Add support for multiple thresholds, patch by Arnaud Bellec

NEWS.txt

@@ -20,6 +20,9 @@ Changes:
 - Support for setting the interval between redraws of the overlay
   canvas with redrawOverlayInterval (suggested in issue 185).
 
+- Support for multiple thresholds in thresholds plugin (patch by
+  Arnaud Bellec, issue 523).
+
 Bug fixes
 
 - Fix problem with null values and pie plugin (patch by gcruxifix,

jquery.flot.threshold.js

@@ -12,6 +12,19 @@ Flot plugin for thresholding data. Controlled through the option
 or in a specific series
 
   $.plot($("#placeholder"), [{ data: [ ... ], threshold: { ... }}])
+  
+An array can be passed for multiple thresholding
+
+  threshold: [{
+    below: number1
+    color: color1
+  },{
+    below: number2
+    color: color2
+  }]
+
+These multiple threshold objects can be passed in any order since they
+are sorted by the processing function.
 
 The data points below "below" are drawn with the specified color. This
 makes it easy to mark points below 0, e.g. for budget data.
@@ -29,22 +42,18 @@ events.
     };
     
     function init(plot) {
-        function thresholdData(plot, s, datapoints) {
-            if (!s.threshold)
-                return;
-            
+        function thresholdData(plot, s, datapoints, below, color) {
             var ps = datapoints.pointsize, i, x, y, p, prevp,
                 thresholded = $.extend({}, s); // note: shallow copy
 
             thresholded.datapoints = { points: [], pointsize: ps };
             thresholded.label = null;
-            thresholded.color = s.threshold.color;
+            thresholded.color = color;
             thresholded.threshold = null;
             thresholded.originSeries = s;
             thresholded.data = [];
-
-            var below = s.threshold.below,
-                origpoints = datapoints.points,
+ 
+            var origpoints = datapoints.points,
                 addCrossingPoints = s.lines.show;
 
             threspoints = [];
@@ -93,13 +102,31 @@ events.
             // FIXME: there are probably some edge cases left in bars
         }
         
-        plot.hooks.processDatapoints.push(thresholdData);
+        function processThresholds(plot, s, datapoints) {
+            if (!s.threshold)
+                return;
+            
+            if (s.threshold instanceof Array) {
+                s.threshold.sort(function(a, b) {
+                    return a.below - b.below;
+                });
+                
+                $(s.threshold).each(function(i, th) {
+                    thresholdData(plot, s, datapoints, th.below, th.color);
+                });
+            }
+            else {
+                thresholdData(plot, s, datapoints, s.threshold.below, s.threshold.color);
+            }
+        }
+        
+        plot.hooks.processDatapoints.push(processThresholds);
     }
     
     $.plot.plugins.push({
         init: init,
         options: options,
         name: 'threshold',
-        version: '1.1'
+        version: '1.2'
     });
 })(jQuery);