Fix excerpt content height when switching from edit back to view mode

The 'max-height' style property was not updated when the <excerpt>'s
enabled state changed from false to true which happened when switching
from annotation edit mode back to view mode.

Use ngStyle to ensure the inline styles applied to the <excerpt>'s
content element are updated as necessary in this case.

h/static/scripts/directive/excerpt.js

@@ -13,17 +13,12 @@ function ExcerptController() {
     return true;
   };
 
-  // Test seam. Overwritten in the link function
-  this.overflowing = function () {
-    return false;
-  };
-
   this.isExpandable = function () {
-    return this.collapse && this.overflowing();
+    return this.overflowing() && this.collapse;
   };
 
   this.isCollapsible = function () {
-    return !this.collapse;
+    return this.overflowing() && !this.collapse;
   };
 
   this.toggle = function () {
@@ -31,7 +26,7 @@ function ExcerptController() {
   };
 
   this.showInlineControls = function () {
-    return this.inlineControls && (this.isExpandable() || this.isCollapsible())
+    return this.overflowing() && this.inlineControls;
   }
 }
 
@@ -56,18 +51,26 @@ function excerpt() {
     link: function (scope, elem, attrs, ctrl) {
       var contentElem;
 
-      function checkForOverflowChange() {
-        scope.$digest();
-        updateContentMaxHeight();
+      ctrl.contentStyle = function contentStyle() {
+        if (!contentElem) {
+          return {};
         }
 
-      function updateContentMaxHeight() {
+        var maxHeight;
         if (ctrl.collapse) {
-          contentElem.style.maxHeight = toPx(ctrl.collapsedHeight);
+          maxHeight = toPx(ctrl.collapsedHeight);
+        } else if (ctrl.animate) {
+          // animating the height change requires that the final
+          // height be specified exactly, rather than relying on
+          // auto height
+          maxHeight = toPx(contentElem.scrollHeight);
         } else {
-          contentElem.style.maxHeight =
-            ctrl.animate ? toPx(contentElem.scrollHeight) : '';
+          maxHeight = '';
         }
+
+        return {
+          'max-height': maxHeight,
+        };
       }
 
       ctrl.overflowing = function overflowing() {
@@ -77,46 +80,26 @@ function excerpt() {
         return contentElem.scrollHeight > ctrl.collapsedHeight;
       };
 
-      // init function which sets up watches that perform the initial
-      // call to updateContentMaxHeight() to collapse the <excerpt> and
-      // alter the state if the <excerpt> is expanded/collapsed in future
-      function init() {
       scope.$watch('vm.enabled()', function (isEnabled) {
         if (isEnabled) {
           contentElem = elem[0].querySelector('.excerpt');
 
-            // trigger a recalculation of ctrl.overflowing() and properties
-            // which depend upon it when embedded media loads.
-            //
-            // In future we might wish to trigger checking for other events
-            // outside of Angular's knowledge as well, eg. loading of embedded
-            // media
-            contentElem.addEventListener('load', checkForOverflowChange,
+          // trigger an update of the excerpt when events happen
+          // outside of Angular's knowledge that might affect the content
+          // size. For now, the only event we handle is loading of
+          // embedded media or frames
+          contentElem.addEventListener('load', scope.$digest.bind(scope),
             true /* capture. 'load' events do not bubble */);
         } else {
           contentElem = undefined;
         }
       });
 
-        scope.$watch('vm.collapse', function (isCollapsed) {
-          if (!contentElem) {
-            return;
-          }
-          updateContentMaxHeight();
-        });
-
       scope.$watch('vm.overflowing()', function () {
         if (ctrl.onCollapsibleChanged) {
           ctrl.onCollapsibleChanged({collapsible: ctrl.overflowing()});
         }
       });
-      }
-
-      // run the init() function asynchronously so that any
-      // directives in the transcluded content of the DOM have been
-      // processed by the time the first call to updateContentMaxHeight()
-      // happens.
-      scope.$evalAsync(init);
     },
     scope: {
       /** Whether or not expansion should be animated. Defaults to true. */

h/static/scripts/directive/test/excerpt-test.js

@@ -21,6 +21,10 @@ describe('excerpt directive', function () {
     return util.createDirective(document, 'excerpt', attrs, {}, content);
   }
 
+  function height(el) {
+    return el.querySelector('.excerpt').offsetHeight;
+  }
+
   before(function () {
     angular.module('app', [])
       .directive('excerpt', excerpt.directive);
@@ -50,6 +54,13 @@ describe('excerpt directive', function () {
       assert.equal(element.find('.excerpt #foo').length, 0);
       assert.equal(element.find('#foo').length, 1);
     });
+
+    it('truncates long contents when enabled', function () {
+      var element = excerptDirective({enabled: false}, TALL_DIV);
+      element.scope.enabled = true;
+      element.scope.$digest();
+      assert.isBelow(height(element[0]), 100);
+    });
   });
 
   function isHidden(el) {
@@ -100,10 +111,6 @@ describe('excerpt directive', function () {
   });
 
   describe('.collapse', function () {
-    function height(el) {
-      return el.querySelector('.excerpt').offsetHeight;
-    }
-
     it('collapses the body if collapse is true', function () {
       var element = excerptDirective({collapse: true}, TALL_DIV);
       assert.isBelow(height(element[0]), 100);

h/templates/client/excerpt.html

 <div ng-transclude ng-if="!vm.enabled()"></div>
 <div class="excerpt__container" ng-if="vm.enabled()">
-  <div class="excerpt">
+  <div class="excerpt" ng-style="vm.contentStyle()">
     <div ng-transclude></div>
     <div class="excerpt__inline-controls"
          ng-show="vm.showInlineControls()">