Add speed option (#215)

Add speed option

Author: jledentu

README.md

@@ -18,7 +18,7 @@ To configure the zoom and pan plugin, you can simply add new config options to y
 		// Boolean to enable panning
 		enabled: true,
 
-		// Panning directions. Remove the appropriate direction to disable 
+		// Panning directions. Remove the appropriate direction to disable
 		// Eg. 'y' would only allow panning in the y direction
 		mode: 'xy',
 		rangeMin: {
@@ -35,7 +35,7 @@ To configure the zoom and pan plugin, you can simply add new config options to y
 		// Useful for dynamic data loading
 		onPan: function({chart}) { console.log(`I was panned!!!`); }
 	},
-	
+
 	// Container for zoom options
 	zoom: {
 		// Boolean to enable zooming
@@ -51,9 +51,10 @@ To configure the zoom and pan plugin, you can simply add new config options to y
 		// 	 backgroundColor: 'rgb(225,225,225)'
 		// },
 
-		// Zooming directions. Remove the appropriate direction to disable 
+		// Zooming directions. Remove the appropriate direction to disable
 		// Eg. 'y' would only allow zooming in the y direction
 		mode: 'xy',
+
 		rangeMin: {
 			// Format of min zoom range depends on scale type
 			x: null,
@@ -64,6 +65,11 @@ To configure the zoom and pan plugin, you can simply add new config options to y
 			x: null,
 			y: null
 		},
+
+		// Speed of zoom via mouse wheel
+		// (percentage of zoom on a wheel event)
+		speed: 0.1,
+
 		// Function called once zooming is completed
 		// Useful for dynamic data loading
 		onZoom: function({chart}) { console.log(`I was zoomed!!!`); }

samples/zoom-time.html

@@ -108,7 +108,8 @@
 				zoom: {
 					enabled: true,
 					drag: true,
-					mode: 'x'
+					mode: 'x',
+					speed: 0.05
 				}
 			}
 		};

src/plugin.js

@@ -23,7 +23,8 @@ var defaultOptions = zoomNS.defaults = {
 	zoom: {
 		enabled: true,
 		mode: 'xy',
-		sensitivity: 3
+		sensitivity: 3,
+		speed: 0.1
 	}
 };
 // Stores the original options of the scales
@@ -454,11 +455,13 @@ var zoomPlugin = {
 					y: offsetY
 				};
 
-				if (event.deltaY < 0) {
-					doZoom(chartInstance, 1.1, 1.1, center);
-				} else {
-					doZoom(chartInstance, 0.909, 0.909, center);
+				var speedPercent = helpers.getValueOrDefault(chartInstance.options.zoom.speed, defaultOptions.zoom.speed);
+
+				if (event.deltaY >= 0) {
+					speedPercent = -speedPercent;
 				}
+				doZoom(chartInstance, 1 + speedPercent, 1 + speedPercent, center);
+
 				// Prevent the event from triggering the default behavior (eg. Content scrolling).
 				event.preventDefault();
 			}