Initial commit: Chatter — assistive-writing app for reMarkable Paper Pro Move

Direct-framebuffer ink pipeline (stock-quality strokes), finger-wipe erase, growable scrolling canvas with color-ghost cleanup, bidirectional toggle with a persistent 4-finger return launcher, instant button feedback. Includes prebuilt aarch64 binaries (dist/), build/deploy/install scripts, a user guide, and a complete technical reference. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
2026-06-27 16:34:28 +02:00
commit 5f21d9099c
43 changed files with 2878 additions and 0 deletions
--- a/tools/chatter_launcher.c
+++ b/tools/chatter_launcher.c
@@ -0,0 +1,86 @@
+// Chatter launcher daemon. Runs always (systemd service), reads the touch device
+// (event3) WITHOUT grabbing it, and when it sees a multi-finger hold gesture
+// (>= FINGERS contacts held >= HOLD_MS) while xochitl is the active app, it
+// switches to Chatter. This is the "return to Chatter from the standard
+// interface" trigger (xochitl has no plugin API to add a real button).
+
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/input.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <unistd.h>
+
+#define DEV "/dev/input/event3"
+#define MAX_SLOTS 16
+#define FINGERS 4          // contacts required
+#define HOLD_MS 700        // how long they must be held
+#define COOLDOWN_MS 4000   // ignore re-triggers for this long
+
+static long now_ms(void)
+{
+    struct timespec ts;
+    clock_gettime(CLOCK_MONOTONIC, &ts);
+    return ts.tv_sec * 1000L + ts.tv_nsec / 1000000L;
+}
+
+int main(void)
+{
+    long lastTrigger = 0;
+    fprintf(stderr, "chatter-launcher: started (fingers=%d hold=%dms)\n", FINGERS, HOLD_MS);
+
+    // Outer loop: (re)open the device forever, so a read interruption (e.g. the
+    // device sleeping/waking) never kills the daemon.
+    for (;;) {
+        int fd = open(DEV, O_RDONLY);
+        if (fd < 0) { sleep(2); continue; }
+
+        int slot = 0;
+        int tid[MAX_SLOTS];
+        for (int i = 0; i < MAX_SLOTS; i++)
+            tid[i] = -1;
+        long holdStart = 0;
+        int triggered = 0;
+
+        struct input_event ev;
+        while (read(fd, &ev, sizeof(ev)) == (ssize_t)sizeof(ev)) {
+            if (ev.type == EV_ABS) {
+                if (ev.code == ABS_MT_SLOT) {
+                    slot = ev.value;
+                    if (slot < 0) slot = 0;
+                    if (slot >= MAX_SLOTS) slot = MAX_SLOTS - 1;
+                } else if (ev.code == ABS_MT_TRACKING_ID) {
+                    tid[slot] = ev.value; // >=0 active, -1 released
+                }
+            } else if (ev.type == EV_SYN && ev.code == SYN_REPORT) {
+                int active = 0;
+                for (int i = 0; i < MAX_SLOTS; i++)
+                    if (tid[i] >= 0) active++;
+
+                const long t = now_ms();
+                if (active >= FINGERS) {
+                    if (holdStart == 0)
+                        holdStart = t;
+                    else if (!triggered && (t - holdStart) >= HOLD_MS &&
+                             (t - lastTrigger) >= COOLDOWN_MS) {
+                        triggered = 1;
+                        lastTrigger = t;
+                        if (system("systemctl is-active --quiet xochitl") == 0) {
+                            fprintf(stderr, "chatter-launcher: gesture -> switching to Chatter\n");
+                            system("/home/root/chatter/to-chatter.sh >/dev/null 2>&1 &");
+                        }
+                    }
+                } else {
+                    holdStart = 0;
+                    triggered = 0;
+                }
+            }
+        }
+
+        close(fd);
+        fprintf(stderr, "chatter-launcher: input read ended, reopening\n");
+        sleep(1);
+    }
+    return 0;
+}