Convert `Excerpt` component to Preact

Convert the `Excerpt` component to Preact. Rather than convert the
existing implementation verbatim, this is a completely new implementation which
should be easier to understand and use. Instead of requiring callers to
provide an input property which represents the displayed data, which triggers a
re-measurement if it changes, the new implementation observes the DOM
directly for size changes.

This component renders caller-provided content (ie. it accepts a `children`
prop), which is not supported by the Preact <-> Angular bridge. Therefore it was
also necessary to create components (`AnnotationBody`, `AnnotationQuote`) that
encapsulate uses of `Excerpt` inside the `<annotation>` component.

 - Add `observe-element-size` utility module to watch for changes in
   the size of a DOM node using APIs available in the current browser

 - Add new `Excerpt` implementation and remove the old one

 - Remove `excerpt-overflow-monitor` utility that is not used by the new
   implementation

 - Add `AnnotationBody` component to render an annotation's markup body
   inside a (new) excerpt and convert the Angular template for
   `<annotation>` (annotation.html) to use it.

 - Add `AnnotationQuote` component to render an annotation's quote
   inside an excerpt and convert `annotation.html` to use it

src/sidebar/components/annotation-body.js

+'use strict';
+
+const { createElement } = require('preact');
+const propTypes = require('prop-types');
+
+const Excerpt = require('./excerpt');
+const MarkdownEditor = require('./markdown-editor');
+const MarkdownView = require('./markdown-view');
+
+/**
+ * Display the rendered content of an annotation.
+ */
+function AnnotationBody({
+  collapse,
+  isEditing,
+  isHiddenByModerator,
+  hasContent,
+  onCollapsibleChanged,
+  onEditText,
+  onToggleCollapsed,
+  text,
+}) {
+  return (
+    <section className="annotation-body">
+      {!isEditing && (
+        <Excerpt
+          collapse={collapse}
+          collapsedHeight={400}
+          inlineControls={false}
+          onCollapsibleChanged={onCollapsibleChanged}
+          onToggleCollapsed={collapsed => onToggleCollapsed({ collapsed })}
+          overflowHystersis={20}
+        >
+          <MarkdownView
+            markdown={text}
+            textClass={{
+              'annotation-body is-hidden': isHiddenByModerator,
+              'has-content': hasContent,
+            }}
+          />
+        </Excerpt>
+      )}
+      {isEditing && <MarkdownEditor text={text} onEditText={onEditText} />}
+    </section>
+  );
+}
+
+AnnotationBody.propTypes = {
+  collapse: propTypes.bool,
+  hasContent: propTypes.bool,
+  isEditing: propTypes.bool,
+  isHiddenByModerator: propTypes.bool,
+  onCollapsibleChanged: propTypes.func,
+  onEditText: propTypes.func,
+  onToggleCollapsed: propTypes.func,
+  text: propTypes.string,
+};
+
+module.exports = AnnotationBody;

src/sidebar/components/annotation-quote.js

+'use strict';
+
+const classnames = require('classnames');
+const { createElement } = require('preact');
+const propTypes = require('prop-types');
+
+const { withServices } = require('../util/service-context');
+const { applyTheme } = require('../util/theme');
+const Excerpt = require('./excerpt');
+
+/**
+ * Display the selected text from the document associated with an annotation.
+ */
+function AnnotationQuote({ isOrphan, quote, settings = {} }) {
+  return (
+    <section
+      className={classnames('annotation-quote-list', isOrphan && 'is-orphan')}
+    >
+      <Excerpt
+        collapsedHeight={35}
+        inlineControls={true}
+        overflowHystersis={20}
+      >
+        <blockquote
+          className="annotation-quote"
+          style={applyTheme(['selectionFontFamily'], settings)}
+        >
+          {quote}
+        </blockquote>
+      </Excerpt>
+    </section>
+  );
+}
+
+AnnotationQuote.propTypes = {
+  isOrphan: propTypes.bool,
+  quote: propTypes.string,
+
+  // Used for theming.
+  settings: propTypes.object,
+};
+
+AnnotationQuote.injectedProps = ['settings'];
+
+module.exports = withServices(AnnotationQuote);

