feat: Add keepAlign support (#36)

* feat: Add keepAlign support

* add test case

Author: zombieJ

examples/position.js

@@ -0,0 +1,79 @@
+import React, { Component } from 'react';
+import Align from '../src';
+
+const align = {
+  points: ['cc', 'cc'],
+};
+
+class Demo extends Component {
+  state = {
+    left: 0,
+    top: 0,
+  };
+
+  eleRef = React.createRef();
+
+  render() {
+    const { left, top } = this.state;
+
+    return (
+      <div style={{ marginBottom: 170 }}>
+        <div
+          style={{
+            margin: 20,
+            border: '1px solid red',
+            padding: '100px 0',
+            textAlign: 'center',
+            position: 'relative',
+          }}
+          onClick={this.onClick}
+        >
+          <div
+            ref={this.eleRef}
+            style={{
+              width: 10,
+              height: 10,
+              background: 'red',
+              position: 'absolute',
+              left,
+              top,
+            }}
+          />
+        </div>
+
+        <Align
+          ref={this.alignRef}
+          target={() => this.eleRef.current}
+          align={align}
+          keepingAlign
+        >
+          <div
+            style={{
+              position: 'absolute',
+              width: 100,
+              height: 100,
+              background: 'rgba(0, 255, 0, 0.5)',
+              pointerEvents: 'none',
+            }}
+          >
+            Align
+          </div>
+        </Align>
+
+        <button
+          type="button"
+          onClick={() => {
+            this.setState({
+              left: Math.random() * 500,
+              top: Math.random() * 200,
+            });
+          }}
+        >
+          Random Position
+        </button>
+      </div>
+    );
+  }
+}
+
+export default Demo;

src/Align.tsx

@@ -22,6 +22,8 @@ export interface AlignProps {
   monitorWindowResize?: boolean;
   disabled?: boolean;
   children: React.ReactElement;
+  /** Always trigger align with each render */
+  keepAlign?: boolean;
 }
 
 interface MonitorRef {
@@ -43,11 +45,27 @@ function getPoint(point: TargetType) {
   return point;
 }
 
+interface InternalTestProps {
+  INTERNAL_TRIGGER_ALIGN?: Function;
+}
+
 const Align: React.RefForwardingComponent<RefAlign, AlignProps> = (
-  { children, disabled, target, align, onAlign, monitorWindowResize, monitorBufferTime = 0 },
+  {
+    children,
+    disabled,
+    target,
+    align,
+    onAlign,
+    monitorWindowResize,
+    monitorBufferTime = 0,
+    keepAlign,
+    ...restProps
+  },
   ref,
 ) => {
-  const cacheRef = React.useRef<{ element?: HTMLElement; point?: TargetPoint }>({});
+  const cacheRef = React.useRef<{ element?: HTMLElement; point?: TargetPoint }>(
+    {},
+  );
   const nodeRef = React.useRef();
   let childNode = React.Children.only(children);
 
@@ -63,7 +81,17 @@ const Align: React.RefForwardingComponent<RefAlign, AlignProps> = (
   forceAlignPropsRef.current.onAlign = onAlign;
 
   const [forceAlign, cancelForceAlign] = useBuffer(() => {
-    const { disabled: latestDisabled, target: latestTarget } = forceAlignPropsRef.current;
+    if (
+      process.env.NODE_ENV !== 'production' &&
+      (restProps as InternalTestProps).INTERNAL_TRIGGER_ALIGN
+    ) {
+      (restProps as InternalTestProps).INTERNAL_TRIGGER_ALIGN();
+    }
+
+    const {
+      disabled: latestDisabled,
+      target: latestTarget,
+    } = forceAlignPropsRef.current;
     if (!latestDisabled && latestTarget) {
       const source = nodeRef.current;
 
@@ -112,10 +140,16 @@ const Align: React.RefForwardingComponent<RefAlign, AlignProps> = (
     if (nodeRef.current !== sourceResizeMonitor.current.element) {
       sourceResizeMonitor.current.cancel();
       sourceResizeMonitor.current.element = nodeRef.current;
-      sourceResizeMonitor.current.cancel = monitorResize(nodeRef.current, forceAlign);
+      sourceResizeMonitor.current.cancel = monitorResize(
+        nodeRef.current,
+        forceAlign,
+      );
     }
 
-    if (cacheRef.current.element !== element || !isSamePoint(cacheRef.current.point, point)) {
+    if (
+      cacheRef.current.element !== element ||
+      !isSamePoint(cacheRef.current.point, point)
+    ) {
       forceAlign();
 
       // Add resize observer
@@ -136,6 +170,15 @@ const Align: React.RefForwardingComponent<RefAlign, AlignProps> = (
     }
   }, [disabled]);
 
+  /**
+   * [Legacy] Should keep re-algin since we don't know if target position changed.
+   */
+  React.useEffect(() => {
+    if (keepAlign && !disabled) {
+      forceAlign(true);
+    }
+  });
+
   // Listen for window resize
   const winResizeRef = React.useRef<{ remove: Function }>(null);
   React.useEffect(() => {

tests/element.test.js

@@ -26,7 +26,10 @@ describe('element align', () => {
     render() {
       return (
         <div style={{ paddingTop: 100 }}>
-          <div ref={this.targetRef} style={{ display: 'inline-block', width: 50, height: 50 }}>
+          <div
+            ref={this.targetRef}
+            style={{ display: 'inline-block', width: 50, height: 50 }}
+          >
             target
           </div>
           <Align target={this.getTarget} align={align} {...this.props}>
@@ -73,12 +76,33 @@ describe('element align', () => {
   it('disabled should trigger align', () => {
     const onAlign = jest.fn();
 
-    const wrapper = mount(<Test monitorWindowResize onAlign={onAlign} disabled />);
+    const wrapper = mount(
+      <Test monitorWindowResize onAlign={onAlign} disabled />,
+    );
     expect(onAlign).not.toHaveBeenCalled();
 
     wrapper.setProps({ disabled: false });
     jest.runAllTimers();
     expect(onAlign).toHaveBeenCalled();
   });
+
+  it('keepAlign', () => {
+    const triggerAlign = jest.fn();
+
+    class TestAlign extends React.Component {
+      state = {};
+
+      render = () => <Test INTERNAL_TRIGGER_ALIGN={triggerAlign} keepAlign />;
+    }
+
+    const wrapper = mount(<TestAlign />);
+    const times = triggerAlign.mock.calls.length;
+
+    for (let i = 0; i < 10; i += 1) {
+      wrapper.instance().forceUpdate();
+    }
+
+    expect(triggerAlign.mock.calls.length > times).toBeTruthy();
+  });
 });
 /* eslint-enable */