                 per_frame_colour=per_frame_colour,
                 # Read here rather than as a parameter default: the module constant is
                 # the display decision, and a caller that flips it (a build, a test)