improved measuraments ,cursors, zooming and user interactions

src/model.cpp

@@ -372,6 +372,40 @@ void ScopeModel::reset_live_history_locked() {
   }
 }
 
+void ScopeModel::publish_pause_view(double lo_s, double hi_s) {
+  auto snap = std::make_shared<EventSnapshot>();
+  std::lock_guard<std::mutex> lock(mutex_);
+  BufferStore& src = live();
+  u64 first = 0;
+  u64 last = 0;
+  live_window_locked(lo_s, hi_s, first, last);
+  const u64 n = last - first;
+  snap->stamps.resize(static_cast<std::size_t>(n));
+  if (n > 0) {
+    // The stamps go in *as the ring holds them*: the stream's own seconds, which is the
+    // coordinate the axis was already reading. Nothing is rebased, so a pause does not move the
+    // dates under the reader the way a trigger event's edge-relative axis deliberately does.
+    src.time().copy_from(first, n, snap->stamps.data());
+  }
+  snap->values.resize(channels_.size());
+  snap->y.resize(channels_.size(), plot::Range{0.0, 0.0});
+  for (std::size_t c = 0; c < channels_.size(); ++c) {
+    const u64 stride = std::max<u64>(1, part_.stride[c]);
+    auto& vals = snap->values[c];
+    const u64 take = std::min(n / stride, src.values(c).size());
+    vals.resize(static_cast<std::size_t>(take));
+    if (take > 0) src.values(c).copy_from(first + n - take, take, vals.data());
+    f32 lo = vals.empty() ? 0.0f : vals.front();
+    f32 hi = lo;
+    for (f32 v : vals) {
+      lo = std::min(lo, v);
+      hi = std::max(hi, v);
+    }
+    snap->y[c] = plot::Range{lo, hi};
+  }
+  pause_view_.store(std::move(snap), std::memory_order_release);
+}
+
 void ScopeModel::publish_event(double pre_s, double post_s, double edge) {
   auto snap = std::make_shared<EventSnapshot>();
   BufferStore& src = live();