feat: a search's hits are marked on every row, and the panel says how many of them it is showing

src/plot_host.hpp

@@ -53,6 +53,10 @@ class RowSet {
   /// measurements to be shown at once, and a fixed number because a `Plot` fixes its cursor
   /// set at construction.
   static constexpr int kMeasureMarks = 6;
+  /// Search hits drawn at once, per row. A scan can return thousands; a plot cannot grow its
+  /// cursor set, and sixteen lines over one window is already the most a reader can count. The
+  /// panel states how many of the hits it is showing.
+  static constexpr int kSearchMarks = 16;
 
   RowSet();
 
@@ -112,6 +116,10 @@ class RowSet {
     std::array<plot::u32, kMeasureMarks> measure_h{};
     std::array<plot::u32, kMeasureMarks> measure_v{};
 
+    /// The search hits' marks: the same arrangement as the measurement pool above, vertical only
+    /// (a hit is an instant, never a level).
+    std::array<plot::u32, kSearchMarks> search_v{};
+
     /// One marker per trace per cursor: where each vertical cursor crosses that trace's
     /// series, drawn only in `mix` mode. Two per slot because the pair crosses a trace
     /// at two places, and an annotation cannot be shared between them.
@@ -255,6 +263,17 @@ class RowSet {
   /// measurement is drawn", as opposed to merely computed.
   int measure_marks_placed() const noexcept { return measure_marks_placed_; }
 
+  /// Places the search hits' marks and parks the rest of the pool. `xs` are **display** x values
+  /// (the caller has already taken `stream_at_x0()` off a stream time), the same convention
+  /// `set_measure_marks()` takes a time mark in, and the marks are unselectable for the same
+  /// reason: a hit is where the scope found the condition, not something the pointer may move.
+  ///
+  /// `current` indexes the one the navigation is standing on, which is drawn in its own colour, or
+  /// is negative for none. The caller orders `xs`; this places them in the order it is given.
+  void set_search_marks(const std::vector<double>& xs, int current);
+  /// How many search marks the last call placed, which is `min(xs.size(), kSearchMarks)`.
+  int search_marks_placed() const noexcept { return search_marks_placed_; }
+
   /// Whether every instrument this app *computed* is out of the pointer's reach: the trigger
   /// marker and the measurement marks. They are readouts -- where the scope put the edge, what a
   /// measurement measured -- and a user must not be able to drag them; the report in the dump is
@@ -479,6 +498,7 @@ class RowSet {
   /// back, one row's stale echo at a time.
 
   int measure_marks_placed_ = 0;
+  int search_marks_placed_ = 0;
   /// The one stream time each vertical cursor is at, whatever row's copy was last moved.
   double cursor_a_x_ = 0.0;
   double cursor_b_x_ = 0.0;