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/src/main.cpp
+++ b/src/main.cpp
@@ -0,0 +1,89 @@
+// Chatter — Qt Quick app with a direct-framebuffer ink pipeline.
+// Pen strokes are drawn straight into the e-paper framebuffer (captured by
+// FbCapture) and refreshed with an explicit solid swap (InkEngine). Qt Quick is
+// used only for the static UI (Back / Clear). This is what gives stock-quality
+// solid, low-latency ink — the Qt scene graph can't.
+
+#include <QGuiApplication>
+#include <QQmlApplicationEngine>
+#include <QQmlContext>
+#include <QScreen>
+#include <QSettings>
+#include <QVariantMap>
+#include <QColor>
+#include <QRegion>
+#include <QRect>
+
+#include "PenDevice.h"
+#include "AppControl.h"
+#include "InkEngine.h"
+#include "FbCapture.h" // links the setBuffers interposer into the executable
+
+struct PenStyle {
+    int type = 2;
+    qreal size = 2.0;
+    QColor color = Qt::black;
+};
+
+// Read the pen the user last selected in the standard GUI (xochitl.conf,
+// [General]/LastWritingTool — flushed when xochitl stops, i.e. on Back).
+static PenStyle readPenStyle()
+{
+    PenStyle ps;
+    QSettings xs(QStringLiteral("/home/root/.config/remarkable/xochitl.conf"),
+                 QSettings::IniFormat);
+    const QVariantMap t = xs.value(QStringLiteral("LastWritingTool")).toMap();
+    if (t.isEmpty()) {
+        qWarning("readPenStyle: LastWritingTool unreadable; using defaults");
+        return ps;
+    }
+    ps.type = t.value("LastPen").toInt();
+    ps.size = t.value("LastPenSize").toDouble();
+    const uint code = t.value("LastPenColorCode").toUInt();
+    if (code != 0)
+        ps.color = QColor::fromRgba(QRgb(code));
+    qInfo("readPenStyle: pen=%d size=%.2f color=%s", ps.type, ps.size,
+          qPrintable(ps.color.name(QColor::HexArgb)));
+    return ps;
+}
+
+int main(int argc, char *argv[])
+{
+    QGuiApplication app(argc, argv);
+    const PenStyle penStyle = readPenStyle();
+
+    const QSize screen = app.primaryScreen()->geometry().size();
+    PenDevice pen(screen.width(), screen.height());
+    AppControl appControl;
+
+    InkEngine ink;
+    ink.setInkColor(penStyle.color);
+    // reMarkable exposes only the size CATEGORY (LastPenSize 1/2/3 =
+    // thin/thicker/thickest). Calibrate to measured widths on this 264-PPI panel:
+    // thicker ~1mm, thickest ~2mm, thinnest ~2px. px/mm = 264/25.4 ~= 10.4.
+    constexpr double pxPerMm = 264.0 / 25.4;
+    const double maxMm = qMax(0.2, (penStyle.size - 1.0) * 1.0); // sz3->2mm, sz2->1mm
+    ink.setWidthRange(2.0, maxMm * pxPerMm);
+    ink.setPenType(penStyle.type);
+
+    // Back button (finger or stylus) → return to the standard GUI.
+    QObject::connect(&ink, &InkEngine::backRequested, &appControl, &AppControl::returnToStandard);
+
+    // Pen drives the ink engine directly (no QML in the ink loop).
+    QObject::connect(&pen, &PenDevice::strokeStart, &ink, &InkEngine::strokeStart);
+    QObject::connect(&pen, &PenDevice::strokeMove, &ink, &InkEngine::strokeMove);
+    QObject::connect(&pen, &PenDevice::strokeEnd, &ink, &InkEngine::strokeEnd);
+
+    QQmlApplicationEngine engine;
+    engine.rootContext()->setContextProperty("appControl", &appControl);
+    engine.rootContext()->setContextProperty("ink", &ink);
+
+    QObject::connect(
+        &engine, &QQmlApplicationEngine::objectCreationFailed,
+        &app, []() { QCoreApplication::exit(-1); },
+        Qt::QueuedConnection);
+
+    engine.loadFromModule("Chatter", "Main");
+
+    return app.exec();
+}