RTL support

README.md

@@ -20,6 +20,7 @@
 * No matter what changes the content - scrollbars always stay actual
 * Total tests coverage
 * Scrollbars nesting
+* RTL support ([read more]())
 
 >**IMPORTANT:** default component styles uses [Flexible Box Layout](https://developer.mozilla.org/ru/docs/Web/CSS/CSS_Flexible_Box_Layout) for proper scrollbars display.  
 >But you can customize it with help pf inline or linked styles as you wish ([see docs](https://github.com/xobotyi/react-scrollbars-custom/blob/master/docs/CUSTOMISATION.md)). 

docs/API.md

@@ -6,7 +6,8 @@
     * `defaultStyles`: _(boolean)_ Apply default inline styles _(default: false)_
     * `fallbackScrollbarWidth`: _(number)_ Number of pixels that will be treated as scrollbar width if automated scrollbar width detection will fail. _This parameter used on mobiles, because scrollbars there has an absolute positioning and can't be measured._ _(default: 20)_
     * `minimalThumbsSize`: _(number)_ Minimal size of thumb in pixels _(default: 30)_
-    * `noScroll`: _(boolean)_ Disable both vertical and horizontal scrolling_(default: false)_
+    * `rtl`: _(boolean)_ Override the direction style parameter _(default: undefined)_
+    * `noScroll`: _(boolean)_ Disable both vertical and horizontal scrolling _(default: false)_
     * `noScrollY`: _(boolean)_ Disable vertical scrolling _(default: false)_
     * `noScrollX`: _(boolean)_ Disable horizontal scrolling _(default: false)_
     * `permanentScrollbars`: _(boolean)_ Display both, vertical and horizontal scrollbars permanently, in spite of scrolling possibility _(default: false)_
@@ -63,5 +64,7 @@
 * `scrollToBottom()`: _(Scrollbar)_ Scroll to the bottom border
 * `scrollToLeft()`: _(Scrollbar)_ Scroll to the left border
 * `scrollToRight()`: _(Scrollbar)_ Scroll to the right border
-* `update(forced=false)`: _(Scrollbar)_ Updates the scrollbars. By default if content or wrapper sizes did not changed - update will not be performed. But you can force the update by passing `true` as first parameter.  
+* `update(forced=false, rtlAutodetect=false)`: _(Scrollbar)_ Updates the scrollbars. By default if content or wrapper sizes did not changed - update will not be performed.
+    * `forced`: _(boolean)_ Whether to update the scrollbars even nothing has changed _(default: false)_
+    * `rtlAutodetect`: _(boolean)_ Whether to check and actualize CSS direction value _(default: false)_
 Keep in mind that forced update will either trigger `onScroll` callback.  

