Fix getValueForPixel in time scale (#6328)

* Fix getValueForPixel in time scale * Minor refactoring
chartjs · Jun 22, 2019 · 1c85700 · 1c85700
1 parent 07109b6
commit 1c85700
Show file tree

Hide file tree

Showing 2 changed files with 45 additions and 7 deletions.
diff --git a/src/scales/scale.time.js b/src/scales/scale.time.js
@@ -401,7 +401,7 @@ function computeOffsets(table, ticks, min, max, options) {
 		}
 	}
 
-	return {start: start, end: end};
+	return {start: start, end: end, factor: 1 / (start + 1 + end)};
 }
 
 function setMajorTicks(scale, ticks, map, majorUnit) {
@@ -723,13 +723,14 @@ module.exports = Scale.extend({
 	 */
 	getPixelForOffset: function(time) {
 		var me = this;
-		var isReverse = me.options.ticks.reverse;
+		var offsets = me._offsets;
 		var size = me._horizontal ? me.width : me.height;
-		var start = me._horizontal ? isReverse ? me.right : me.left : isReverse ? me.bottom : me.top;
 		var pos = interpolate(me._table, 'time', time, 'pos');
-		var offset = size * (me._offsets.start + pos) / (me._offsets.start + 1 + me._offsets.end);
+		var offset = size * (offsets.start + pos) * offsets.factor;
 
-		return isReverse ? start - offset : start + offset;
+		return me.options.ticks.reverse ?
+			(me._horizontal ? me.right : me.bottom) - offset :
+			(me._horizontal ? me.left : me.top) + offset;
 	},
 
 	getPixelForValue: function(value, index, datasetIndex) {
@@ -758,9 +759,12 @@ module.exports = Scale.extend({
 
 	getValueForPixel: function(pixel) {
 		var me = this;
+		var offsets = me._offsets;
 		var size = me._horizontal ? me.width : me.height;
-		var start = me._horizontal ? me.left : me.top;
-		var pos = (size ? (pixel - start) / size : 0) * (me._offsets.start + 1 + me._offsets.start) - me._offsets.end;
+		var offset = me.options.ticks.reverse ?
+			(me._horizontal ? me.right : me.bottom) - pixel :
+			pixel - (me._horizontal ? me.left : me.top);
+		var pos = offset / size / offsets.factor - offsets.start;
 		var time = interpolate(me._table, 'pos', pos, 'time');
 
 		// DEPRECATION, we should return time directly

diff --git a/test/specs/scale.time.tests.js b/test/specs/scale.time.tests.js
@@ -1517,6 +1517,18 @@ describe('Time scale tests', function() {
 				expect(scale.getPixelForValue('2042')).toBeCloseToPixel(scale.left);
 			});
 
+			it ('should reverse the values for pixels', function() {
+				var scale = this.chart.chart.scales.x;
+				expect(scale.getValueForPixel(scale.left)).toBeCloseToTime({
+					value: moment('2042-01-01T00:00:00'),
+					unit: 'hour',
+				});
+				expect(scale.getValueForPixel(scale.left + scale.width)).toBeCloseToTime({
+					value: moment('2017-01-01T00:00:00'),
+					unit: 'hour',
+				});
+			});
+
 			it ('should reverse the bars and add offsets if offset is true', function() {
 				var chart = this.chart;
 				var scale = chart.scales.x;
@@ -1532,6 +1544,28 @@ describe('Time scale tests', function() {
 				expect(scale.getPixelForValue('2017')).toBeCloseToPixel(scale.left + scale.width - lastTickInterval / 2);
 				expect(scale.getPixelForValue('2042')).toBeCloseToPixel(scale.left + firstTickInterval / 2);
 			});
+
+			it ('should reverse the values for pixels if offset is true', function() {
+				var chart = this.chart;
+				var scale = chart.scales.x;
+				var options = chart.options.scales.xAxes[0];
+
+				options.offset = true;
+				chart.update();
+
+				var numTicks = scale.ticks.length;
+				var firstTickInterval = scale.getPixelForTick(1) - scale.getPixelForTick(0);
+				var lastTickInterval = scale.getPixelForTick(numTicks - 1) - scale.getPixelForTick(numTicks - 2);
+
+				expect(scale.getValueForPixel(scale.left + firstTickInterval / 2)).toBeCloseToTime({
+					value: moment('2042-01-01T00:00:00'),
+					unit: 'hour',
+				});
+				expect(scale.getValueForPixel(scale.left + scale.width - lastTickInterval / 2)).toBeCloseToTime({
+					value: moment('2017-01-01T00:00:00'),
+					unit: 'hour',
+				});
+			});
 		});
 	});