Enable bounds option to all cartesian axes (#8060)

src/core/core.scale.js

@@ -17,6 +17,15 @@ defaults.set('scale', {
 	reverse: false,
 	beginAtZero: false,
 
+	/**
+	 * Scale boundary strategy (bypassed by min/max time options)
+	 * - `data`: make sure data are fully visible, ticks outside are removed
+	 * - `ticks`: make sure ticks are fully visible, data outside are truncated
+	 * @see https://github.com/chartjs/Chart.js/pull/4556
+	 * @since 3.0.0
+	 */
+	bounds: 'ticks',
+
 	// grid line settings
 	gridLines: {
 		display: true,

src/scales/scale.category.js

@@ -27,10 +27,20 @@ export default class CategoryScale extends Scale {
 
 	determineDataLimits() {
 		const me = this;
-		const max = me.getLabels().length - 1;
+		const {minDefined, maxDefined} = me.getUserBounds();
+		let {min, max} = me.getMinMax(true);
 
-		me.min = Math.max(me._userMin || 0, 0);
-		me.max = Math.min(me._userMax || max, max);
+		if (me.options.bounds === 'ticks') {
+			if (!minDefined) {
+				min = 0;
+			}
+			if (!maxDefined) {
+				max = me.getLabels().length - 1;
+			}
+		}
+
+		me.min = min;
+		me.max = max;
 	}
 
 	buildTicks() {

src/scales/scale.linearbase.js

@@ -203,9 +203,11 @@ export default class LinearScaleBase extends Scale {
 		};
 		const ticks = generateTicks(numericGeneratorOptions, me);
 
-		// At this point, we need to update our max and min given the tick values since we have expanded the
-		// range of the scale
-		_setMinAndMaxByKey(ticks, me, 'value');
+		// At this point, we need to update our max and min given the tick values,
+		// since we probably have expanded the range of the scale
+		if (opts.bounds === 'ticks') {
+			_setMinAndMaxByKey(ticks, me, 'value');
+		}
 
 		if (opts.reverse) {
 			ticks.reverse();

src/scales/scale.logarithmic.js

@@ -124,9 +124,11 @@ export default class LogarithmicScale extends Scale {
 		};
 		const ticks = generateTicks(generationOptions, me);
 
-		// At this point, we need to update our max and min given the tick values since we have expanded the
-		// range of the scale
-		_setMinAndMaxByKey(ticks, me, 'value');
+		// At this point, we need to update our max and min given the tick values,
+		// since we probably have expanded the range of the scale
+		if (opts.bounds === 'ticks') {
+			_setMinAndMaxByKey(ticks, me, 'value');
+		}
 
 		if (opts.reverse) {
 			ticks.reverse();

test/specs/scale.category.tests.js

@@ -475,4 +475,33 @@ describe('Category scale tests', function() {
 		expect(yScale.getPixelForValue(3)).toBeCloseToPixel(426);
 		expect(yScale.getPixelForValue(4)).toBeCloseToPixel(538);
 	});
+
+	it('Should bound to ticks/data', function() {
+		var chart = window.acquireChart({
+			type: 'line',
+			data: {
+				labels: ['a', 'b', 'c', 'd'],
+				datasets: [{
+					data: {b: 1, c: 99}
+				}]
+			},
+			options: {
+				scales: {
+					x: {
+						type: 'category',
+						bounds: 'data'
+					}
+				}
+			}
+		});
+
+		expect(chart.scales.x.min).toEqual(1);
+		expect(chart.scales.x.max).toEqual(2);
+
+		chart.options.scales.x.bounds = 'ticks';
+		chart.update();
+
+		expect(chart.scales.x.min).toEqual(0);
+		expect(chart.scales.x.max).toEqual(3);
+	});
 });

test/specs/scale.linear.tests.js

@@ -759,6 +759,28 @@ describe('Linear Scale', function() {
 		expect(getLabels(chart.scales.y)).toEqual(['0.3', '0.8', '1.3', '1.8', '2.3', '2.8']);
 	});
 
+	it('Should bound to data', function() {
+		var chart = window.acquireChart({
+			type: 'line',
+			data: {
+				labels: ['a', 'b'],
+				datasets: [{
+					data: [1, 99]
+				}]
+			},
+			options: {
+				scales: {
+					y: {
+						bounds: 'data'
+					}
+				}
+			}
+		});
+
+		expect(chart.scales.y.min).toEqual(1);
+		expect(chart.scales.y.max).toEqual(99);
+	});
+
 	it('Should build labels using the user supplied callback', function() {
 		var chart = window.acquireChart({
 			type: 'bar',

test/specs/scale.logarithmic.tests.js

@@ -1142,4 +1142,27 @@ describe('Logarithmic Scale tests', function() {
 		expect(chart.scales.y.min).toBe(10);
 		expect(chart.scales.y.max).toBe(100);
 	});
+
+	it('Should bound to data', function() {
+		var chart = window.acquireChart({
+			type: 'line',
+			data: {
+				labels: ['a', 'b'],
+				datasets: [{
+					data: [1.1, 99]
+				}]
+			},
+			options: {
+				scales: {
+					y: {
+						type: 'logarithmic',
+						bounds: 'data'
+					}
+				}
+			}
+		});
+
+		expect(chart.scales.y.min).toEqual(1.1);
+		expect(chart.scales.y.max).toEqual(99);
+	});
 });