docs/USAGE.md

@@ -87,3 +87,19 @@ class App extends Component
     }
 }
 ```
+
+### RTL support
+`react-scrollbars-custom` supports right-to-left direction out of the box, you don't have to pass extra properties to make it work, everything is automated, but you can override it.  
+But it has several nuances you should know: 
+* Due to performance reasons, direction detection happens in 3 situations:
+    * On component mount;
+    * On rtl property change;
+    * On call `scrollbar.update(undefined, true);`;
+* When rtl direction detected - `ScrollbarsCustom-RTL` classname will be added to the holder;
+* If `rtl` property has not set at all (undefined) - direction will be determined according to CSS;
+* If `rtl` property has `true` - `direction: rtl;` style will be applied to holder;
+* If `rtl` property has `false` - `direction: ltr;` style will be applied to holder;
+* `rtl` property has priority over the `style` property.  
+```javascript
+<Scrollbar style={{direction: 'ltr'}} rtl /> // will have RTL direction
+```

examples/app/components/Body.js

@@ -22,6 +22,7 @@ export default class Head extends React.Component
                     <li>No matter what changes the content - scrollbars always stay actual</li>
                     <li>Total tests coverage</li>
                     <li>Scrollbars nesting</li>
+                    <li>RTL support</li>
                 </ul>
                 <p><a href="https://github.com/xobotyi/react-scrollbars-custom/tree/master/docs">Docs on GitHub</a> | <a href="./#benchmark" target="_blank">Benchmark</a></p>
             </div>

examples/app/components/blocks/SandboxBlock.js

@@ -20,12 +20,15 @@ export default class SandboxBlock extends React.Component
         this.handleScrollBottomClick = this.handleScrollBottomClick.bind(this);
         this.handleScrollLeftClick = this.handleScrollLeftClick.bind(this);
         this.handleScrollRightClick = this.handleScrollRightClick.bind(this);
+        this.toggleRtl = this.toggleRtl.bind(this);
 
         this.state = {
             noScroll:  false,
             noScrollY: false,
             noScrollX: false,
 
+            rtl: false,
+
             permanentTracks: false,
             permanentTrackY: false,
             permanentTrackX: false,
@@ -91,6 +94,13 @@ export default class SandboxBlock extends React.Component
                       });
     }
 
+    toggleRtl() {
+        this.setState({
+                          ...this.state,
+                          rtl: !this.state.rtl,
+                      });
+    }
+
     handleAddParagraphClick() {
         this.setState({
                           ...this.state,
@@ -120,7 +130,7 @@ export default class SandboxBlock extends React.Component
     }
 
     render() {
-        const {noScroll, noScrollY, noScrollX, permanentTracks, permanentTrackY, permanentTrackX} = this.state;
+        const {noScroll, noScrollY, noScrollX, permanentTracks, permanentTrackY, permanentTrackX, rtl} = this.state;
 
         return (
                 <div className="block" id="SandboxBlock">
@@ -133,6 +143,7 @@ export default class SandboxBlock extends React.Component
                         <div className="button" key="permanentTracks" onClick={ this.togglePermanentTracks }>{ permanentTracks ? "Show tracks if needed" : "Always show tracks" }</div>
                         <div className="button" key="permanentTracksY" onClick={ this.togglePermanentTrackY }>{ permanentTrackY || permanentTracks ? "Show track Y if needed" : "Always show track Y" }</div>
                         <div className="button" key="permanentTracksX" onClick={ this.togglePermanentTrackX }>{ permanentTrackX || permanentTracks ? "Show track X if needed" : "Always show track X" }</div>
+                        <div className="button" key="direction" onClick={ this.toggleRtl }>{ rtl ? "set direction LRT" : "set direction RTL" }</div>
                         <br />
                         <div className="button" key="randomPosition" onClick={ this.handleRandomPositionClick }>Random position</div>
                         <div className="button" key="scrollTop" onClick={ this.handleScrollTopClick }>Scroll top</div>
@@ -149,6 +160,7 @@ export default class SandboxBlock extends React.Component
                                 noScroll={ noScroll }
                                 noScrollY={ noScrollY }
                                 noScrollX={ noScrollX }
+                                rtl={ rtl }
                                 permanentScrollbars={ permanentTracks }
                                 permanentScrollbarY={ permanentTrackY }
                                 permanentScrollbarX={ permanentTrackX }>

src/index.js

@@ -127,13 +127,13 @@ export default class Scrollbar extends React.Component
         LoopController.registerScrollbar(this);
 
         this.addListeners();
-        this.update();
+        this.update(true, true);
     }
 
     componentDidUpdate(prevProps, prevState, snapshot) {
-        if (prevProps.noScroll !== this.props.noScroll || prevProps.noScrollY !== this.props.noScrollY || prevProps.noScrollX !== this.props.noScrollX
+        if (prevProps.noScroll !== this.props.noScroll || prevProps.noScrollY !== this.props.noScrollY || prevProps.noScrollX !== this.props.noScrollX || prevProps.rtl !== this.props.rtl
