[BD-46] feat: development Truncate component

src/Card/Card.scss

@@ -173,6 +173,7 @@
 }
 
 .pgn__card-footer-text {
+  width: 100%;
   color: $gray-700;
   order: 1;
   font-size: $card-footer-text-font-size;

src/Truncate/README.md

@@ -0,0 +1,72 @@
+---
+title: 'Truncate'
+type: 'component'
+components:
+- Truncate
+status: 'New'
+designStatus: 'Done'
+devStatus: 'Done'
+---
+
+A Truncate component can help you crop multiline text. There will be three dots at the end of the text.
+
+### Basic Usage
+
+```jsx live
+  <Truncate lines={2}>
+    Learners, course teams, researchers, developers: the edX community includes groups with a range of reasons 
+    for using the platform and objectives to accomplish. To help members of each group learn about what edX 
+    offers, reach goals, and solve problems, edX provides a variety of information resources.
+    Learners, course teams, researchers, developers: the edX community includes groups with a range of reasons
+    for using the platform and objectives to accomplish. To help members of each group learn about what edX
+    offers, reach goals, and solve problems, edX provides a variety of information resources.
+  </Truncate>
+```
+
+### With the custom ellipsis
+
+```jsx live
+  <Truncate lines={2} ellipsis="🎉🎉🎉" whiteSpace>
+    Learners, course teams, researchers, developers: the edX community includes groups with a range of reasons 
+    for using the platform and objectives to accomplish. To help members of each group learn about what edX 
+    offers, reach goals, and solve problems, edX provides a variety of information resources.
+  </Truncate>
+```
+
+### Usage in component properties
+
+```jsx live
+() => {
+  const isExtraSmall = useMediaQuery({ maxWidth: breakpoints.extraSmall.maxWidth });
+
+  return (
+    <Card style={{ width: isExtraSmall ? "100%" : "18rem" }} isClickable>
+      <Card.ImageCap
+        src="https://source.unsplash.com/360x200/?nature,flower"
+        srcAlt="Card image"
+      />
+      <Card.Header
+        title={
+          <Truncate lines={2}>
+            Using Enhanced Capabilities In Your Course
+          </Truncate>}
+      />
+      <Card.Section>
+        <Truncate lines={4}>
+          Learners, course teams, researchers, developers: the edX community includes groups with a range of reasons
+          for using the platform and objectives to accomplish. To help members of each group learn about what edX
+          offers, reach goals, and solve problems, edX provides a variety of information resources.
+        </Truncate>
+      </Card.Section>
+      <Card.Footer 
+        textElement={
+          <Truncate lines={2}>
+            Using Enhanced Capabilities In Your Course
+          </Truncate>}
+      >
+        <Button style={{ width: '100%' }}>Action 1</Button>
+      </Card.Footer>
+    </Card>
+  )
+}
+```

src/Truncate/Truncate.test.js

@@ -0,0 +1,50 @@
+import { constructString, cropText, truncateLines } from './utils';
+
+describe('utils', () => {
+  describe('cropText', () => {
+    it('return the contents of the sliced text', () => {
+      const text = 'Learners, course teams, researchers, developers';
+      const cropDecrement = 0.70;
+      const croppedText = cropText(text, cropDecrement);
+      expect(croppedText).toEqual('Learners, course teams, research');
+    });
+  });
+
+  describe('constructString', () => {
+    it('return new string text after constructed', () => {
+      const string = 'Learners, course teams, researchers, developers';
+      const whiteSpace = true;
+      const ellipsis = '...';
+      const finalString = constructString(string, whiteSpace, ellipsis);
+      expect(finalString).toEqual('Learners, course teams, researchers, developers ...');
+    });
+  });
+
+  describe('truncateLines', () => {
+    it('returned truncate lines', () => {
+      const element = document.createElement('div');
+      jest.spyOn(document, 'createElement').mockReturnValue({
+        parentNode: {
+          removeChild: () => {},
+        },
+        scrollHeight: 220,
+        setAttribute: () => {},
+        set innerHTML(val) {
+          this.scrollHeight -= 60;
+        },
+      });
+
+      const text = 'Learners, course teams, researchers, developers: the edX community includes groups with '
+        + 'a range of reasons for using the platform and objectives to accomplish.';
+      const lines = 2;
+      const whiteSpace = false;
+      const ellipsis = '___';
+      expect(truncateLines(text, element, {
+        lines,
+        whiteSpace,
+        ellipsis,
+      })).toEqual('Learners, course teams, researchers, developers: the edX community includes groups with a range of '
+        + 'reasons for using the platform and objectives to accompl___');
+    });
+  });
+});

