feat(cdk-scrollable): add methods to normalize scrolling in RTL

src/cdk/platform/features.ts

@@ -8,6 +8,7 @@
 
 /** Cached result of whether the user's browser supports passive event listeners. */
 let supportsPassiveEvents: boolean;
+let rtlScrollAxisType: 'normal' | 'negated' | 'inverted';
 
 /**
  * Checks whether the user's browser supports passive event listeners.
@@ -89,3 +90,45 @@ export function getSupportedInputTypes(): Set<string> {
 
   return supportedInputTypes;
 }
+
+/**
+ * Checks the type of RTL scroll axis used by this browser. The possible values are
+ * - normal: scrollLeft is 0 when scrolled all the way left and (scrollWidth - clientWidth) when
+ *     scrolled all the way right.
+ * - negated: scrollLeft is -(scrollWidth - clientWidth) when scrolled all the way left and 0 when
+ *     scrolled all the way right.
+ * - inverted: scrollLeft is (scrollWidth - clientWidth) when scrolled all the way left and 0 when
+ *     scrolled all the way right.
+ */
+export function getRtlScrollAxisType(): 'normal' | 'negated' | 'inverted' {
+  // We can't check unless we're on the browser. Just assume 'normal' if we're not.
+  if (typeof document !== 'object' || !document) {
+    return 'normal';
+  }
+
+  if (!rtlScrollAxisType) {
+    const viewport = document.createElement('div');
+    viewport.dir = 'rtl';
+    viewport.style.height = '1px';
+    viewport.style.width = '1px';
+    viewport.style.overflow = 'auto';
+    viewport.style.visibility = 'hidden';
+    viewport.style.pointerEvents = 'none';
+    viewport.style.position = 'absolute';
+
+    const content = document.createElement('div');
+    content.style.width = '2px';
+    content.style.height = '1px';
+
+    viewport.appendChild(content);
+    document.body.appendChild(viewport);
+
+    rtlScrollAxisType = 'normal';
+    if (viewport.scrollLeft == 0) {
+      viewport.scrollLeft = 1;
+      rtlScrollAxisType = viewport.scrollLeft == 0 ? 'negated' : 'inverted';
+    }
+    document.body.removeChild(viewport);
+  }
+  return rtlScrollAxisType;
+}