             || prevProps.permanentScrollbars !== this.props.permanentScrollbars || prevProps.permanentScrollbarX !== this.props.permanentScrollbarX || prevProps.permanentScrollbarY !== this.props.permanentScrollbarY) {
-            this.update(true);
+            this.update(true, prevProps.rtl !== this.props.rtl);
         }
 
         this.addListeners();
@@ -498,8 +498,9 @@ export default class Scrollbar extends React.Component
      * Performs an actualisation of scrollbars and its thumbs
      *
      * @param forced {boolean} Whether to perform an update even if nothing has changed
+     * @param rtlAutodetect {boolean} Whether to check the CSS value `direction`
      */
-    update = (forced = false) => {
+    update = (forced = false, rtlAutodetect = false) => {
         // No need to update scrollbars if values had not changed
         if (!forced && (this.previousScrollValues || false)) {
             if (this.previousScrollValues.scrollTop === this.content.scrollTop &&
@@ -512,9 +513,23 @@ export default class Scrollbar extends React.Component
             }
         }
 
+        this.isRtl = this.props.rtl || this.isRtl || (rtlAutodetect ? getComputedStyle(this.content).direction === "rtl" : false);
+
+        this.holder.classList.toggle("ScrollbarsCustom-RTL", this.isRtl);
+
         const verticalScrollPossible   = this.content.scrollHeight > this.content.clientHeight && !this.props.noScroll && !this.props.noScrollY,
               horizontalScrollPossible = this.content.scrollWidth > this.content.clientWidth && !this.props.noScroll && !this.props.noScrollX;
 
+        if (verticalScrollPossible && ((this.previousScrollValues || true) || this.isRtl !== (this.previousScrollValues.rtl || false))) {
+            const browserScrollbarWidth  = getScrollbarWidth(),
+                  fallbackScrollbarWidth = this.props.fallbackScrollbarWidth;
+
+            this.content.style.marginLeft = this.isRtl ? -(browserScrollbarWidth || fallbackScrollbarWidth) + "px" : null;
+            this.content.style.paddingLeft = this.isRtl ? (browserScrollbarWidth ? null : fallbackScrollbarWidth) + "px" : null;
+            this.content.style.marginRight = this.isRtl ? null : -(browserScrollbarWidth || fallbackScrollbarWidth) + "px";
+            this.content.style.paddingRight = this.isRtl ? null : (browserScrollbarWidth ? null : fallbackScrollbarWidth) + "px";
+        }
+
         this.trackVertical.style.display = (verticalScrollPossible || this.props.permanentScrollbars || this.props.permanentScrollbarY) ? null : "none";
         this.trackVertical.visibility = (verticalScrollPossible || this.props.permanentScrollbars || this.props.permanentScrollbarY) ? null : "hidden";
 
@@ -524,7 +539,9 @@ export default class Scrollbar extends React.Component
         if (verticalScrollPossible) {
             const trackVerticalInnerHeight = getInnerHeight(this.trackVertical);
             const thumbVerticalHeight = this.computeThumbVerticalHeight(trackVerticalInnerHeight);
-            const thumbVerticalOffset = thumbVerticalHeight ? this.content.scrollTop / (this.content.scrollHeight - this.content.clientHeight) * (trackVerticalInnerHeight - thumbVerticalHeight) : 0;
+            const thumbVerticalOffset = thumbVerticalHeight
+                                        ? this.content.scrollTop / (this.content.scrollHeight - this.content.clientHeight) * (trackVerticalInnerHeight - thumbVerticalHeight)
+                                        : 0;
 
             this.thumbVertical.style.transform = `translateY(${thumbVerticalOffset}px)`;
             this.thumbVertical.style.height = thumbVerticalHeight + "px";
@@ -537,7 +554,13 @@ export default class Scrollbar extends React.Component
         if (horizontalScrollPossible) {
             const trackHorizontalInnerWidth = getInnerWidth(this.trackHorizontal);
             const thumbHorizontalWidth = this.computeThumbHorizontalWidth(trackHorizontalInnerWidth);
-            const thumbHorizontalOffset = thumbHorizontalWidth ? this.content.scrollLeft / (this.content.scrollWidth - this.content.clientWidth) * (trackHorizontalInnerWidth - thumbHorizontalWidth) : 0;
+            let thumbHorizontalOffset = thumbHorizontalWidth
+                                        ? this.content.scrollLeft / (this.content.scrollWidth - this.content.clientWidth) * (trackHorizontalInnerWidth - thumbHorizontalWidth)
+                                        : 0;
+
+            if (this.isRtl) {
+                thumbHorizontalOffset = -(trackHorizontalInnerWidth - thumbHorizontalWidth - thumbHorizontalOffset);
+            }
 
             this.thumbHorizontal.style.transform = `translateX(${thumbHorizontalOffset}px)`;
             this.thumbHorizontal.style.width = thumbHorizontalWidth + "px";
@@ -554,6 +577,7 @@ export default class Scrollbar extends React.Component
             scrollWidth:  this.content.scrollWidth,
             clientHeight: this.content.clientHeight,
             clientWidth:  this.content.clientWidth,
+            rtl:          this.props.rtl,
         };
 
         (this.previousScrollValues || false) && this.props.onScroll && this.props.onScroll(currentScrollValues, this);
@@ -569,7 +593,7 @@ export default class Scrollbar extends React.Component
                   minimalThumbsSize, fallbackScrollbarWidth, scrollDetectionThreshold,
 
                   // boolean props
-                  defaultStyles, noScroll, noScrollX, noScrollY, permanentScrollbars, permanentScrollbarX, permanentScrollbarY,
