From ef539bf4a70534e178f16e317fac01a308373065 Mon Sep 17 00:00:00 2001
From: Jan Kalina <jkalina@redhat.com>
Date: Wed, 2 Sep 2015 23:14:12 +0200
Subject: [PATCH] Reverse scale on radar/polar area

---
 samples/polar-area.html          |  6 +++++-
 samples/radar.html               |  6 ++++++
 samples/scatter-multi-axis.html  |  1 +
 src/scales/scale.radialLinear.js | 18 +++++++++++++-----
 4 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/samples/polar-area.html b/samples/polar-area.html
index e7c992d8ea5..89915530bc9 100644
--- a/samples/polar-area.html
+++ b/samples/polar-area.html
@@ -58,7 +58,11 @@ <h3>Legend</h3>
             ]
         },
         options: {
-            responsive: true
+            responsive: true,
+            scale: {
+                beginAtZero: true,
+                reverse: false
+            }
         }
     };
 
diff --git a/samples/radar.html b/samples/radar.html
index b84b8458369..80b544e0d12 100644
--- a/samples/radar.html
+++ b/samples/radar.html
@@ -50,6 +50,12 @@ <h3>Legend</h3>
                 pointHighlightStroke: "rgba(151,187,205,1)",
                 data: [null, randomScalingFactor(), randomScalingFactor(), randomScalingFactor(), randomScalingFactor(), randomScalingFactor(), randomScalingFactor()]
             }]
+        },
+        options: {
+            scale: {
+                beginAtZero: true,
+                reverse: false
+            }
         }
     };
 
diff --git a/samples/scatter-multi-axis.html b/samples/scatter-multi-axis.html
index a25c5f1b12a..e8af68cd475 100644
--- a/samples/scatter-multi-axis.html
+++ b/samples/scatter-multi-axis.html
@@ -111,6 +111,7 @@
 		                type: "linear", // only linear but allow scale type registration. This allows extensions to exist solely for log scale for instance
 		                display: true,
 		                position: "right",
+		                reverse: true,
 		                id: "y-axis-2",
 		        
 		                // grid line settings
diff --git a/src/scales/scale.radialLinear.js b/src/scales/scale.radialLinear.js
index 0e9c763b30d..5c24bd5c668 100644
--- a/src/scales/scale.radialLinear.js
+++ b/src/scales/scale.radialLinear.js
@@ -27,6 +27,7 @@
 		},
 
 		// scale numbers
+		reverse: false,
 		beginAtZero: true,
 
 		// label settings
@@ -94,6 +95,8 @@
 
 			helpers.each(this.data.datasets, function(dataset) {
 				helpers.each(dataset.data, function(value, index) {
+					if (value === null) return;
+
 					if (this.min === null) {
 						this.min = value;
 					} else if (value < this.min) {
@@ -327,9 +330,14 @@
 			return index * angleMultiplier - (Math.PI / 2);
 		},
 		getDistanceFromCenterForValue: function(value) {
+			if (value === null) return 0; // null always in center
 			// Take into account half font size + the yPadding of the top value
 			var scalingFactor = this.drawingArea / (this.max - this.min);
-			return (value - this.min) * scalingFactor;
+			if (this.options.reverse) {
+				return (this.max - value) * scalingFactor;
+			} else {
+				return (value - this.min) * scalingFactor;
+			}
 		},
 		getPointPosition: function(index, distanceFromCenter) {
 			var thisAngle = this.getIndexAngle(index);
@@ -345,8 +353,8 @@
 			if (this.options.display) {
 				var ctx = this.ctx;
 				helpers.each(this.yLabels, function(label, index) {
-					// Don't draw a centre value
-					if (index > 0) {
+					// Don't draw a centre value (if it is minimum)
+					if (index > 0 || this.options.reverse) {
 						var yCenterOffset = this.getDistanceFromCenterForValue(this.ticks[index]);
 						var yHeight = this.yCenter - yCenterOffset;
 
@@ -405,7 +413,7 @@
 
 					for (var i = this.getValueCount() - 1; i >= 0; i--) {
 						if (this.options.angleLines.show) {
-							var outerPosition = this.getPointPosition(i, this.getDistanceFromCenterForValue(this.max));
+							var outerPosition = this.getPointPosition(i, this.getDistanceFromCenterForValue(this.options.reverse ? this.min : this.max));
 							ctx.beginPath();
 							ctx.moveTo(this.xCenter, this.yCenter);
 							ctx.lineTo(outerPosition.x, outerPosition.y);
@@ -413,7 +421,7 @@
 							ctx.closePath();
 						}
 						// Extra 3px out for some label spacing
-						var pointLabelPosition = this.getPointPosition(i, this.getDistanceFromCenterForValue(this.max) + 5);
+						var pointLabelPosition = this.getPointPosition(i, this.getDistanceFromCenterForValue(this.options.reverse ? this.min : this.max) + 5);
 						ctx.font = helpers.fontString(this.options.pointLabels.fontSize, this.options.pointLabels.fontStyle, this.options.pointLabels.fontFamily);
 						ctx.fillStyle = this.options.pointLabels.fontColor;