Make cursor pair drop precision when too small

[pulseview.git] / pv / views / trace / cursorpair.cpp

diff --git a/pv/views/trace/cursorpair.cpp b/pv/views/trace/cursorpair.cpp
index 933eb8fff33e0c3aaf2ed255dc2a6e00bc5b8754..562584c2f903fdde8f93b0bbd32005bc58c1673b 100644 (file)
--- a/pv/views/trace/cursorpair.cpp
+++ b/pv/views/trace/cursorpair.cpp
@@ -129,19 +129,14 @@ void CursorPair::paint_label(QPainter &p, const QRect &rect, bool hover)
        const QColor text_color = ViewItem::select_text_color(Cursor::FillColor);
        p.setPen(text_color);
 
-       QString text = format_string();
-       text_size_ = p.boundingRect(QRectF(), 0, text).size();
-
        QRectF delta_rect(label_rect(rect));
        const int radius = delta_rect.height() / 2;
        QRectF text_rect(delta_rect.intersected(rect).adjusted(radius, 0, -radius, 0));
 
-       if (text_rect.width() < text_size_.width()) {
-               text = "...";
-               text_size_ = p.boundingRect(QRectF(), 0, text).size();
-               label_incomplete_ = true;
-       } else
-               label_incomplete_ = false;
+       QString text = format_string(text_rect.width(), [&p](const QString& s) -> qreal {
+                       return p.boundingRect(QRectF(), 0, s).width();
+               });
+       text_size_ = p.boundingRect(QRectF(), 0, text).size();
 
        if (selected()) {
                p.setBrush(Qt::transparent);
@@ -178,17 +173,50 @@ void CursorPair::paint_back(QPainter &p, ViewItemPaintParams &pp)
        p.drawRect(l, pp.top(), r - l, pp.height());
 }
 
-QString CursorPair::format_string()
+QString CursorPair::format_string(qreal max_width, std::function<qreal(const QString&)> query_size)
 {
+       constexpr int time_precision = 12;
+       constexpr int freq_precision = 4;
+
        const pv::util::SIPrefix prefix = view_.tick_prefix();
        const pv::util::Timestamp diff = abs(second_->time() - first_->time());
 
-       const QString s1 = Ruler::format_time_with_distance(
-               diff, diff, prefix, view_.time_unit(), 12, false);  /* Always use 12 precision digits */
-       const QString s2 = util::format_time_si(
-               1 / diff, pv::util::SIPrefix::unspecified, 4, "Hz", false);
+       const QString time = Ruler::format_time_with_distance(
+                       diff, diff, prefix, view_.time_unit(), time_precision, false);
+       const QString freq = util::format_time_si(
+               1 / diff, pv::util::SIPrefix::unspecified, freq_precision, "Hz", false);
+       const QString out = QString("%1 / %2").arg(time, freq);
+
+       // Try full "{time} ms / {freq} Hz" format
+       if (max_width <= 0 || query_size(out) <= max_width) {
+               label_incomplete_ = false;
+               return out;
+       }
+
+       label_incomplete_ = true;
+
+       // Try just "{time}ms" format and gradually reduce time precision down to zero
+       for (int shrinkage=0; shrinkage <= time_precision; shrinkage++) {
+               int prec = time_precision - shrinkage ;
+
+               const QString time = Ruler::format_time_with_distance(
+                       diff, diff, prefix, view_.time_unit(),
+                       prec, false);
+
+               if (query_size(time) <= max_width)
+                       return time;
+       }
+
+       // Try no trailing digits and drop the unit to at least display something. The unit should be obvious from the ruler
+       // anyway.
+       const QString bare_number = Ruler::format_time_with_distance(
+               diff, diff, prefix, view_.time_unit(),
+               0, false, false);
+       if (query_size(bare_number) <= max_width)
+               return bare_number;
 
-       return QString("%1 / %2").arg(s1, s2);
+       // Give up.
+       return "...";
 }
 
 pair<float, float> CursorPair::get_cursor_offsets() const