feat(showHide): Introduce directives to notify child directives on hide/show.

Features extreme tail-hooking technology.

Author: kseamon

src/components/showHide/showHide.js

@@ -0,0 +1,32 @@
+/**
+ * @ngdoc module
+ * @name material.components.showHide
+ */
+
+angular.module('material.components.showHide', [
+  'material.core'
+])
+  .directive('ngShow', createDirective('ngShow', true))
+  .directive('ngHide', createDirective('ngHide', false));
+
+
+// Add additional handlers to ng-show and ng-hide that notify directives
+// contained within that they should recompute their size.
+function createDirective(name, targetValue) {
+  return ['$mdUtil', function($mdUtil) {
+    return {
+      restrict: 'A',
+      multiElement: true,
+      link: function($scope, $element, $attr) {
+        $scope.$watch($attr[name], function(value) {
+          if (!!value === targetValue) {
+            $scope.$broadcast('$md-resize');
+            $mdUtil.dom.animator.waitTransitionEnd($element).then(function() {
+              $scope.$broadcast('$md-resize');
+            });
+          }
+        });
+      }
+    };
+  }];
+}

src/components/showHide/showHide.spec.js

@@ -0,0 +1,77 @@
+describe('showHide', function() {
+  var $compile, defered, scope, spy;
+
+  beforeEach(module('material.components.showHide'));
+
+  beforeEach(inject(function(_$compile_, $mdUtil, $q, $rootScope) {
+    $compile = _$compile_;
+    defered = $q.defer();
+    scope = $rootScope.$new();
+    spy = jasmine.createSpy();
+
+    scope.$on('$md-resize', spy);
+    spyOn($mdUtil.dom.animator, 'waitTransitionEnd').and.returnValue(defered.promise);
+  }));
+
+  afterEach(function() {
+    scope.$destroy();
+  });
+
+  describe('ng-hide', function() {
+    it('should notify when the node unhides', function() {
+      scope.hide = true;
+      var element = $compile('<div ng-hide="hide"></div>')(scope);
+      scope.$apply();
+      expect(spy).not.toHaveBeenCalled();
+
+      scope.hide = false;
+      scope.$apply();
+      expect(spy).toHaveBeenCalled();
+
+      spy.calls.reset();
+      defered.resolve();
+      scope.$apply();
+      expect(spy).toHaveBeenCalled();
+    });
+
+    it('should not notify on hide', function() {
+      scope.hide = true;
+      var element = $compile('<div ng-hide="hide"></div>')(scope);
+      scope.$apply();
+
+      expect(spy).not.toHaveBeenCalled();
+      defered.resolve();
+      scope.$apply();
+      expect(spy).not.toHaveBeenCalled();
+    });
+  });
+
+  describe('ng-show', function() {
+    it('should notify when the node unhides', function() {
+      scope.show = false;
+      var element = $compile('<div ng-show="show"></div>')(scope);
+      scope.$apply();
+      expect(spy).not.toHaveBeenCalled();
+
+      scope.show = true;
+      scope.$apply();
+      expect(spy).toHaveBeenCalled();
+
+      spy.calls.reset();
+      defered.resolve();
+      scope.$apply();
+      expect(spy).toHaveBeenCalled();
+    });
+
+    it('should not notify on hide', function() {
+      scope.show = false;
+      var element = $compile('<div ng-show="show"></div>')(scope);
+      scope.$apply();
+
+      expect(spy).not.toHaveBeenCalled();
+      defered.resolve();
+      scope.$apply();
+      expect(spy).not.toHaveBeenCalled();
+    });
+  });
+});