LP-567 uavobjectbrowser: improve highlight handling

keep track of when to check highlight and schedule timer accordingly
old way would do that at a fixed periodicity leading to aliasing

ground/gcs/src/plugins/uavobjectbrowser/treeitem.cpp

@@ -28,11 +28,12 @@
 #include "treeitem.h"
 
 /* Constructor */
-HighLightManager::HighLightManager(long checkingInterval)
+HighLightManager::HighLightManager()
 {
-    // Start the timer and connect it to the callback
-    m_expirationTimer.start(checkingInterval);
-    connect(&m_expirationTimer, SIGNAL(timeout()), this, SLOT(checkItemsExpired()));
+    // Initialize the timer and connect it to the callback
+    m_expirationTimer.setTimerType(Qt::PreciseTimer);
+    m_expirationTimer.setSingleShot(true);
+    connect(&m_expirationTimer, &QTimer::timeout, this, &HighLightManager::checkItemsExpired);
 }
 
 /*
@@ -52,6 +53,20 @@ bool HighLightManager::add(TreeItem *itemToAdd)
     return false;
 }
 
+bool HighLightManager::startTimer(QTime expirationTime)
+{
+    // Lock to ensure thread safety
+    QMutexLocker locker(&m_mutex);
+
+    if (!m_expirationTimer.isActive()) {
+        int msec = QTime::currentTime().msecsTo(expirationTime);
+        // qDebug() << "start" << msec;
+        m_expirationTimer.start((msec < 10) ? 10 : msec);
+        return true;
+    }
+    return false;
+}
+
 /*
  * Called to remove item from list.
  * Returns true if item was removed, otherwise false.
@@ -81,35 +96,48 @@ void HighLightManager::checkItemsExpired()
 
     // This is the timestamp to compare with
     QTime now = QTime::currentTime();
+    QTime next;
 
     // Loop over all items, check if they expired.
     while (iter.hasNext()) {
         TreeItem *item = iter.next();
-        if (item->getHiglightExpires() < now) {
-            // If expired, call removeHighlight
+        if (item->getHiglightExpires() <= now) {
+            // expired, call removeHighlight
             item->removeHighlight();
 
             // Remove from list since it is restored.
             iter.remove();
+        } else {
+            // not expired, check if next to expire
+            if (!next.isValid() || (next > item->getHiglightExpires())) {
+                next = item->getHiglightExpires();
+            }
         }
     }
+    if (next.isValid()) {
+        int msec = QTime::currentTime().msecsTo(next);
+        // qDebug() << "restart" << msec;
+        m_expirationTimer.start((msec < 10) ? 10 : msec);
+    }
 }
 
-int TreeItem::m_highlightTimeMs = 500;
+int TreeItem::m_highlightTimeMs = 300;
 
 TreeItem::TreeItem(const QList<QVariant> &data, TreeItem *parent) :
     QObject(0),
     m_data(data),
     m_parent(parent),
     m_highlight(false),
-    m_changed(false)
+    m_changed(false),
+    m_highlightManager(0)
 {}
 
 TreeItem::TreeItem(const QVariant &data, TreeItem *parent) :
     QObject(0),
     m_parent(parent),
     m_highlight(false),
-    m_changed(false)
+    m_changed(false),
+    m_highlightManager(0)
 {
     m_data << data << "" << "";
 }
@@ -180,24 +208,27 @@ void TreeItem::apply()
 }
 
 /*
- * Called after a value has changed to trigger highlightning of tree item.
+ * Called after a value has changed to trigger highlighting of tree item.
  */
 void TreeItem::setHighlight(bool highlight)
 {
-    m_highlight = highlight;
     m_changed   = false;
-    if (highlight) {
-        // Update the expires timestamp
-        m_highlightExpires = QTime::currentTime().addMSecs(m_highlightTimeMs);
-
-        // Add to highlightmanager
-        if (m_highlightManager->add(this)) {
-            // Only emit signal if it was added
+    if (m_highlight != highlight) {
+        m_highlight = highlight;
+        if (highlight) {
+            // Add to highlight manager
+            if (m_highlightManager->add(this)) {
+                // Only emit signal if it was added
+                emit updateHighlight(this);
+            }
+            // Update expiration timeout
+            m_highlightExpires = QTime::currentTime().addMSecs(m_highlightTimeMs);
+            // start expiration timer if necessary
+            m_highlightManager->startTimer(m_highlightExpires);
+        } else if (m_highlightManager->remove(this)) {
+            // Only emit signal if it was removed
             emit updateHighlight(this);
         }
-    } else if (m_highlightManager->remove(this)) {
-        // Only emit signal if it was removed
-        emit updateHighlight(this);
     }
 
     // If we have a parent, call recursively to update highlight status of parents.

ground/gcs/src/plugins/uavobjectbrowser/treeitem.h

@@ -49,7 +49,7 @@ class TreeItem;
  * non highlighted state in a linked list.
  * A timer traverses this list periodically to find out
  * if any of the items should be restored. All items are
- * updated withan expiration timestamp when they expires.
+ * updated with an expiration timestamp when they expires.
  * An item that is beeing restored is removed from the
  * list and its removeHighlight() method is called. Items
  * that are not expired are left in the list til next time.
@@ -60,8 +60,7 @@ class TreeItem;
 class HighLightManager : public QObject {
     Q_OBJECT
 public:
-    // Constructor taking the checking interval in ms.
-    HighLightManager(long checkingInterval);
+    HighLightManager();
 
     // This is called when an item has been set to
     // highlighted = true.
@@ -70,6 +69,8 @@ public:
     // This is called when an item is set to highlighted = false;
     bool remove(TreeItem *itemToRemove);
 
+    bool startTimer(QTime time);
+
 private slots:
     // Timer callback method.
     void checkItemsExpired();

ground/gcs/src/plugins/uavobjectbrowser/uavobjecttreemodel.cpp

@@ -52,8 +52,7 @@ UAVObjectTreeModel::UAVObjectTreeModel(QObject *parent, bool categorize, bool sh
 
     Q_ASSERT(objManager);
 
-    // Create highlight manager, let it run every 300 ms.
-    m_highlightManager = new HighLightManager(300);
+    m_highlightManager = new HighLightManager();
     connect(objManager, SIGNAL(newObject(UAVObject *)), this, SLOT(newObject(UAVObject *)));
     connect(objManager, SIGNAL(newInstance(UAVObject *)), this, SLOT(newObject(UAVObject *)));