+                  defaultStyles, noScroll, noScrollX, noScrollY, permanentScrollbars, permanentScrollbarX, permanentScrollbarY, rtl,
 
                   // holder element props
                   tagName, children, style, className,
@@ -614,6 +638,7 @@ export default class Scrollbar extends React.Component
         const holderStyles          = {
                   ...style,
                   ...(defaultStyles && defaultElementsStyles.holder),
+                  ...({direction: (rtl === true && "rtl") || (rtl === false && "ltr") || null}),
               },
               wrapperStyles         = {
                   ...wrapperStyle,
@@ -626,9 +651,7 @@ export default class Scrollbar extends React.Component
                   ...defaultElementsStyles.content,
                   overflowX:     "scroll",
                   overflowY:     "scroll",
-                  marginRight:   -(browserScrollbarWidth || fallbackScrollbarWidth),
                   marginBottom:  -(browserScrollbarWidth || fallbackScrollbarWidth),
-                  paddingRight:  (browserScrollbarWidth ? null : fallbackScrollbarWidth),
                   paddingBottom: (browserScrollbarWidth ? null : fallbackScrollbarWidth),
               },
               trackVerticalStyles   = {

tests/Scrollbar/rendering.js

@@ -198,7 +198,6 @@ export default function performTests() {
                             expect(this.content.style.left).toBe(0 + 'px');
                             expect(this.content.style.right).toBe(0 + 'px');
                             expect(this.content.style.overflow).toBe("scroll");
-                            expect(this.content.style.marginRight).toBe(-getScrollbarWidth() + 'px');
                             expect(this.content.style.marginBottom).toBe(-getScrollbarWidth() + 'px');
                             done();
                         });
@@ -286,6 +285,76 @@ export default function performTests() {
             });
         });
 
+        describe("when RTL is set", () => {
+            it("left part of content should be hidden", (done) => {
+                render(<Scrollbar style={ {width: 100, height: 100} } rtl>
+                            <div style={ {width: 200, height: 200} } />
+                        </Scrollbar>,
+                        node,
+                        function () {
+                            setTimeout(() => {
+                                expect(this.content.style.marginRight).toBe("");
+                                expect(this.content.style.marginLeft).toBe(-getScrollbarWidth() + 'px');
+
+                                done();
+                            }, 100);
+                        });
+            });
+
+            it("should override direction value", (done) => {
+                let scrollbar = null;
+                render(<div style={ {direction: "rtl"} }>
+                            <Scrollbar style={ {width: 100, height: 100} } ref={ (ref) => {scrollbar = ref;} } rtl={ false }>
+                                <div style={ {width: 200, height: 200} } />
+                            </Scrollbar>
+                        </div>,
+                        node,
+                        function () {
+                            setTimeout(() => {
+                                expect(scrollbar.holder.classList.contains("ScrollbarsCustom-RTL")).toBeFalsy();
+
+                                done();
+                            }, 100);
+                        });
+            });
+        });
+
+        describe("when RTL is not set", () => {
+            it("should autodetect direction (when set rtl)", (done) => {
+                let scrollbar = null;
+                render(<div style={ {direction: "rtl"} }>
+                            <Scrollbar style={ {width: 100, height: 100} } ref={ (ref) => {scrollbar = ref;} }>
+                                <div style={ {width: 200, height: 200} } />
+                            </Scrollbar>
+                        </div>,
+                        node,
+                        function () {
+                            setTimeout(() => {
+                                expect(scrollbar.holder.classList.contains("ScrollbarsCustom-RTL")).toBeTruthy();
+
+                                done();
+                            }, 100);
+                        });
+            });
+
+            it("should autodetect direction (when set ltr)", (done) => {
+                let scrollbar = null;
+                render(<div style={ {direction: "ltr"} }>
+                            <Scrollbar style={ {width: 100, height: 100} } ref={ (ref) => {scrollbar = ref;} } rtl={ false }>
+                                <div style={ {width: 200, height: 200} } />
+                            </Scrollbar>
+                        </div>,
+                        node,
+                        function () {
+                            setTimeout(() => {
+                                expect(scrollbar.holder.classList.contains("ScrollbarsCustom-RTL")).toBeFalsy();
+
+                                done();
+                            }, 100);
+                        });
+            });
+        });
+
         describe("only vertical scroll should be blocked", () => {
             it("if noScrollY={ true } is passed", (done) => {
                 render(<Scrollbar style={ {width: 100, height: 100} } noScrollY={ true }>