From 29911b37d6fa377e648ca60161ba6381555b0ef4 Mon Sep 17 00:00:00 2001
From: Samuel Fadel <samuelfadel@gmail.com>
Date: Wed, 27 Jan 2016 18:47:31 +0100
Subject: Scatterplot: now possible to use brush to select points.

---
 scatterplot.cpp | 43 +++++++++++++++++++++++++++++++++++--------
 1 file changed, 35 insertions(+), 8 deletions(-)

diff --git a/scatterplot.cpp b/scatterplot.cpp
index f10f1b4..8a2bd13 100644
--- a/scatterplot.cpp
+++ b/scatterplot.cpp
@@ -539,7 +539,9 @@ void Scatterplot::updateGlyphs(QSGNode *glyphsNode)
 void Scatterplot::updateBrush(QSGNode *node)
 {
     QMatrix4x4 transform;
-    if (m_brushedItem < 0) {
+    if (m_brushedItem < 0
+        || (m_currentInteractionState != INTERACTION_NONE
+            && m_currentInteractionState != INTERACTION_SELECTED)) {
         transform.translate(-width(), -height());
     } else {
         const arma::rowvec &row = m_xy.row(m_brushedItem);
@@ -557,8 +559,6 @@ void Scatterplot::mousePressEvent(QMouseEvent *event)
     case INTERACTION_SELECTED:
         if (event->modifiers() == Qt::ShiftModifier) {
             m_currentInteractionState = INTERACTION_BEGIN_MOVING;
-        } else {
-            m_currentInteractionState = INTERACTION_SELECTING;
         }
         m_dragOriginPos = event->localPos();
         m_dragCurrentPos = m_dragOriginPos;
@@ -566,6 +566,7 @@ void Scatterplot::mousePressEvent(QMouseEvent *event)
     case INTERACTION_SELECTING:
     case INTERACTION_BEGIN_MOVING:
     case INTERACTION_MOVING:
+        // Probably shouldn't reach these
         event->ignore();
         break;
     }
@@ -587,20 +588,48 @@ void Scatterplot::mouseMoveEvent(QMouseEvent *event)
         break;
     case INTERACTION_NONE:
     case INTERACTION_SELECTED:
-        event->ignore();
-        return;
+        m_currentInteractionState = INTERACTION_SELECTING;
+        break;
     }
 }
 
 void Scatterplot::mouseReleaseEvent(QMouseEvent *event)
 {
     switch (m_currentInteractionState) {
+    case INTERACTION_NONE:
+    case INTERACTION_SELECTED:
+        if (m_brushedItem < 0) {
+            // Mouse clicked with no brush target; clear selection, if any
+            m_selection.assign(m_selection.size(), false);
+            m_shouldUpdateMaterials = true;
+            update();
+        } else {
+            // Mouse clicked with brush target; set new selection or append to
+            // current
+            bool mergeSelection = (event->modifiers() == Qt::ControlModifier);
+            if (!mergeSelection) {
+                m_selection.assign(m_selection.size(), false);
+            }
+            m_selection[m_brushedItem] = true;
+            emit selectionInteractivelyChanged(m_selection);
+
+            m_shouldUpdateMaterials = true;
+            update();
+        }
+        break;
     case INTERACTION_SELECTING:
         {
+            // Selecting points and mouse is now released; update selection and
+            // brush
             bool mergeSelection = (event->modifiers() == Qt::ControlModifier);
             bool anySelected = interactiveSelection(mergeSelection);
             m_currentInteractionState = anySelected ? INTERACTION_SELECTED
                                                     : INTERACTION_NONE;
+
+            QPoint pos = event->pos();
+            m_brushedItem = m_quadtree->nearestTo(pos.x(), pos.y());
+            emit itemInteractivelyBrushed(m_brushedItem);
+
             m_shouldUpdateMaterials = true;
             update();
         }
@@ -609,15 +638,13 @@ void Scatterplot::mouseReleaseEvent(QMouseEvent *event)
         m_currentInteractionState = INTERACTION_SELECTED;
         break;
     case INTERACTION_MOVING:
+        // Moving points and now stopped; apply manipulation
         m_currentInteractionState = INTERACTION_SELECTED;
         applyManipulation();
         m_shouldUpdateGeometry = true;
         update();
         m_dragOriginPos = m_dragCurrentPos;
         break;
-    case INTERACTION_NONE:
-    case INTERACTION_SELECTED:
-        break; // should not be reached
     }
 }
 
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