[BottomSheet] Add property so clients can set a custom height for bot…

…tom sheet (#5139)

Previously clients could only set a custom height for bottom sheet by setting the `preferredContentSize` this adds a property so clients can set a specific height and not touch `preferredContentSize`.

Related to #4945

components/BottomSheet/src/MDCBottomSheetPresentationController.h

@@ -64,6 +64,18 @@
  */
 @property(nonatomic, assign) BOOL dismissOnBackgroundTap;
 
+/**
+ This is used to set a custom height on the sheet view.
+
+ @note If a positive value is passed then the sheet view will be that height even if
+ perferredContentSize has been set. Otherwise the sheet will open up to half the screen height or
+ the size of the presentedViewController's preferredContentSize whatever value is smaller.
+ @note The preferredSheetHeight can never be taller than the height of the content, if the content
+ is smaller than the value passed to preferredSheetHeight then the sheet view will be the size of
+ the content height.
+ */
+@property(nonatomic, assign) CGFloat preferredSheetHeight;
+
 /**
  If @c YES, then the dimmed scrim view will act as an accessibility element for dismissing the
  bottom sheet.

components/BottomSheet/src/MDCBottomSheetPresentationController.m

@@ -108,7 +108,7 @@ - (void)presentationTransitionWillBegin {
   [containerView addSubview:_dimmingView];
   [containerView addSubview:self.sheetView];
 
-  [self setPreferredSheetHeight:self.presentedViewController.preferredContentSize.height];
+  [self updatePreferredSheetHeight];
 
   // Add tap handler to dismiss the sheet.
   UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self
@@ -155,7 +155,7 @@ - (void)preferredContentSizeDidChangeForChildContentContainer:(id<UIContentConta
   [super preferredContentSizeDidChangeForChildContentContainer:container];
   self.sheetView.frame = [self frameOfPresentedViewInContainerView];
   [self.sheetView layoutIfNeeded];
-  [self setPreferredSheetHeight:self.presentedViewController.preferredContentSize.height];
+  [self updatePreferredSheetHeight];
 }
 
 - (void)viewWillTransitionToSize:(CGSize)size
@@ -167,7 +167,7 @@ - (void)viewWillTransitionToSize:(CGSize)size
           __unused id<UIViewControllerTransitionCoordinatorContext> _Nonnull context) {
         self.sheetView.frame = [self frameOfPresentedViewInContainerView];
         [self.sheetView layoutIfNeeded];
-        [self setPreferredSheetHeight:self.presentedViewController.preferredContentSize.height];
+        [self updatePreferredSheetHeight];
       }
                       completion:nil];
 }
@@ -176,11 +176,16 @@ - (void)viewWillTransitionToSize:(CGSize)size
  Sets the new value of @c sheetView.preferredSheetHeight.
  If @c preferredContentHeight is non-positive, it will set it to half of sheetView's
  frame's height.
-
- @param preferredSheetHeight If positive, the new value for @sheetView.preferredSheetHeight.
  */
-- (void)setPreferredSheetHeight:(CGFloat)preferredSheetHeight {
+- (void)updatePreferredSheetHeight {
   // If |preferredSheetHeight| has not been specified, use half of the current height.
+  CGFloat preferredSheetHeight;
+  if (self.preferredSheetHeight > 0.f) {
+    preferredSheetHeight = self.preferredSheetHeight;
+  } else {
+    preferredSheetHeight = self.presentedViewController.preferredContentSize.height;
+  }
+
   if (MDCCGFloatEqual(preferredSheetHeight, 0)) {
     preferredSheetHeight = MDCRound(CGRectGetHeight(self.sheetView.frame) / 2);
   }
@@ -244,6 +249,11 @@ - (UIAccessibilityTraits)scrimAccessibilityTraits {
   return _scrimAccessibilityTraits;
 }
 
+- (void)setPreferredSheetHeight:(CGFloat)preferredSheetHeight {
+  _preferredSheetHeight = preferredSheetHeight;
+  [self updatePreferredSheetHeight];
+}
+
 #pragma mark - MDCSheetContainerViewDelegate
 
 - (void)sheetContainerViewDidHide:(nonnull __unused MDCSheetContainerView *)containerView {

components/BottomSheet/src/MDCBottomSheetTransitionController.h

@@ -45,6 +45,19 @@
  */
 @property(nonatomic, assign) BOOL dismissOnBackgroundTap;
 
