Make the hover text conform to data displayed.

Start of code to be more selective about the association between the
hover text and the underling graph. Also, show the data set name in hover text.

* grapher/GraphStyle.hxx (dataIndexAtPoint): New virtual function.
* grapher/GraphStyle.cxx (dataIndexAtPoint): Implementation for bar graphs
* grapher/GraphWidget.cxx (onHoverTimeout): Use dataIndexAtPoint.

7 files changed, 73 insertions, 26 deletions

diff --git a/grapher/Graph.cxx b/grapher/Graph.cxx
index 4b5b8eb6..55ffcdf2 100644
--- a/grapher/Graph.cxx
+++ b/grapher/Graph.cxx
@@ -13,7 +13,8 @@ namespace systemtap
     : _width(600), _height(200), _graphX(0), _graphY(0),
       _graphWidth(580), _graphHeight(180),
       _lineWidth(2), _autoScaling(true), _autoScrolling(true),
-      _zoomFactor(1.0), _playButton(new CairoPlayButton),
+      _zoomFactor(1.0), _xOffset(20.0), _yOffset(0.0),
+      _playButton(new CairoPlayButton),
       _left(0), _right(1), _top(5.0), _bottom(0.0)
   {
     setOrigin(x, y);
@@ -80,7 +81,7 @@ namespace systemtap
     cr->save();
     double horizScale
         = _zoomFactor * _graphWidth / static_cast<double>(_right - _left);
-    cr->translate(20.0, 0.0);
+    cr->translate(_xOffset, _yOffset);
     cr->set_line_width(_lineWidth);
 
     for (DatasetList::iterator itr = _datasets.begin(), e = _datasets.end();
@@ -134,9 +135,9 @@ namespace systemtap
     cr->select_font_face("Sans", Cairo::FONT_SLANT_NORMAL,
                          Cairo::FONT_WEIGHT_NORMAL);
     cr->set_font_size(10.0);
-    cr->move_to(20.0, 0.0);
-    cr->line_to(20.0, _height);
-    cr->move_to(20.0, _graphHeight);
+    cr->move_to(_xOffset, _yOffset);
+    cr->line_to(_xOffset, _height);
+    cr->move_to(_xOffset, _graphHeight);
     cr->line_to(_graphWidth, _graphHeight);
     cr->stroke();
     std::valarray<double> dash(1);
@@ -145,8 +146,8 @@ namespace systemtap
     double prevTextAdvance = 0;
     for (int64_t tickVal = startTime; tickVal <= _right; tickVal += majorUnit)
       {
-        double x = (tickVal - _left) * horizScale + 20.0;
-        cr->move_to(x, 0.0);
+        double x = (tickVal - _left) * horizScale + _xOffset;
+        cr->move_to(x, _yOffset);
         cr->line_to(x, _graphHeight);
         std::ostringstream stream;
         stream << tickVal;
@@ -201,6 +202,7 @@ namespace systemtap
 
   int64_t Graph::getTimeAtPoint(double x)
   {
-    return _left + (_right - _left) * ((x - 20.0)/(_zoomFactor * _graphWidth));
+    return (_left
+            + (_right - _left) * ((x - _xOffset)/(_zoomFactor * _graphWidth)));
   }
 }
diff --git a/grapher/Graph.hxx b/grapher/Graph.hxx
index e0e864d6..b9efb2a2 100644
--- a/grapher/Graph.hxx
+++ b/grapher/Graph.hxx
@@ -36,6 +36,8 @@ namespace systemtap
     bool _autoScaling;
     bool _autoScrolling;
     double _zoomFactor;
+    double _xOffset;
+    double _yOffset;
     std::tr1::shared_ptr<CairoPlayButton> _playButton;
     DatasetList& getDatasets() { return _datasets; }
     int64_t getTimeAtPoint(double x);
diff --git a/grapher/GraphData.hxx b/grapher/GraphData.hxx
index 9a267fc5..04f415f3 100644
--- a/grapher/GraphData.hxx
+++ b/grapher/GraphData.hxx
@@ -27,6 +27,7 @@ namespace systemtap
     }
     virtual std::string elementAsString(size_t element) = 0;
     // size of grid square at "normal" viewing
+    std::string name;
     double scale;
     double color[3];
     GraphStyle* style;
diff --git a/grapher/GraphStyle.cxx b/grapher/GraphStyle.cxx
index 887ed55f..55fc73f4 100644
--- a/grapher/GraphStyle.cxx
+++ b/grapher/GraphStyle.cxx
@@ -8,6 +8,9 @@ namespace systemtap
   using namespace std;
   using namespace tr1;
 
+  typedef pair<GraphDataBase::TimeList::iterator,
+               GraphDataBase::TimeList::iterator>  TimeListPair;
+
   GraphStyleBar GraphStyleBar::instance;
   
   void GraphStyleBar::draw(std::tr1::shared_ptr<GraphDataBase> graphData,
@@ -41,6 +44,29 @@ namespace systemtap
       }
   }
 