src/Truncate/Truncate.test.jsx

@@ -0,0 +1,15 @@
+import React from 'react';
+import { mount } from 'enzyme';
+import Truncate from './index';
+
+describe('<Truncate />', () => {
+  const wrapper = mount(
+    <Truncate>
+      Learners, course teams, researchers, developers.
+    </Truncate>,
+  );
+  it('render with className', () => {
+    wrapper.setProps({ className: 'pgn__truncate' });
+    expect(wrapper.hasClass('pgn__truncate')).toEqual(true);
+  });
+});

src/Truncate/index.jsx

@@ -0,0 +1,57 @@
+import React, {
+  useEffect, useRef, useState,
+} from 'react';
+import PropTypes from 'prop-types';
+import { truncateLines } from './utils';
+import { useWindowSize } from '../index';
+
+const DEFAULT_TRUNCATE_LINES = 1;
+const DEFAULT_TRUNCATE_ELLIPSIS = '...';
+const DEFAULT_TRUNCATE_ELEMENT_TYPE = 'div';
+
+const Truncate = ({
+  children, lines, ellipsis, elementType, className, whiteSpace,
+}) => {
+  const [truncateText, setTruncateText] = useState('');
+  const textContainer = useRef();
+  const { width } = useWindowSize();
+
+  useEffect(() => {
+    const newTruncateText = truncateLines(children, textContainer.current, {
+      ellipsis,
+      whiteSpace,
+      lines,
+    });
+    setTruncateText(newTruncateText);
+  }, [children, ellipsis, lines, whiteSpace, width]);
+
+  return React.createElement(elementType, {
+    ref: textContainer,
+    className,
+  }, truncateText);
+};
+
+Truncate.propTypes = {
+  /** The expected text to which the ellipsis would be applied. */
+  children: PropTypes.string.isRequired,
+  /** The number of lines the text to be truncated to. */
+  lines: PropTypes.oneOfType([PropTypes.string, PropTypes.number]),
+  /** Text content for the ellipsis - will appear after the truncated lines. */
+  ellipsis: PropTypes.oneOfType([PropTypes.string, PropTypes.number, PropTypes.node]),
+  /** The whitespace from before the ellipsis. */
+  whiteSpace: PropTypes.bool,
+  /** Custom html element for truncated text. */
+  elementType: PropTypes.string,
+  /** Specifies class name to append to the base element. */
+  className: PropTypes.string,
+};
+
+Truncate.defaultProps = {
+  lines: DEFAULT_TRUNCATE_LINES,
+  ellipsis: DEFAULT_TRUNCATE_ELLIPSIS,
+  whiteSpace: false,
+  elementType: DEFAULT_TRUNCATE_ELEMENT_TYPE,
+  className: null,
+};
+
+export default Truncate;

src/Truncate/utils.js

@@ -0,0 +1,55 @@
+const LINE_HEIGHT_VALUE = 40;
+const CROP_DECREMENT_STEP = 0.01;
+
+const createCopyElement = (element) => {
+  const newElement = document.createElement(element.tagName);
+  newElement.setAttribute(
+    'style',
+    `line-height: ${LINE_HEIGHT_VALUE}px; display: inline-block;`,
+  );
+  return newElement;
+};
+
+const constructString = (text, whiteSpace, ellipsis) => {
+  const spacer = whiteSpace ? ' ' : '';
+  return `${text.trim()}${spacer}${ellipsis}`;
+};
+
+const cropText = (text, cropDecrement) => {
+  const sliceIndex = Math.floor(text.length * cropDecrement);
+  return text.slice(0, sliceIndex);
+};
+
+const truncateLines = (text, element, { lines, whiteSpace, ellipsis }) => {
+  const visibilityArea = LINE_HEIGHT_VALUE * Number(lines);
+  const newElement = createCopyElement(element);
+  let truncateText = text;
+  let cropDecrement = 1;
+
+  element.append(newElement);
+  newElement.innerHTML = constructString(text, whiteSpace, ellipsis);
+
+  let newElementTextHeight = newElement.scrollHeight;
+
+  if (visibilityArea > newElementTextHeight) {
+    newElement.parentNode.removeChild(newElement);
+    return truncateText;
+  }
+
+  while (newElementTextHeight > visibilityArea) {
+    cropDecrement -= CROP_DECREMENT_STEP;
+    truncateText = cropText(text, cropDecrement);
+    newElement.innerHTML = constructString(truncateText, whiteSpace, ellipsis);
+    newElementTextHeight = newElement.scrollHeight;
+  }
+
+  newElement.parentNode.removeChild(newElement);
+  return constructString(truncateText, whiteSpace, ellipsis);
+};
+
+module.exports = {
+  cropText,
+  truncateLines,
+  constructString,
+  createCopyElement,
+};

src/index.js

@@ -193,3 +193,4 @@ export { default as Bubble } from './Bubble';
 export { default as Dropzone } from './Dropzone';
 
 export { default as messages } from './i18n';
+export { default as Truncate } from './Truncate';