UI Nits: LTM Sidebar (Part 2 of 3)

The last of a series of recent patches to address performance
degradation from the introduction of the LTMSiebar. This last
patch introduces a CPX aggregates cache to re-use aggregated
CPX data (e.g. for plotting a specific season or date range).

The cache is set to only hold 25 caches, which should be enough
for most folks list of seasons. But won't get unwieldy if they
scroll around in the diary view.

The following will be introduced in the last patch of
this series:

1. Introduce 'events' within a season and plot them on the
   LTM chart -- a form of 'annotation' but also the beginning
   of planned events in the future too.

2. Implement click functionality on LTM charts but decide if
   we use click to annotate or to define a new date range or
   both?

src/RideFileCache.cpp

@@ -27,6 +27,8 @@
 #include <QMessageBox>
 #include <QtAlgorithms> // for qStableSort
 
+static const int maxcache = 25; // lets max out at 25 caches
+
 // cache from ride
 RideFileCache::RideFileCache(MainWindow *main, QString fileName, RideFile *passedride, bool check) :
                main(main), rideFileName(fileName), ride(passedride)
@@ -870,8 +872,17 @@ static void distAggregate(QVector<double> &into, QVector<double> &other)
 }
 
 RideFileCache::RideFileCache(MainWindow *main, QDate start, QDate end, bool filter, QStringList files)
-               : main(main), rideFileName(""), ride(0)
+               : main(main), rideFileName(""), ride(0), start(start), end(end)
 {
+
+    // Oh lets get from the cache if we can
+    foreach(RideFileCache *p, main->cpxCache) {
+        if (p->start == start && p->end == end) {
+            *this = *p;
+            return;
+        }
+    }
+
     // resize all the arrays to zero - expand as neccessary
     xPowerMeanMax.resize(0);
     npMeanMax.resize(0);
@@ -941,6 +952,14 @@ RideFileCache::RideFileCache(MainWindow *main, QDate start, QDate end, bool filt
 
     // set the cursor back to normal
     main->setCursor(Qt::ArrowCursor);
+
+    // lets add to the cache for others to re-use
+    if (main->cpxCache.count() > maxcache) {
+        delete(main->cpxCache.at(0));
+        main->cpxCache.removeAt(0);
+    }
+    main->cpxCache.append(new RideFileCache(this));
+
 }
 
 //