From a53af7ac65ec4c18fa44ae0cd24f5803a338d939 Mon Sep 17 00:00:00 2001
From: Robin Hu <robinfhu@gmail.com>
Date: Mon, 28 Oct 2013 11:05:50 -0400
Subject: [PATCH] Piechart: Added solution to overlapping pie chart labels.
 Needs more refinement, but it works for very narrow situations.

---
 nv.d3.js          | 21 ++++++++++++++++++++-
 src/models/pie.js | 21 ++++++++++++++++++++-
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/nv.d3.js b/nv.d3.js
index 97c2bea..d0efdfd 100644
--- a/nv.d3.js
+++ b/nv.d3.js
@@ -10388,6 +10388,13 @@ nv.models.pie = function() {
 
             });
 
+          var labelLocationHash = {};
+          var avgHeight = 14;
+          var avgWidth = 140;
+          var createHashKey = function(coordinates) {
+
+              return Math.floor(coordinates[0]/avgWidth) * avgWidth + ',' + Math.floor(coordinates[1]/avgHeight) * avgHeight;
+          };
           pieLabels.transition()
                 .attr('transform', function(d) {
                   if (labelSunbeamLayout) {
@@ -10403,7 +10410,19 @@ nv.models.pie = function() {
                     } else {
                       d.outerRadius = radius + 10; // Set Outer Coordinate
                       d.innerRadius = radius + 15; // Set Inner Coordinate
-                      return 'translate(' + labelsArc.centroid(d) + ')'
+
+                      /*
+                      Overlapping pie labels are not good. What this attempts to do is, prevent overlapping.
+                      Each label location is hashed, and if a hash collision occurs, we assume an overlap.
+                      Adjust the label's y-position to remove the overlap.
+                      */
+                      var center = labelsArc.centroid(d);
+                      var hashKey = createHashKey(center);
+                      if (labelLocationHash[hashKey]) {
+                        center[1] -= avgHeight;
+                      }
+                      labelHash[createHashKey(center)] = true;
+                      return 'translate(' + center + ')'
                     }
                 });
           pieLabels.select(".nv-label text")
diff --git a/src/models/pie.js b/src/models/pie.js
index 9b98a3b..b0ab998 100644
--- a/src/models/pie.js
+++ b/src/models/pie.js
@@ -191,6 +191,13 @@ nv.models.pie = function() {
 
             });
 
+          var labelLocationHash = {};
+          var avgHeight = 14;
+          var avgWidth = 140;
+          var createHashKey = function(coordinates) {
+
+              return Math.floor(coordinates[0]/avgWidth) * avgWidth + ',' + Math.floor(coordinates[1]/avgHeight) * avgHeight;
+          };
           pieLabels.transition()
                 .attr('transform', function(d) {
                   if (labelSunbeamLayout) {
@@ -206,7 +213,19 @@ nv.models.pie = function() {
                     } else {
                       d.outerRadius = radius + 10; // Set Outer Coordinate
                       d.innerRadius = radius + 15; // Set Inner Coordinate
-                      return 'translate(' + labelsArc.centroid(d) + ')'
+
+                      /*
+                      Overlapping pie labels are not good. What this attempts to do is, prevent overlapping.
+                      Each label location is hashed, and if a hash collision occurs, we assume an overlap.
+                      Adjust the label's y-position to remove the overlap.
+                      */
+                      var center = labelsArc.centroid(d);
+                      var hashKey = createHashKey(center);
+                      if (labelLocationHash[hashKey]) {
+                        center[1] -= avgHeight;
+                      }
+                      labelHash[createHashKey(center)] = true;
+                      return 'translate(' + center + ')'
                     }
                 });
           pieLabels.select(".nv-label text")