added dd06 test support, organized 2d viewer and 3d viewer code organization.

examples/gui/viewer3d/mesh_view_state.py

@@ -0,0 +1,32 @@
+"""Runtime mesh viewport UI state shared by settings and the 3D mesh panel."""
+
+from __future__ import annotations
+
+from PyQt5.QtCore import QObject, pyqtSignal
+
+from .layout import DashboardLayout, LAYOUT
+
+
+class MeshViewState(QObject):
+    """Mutable runtime toggles for the embedded mesh viewport."""
+
+    flow_arrows_changed = pyqtSignal(bool)
+
+    def __init__(self, *, flow_arrows_enabled: bool = True):
+        super().__init__()
+        self._flow_arrows_enabled = bool(flow_arrows_enabled)
+
+    @property
+    def flow_arrows_enabled(self) -> bool:
+        return self._flow_arrows_enabled
+
+    @classmethod
+    def from_layout(cls, layout: DashboardLayout = LAYOUT) -> MeshViewState:
+        return cls(flow_arrows_enabled=layout.mesh_flow_arrow.enabled)
+
+    def set_flow_arrows_enabled(self, enabled: bool) -> None:
+        enabled = bool(enabled)
+        if enabled == self._flow_arrows_enabled:
+            return
+        self._flow_arrows_enabled = enabled
+        self.flow_arrows_changed.emit(enabled)