src/sidebar/components/annotation.js

@@ -562,10 +562,6 @@ function AnnotationController(
       return;
     }
     self.canCollapseBody = canCollapse;
-
-    // This event handler is called from outside the digest cycle, so
-    // explicitly trigger a digest.
-    $scope.$digest();
   };
 
   this.setText = function(text) {

src/sidebar/components/test/annotation-body-test.js

+'use strict';
+
+const { createElement } = require('preact');
+const { mount } = require('enzyme');
+
+const AnnotationBody = require('../annotation-body');
+const mockImportedComponents = require('./mock-imported-components');
+
+describe('AnnotationBody', () => {
+  function createBody(props = {}) {
+    return mount(<AnnotationBody text="test comment" {...props} />);
+  }
+
+  beforeEach(() => {
+    AnnotationBody.$imports.$mock(mockImportedComponents());
+  });
+
+  afterEach(() => {
+    AnnotationBody.$imports.$restore();
+  });
+
+  it('displays the comment if `isEditing` is false', () => {
+    const wrapper = createBody({ isEditing: false });
+    assert.isFalse(wrapper.exists('MarkdownEditor'));
+    assert.isTrue(wrapper.exists('MarkdownView'));
+  });
+
+  it('displays an editor if `isEditing` is true', () => {
+    const wrapper = createBody({ isEditing: true });
+    assert.isTrue(wrapper.exists('MarkdownEditor'));
+    assert.isFalse(wrapper.exists('MarkdownView'));
+  });
+});

src/sidebar/components/test/annotation-quote-test.js

+'use strict';
+
+const { createElement } = require('preact');
+const { mount } = require('enzyme');
+
+const AnnotationQuote = require('../annotation-quote');
+const mockImportedComponents = require('./mock-imported-components');
+
+describe('AnnotationQuote', () => {
+  function createQuote(props) {
+    return mount(
+      <AnnotationQuote quote="test quote" settings={{}} {...props} />
+    );
+  }
+
+  beforeEach(() => {
+    AnnotationQuote.$imports.$mock(mockImportedComponents());
+  });
+
+  afterEach(() => {
+    AnnotationQuote.$imports.$restore();
+  });
+
+  it('renders the quote', () => {
+    const wrapper = createQuote();
+    const quote = wrapper.find('blockquote');
+    assert.equal(quote.text(), 'test quote');
+  });
+});

src/sidebar/components/test/annotation-test.js

@@ -156,16 +156,22 @@ describe('annotation', function() {
             onClick: '&',
           },
         })
-        .component('markdownEditor', {
+        .component('annotationBody', {
           bindings: {
-            text: '<',
+            collapse: '<',
+            hasContent: '<',
+            isEditing: '<',
+            isHiddenByModerator: '<',
+            onCollapsibleChanged: '&',
             onEditText: '&',
+            onToggleCollapsed: '&',
+            text: '<',
           },
         })
-        .component('markdownView', {
+        .component('annotationQuote', {
           bindings: {
-            markdown: '<',
-            textClass: '<',
+            isOrphan: '<',
+            quote: '<',
           },
         });
     });
@@ -1256,18 +1262,6 @@ describe('annotation', function() {
       });
     });
 
