feat: Hammerspoon IPC cursor tracking + split magnifier (SPC z m)

hammerspoon/cursor-warp.lua

@@ -0,0 +1,105 @@
+-- cursor-warp.lua — Emacs cursor tracking for macOS Zoom
+--
+-- WHAT: Reads cursor coordinates written by Emacs to ~/.emacs-cursor-pos
+--        and posts a real mouseMoved HID event so macOS Zoom follows the
+--        text cursor. CGWarpMouseCursorPosition (used by Emacs internally)
+--        is silently ignored by macOS Zoom — this workaround fixes that.
+--
+-- SETUP:
+--   1. Install Hammerspoon: https://www.hammerspoon.org/
+--   2. Grant Accessibility permission: System Settings → Privacy & Security
+--      → Accessibility → enable Hammerspoon
+--   3. Copy this file to ~/.hammerspoon/cursor-warp.lua
+--   4. In ~/.hammerspoon/init.lua add:  require("cursor-warp")
+--   5. In Emacs: SPC z t enables cursor tracking (writes ~/.emacs-cursor-pos)
+--   6. Toggle in Hammerspoon: call emacsZoomToggle() or bind a hotkey
+--
+-- FILE FORMAT (~/.emacs-cursor-pos):
+--   Line 1: X Y    (screen-absolute cursor position)
+--   Line 2: FX FY  (frame-position, for debug cross-check)
+
+local M = {}
+
+-- Global toggle
+emacsZoomEnabled = true
+emacsZoomDebug = false
+
+local cursorPosFile = os.getenv("HOME") .. "/.emacs-cursor-pos"
+local lastMtime = 0
+local pollTimer = nil
+
+local function readCursorPos()
+    local f = io.open(cursorPosFile, "r")
+    if not f then return nil end
+    local line1 = f:read("*l")
+    local line2 = f:read("*l")
+    f:close()
+    if not line1 then return nil end
+    local x, y = line1:match("^(%d+) (%d+)$")
+    if not x then return nil end
+    local fx, fy = nil, nil
+    if line2 then
+        fx, fy = line2:match("^(%-?%d+) (%-?%d+)$")
+    end
+    return tonumber(x), tonumber(y), tonumber(fx), tonumber(fy)
+end
+
+local function pollAndWarp()
+    if not emacsZoomEnabled then return end
+
+    -- Check file modification time to avoid unnecessary reads
+    local attrs = hs.fs.attributes(cursorPosFile)
+    if not attrs then return end
+    local mtime = attrs.modification
+    if mtime == lastMtime then return end
+    lastMtime = mtime
+
+    local x, y, fx, fy = readCursorPos()
+    if not x then return end
+
+    -- Post a real mouseMoved event (not CGWarp)
+    hs.eventtap.event.newMouseEvent(
+        hs.eventtap.event.types.mouseMoved,
+        hs.geometry.point(x, y)
+    ):post()
+
+    if emacsZoomDebug then
+        local msg = string.format("cursor-warp: move to (%d, %d)", x, y)
+        if fx then
+            -- Cross-check with Hammerspoon's view of Emacs frame
+            local emacs = hs.application.get("Emacs")
+            if emacs then
+                local win = emacs:focusedWindow()
+                if win then
+                    local frame = win:frame()
+                    msg = msg .. string.format(
+                        " | emacs-frame=(%d,%d) hs-frame=(%d,%d)",
+                        fx, fy, math.floor(frame.x), math.floor(frame.y))
+                end
+            end
+        end
+        print(msg)
+    end
+end
+
+function emacsZoomToggle()
+    emacsZoomEnabled = not emacsZoomEnabled
+    local state = emacsZoomEnabled and "ON" or "OFF"
+    hs.alert.show("Emacs Zoom tracking: " .. state)
+    print("cursor-warp: " .. state)
+end
+
+function emacsZoomDebugToggle()
+    emacsZoomDebug = not emacsZoomDebug
+    hs.alert.show("Emacs Zoom debug: " .. (emacsZoomDebug and "ON" or "OFF"))
+end
+
+-- Start polling
+pollTimer = hs.timer.doEvery(0.05, pollAndWarp)
+
+-- Optional hotkey: Ctrl+Opt+Cmd+Z to toggle
+hs.hotkey.bind({"ctrl", "alt", "cmd"}, "Z", emacsZoomToggle)
+
+print("cursor-warp: loaded (polling every 50ms, hotkey Ctrl+Opt+Cmd+Z)")
+
+return M