simplify touchpad

vterm/mouse.py

@@ -1,6 +1,4 @@
 """ SGR mouse reporting while the app tracks the mouse; otherwise sublime keeps drag_select """
-import math
-
 import sublime
 import sublime_plugin
 
@@ -115,18 +113,17 @@ class VtermScrollCommand(sublime_plugin.TextCommand):
         return True
 
 
-def ensure_trackpad(terminal):
+def start_trackpad(terminal):
     """Start the poller that turns trackpad scrolling into wheel lines.
 
     The trackpad never fires the mousemap scroll bindings on macOS
     (sublime_text#1838); its only trace is viewport movement. While the app
     owns the wheel the mousemap keeps the physical wheel off the viewport, so
     any displacement from the follow anchor is trackpad scroll: harvest whole
-    lines from it, send them like wheel lines, and snap the viewport back."""
+    lines from it, send them like wheel lines, and snap the viewport back.
-    if terminal._trackpad_running:
+
-        return
+    The caller checks _trackpad_running; the first tick arms the baseline."""
     terminal._trackpad_running = True
-    terminal._trackpad_acc = 0.0
     terminal._trackpad_engaged = True
     terminal._trackpad_baseline = None
     sublime.set_timeout(lambda: _trackpad_tick(terminal), TRACKPAD_POLL_MS)
@@ -136,7 +133,7 @@ def _trackpad_tick(terminal):
     """One poll: harvest viewport displacement, reschedule while captured."""
     view = terminal.view
     if Terminal.from_id(view.id()) is not terminal or not terminal.alive \
-            or not terminal._wheel_captured:
+            or not terminal._wheel_captured or not terminal.is_visible():
         terminal._trackpad_running = False
         return
     anchor = terminal.viewport_y
@@ -146,13 +143,13 @@ def _trackpad_tick(terminal):
         # around the new position instead of reading the move as a gesture
         terminal._trackpad_baseline = (anchor, extent)
         terminal._trackpad_acc = 0.0
-    else:
+    elif not terminal._trackpad_engaged:
-        dy = view.viewport_position()[1] - anchor
-        if not terminal._trackpad_engaged:
         if following(view, terminal):
             terminal._trackpad_engaged = True
             terminal._trackpad_acc = 0.0
-        elif dy == 0:
+    else:
+        dy = view.viewport_position()[1] - anchor
+        if dy == 0:
             # at rest a stale fraction must not fire on the next gesture
             terminal._trackpad_acc = 0.0
         elif abs(dy) >= extent:
@@ -161,7 +158,7 @@ def _trackpad_tick(terminal):
             terminal._trackpad_engaged = False
         else:
             terminal._trackpad_acc += dy / view.line_height()
-            lines = math.trunc(terminal._trackpad_acc)
+            lines = int(terminal._trackpad_acc)
             terminal._trackpad_acc -= lines
             if lines:
                 send_scroll(terminal, up=lines < 0, lines=abs(lines))

vterm/render.py

@@ -172,7 +172,7 @@ class VtermRenderCommand(sublime_plugin.TextCommand):
             terminal.pending_clear_screen = False
             self.clear_view(edit, terminal, wipe_screen=True)
 
-        if view.size() == 0 and terminal.offset == 0:
+        if terminal.offset == 0 and view.size() == 0:
             # one blank scrollback row above a fresh screen: sublime has no
             # layout above row 0, and the trackpad poller needs upward slack —
             # without it, trackpad-up is dead until a line retires, which on
@@ -217,15 +217,15 @@ class VtermRenderCommand(sublime_plugin.TextCommand):
         alt = terminal.screen.alternate_buffer_mode
         if not alt and not terminal.applied_alt_screen:
             return
+        entering = alt and not terminal.applied_alt_screen
         terminal.applied_alt_screen = alt
         end = view.text_point(terminal.offset, 0) - 1 if alt and terminal.offset else 0
         want = [(0, end)] if end > 0 else []
-        had = [(r.begin(), r.end()) for r in view.folded_regions()]
+        if [(r.begin(), r.end()) for r in view.folded_regions()] == want:
-        if had == want:
             return
         view.unfold(sublime.Region(0, view.size()))
-        if want and view.fold(sublime.Region(0, end)) and not had:
+        if want and view.fold(sublime.Region(0, end)) and entering:
-            # a fresh fold collapses the layout; a stale viewport anchor would
+            # entering collapses the layout; a stale viewport anchor would
             # stop the follow-scroll gate from re-engaging. re-asserting a
             # disturbed fold keeps the anchor: apps repaint the boundary row
             # every scroll, and resetting per repair thrashes the poller
@@ -545,7 +545,7 @@ def scroll_to_cursor(view, terminal):
     """Follow the output: pin the viewport to the bottom of the live screen."""
     terminal._scroll_pending = False
     y = bottom_y(view, terminal)
-    if y == terminal.viewport_y and terminal._trackpad_running and terminal._trackpad_engaged:
+    if y == terminal.viewport_y and terminal.trackpad_pinning():
         # the anchor is unchanged and the trackpad poller owns the pin:
         # re-pinning here would discard displacement it has not harvested yet,
         # and apps repaint while scrolling, so this races every gesture

vterm/terminal.py

@@ -109,7 +109,7 @@ class Terminal:
         self._send_lock = threading.Lock()
         self._wheel_captured = False
         self._scroll_pending = False
-        # trackpad poller (mouse.ensure_trackpad): reschedule guard, fractional
+        # trackpad poller (mouse.start_trackpad): reschedule guard, fractional
         # line remainder, harvesting vs. browsing, last seen (anchor, extent)
         self._trackpad_running = False
         self._trackpad_acc = 0.0
@@ -152,6 +152,10 @@ class Terminal:
             self._visible = group >= 0 and window.active_view_in_group(group) == self.view
         return self._visible
 
+    def trackpad_pinning(self):
+        """Whether the trackpad poller owns pinning the viewport to the anchor."""
+        return self._trackpad_running and self._trackpad_engaged
+
     def is_render_due(self):
         """Whether an unfocused terminal may draw again.
 
@@ -398,11 +402,11 @@ class Terminal:
         if captured != self._wheel_captured:
             self._wheel_captured = captured
             self.view.settings().set("vterm_view.wheel_captured", captured)
-        if captured and not self._trackpad_running:
+        if captured and not self._trackpad_running and self.is_visible():
-            # checked every renderer tick, so a poller that just stopped on a
+            # checked every renderer tick, so a poller that stopped on a
-            # capture flap is restarted within a frame or two
+            # capture flap or a hidden tab restarts within a frame or two
-            from .mouse import ensure_trackpad  # module-level import would cycle
+            from .mouse import start_trackpad  # module-level import would cycle
-            ensure_trackpad(self)
+            start_trackpad(self)
 
     def send_focus(self, focused):
         """Report focus gain or loss, when the app asked for it (?1004)."""