Fix #121 by implementing sticky scrolling

[pulseview.git] / pv / view / view.cpp

diff --git a/pv/view/view.cpp b/pv/view/view.cpp
index 2ae0a7144cba4b9b15abbc34f3e9265e14f43250..130d2d788cfaf862cbb2c83b03fbac8e48f7e4a0 100644 (file)
--- a/pv/view/view.cpp
+++ b/pv/view/view.cpp
@@ -86,6 +86,7 @@ const double View::MaxScale = 1e9;
 const double View::MinScale = 1e-15;
 
 const int View::MaxScrollValue = INT_MAX / 2;
+const int View::MaxViewAutoUpdateRate = 25; // No more than 25 Hz
 
 const int View::ScaleUnits[3] = {1, 2, 5};
 
@@ -98,6 +99,7 @@ View::View(Session &session, QWidget *parent) :
        scale_(1e-3),
        offset_(0),
        updating_scroll_(false),
+       sticky_scrolling_(false), // Default setting is set in MainWindow::setup_ui()
        tick_period_(0.0),
        tick_prefix_(0),
        show_cursors_(false),
@@ -136,6 +138,11 @@ View::View(Session &session, QWidget *parent) :
                this, SLOT(process_sticky_events()));
        lazy_event_handler_.setSingleShot(true);
 
+       connect(&delayed_view_updater_, SIGNAL(timeout()),
+               this, SLOT(perform_delayed_view_update()));
+       delayed_view_updater_.setSingleShot(true);
+       delayed_view_updater_.setInterval(1000 / MaxViewAutoUpdateRate);
+
        setViewport(viewport_);
 
        viewport_->installEventFilter(this);
@@ -288,6 +295,13 @@ void View::zoom_one_to_one()
 
 void View::set_scale_offset(double scale, double offset)
 {
+       // Disable sticky scrolling when acquisition runs and user drags the viewport
+       if ((scale_ == scale) && (offset_ != offset) &&
+                       sticky_scrolling_ && (session_.get_capture_state() == Session::Running)) {
+               sticky_scrolling_ = false;
+               sticky_scrolling_changed(false);
+       }
+
        scale_ = scale;
        offset_ = offset;
 
@@ -339,6 +353,11 @@ pair<double, double> View::get_time_extents() const
        return make_pair(left_time, right_time);
 }
 
+void View::enable_sticky_scrolling(bool state)
+{
+       sticky_scrolling_ = state;
+}
+
 bool View::cursors_shown() const
 {
        return show_cursors_;
@@ -674,6 +693,13 @@ void View::h_scroll_value_changed(int value)
        if (updating_scroll_)
                return;
 
+       // Disable sticky scrolling when user moves the horizontal scroll bar
+       // during a running acquisition
+       if (sticky_scrolling_ && (session_.get_capture_state() == Session::Running)) {
+               sticky_scrolling_ = false;
+               sticky_scrolling_changed(false);
+       }
+
        const int range = horizontalScrollBar()->maximum();
        if (range < MaxScrollValue)
                offset_ = scale_ * value;
@@ -821,10 +847,31 @@ void View::signals_changed()
 
 void View::data_updated()
 {
-       // Update the scroll bars
-       update_scroll();
+       if (sticky_scrolling_) {
+               if (!delayed_view_updater_.isActive())
+                       delayed_view_updater_.start();
+       } else {
+               update_scroll();
+               ruler_->update();
+               viewport_->update();
+       }
+}
+
+void View::perform_delayed_view_update()
+{
+       if (sticky_scrolling_) {
+               // Make right side of the view sticky
+               double length = 0, offset;
+               get_scroll_layout(length, offset);
+
+               const QSize areaSize = viewport_->size();
+               length = max(length - areaSize.width(), 0.0);
+
+               offset_ = scale_ * length;
+       }
 
-       // Repaint the view
+       update_scroll();
+       ruler_->update();
        viewport_->update();
 }