src/cdk/scrolling/scrollable.spec.ts

@@ -0,0 +1,291 @@
+import {Direction} from '@angular/cdk/bidi';
+import {CdkScrollable, ScrollingModule} from '@angular/cdk/scrolling';
+import {Component, ElementRef, Input, ViewChild} from '@angular/core';
+import {async, ComponentFixture, TestBed} from '@angular/core/testing';
+
+function checkIntersecting(r1: {top: number, left: number, bottom: number, right: number},
+                           r2: {top: number, left: number, bottom: number, right: number},
+                           expected = true) {
+  const actual =
+      r1.left < r2.right && r1.right > r2.left && r1.top < r2.bottom && r1.bottom > r2.top;
+  if (expected) {
+    expect(actual)
+        .toBe(expected, `${JSON.stringify(r1)} should intersect with ${JSON.stringify(r2)}`);
+  } else {
+    expect(actual)
+        .toBe(expected, `${JSON.stringify(r1)} should not intersect with ${JSON.stringify(r2)}`);
+  }
+}
+
+fdescribe('CdkScrollable', () => {
+  let fixture: ComponentFixture<ScrollableViewport>;
+  let testComponent: ScrollableViewport;
+
+  beforeEach(async(() => {
+    TestBed.configureTestingModule({
+      imports: [ScrollingModule],
+      declarations: [ScrollableViewport],
+    }).compileComponents();
+
+    fixture = TestBed.createComponent(ScrollableViewport);
+    testComponent = fixture.componentInstance;
+  }));
+
+  describe('in LTR context', () => {
+    let maxOffset = 0;
+
+    beforeEach(() => {
+      fixture.detectChanges();
+      maxOffset = testComponent.viewport.nativeElement.scrollHeight -
+          testComponent.viewport.nativeElement.clientHeight;
+    });
+
+    it('should initially be scrolled to top-left', () => {
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topStart.nativeElement.getBoundingClientRect(), true);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topEnd.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomStart.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomEnd.nativeElement.getBoundingClientRect(), false);
+
+      expect(testComponent.scrollable.measureScrollOffset('top')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('bottom')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('left')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('right')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('start')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('end')).toBe(maxOffset);
+    });
+
+    it('should scrollTo top-left', () => {
+      testComponent.scrollable.scrollTo({top: 0, left: 0});
+
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topStart.nativeElement.getBoundingClientRect(), true);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topEnd.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomStart.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomEnd.nativeElement.getBoundingClientRect(), false);
+
+      expect(testComponent.scrollable.measureScrollOffset('top')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('bottom')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('left')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('right')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('start')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('end')).toBe(maxOffset);
+    });
+
+    it('should scrollTo bottom-right', () => {
+      testComponent.scrollable.scrollTo({bottom: 0, right: 0});
+
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topStart.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topEnd.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomStart.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomEnd.nativeElement.getBoundingClientRect(), true);
+
+      expect(testComponent.scrollable.measureScrollOffset('top')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('bottom')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('left')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('right')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('start')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('end')).toBe(0);
+    });
+
+    it('should scroll to top-end', () => {
+      testComponent.scrollable.scrollTo({top: 0, end: 0});
+
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topStart.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topEnd.nativeElement.getBoundingClientRect(), true);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomStart.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomEnd.nativeElement.getBoundingClientRect(), false);
+
+      expect(testComponent.scrollable.measureScrollOffset('top')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('bottom')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('left')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('right')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('start')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('end')).toBe(0);
+    });
+
+    it('should scroll to bottom-start', () => {
+      testComponent.scrollable.scrollTo({bottom: 0, start: 0});
+
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topStart.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topEnd.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomStart.nativeElement.getBoundingClientRect(), true);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomEnd.nativeElement.getBoundingClientRect(), false);
+
+      expect(testComponent.scrollable.measureScrollOffset('top')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('bottom')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('left')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('right')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('start')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('end')).toBe(maxOffset);
+    });
+  });
+
+  describe('in RTL context', () => {
+    let maxOffset = 0;
+
+    beforeEach(() => {
+      testComponent.dir = 'rtl';
+      fixture.detectChanges();
+      maxOffset = testComponent.viewport.nativeElement.scrollHeight -
+          testComponent.viewport.nativeElement.clientHeight;
+    });
+
+    it('should initially be scrolled to top-right', () => {
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topStart.nativeElement.getBoundingClientRect(), true);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topEnd.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomStart.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomEnd.nativeElement.getBoundingClientRect(), false);
+
+      expect(testComponent.scrollable.measureScrollOffset('top')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('bottom')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('left')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('right')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('start')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('end')).toBe(maxOffset);
+    });
+
+    it('should scrollTo top-left', () => {
+      testComponent.scrollable.scrollTo({top: 0, left: 0});
+
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topStart.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topEnd.nativeElement.getBoundingClientRect(), true);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomStart.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomEnd.nativeElement.getBoundingClientRect(), false);
+
+      expect(testComponent.scrollable.measureScrollOffset('top')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('bottom')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('left')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('right')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('start')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('end')).toBe(0);
+    });
+
+    it('should scrollTo bottom-right', () => {
+      testComponent.scrollable.scrollTo({bottom: 0, right: 0});
+
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topStart.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topEnd.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomStart.nativeElement.getBoundingClientRect(), true);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomEnd.nativeElement.getBoundingClientRect(), false);
+
+      expect(testComponent.scrollable.measureScrollOffset('top')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('bottom')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('left')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('right')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('start')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('end')).toBe(maxOffset);
+    });
+
+    it('should scroll to top-end', () => {
+      testComponent.scrollable.scrollTo({top: 0, end: 0});
+
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topStart.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topEnd.nativeElement.getBoundingClientRect(), true);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomStart.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomEnd.nativeElement.getBoundingClientRect(), false);
+
+      expect(testComponent.scrollable.measureScrollOffset('top')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('bottom')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('left')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('right')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('start')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('end')).toBe(0);
+    });
+
+    it('should scroll to bottom-start', () => {
+      testComponent.scrollable.scrollTo({bottom: 0, start: 0});
+
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topStart.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.topEnd.nativeElement.getBoundingClientRect(), false);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomStart.nativeElement.getBoundingClientRect(), true);
+      checkIntersecting(testComponent.viewport.nativeElement.getBoundingClientRect(),
+          testComponent.bottomEnd.nativeElement.getBoundingClientRect(), false);
+
+      expect(testComponent.scrollable.measureScrollOffset('top')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('bottom')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('left')).toBe(maxOffset);
+      expect(testComponent.scrollable.measureScrollOffset('right')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('start')).toBe(0);
+      expect(testComponent.scrollable.measureScrollOffset('end')).toBe(maxOffset);
+    });
+  });
+});
+
+@Component({
+  template: `
+    <div #viewport class="viewport" cdkScrollable [dir]="dir">
+      <div class="row">
+        <div #topStart class="cell"></div>
+        <div #topEnd class="cell"></div>
+      </div>
+      <div class="row">
+        <div #bottomStart class="cell"></div>
+        <div #bottomEnd class="cell"></div>
+      </div>
+    </div>`,
+  styles: [`
+    .viewport {
+      width: 100px;
+      height: 100px;
+      overflow: auto;
+    }
+
+    .row {
+      display: flex;
+      flex-direction: row;
+    }
+
+    .cell {
+      flex: none;
+      width: 100px;
+      height: 100px;
+    }  
+  `]
+})
+class ScrollableViewport {
+  @Input() dir: Direction;
+  @ViewChild(CdkScrollable) scrollable: CdkScrollable;
+  @ViewChild('viewport') viewport: ElementRef<HTMLElement>;
+  @ViewChild('topStart') topStart: ElementRef<HTMLElement>;
+  @ViewChild('topEnd') topEnd: ElementRef<HTMLElement>;
+  @ViewChild('bottomStart') bottomStart: ElementRef<HTMLElement>;
+  @ViewChild('bottomEnd') bottomEnd: ElementRef<HTMLElement>;
+}