-    it('renders quotes as plain text', function() {
-      const ann = fixtures.defaultAnnotation();
-      ann.target[0].selector = [
-        {
-          type: 'TextQuoteSelector',
-          exact: '<<-&->>',
-        },
-      ];
-      const el = createDirective(ann).element;
-      assert.equal(el[0].querySelector('blockquote').textContent, '<<-&->>');
-    });
-
     [
       {
         context: 'for moderators',
@@ -1275,10 +1269,8 @@ describe('annotation', function() {
           // Content still present.
           text: 'Some offensive content',
         }),
-        textClass: {
-          'annotation-body is-hidden': true,
-          'has-content': true,
-        },
+        isHiddenByModerator: true,
+        hasContent: true,
       },
       {
         context: 'for non-moderators',
@@ -1287,18 +1279,17 @@ describe('annotation', function() {
           tags: [],
           text: '',
         }),
-        textClass: {
-          'annotation-body is-hidden': true,
-          'has-content': false,
+        isHiddenByModerator: true,
+        hasContent: false,
       },
-      },
-    ].forEach(testCase => {
-      it(`renders hidden annotations with a custom text class (${testCase.context})`, () => {
-        const el = createDirective(testCase.ann).element;
+    ].forEach(({ ann, context, isHiddenByModerator, hasContent }) => {
+      it(`passes moderation status to annotation body (${context})`, () => {
+        const el = createDirective(ann).element;
         assert.match(
-          el.find('markdown-view').controller('markdownView'),
+          el.find('annotation-body').controller('annotationBody'),
           sinon.match({
-            textClass: testCase.textClass,
+            isHiddenByModerator,
+            hasContent,
           })
         );
       });

src/sidebar/index.js

@@ -130,6 +130,10 @@ function startAngularApp(config) {
 
     // UI components
     .component('annotation', require('./components/annotation'))
+    .component(
+      'annotationBody',
+      wrapReactComponent(require('./components/annotation-body'))
+    )
     .component(
       'annotationHeader',
       wrapReactComponent(require('./components/annotation-header'))
@@ -142,6 +146,10 @@ function startAngularApp(config) {
       'annotationPublishControl',
       wrapReactComponent(require('./components/annotation-publish-control'))
     )
+    .component(
+      'annotationQuote',
+      wrapReactComponent(require('./components/annotation-quote'))
+    )
     .component(
       'annotationShareDialog',
       require('./components/annotation-share-dialog')
@@ -151,7 +159,6 @@ function startAngularApp(config) {
       'annotationViewerContent',
       require('./components/annotation-viewer-content')
     )
-    .component('excerpt', require('./components/excerpt'))
     .component(
       'helpPanel',
       wrapReactComponent(require('./components/help-panel'))
@@ -160,14 +167,6 @@ function startAngularApp(config) {
       'loggedOutMessage',
       wrapReactComponent(require('./components/logged-out-message'))
     )
-    .component(
-      'markdownEditor',
-      wrapReactComponent(require('./components/markdown-editor'))
-    )
-    .component(
-      'markdownView',
-      wrapReactComponent(require('./components/markdown-view'))
-    )
     .component(
       'moderationBanner',
       wrapReactComponent(require('./components/moderation-banner'))
@@ -232,7 +231,6 @@ function startAngularApp(config) {
 
     // Utilities
     .value('Discovery', require('../shared/discovery'))
-    .value('ExcerptOverflowMonitor', require('./util/excerpt-overflow-monitor'))
     .value('OAuthClient', require('./util/oauth-client'))
     .value('VirtualThreadList', require('./virtual-thread-list'))
     .value('isSidebar', isSidebar)

src/sidebar/templates/annotation.html

@@ -13,45 +13,22 @@
                          show-document-info="vm.showDocumentInfo">
   </annotation-header>
 
-  <!-- Excerpts -->
-  <section class="annotation-quote-list"
-    ng-class="{'is-orphan' : vm.isOrphan()}"
+  <annotation-quote
+    quote="vm.quote()"
+    is-orphan="vm.isOrphan()"
     ng-if="vm.quote()">
-    <excerpt collapsed-height="35"
-      inline-controls="true"
-      overflow-hysteresis="20"
-      content-data="selector.exact">
-      <blockquote class="annotation-quote"
-        h-branding="selectionFontFamily"
-        ng-bind="vm.quote()"></blockquote>
-    </excerpt>
-  </section>
+  </annotation-quote>
 
