Graph: pan with left or right, open with the other

Client/Graph.py

@@ -5,8 +5,8 @@ colours by depth, files White), joined to its parent directory and to every file
 On a server the graph comes from /api/graph; locally BuildLocalGraph makes
 the same one with the same reference rules as Backend/Graph.py. The layout is
 the web view's force simulation (same constants), in numpy, drawn as it
-settles. Scroll to zoom, pan with the button picked in Settings > Graph,
-hover a dot to light up its links, click it to open it."""
+settles. Scroll to zoom, hover a dot to light up its links; one mouse button
+pans and the other opens a dot (Settings > Graph)."""
 
 import math
 import re
@@ -238,9 +238,8 @@ def FilterGraph(Graph: dict, ShowDirectories: bool) -> dict:
 
 class GraphView(ft.Container):
     """Pan and zoom are done here rather than with an InteractiveViewer, so
-    the pan button can be picked (Settings > Graph). Flet reports drags for
-    the left and right buttons only, so Middle works like middle-click
-    autoscroll: click it to grab the graph, move to pan, click again to let go."""
+    the buttons can be picked (Settings > Graph): one mouse button pans, the
+    other opens the dot it clicks."""
 
     def __init__(self, TheApp: App, Root: str, DirectoryPath: str,
                  OnOpenNode: Callable[[dict], None], OnClose: Callable[[], None]):
@@ -248,7 +247,9 @@ class GraphView(ft.Container):
         self.Root = Root
         self.DirectoryPath = DirectoryPath
         self.OnOpenNode = OnOpenNode
-        self.PanButton = TheApp.Config.GraphPanButton
+        # Anything but "Left" (including an old "Middle") pans with Right.
+        self.PanButton = "Left" if TheApp.Config.GraphPanButton == "Left" else "Right"
+        self.OpenButton = "Right" if self.PanButton == "Left" else "Left"
         self.ShowDirectories = TheApp.Config.GraphShowDirectories
         self.Layout: Optional[Layout] = None
         self.ScopePath = ""
@@ -264,7 +265,6 @@ class GraphView(ft.Container):
         self.PanX = 0.0
         self.PanY = 0.0
         self.DragFrom: Optional[tuple[float, float]] = None
-        self.Grabbed = False  # Middle: grabbed by a middle click
 
         self.ScopePicker = ft.Dropdown(
             value="Root",
@@ -288,21 +288,21 @@ class GraphView(ft.Container):
         # Hidden (not just its text) once the graph is up: even empty, it sits
         # over the graph and would catch every click.
         self.StatusBox = ft.Container(self.Status, alignment=ft.Alignment.CENTER)
-        Hint = {"Left": "Drag to pan", "Right": "Right-drag to pan",
-                "Middle": "Middle-click to grab and pan, again to let go"}.get(self.PanButton, "")
+        Hint = ("Drag to pan, right-click a dot to open it" if self.PanButton == "Left"
+                else "Right-drag to pan, click a dot to open it")
         self.Surface = ft.GestureDetector(
             content=ft.Container(self.Plane, expand=True, clip_behavior=ft.ClipBehavior.HARD_EDGE, bgcolor=Palette.Base),
-            on_tap_up=self._OnTap,
+            on_tap_up=lambda e: self._OnClick(e, "Left"),
+            on_secondary_tap_up=lambda e: self._OnClick(e, "Right"),
             on_hover=self._OnHover,
             on_exit=lambda e: self._SetHovered(None),
             on_scroll=self._OnScroll,
-            on_pan_start=lambda e: self._StartDrag(e, "Left"),
+            on_pan_down=lambda e: self._StartDrag(e, "Left"),  # down, not start: start comes after the drag slop
             on_pan_update=lambda e: self._Drag(e, "Left"),
             on_pan_end=lambda e: self._EndDrag(),
             on_right_pan_start=lambda e: self._StartDrag(e, "Right"),
             on_right_pan_update=lambda e: self._Drag(e, "Right"),
             on_right_pan_end=lambda e: self._EndDrag(),
-            on_tertiary_tap_up=self._OnMiddleClick,
             hover_interval=20,
             drag_interval=16,
             expand=True,
@@ -317,7 +317,7 @@ class GraphView(ft.Container):
                 ], spacing=12),
                 ft.Divider(height=1, color=Palette.Surface1),
                 ft.Stack([self.Surface, self.StatusBox], expand=True),
-                ft.Text(f"{Hint}, scroll to zoom, click a dot to open it.", size=11, color=Palette.Overlay0),
+                ft.Text(f"{Hint}, scroll to zoom.", size=11, color=Palette.Overlay0),
             ], spacing=8, expand=True),
             expand=True, bgcolor=Palette.Base, padding=12,
         )
@@ -488,29 +488,15 @@ class GraphView(ft.Container):
 
     def _OnHover(self, Event) -> None:
         X, Y = Event.local_position.x, Event.local_position.y
-        if self.Grabbed and self.DragFrom is not None:
-            self._PanBy(X - self.DragFrom[0], Y - self.DragFrom[1])
-            self.DragFrom = (X, Y)
-            return
         self._SetHovered(self._NodeAt(X, Y))
 
-    def _OnTap(self, Event) -> None:
-        if self.Grabbed:  # a left click also lets go
-            self.Grabbed = False
-            self.DragFrom = None
+    def _OnClick(self, Event, Button: str) -> None:
+        if Button != self.OpenButton:
             return
         Number = self._NodeAt(Event.local_position.x, Event.local_position.y)
         if Number is not None:
             self.OnOpenNode(self.Layout.Nodes[Number])
 
-    def _OnMiddleClick(self, Event) -> None:
-        if self.PanButton != "Middle":
-            return
-        self.Grabbed = not self.Grabbed
-        self.DragFrom = (Event.local_position.x, Event.local_position.y) if self.Grabbed else None
-        self.Surface.mouse_cursor = ft.MouseCursor.MOVE if self.Grabbed else ft.MouseCursor.BASIC
-        self.Surface.update()
-
     def _StartDrag(self, Event, Button: str) -> None:
         if Button == self.PanButton:
             self.DragFrom = (Event.local_position.x, Event.local_position.y)
@@ -523,8 +509,7 @@ class GraphView(ft.Container):
         self.DragFrom = (X, Y)
 
     def _EndDrag(self) -> None:
-        if not self.Grabbed:
-            self.DragFrom = None
+        self.DragFrom = None
 
     def _OnScroll(self, Event) -> None:
         """Zooms around the pointer."""