Slide sideways on space to move the cursor

As on phone keyboards: a sideways move on space moves the cursor right
away, along the line only, without blanking the keys. Long-press space
still opens the full trackpad.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/input/PointerTracker.cpp

@@ -26,8 +26,14 @@ void PointerTracker::moveTo(QPointF pos)
         return;
     m_moved = true;
 
-    if (m_key.type == KeyType::LayerSwitch)
+    if (m_key.type == KeyType::LayerSwitch) {
         m_gesture = Gesture::Slide;
+    } else if (m_config.gestures && m_key.type == KeyType::Space && qAbs(delta.x()) > qAbs(delta.y())) {
+        // From the press point: the slop counts towards the first step.
+        m_gesture = Gesture::Trackpad;
+        m_trackpadOrigin = m_start;
+        m_trackpadLines = false;
+    }
     else if (m_config.gestures && !m_key.flick.isEmpty() && delta.y() > qAbs(delta.x()))
         m_gesture = Gesture::Flick;
 }
@@ -63,7 +69,8 @@ QPoint PointerTracker::takeTrackpadSteps()
 
     const QPointF travel = m_position - m_trackpadOrigin;
     // Truncate towards zero so jitter around the origin doesn't step.
-    const QPoint total(int(travel.x() / m_config.trackpadStep), int(travel.y() / m_config.trackpadRowStep));
+    const int rows = m_trackpadLines ? int(travel.y() / m_config.trackpadRowStep) : 0;
+    const QPoint total(int(travel.x() / m_config.trackpadStep), rows);
     const QPoint steps = total - m_trackpadStepsTaken;
     m_trackpadStepsTaken = total;
     return steps;

src/input/PointerTracker.h

@@ -11,7 +11,8 @@
 //   Tap        pressed, not (yet) anything else
 //   Flick      moved down on a key with a flick symbol
 //   LongPress  held still on a key with alternates
-//   Trackpad   held still on space; movement moves the text cursor
+//   Trackpad   held still on space; movement moves the text cursor. Sliding
+//              sideways on space moves it too, along the line only.
 //   Slide      moved off a layer key (type a symbol, then switch back)
 class PointerTracker
 {
@@ -56,5 +57,6 @@ private:
     Gesture m_gesture = Gesture::Tap;
     bool m_moved = false;
     QPointF m_trackpadOrigin;
+    bool m_trackpadLines = true; // vertical travel moves between lines
     QPoint m_trackpadStepsTaken;
 };