-  <!-- / Excerpts -->
-
-  <!-- Body -->
-  <section name="text" class="annotation-body">
-    <excerpt
-      inline-controls="false"
-      on-collapsible-changed="vm.setBodyCollapsible(collapsible)"
+  <annotation-body
     collapse="vm.collapseBody"
-      collapsed-height="400"
-      overflow-hysteresis="20"
-      content-data="vm.state().text"
-      ng-if="!vm.editing()">
-      <markdown-view
-        markdown="vm.state().text"
-        text-class="{'annotation-body is-hidden':vm.isHiddenByModerator(),
-                     'has-content':vm.hasContent()}">
-      </markdown-view>
-    </excerpt>
-    <markdown-editor
-      text="vm.state().text"
+    has-content="vm.hasContent()"
+    is-editing="vm.editing()"
+    is-hidden-by-moderator="vm.isHiddenByModerator()"
+    on-collapsible-changed="vm.setBodyCollapsible(collapsible)"
     on-edit-text="vm.setText(text)"
-      ng-if="vm.editing()">
-    </markdown-editor>
-  </section>
-  <!-- / Body -->
+    on-toggle-collapsed="vm.collapseBody = collapsed"
+    text="vm.state().text">
+  </annotation-body>
 
   <!-- Tags -->
   <div class="annotation-body form-field" ng-if="vm.editing()">

src/sidebar/templates/excerpt.html

-<div class="excerpt__container">
-  <div class="excerpt" ng-style="vm.contentStyle()">
-    <div ng-transclude></div>
-    <div ng-click="vm.expand()"
-         ng-class="vm.bottomShadowStyles()"
-         title="Show the full excerpt"></div>
-    <div class="excerpt__inline-controls"
-         ng-show="vm.showInlineControls()">
-      <span class="excerpt__toggle-link" ng-show="vm.isExpandable()">
-        … <a ng-click="vm.toggle($event)"
-            title="Show the full excerpt"
-            h-branding="accentColor, selectionFontFamily">More</a>
-      </span>
-      <span class="excerpt__toggle-link" ng-show="vm.isCollapsible()">
-        <a ng-click="vm.toggle($event)"
-            title="Show the first few lines only"
-            h-branding="accentColor, selectionFontFamily">Less</a>
-      </span>
-    </div>
-  </div>
-</div>

src/sidebar/util/excerpt-overflow-monitor.js

-'use strict';
-
-function toPx(val) {
-  return val.toString() + 'px';
-}
-
-/**
- * Interface used by ExcerptOverflowMonitor to retrieve the state of the
- * <excerpt> and report when the state changes.
- *
- * interface Excerpt {
- *   getState(): State;
- *   contentHeight(): number | undefined;
- *   onOverflowChanged(): void;
- * }
- */
-
-/**
- * A helper for the <excerpt> component which handles determinination of the
- * overflow state and content styling given the current state of the component
- * and the height of its contents.
- *
- * When the state of the excerpt or its content changes, the component should
- * call check() to schedule an async update of the overflow state.
- *
- * @param {Excerpt} excerpt - Interface used to query the current state of the
- *        excerpt and notify it when the overflow state changes.
- * @param {(callback) => number} requestAnimationFrame -
- *        Function called to schedule an async recalculation of the overflow
- *        state.
- */
-function ExcerptOverflowMonitor(excerpt, requestAnimationFrame) {
-  let pendingUpdate = false;
-
-  // Last-calculated overflow state
-  let prevOverflowing;
-
-  function update() {
-    const state = excerpt.getState();
-
-    if (!pendingUpdate) {
-      return;
-    }
-
-    pendingUpdate = false;
-
-    const hysteresisPx = state.overflowHysteresis || 0;
-    const overflowing =
-      excerpt.contentHeight() > state.collapsedHeight + hysteresisPx;
-    if (overflowing === prevOverflowing) {
-      return;
-    }
-
-    prevOverflowing = overflowing;
-    excerpt.onOverflowChanged(overflowing);
-  }
-
-  /**
-   * Schedule a deferred check of whether the content is collapsed.
-   */
-  function check() {
-    if (pendingUpdate) {
-      return;
-    }
-    pendingUpdate = true;
-    requestAnimationFrame(update);
-  }
-
-  /**
-   * Returns an object mapping CSS properties to values that should be applied
-   * to an excerpt's content element in order to truncate it based on the
-   * current overflow state.
-   */
-  function contentStyle() {
-    const state = excerpt.getState();
-
-    let maxHeight = '';
-    if (prevOverflowing) {
-      if (state.collapse) {
-        maxHeight = toPx(state.collapsedHeight);
-      } else if (state.animate) {
-        // Animating the height change requires that the final
-        // height be specified exactly, rather than relying on
-        // auto height
-        maxHeight = toPx(excerpt.contentHeight());
-      }
-    } else if (typeof prevOverflowing === 'undefined' && state.collapse) {
-      // If the excerpt is collapsed but the overflowing state has not yet
-      // been computed then the exact max height is unknown, but it will be
-      // in the range [state.collapsedHeight, state.collapsedHeight +
-      // state.overflowHysteresis]
-      //
-      // Here we guess that the final content height is most likely to be
-      // either less than `collapsedHeight` or more than `collapsedHeight` +
-      // `overflowHysteresis`, in which case it will be truncated to
-      // `collapsedHeight`.
-      maxHeight = toPx(state.collapsedHeight);
-    }
-
-    return {
-      'max-height': maxHeight,
-    };
-  }
-
-  this.contentStyle = contentStyle;
-  this.check = check;
-}
-
-module.exports = ExcerptOverflowMonitor;

