Refactor autoscroll and add autoscrollLimit option in canvas

src/canvas/config/config.js

@@ -26,6 +26,11 @@ module.exports = {
    */
   customBadgeLabel: '',
 
+  /**
+   * Indicate when to start the auto scroll of the canvas on component/block dragging (value in px )
+   */
+  autoscrollLimit: 50,
+
   /**
    * When some textable component is selected and focused (eg. input or text component) the editor
    * stops some commands (eg. disables the copy/paste of components with CTRL+C/V to allow the copy/paste of the text).

src/canvas/index.js

@@ -28,9 +28,11 @@
  * @module Canvas
  */
 
-import { on, off, hasDnd, getElement } from 'utils/mixins';
+import { on, off, hasDnd, getElement, getPointerEvent } from 'utils/mixins';
 import Droppable from 'utils/Droppable';
 
+const { requestAnimationFrame } = window;
+
 module.exports = () => {
   var c = {},
     defaults = require('./config/config'),
@@ -81,6 +83,7 @@ module.exports = () => {
       this.startAutoscroll = this.startAutoscroll.bind(this);
       this.stopAutoscroll = this.stopAutoscroll.bind(this);
       this.autoscroll = this.autoscroll.bind(this);
+      this.updateClientY = this.updateClientY.bind(this);
       return this;
     },
 
@@ -452,22 +455,27 @@ module.exports = () => {
       // By detaching those from the stack avoid browsers lags
       // Noticeable with "fast" drag of blocks
       setTimeout(() => {
-        on(toListen, 'mousemove', this.autoscroll);
+        on(toListen, 'mousemove dragover', this.updateClientY);
         on(toListen, 'mouseup', this.stopAutoscroll);
+        requestAnimationFrame(this.autoscroll);
       }, 0);
     },
 
+    updateClientY(ev) {
+      ev.preventDefault();
+      this.lastClientY = getPointerEvent(ev).clientY;
+    },
+
     /**
      * @private
      */
-    autoscroll(e) {
+    autoscroll() {
-      e.preventDefault();
       if (this.dragging) {
         let frameWindow = this.getFrameEl().contentWindow;
         let actualTop = frameWindow.document.body.scrollTop;
         let nextTop = actualTop;
-        let clientY = e.clientY;
+        let clientY = this.lastClientY;
-        let limitTop = 50;
+        let limitTop = this.getConfig().autoscrollLimit;
         let limitBottom = frameRect.height - limitTop;
 
         if (clientY < limitTop) {
@@ -478,8 +486,8 @@ module.exports = () => {
           nextTop += clientY - limitBottom;
         }
 
-        //console.log(`actualTop: ${actualTop} clientY: ${clientY} nextTop: ${nextTop} frameHeigh: ${frameRect.height}`);
         frameWindow.scrollTo(0, nextTop);
+        requestAnimationFrame(this.autoscroll);
       }
     },
 
@@ -490,7 +498,7 @@ module.exports = () => {
     stopAutoscroll() {
       this.dragging = 0;
       let toListen = this.getScrollListeners();
-      off(toListen, 'mousemove', this.autoscroll);
+      off(toListen, 'mousemove dragover', this.updateClientY);
       off(toListen, 'mouseup', this.stopAutoscroll);
     },
 

src/utils/mixins.js

@@ -121,6 +121,13 @@ const getModel = (el, $) => {
   return model;
 };
 
+/**
+ * Get cross-device pointer event
+ * @param  {Event} ev
+ * @return {Event}
+ */
+const getPointerEvent = (ev) => ev.touches && ev.touches[0] ? ev.touches[0] : ev;
+
 export {
   on,
   off,
@@ -132,5 +139,6 @@ export {
   getElement,
   shallowDiff,
   normalizeFloat,
-  getUnitFromValue
+  getPointerEvent,
+  getUnitFromValue,
 };