[NavigationDrawer] Update cacheLayoutCalculationsWithAddedContentHeig…

…ht recursion check to factor out floating point rounding issues (#7654)

The `_contentHeaderTopInset > _contentHeightSurplus` check in `MDCBottomDrawerContainerViewController`'s `cacheLayoutCalculationsWithAddedContentHeight:` function was erroneously evaluating to `true` when presenting content:

- in full screen
- with no header
- with the content's height being equal to the available height

Because of how `_contentHeightSurplus` is calculated, it was almost (but not quite) equal to `_contentHeaderTopInset`, which was causing the function to infinitely recurse.

This PR also adds an example that demonstrates the issue. To reproduce:

1. Open MDCDragons
1. Navigate to the "Bottom Drawer No Header Less Content" example
1. Rotate the phone/simulator to landscape
1. Show the bottom navigation drawer by tapping on the menu icon

Expected:

The bottom drawer is displayed.

Actual:

The `cacheLayoutCalculationsWithAddedContentHeight:` infinitely recurses and the app crashes due to stack overflow.

Closes #7633

components/NavigationDrawer/examples/BottomDrawerNoHeaderLessContentExample.swift

@@ -0,0 +1,88 @@
+// Copyright 2018-present the Material Components for iOS authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import UIKit
+import MaterialComponents.MaterialBottomAppBar
+import MaterialComponents.MaterialBottomAppBar_ColorThemer
+import MaterialComponents.MaterialColorScheme
+import MaterialComponents.MaterialNavigationDrawer
+
+class BottomDrawerNoHeaderLessContentExample: UIViewController {
+  @objc var colorScheme = MDCSemanticColorScheme()
+  let bottomAppBar = MDCBottomAppBarView()
+
+  let contentViewController = DrawerContentViewController()
+  let bottomDrawerTransitionController = MDCBottomDrawerTransitionController()
+
+  override func viewDidLoad() {
+    super.viewDidLoad()
+
+    contentViewController.preferredHeight = UIScreen.main.bounds.size.height
+
+    view.backgroundColor = colorScheme.backgroundColor
+    contentViewController.view.backgroundColor = colorScheme.primaryColor
+
+    bottomAppBar.isFloatingButtonHidden = true
+    let barButtonLeadingItem = UIBarButtonItem()
+    let menuImage = UIImage(named:"Menu")?.withRenderingMode(.alwaysTemplate)
+    barButtonLeadingItem.image = menuImage
+    barButtonLeadingItem.target = self
+    barButtonLeadingItem.action = #selector(presentNavigationDrawer)
+    bottomAppBar.leadingBarButtonItems = [ barButtonLeadingItem ]
+    MDCBottomAppBarColorThemer.applySurfaceVariant(withSemanticColorScheme: colorScheme,
+                                                   to: bottomAppBar)
+    view.addSubview(bottomAppBar)
+  }
+
+  override func viewDidLayoutSubviews() {
+    super.viewDidLayoutSubviews()
+
+    layoutBottomAppBar()
+  }
+
+  private func layoutBottomAppBar() {
+    let size = bottomAppBar.sizeThatFits(view.bounds.size)
+    var bottomBarViewFrame = CGRect(x: 0,
+                                    y: view.bounds.size.height - size.height,
+                                    width: size.width,
+                                    height: size.height)
+    if #available(iOS 11.0, *) {
+      bottomBarViewFrame.size.height += view.safeAreaInsets.bottom
+      bottomBarViewFrame.origin.y -= view.safeAreaInsets.bottom
+    }
+    bottomAppBar.frame = bottomBarViewFrame
+  }
+
+  @objc func presentNavigationDrawer() {
+    // This shows that it is possible to present the content view controller directly without
+    // the need of the MDCBottomDrawerViewController wrapper. To present the view controller
+    // inside the drawer, both the transition controller and the custom presentation controller
+    // of the drawer need to be set.
+    contentViewController.transitioningDelegate = bottomDrawerTransitionController
+    contentViewController.modalPresentationStyle = .custom
+    present(contentViewController, animated: true, completion: nil)
+  }
+}
+
+extension BottomDrawerNoHeaderLessContentExample {
+
+  @objc class func catalogMetadata() -> [String: Any] {
+    return [
+      "breadcrumbs": ["Navigation Drawer", "Bottom Drawer No Header Less Content"],
+      "primaryDemo": false,
+      "presentable": false,
+    ]
+  }
+
+}

components/NavigationDrawer/src/private/MDCBottomDrawerContainerViewController.m

@@ -786,7 +786,7 @@ - (void)cacheLayoutCalculationsWithAddedContentHeight:(CGFloat)addedContentHeigh
     }
   }
 
-  CGFloat scrollingDistance = _contentHeaderTopInset + contentHeaderHeight + contentHeight;
+  CGFloat scrollingDistance = _contentHeaderTopInset + totalHeight;
   _contentHeightSurplus = scrollingDistance - containerHeight;
   if ([self shouldPresentFullScreen]) {
     self.drawerState = MDCBottomDrawerStateFullScreen;
@@ -795,7 +795,7 @@ - (void)cacheLayoutCalculationsWithAddedContentHeight:(CGFloat)addedContentHeigh
   } else {
     self.drawerState = MDCBottomDrawerStateCollapsed;
   }
-  if (addedContentHeight < kEpsilon && (_contentHeaderTopInset > _contentHeightSurplus) &&
+  if (addedContentHeight < kEpsilon && containerHeight > totalHeight &&
       (_contentHeaderTopInset - _contentHeightSurplus < self.addedContentHeightThreshold)) {
     CGFloat addedContentheight = _contentHeaderTopInset - _contentHeightSurplus;
     [self cacheLayoutCalculationsWithAddedContentHeight:addedContentheight];

components/NavigationDrawer/tests/unit/MDCNavigationDrawerScrollViewTests.m

@@ -323,7 +323,7 @@ - (void)testContentHeightSurplus {
   XCTAssertEqualWithAccuracy(self.fakeBottomDrawer.contentHeightSurplus, 0, 0.001);
 }
 
-- (void)testContentHeightSurplusWithScrollabelContent {
+- (void)testContentHeightSurplusWithScrollableContent {
   // Given
   CGSize fakePreferredContentSize = CGSizeMake(200, 1000);
   [self setupHeaderWithPreferredContentSize:fakePreferredContentSize];
@@ -751,4 +751,21 @@ - (void)testSettingShouldIncludeSafeAreaInContentHeight {
                     .shouldIncludeSafeAreaInContentHeight);
 }
 
+- (void)testFullScreenContentLayoutCalculationsComplete {
+  // Given
+  UIViewController *fakeViewController = [[UIViewController alloc] init];
+  fakeViewController.view.frame = CGRectMake(0, 0, 200, UIScreen.mainScreen.bounds.size.height);
+  self.drawerViewController.contentViewController = fakeViewController;
+  [self.drawerViewController expandToFullscreenWithDuration:0 completion:nil];
+
+  // When
+  MDCBottomDrawerPresentationController *presentationController =
+      (MDCBottomDrawerPresentationController *)self.drawerViewController.presentationController;
+  [presentationController.bottomDrawerContainerViewController cacheLayoutCalculations];
+
+  // Then
+  // This test was put in place to validate that cacheLayoutCalculations doesn't infinitely recurse
+  // It has no visible side effects, so as long as this test finishes, it passes
+}
+
 @end