src/sidebar/util/test/excerpt-overflow-monitor-test.js

-'use strict';
-
-const ExcerptOverflowMonitor = require('../excerpt-overflow-monitor');
-
-describe('ExcerptOverflowMonitor', function() {
-  let contentHeight;
-  let ctrl;
-  let monitor;
-  let state;
-
-  beforeEach(function() {
-    contentHeight = 0;
-
-    state = {
-      animate: true,
-      collapsedHeight: 100,
-      collapse: true,
-      overflowHysteresis: 20,
-    };
-
-    ctrl = {
-      getState: function() {
-        return state;
-      },
-      contentHeight: function() {
-        return contentHeight;
-      },
-      onOverflowChanged: sinon.stub(),
-    };
-
-    monitor = new ExcerptOverflowMonitor(ctrl, function(callback) {
-      callback();
-    });
-  });
-
-  describe('overflow state', function() {
-    it('overflows if height > collaped height + hysteresis', function() {
-      contentHeight = 200;
-      monitor.check();
-      assert.calledWith(ctrl.onOverflowChanged, true);
-    });
-
-    it('does not overflow if height < collapsed height', function() {
-      contentHeight = 80;
-      monitor.check();
-      assert.calledWith(ctrl.onOverflowChanged, false);
-    });
-
-    it('does not overflow if height is in [collapsed height, collapsed height + hysteresis]', function() {
-      contentHeight = 110;
-      monitor.check();
-      assert.calledWith(ctrl.onOverflowChanged, false);
-    });
-  });
-
-  context('#contentStyle', function() {
-    it('sets max-height if collapsed and overflowing', function() {
-      contentHeight = 200;
-      monitor.check();
-      assert.deepEqual(monitor.contentStyle(), { 'max-height': '100px' });
-    });
-
-    it('sets max height to empty if not overflowing', function() {
-      contentHeight = 80;
-      monitor.check();
-      assert.deepEqual(monitor.contentStyle(), { 'max-height': '' });
-    });
-
-    it('sets max-height if overflow state is unknown', function() {
-      // Before the initial overflow check, the state is unknown
-      assert.deepEqual(monitor.contentStyle(), { 'max-height': '100px' });
-    });
-  });
-
-  context('#check', function() {
-    it('calls onOverflowChanged() if state changed', function() {
-      contentHeight = 200;
-      monitor.check();
-
-      ctrl.onOverflowChanged = sinon.stub();
-      contentHeight = 250;
-      monitor.check();
-      assert.notCalled(ctrl.onOverflowChanged);
-    });
-  });
-});

src/styles/sidebar/components/excerpt.scss

@@ -5,6 +5,7 @@
   .excerpt {
     transition: max-height $expand-duration ease-in;
     overflow: hidden;
+    position: relative;
   }
 
   // a container which wraps the <excerpt> and contains the excerpt