+/**
+ This is used to set a custom height on the sheet view. This is can be used to set the initial
+ height when the ViewController is presented.
+
+ @note If a positive value is passed then the sheet view will be that height even if
+ perferredContentSize has been set. Otherwise the sheet will open up to half the screen height or
+ the size of the presentedViewController's preferredContentSize whatever value is smaller.
+ @note The preferredSheetHeight can never be taller than the height of the content, if the content
+ is smaller than the value passed to preferredSheetHeight then the sheet view will be the size of
+ the content height.
+ */
+@property(nonatomic, assign) CGFloat preferredSheetHeight;
+
 @end
 
 @interface MDCBottomSheetTransitionController (ScrimAccessibility)

components/BottomSheet/src/MDCBottomSheetTransitionController.m

@@ -48,6 +48,7 @@ - (instancetype)init {
   presentationController.isScrimAccessibilityElement = _isScrimAccessibilityElement;
   presentationController.scrimAccessibilityHint = _scrimAccessibilityHint;
   presentationController.scrimAccessibilityLabel = _scrimAccessibilityLabel;
+  presentationController.preferredSheetHeight = _preferredSheetHeight;
   return presentationController;
 }
 

components/BottomSheet/tests/unit/MDCBottomSheetPresentationControllerPreferredSheetHeightTests.m

@@ -22,7 +22,7 @@
 // Exposing internal methods for unit testing
 @interface MDCBottomSheetPresentationController (Testing)
 @property(nonatomic, strong) MDCSheetContainerView *sheetView;
-- (void)setPreferredSheetHeight:(CGFloat)preferredSheetHeight;
+- (void)updatePreferredSheetHeight;
 @end
 
 /**
@@ -79,53 +79,150 @@ - (void)setUp {
   self.presentationController.sheetView = self.sheetView;
 }
 
-- (void)testSetPreferredSheetHeightZeroWhenSheetViewHasStandardizedFrame {
+- (void)testUpdatePreferredSheetHeightZeroWhenSheetViewHasStandardizedFrame {
   // Given
   CGFloat sheetFrameHeight = 80;
   self.sheetView.frame = CGRectMake(0, 0, 75, sheetFrameHeight);
 
   // When
-  [self.presentationController setPreferredSheetHeight:0];
+  [self.presentationController updatePreferredSheetHeight];
 
   // Then
   XCTAssertEqualWithAccuracy(self.sheetView.preferredSheetHeight, sheetFrameHeight / 2, 0.001);
 }
 
-- (void)testSetPreferredSheetHeightZeroWhenSheetViewHasUnstandardizedFrame {
+- (void)testUpdatePreferredSheetHeightZeroWhenSheetViewHasUnstandardizedFrame {
   // Given
   CGFloat sheetFrameHeight = -80;
   self.sheetView.frame = CGRectMake(75, 80, -75, sheetFrameHeight);
 
   // When
-  [self.presentationController setPreferredSheetHeight:0];
+  [self.presentationController updatePreferredSheetHeight];
 
   // Then
   XCTAssertEqualWithAccuracy(self.sheetView.preferredSheetHeight,
                              (CGFloat)fabs(sheetFrameHeight / 2), 0.001);
 }
 
-- (void)testSetPreferredSheetHeightPositiveValue {
+- (void)testUpdatePreferredSheetHeightPositiveValue {
   // Given
   CGFloat preferredSheetHeight = 120;
+  self.presentationController.presentedViewController.preferredContentSize =
+      CGSizeMake(100, preferredSheetHeight);
   self.sheetView.frame = CGRectMake(0, 0, 75, 80);
 
   // When
-  [self.presentationController setPreferredSheetHeight:preferredSheetHeight];
+  [self.presentationController updatePreferredSheetHeight];
 
   // Then
   XCTAssertEqualWithAccuracy(self.sheetView.preferredSheetHeight, preferredSheetHeight, 0.001);
 }
 
-- (void)testSetPreferredSheetHeightNegativeValue {
+- (void)testUpdatePreferredSheetHeightNegativeValue {
   // Given
   CGFloat preferredSheetHeight = -120;
+  self.presentationController.presentedViewController.preferredContentSize =
+      CGSizeMake(0, preferredSheetHeight);
   self.sheetView.frame = CGRectMake(0, 0, 75, -80);
 
