From 9cb65d2c97136dab4e6ed8f44f3d3d5dd2cda88b Mon Sep 17 00:00:00 2001
From: Evert Timberg <evert.timberg+github@gmail.com>
Date: Mon, 6 Jan 2020 17:16:00 -0500
Subject: [PATCH] Add API to change data visibility (#6907)

---
 docs/developers/api.md              | 18 +++++++++++++++
 src/core/core.controller.js         | 13 +++++++++++
 test/specs/core.controller.tests.js | 35 +++++++++++++++++++++++++++++
 3 files changed, 66 insertions(+)

diff --git a/docs/developers/api.md b/docs/developers/api.md
index 52df45484..4581d576b 100644
--- a/docs/developers/api.md
+++ b/docs/developers/api.md
@@ -147,3 +147,21 @@ Extensive examples of usage are available in the [Chart.js tests](https://github
 var meta = myChart.getDatasetMeta(0);
 var x = meta.data[0].x;
 ```
+
+## setDatasetVisibility(datasetIndex, visibility)
+
+Sets the visibility for a given dataset. This can be used to build a chart legend in HTML. During click on one of the HTML items, you can call `setDatasetVisibility` to change the appropriate dataset.
+
+```javascript
+chart.setDatasetVisibility(1, false); // hides dataset at index 1
+chart.update(); // chart now renders with dataset hidden
+```
+
+## setDataVisibility(datasetIndex, index, visibility)
+
+Like [setDatasetVisibility](#setdatasetvisibility) except that it hides only a single item in the dataset. **Note** this only applies to polar area and doughnut charts at the moment. It will have no affect on line, bar, radar, or scatter charts.
+
+```javascript
+chart.setDataVisibility(0, 2, false); // hides the item in dataset 0, at index 2
+chart.update(); // chart now renders with item hidden
+```
\ No newline at end of file
diff --git a/src/core/core.controller.js b/src/core/core.controller.js
index 5cb909197..81aaa9ceb 100644
--- a/src/core/core.controller.js
+++ b/src/core/core.controller.js
@@ -810,6 +810,19 @@ class Chart {
 		return typeof meta.hidden === 'boolean' ? !meta.hidden : !this.data.datasets[datasetIndex].hidden;
 	}
 
+	setDatasetVisibility(datasetIndex, visible) {
+		const meta = this.getDatasetMeta(datasetIndex);
+		meta.hidden = !visible;
+	}
+
+	setDataVisibility(datasetIndex, index, visible) {
+		const meta = this.getDatasetMeta(datasetIndex);
+
+		if (meta.data[index]) {
+			meta.data[index].hidden = !visible;
+		}
+	}
+
 	/**
 	 * @private
 	 */
diff --git a/test/specs/core.controller.tests.js b/test/specs/core.controller.tests.js
index d8b59930e..58ea47279 100644
--- a/test/specs/core.controller.tests.js
+++ b/test/specs/core.controller.tests.js
@@ -1347,4 +1347,39 @@ describe('Chart', function() {
 			expect(metasets[3].order).toEqual(3);
 		});
 	});
+
+	describe('data visibility', function() {
+		it('should hide a dataset', function() {
+			var chart = acquireChart({
+				type: 'line',
+				data: {
+					datasets: [{
+						data: [0, 1, 2]
+					}],
+					labels: ['a', 'b', 'c']
+				}
+			});
+
+			chart.setDatasetVisibility(0, false);
+
+			var meta = chart.getDatasetMeta(0);
+			expect(meta.hidden).toBe(true);
+		});
+
+		it('should hide a single data item', function() {
+			var chart = acquireChart({
+				type: 'polarArea',
+				data: {
+					datasets: [{
+						data: [1, 2, 3]
+					}]
+				}
+			});
+
+			chart.setDataVisibility(0, 1, false);
+
+			var meta = chart.getDatasetMeta(0);
+			expect(meta.data[1].hidden).toBe(true);
+		});
+	});
 });
-- 
2.47.2