+  ssize_t GraphStyleBar::dataIndexAtPoint(double x, double y,
+                                          shared_ptr<GraphDataBase> graphData,
+                                          shared_ptr<Graph> graph)
+  {
+    shared_ptr<GraphData<double> > realData
+      = dynamic_pointer_cast<GraphData<double> >(graphData);
+    if (!realData)
+      return -1;
+    int64_t left, right;
+    double top, bottom;
+    graph->getExtents(left, right, top, bottom);
+    double t = graph->getTimeAtPoint(x);
+    TimeListPair range
+      = equal_range(graphData->times.begin(), graphData->times.end(), t);
+    size_t dataIndex = distance(graphData->times.begin(), range.first);
+    double val = realData->data[dataIndex];
+    double ycoord = val * graph->_graphHeight / graphData->scale;
+    if (y >= graph->_yOffset + graph->_graphHeight - ycoord)
+      return static_cast<ssize_t>(dataIndex);
+    else
+      return -1;
+  }
+  
   GraphStyleDot GraphStyleDot::instance;
   
   void GraphStyleDot::draw(std::tr1::shared_ptr<GraphDataBase> graphData,
diff --git a/grapher/GraphStyle.hxx b/grapher/GraphStyle.hxx
index 4a0cd955..9625f451 100644
--- a/grapher/GraphStyle.hxx
+++ b/grapher/GraphStyle.hxx
@@ -14,29 +14,40 @@ namespace systemtap
   public:
     virtual void draw(std::tr1::shared_ptr<GraphDataBase> graphData,
                       Graph* graph, Cairo::RefPtr<Cairo::Context> cr) = 0;
+    virtual ssize_t dataIndexAtPoint(double x, double y,
+                                     std::tr1::shared_ptr<GraphDataBase>
+                                     graphData,
+                                     std::tr1::shared_ptr<Graph> graph)
+    {
+      return -1;
+    }
   };
 
   class GraphStyleBar : public GraphStyle
   {
   public:
-    virtual void draw(std::tr1::shared_ptr<GraphDataBase> graphData,
-                      Graph* graph, Cairo::RefPtr<Cairo::Context> cr);
+    void draw(std::tr1::shared_ptr<GraphDataBase> graphData,
+              Graph* graph, Cairo::RefPtr<Cairo::Context> cr);
+    
     static GraphStyleBar instance;
+    ssize_t dataIndexAtPoint(double x, double y,
+                             std::tr1::shared_ptr<GraphDataBase> graphData,
+                             std::tr1::shared_ptr<Graph> graph);
   };
 
   class GraphStyleDot : public GraphStyle
   {
   public:
-    virtual void draw(std::tr1::shared_ptr<GraphDataBase> graphData,
-                      Graph* graph, Cairo::RefPtr<Cairo::Context> cr);
+    void draw(std::tr1::shared_ptr<GraphDataBase> graphData,
+              Graph* graph, Cairo::RefPtr<Cairo::Context> cr);
     static GraphStyleDot instance;
   };
 
   class GraphStyleEvent : public GraphStyle
   {
   public:
-    virtual void draw(std::tr1::shared_ptr<GraphDataBase> graphData,
-                      Graph* graph, Cairo::RefPtr<Cairo::Context> cr);
+    void draw(std::tr1::shared_ptr<GraphDataBase> graphData,
+              Graph* graph, Cairo::RefPtr<Cairo::Context> cr);
     static GraphStyleEvent instance;
   };  
 }
diff --git a/grapher/GraphWidget.cxx b/grapher/GraphWidget.cxx
index 9a203d87..9067988a 100644
--- a/grapher/GraphWidget.cxx
+++ b/grapher/GraphWidget.cxx
@@ -276,20 +276,23 @@ namespace systemtap
         if (!_hoverText)
           _hoverText = shared_ptr<CairoTextBox>(new CairoTextBox());
         _hoverText->setOrigin(_mouseX + 5, _mouseY - 5);
-        int64_t t = g->getTimeAtPoint(_mouseX);
         Graph::DatasetList& dataSets = g->getDatasets();
-        if (!dataSets.empty())
-          {
-            shared_ptr<GraphDataBase> gdbase = dataSets[0];
-            GraphDataBase::TimeList::iterator itime
-              = std::lower_bound(gdbase->times.begin(), gdbase->times.end(), t);
-            if (itime != gdbase->times.end()) {
-              size_t index = distance(gdbase->times.begin(), itime);
-              _hoverText->contents = gdbase->elementAsString(index);
-              _hoverText->setVisible(true);
-              queue_draw();
+        for (Graph::DatasetList::reverse_iterator ritr = dataSets.rbegin(),
+                 end = dataSets.rend();
+             ritr != end;
+             ++ritr)
+        {
+            ssize_t index
+                = (*ritr)->style->dataIndexAtPoint(_mouseX, _mouseY, *ritr, g);
+            if (index >= 0)
+            {
+                _hoverText->contents = (*ritr)->name
+                    + ": " + (*ritr)->elementAsString(index);
+                _hoverText->setVisible(true);
+                queue_draw();
+                break;
             }
-          }
+        }
       }
     return false;
   }
diff --git a/grapher/StapParser.cxx b/grapher/StapParser.cxx
index af5f2d7d..6218e229 100644
--- a/grapher/StapParser.cxx
+++ b/grapher/StapParser.cxx
@@ -101,6 +101,7 @@ vector<string> commaSplit(const boost::sub_range<Glib::ustring>& range)
                     {
                       std::tr1::shared_ptr<GraphData<double> >
                         dataSet(new GraphData<double>);
+                      dataSet->name = setName;
                       if (style == "dot")
                         dataSet->style = &GraphStyleDot::instance;
                       dataSet->color[0] = (hexColor >> 16) / 255.0;
@@ -114,6 +115,7 @@ vector<string> commaSplit(const boost::sub_range<Glib::ustring>& range)
                     {
                       std::tr1::shared_ptr<GraphData<string> >
                         dataSet(new GraphData<string>);
+                      dataSet->name = setName;
                       dataSet->style = &GraphStyleEvent::instance;
                       dataSet->color[0] = (hexColor >> 16) / 255.0;
                       dataSet->color[1] = ((hexColor >> 8) & 0xff) / 255.0;