   // When
-  [self.presentationController setPreferredSheetHeight:preferredSheetHeight];
+  [self.presentationController updatePreferredSheetHeight];
 
   // Then
   XCTAssertEqualWithAccuracy(self.sheetView.preferredSheetHeight, preferredSheetHeight, 0.001);
 }
 
+- (void)testUpdatePreferredSheetHeight {
+  // Given
+  CGFloat preferredSheetHeight = 100;
+  self.presentationController.preferredSheetHeight = preferredSheetHeight;
+
+  // When
+  [self.presentationController updatePreferredSheetHeight];
+
+  // Then
+  XCTAssertEqualWithAccuracy(self.sheetView.preferredSheetHeight, preferredSheetHeight, 0.001);
+}
+
+- (void)testUpdateNegativePreferredSheetHeight {
+  // Given
+  CGFloat preferrredSheetHeight = -100;
+  self.presentationController.preferredSheetHeight = preferrredSheetHeight;
+  CGFloat sheetHeight = 250;
+  self.sheetView.frame = CGRectMake(0, 0, 75, sheetHeight);
+
+  // When
+  [self.presentationController updatePreferredSheetHeight];
+
+  // Then
+  XCTAssertEqualWithAccuracy(self.sheetView.preferredSheetHeight, (CGFloat)(sheetHeight / 2),
+                             0.001);
+}
+
+- (void)testUpdatePreferredSheetHeightAndPreferredContentSize {
+  // Given
+  CGSize preferredContentSize = CGSizeMake(100, 100);
+  CGFloat preferredSheetHeight = 200;
+  self.presentationController.presentedViewController.preferredContentSize = preferredContentSize;
+  self.presentationController.preferredSheetHeight = preferredSheetHeight;
+
+  // When
+  [self.presentationController updatePreferredSheetHeight];
+
+  // Then
+  XCTAssertEqualWithAccuracy(self.sheetView.preferredSheetHeight, preferredSheetHeight, 0.001);
+}
+
+- (void)testPreferredSheetHeightNegativeAndPreferredContentSizePositive {
+  // Given
+  CGSize preferredContentSize = CGSizeMake(100, 100);
+  CGFloat preferredSheetHeight = -200;
+  self.presentationController.presentedViewController.preferredContentSize = preferredContentSize;
+  self.presentationController.preferredSheetHeight = preferredSheetHeight;
+
+  // When
+  [self.presentationController updatePreferredSheetHeight];
+
+  // Then
+  XCTAssertEqualWithAccuracy(self.sheetView.preferredSheetHeight, preferredContentSize.height,
+                             0.001);
+}
+
+- (void)testPreferredSheetHeightNonZeroThenZero {
+  // Given
+  CGFloat preferredSheetHeight = 200;
+  self.presentationController.preferredSheetHeight = preferredSheetHeight;
+  CGFloat sheetHeight = 300;
+  self.sheetView.frame = CGRectMake(0, 0, 200, sheetHeight);
+
+  // When
+  [self.presentationController updatePreferredSheetHeight];
+  self.presentationController.preferredSheetHeight = 0;
+  [self.presentationController updatePreferredSheetHeight];
+
+  // Then
+  XCTAssertEqualWithAccuracy(self.sheetView.preferredSheetHeight, (CGFloat)(sheetHeight / 2),
+                             0.001);
+}
+
+- (void)testVeryLargePreferredSheetHeightAndSmallContent {
+  // Given
+  CGFloat scrollViewHeight = 100;
+  CGRect smallFrame = CGRectMake(0, 0, 200, scrollViewHeight);
+  UIScrollView *scrollView = [[UIScrollView alloc] initWithFrame:smallFrame];
+  FakeSheetView *sheetView =
+      [[FakeSheetView alloc] initWithFrame:smallFrame
+                               contentView:[[UIView alloc] initWithFrame:smallFrame]
+                                scrollView:scrollView];
+
+  self.presentationController.sheetView = sheetView;
+  self.presentationController.preferredSheetHeight = 5000;
+
+  // When
+  [self.presentationController updatePreferredSheetHeight];
+
+  // Then
+  XCTAssertEqualWithAccuracy(CGRectGetHeight(sheetView.frame), CGRectGetHeight(smallFrame), 0.001);
+}
+
 @end