[ASTableView] Add constrainedSizeForRowAtIndexPath: to control row heights from delegate (#1769)

* [ASTableView] constrainedSizeForRowAtIndexPath

* Quick fix to header file

* Switch to Delegate from DataSource.

* Update testing variables to reflect switch to delegate

AsyncDisplayKit/ASTableView.h

@@ -433,6 +433,18 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (BOOL)shouldBatchFetchForTableView:(ASTableView *)tableView;
 
+/**
+ * Provides the constrained size range for measuring the row at the index path.
+ * Note: the widths in the returned size range are ignored!
+ * 
+ * @param tableView The sender.
+ *
+ * @param indexPath The index path of the node.
+ *
+ * @returns A constrained size range for layout the node at this index path.
+ */
+- (ASSizeRange)tableView:(ASTableView *)tableView constrainedSizeForRowAtIndexPath:(NSIndexPath *)indexPath;
+
 /**
  * Informs the delegate that the table view did remove the node which was previously
  * at the given index path from the view hierarchy.

AsyncDisplayKit/ASTableView.mm

@@ -28,6 +28,7 @@
 
 #import <CoreFoundation/CoreFoundation.h>
 
+static const ASSizeRange kInvalidSizeRange = {CGSizeZero, CGSizeZero};
 static NSString * const kCellReuseIdentifier = @"_ASTableViewCell";
 
 //#define LOG(...) NSLog(__VA_ARGS__)
@@ -125,6 +126,7 @@ static NSString * const kCellReuseIdentifier = @"_ASTableViewCell";
     unsigned int asyncDelegateScrollViewWillEndDraggingWithVelocityTargetContentOffset:1;
     unsigned int asyncDelegateTableViewWillBeginBatchFetchWithContext:1;
     unsigned int asyncDelegateShouldBatchFetchForTableView:1;
+    unsigned int asyncDelegateTableViewConstrainedSizeForRowAtIndexPath:1;
   } _asyncDelegateFlags;
   
   struct {
@@ -316,6 +318,8 @@ static NSString * const kCellReuseIdentifier = @"_ASTableViewCell";
     _asyncDelegateFlags.asyncDelegateShouldBatchFetchForTableView = [_asyncDelegate respondsToSelector:@selector(shouldBatchFetchForTableView:)];
     _asyncDelegateFlags.asyncDelegateScrollViewWillBeginDragging = [_asyncDelegate respondsToSelector:@selector(scrollViewWillBeginDragging:)];
     _asyncDelegateFlags.asyncDelegateScrollViewDidEndDragging = [_asyncDelegate respondsToSelector:@selector(scrollViewDidEndDragging:willDecelerate:)];
+    _asyncDelegateFlags.asyncDelegateTableViewConstrainedSizeForRowAtIndexPath = [_asyncDelegate respondsToSelector:@selector(tableView:constrainedSizeForRowAtIndexPath:)];
+
   }
   
   super.delegate = (id<UITableViewDelegate>)_proxyDelegate;
@@ -1069,8 +1073,17 @@ static NSString * const kCellReuseIdentifier = @"_ASTableViewCell";
 
 - (ASSizeRange)dataController:(ASDataController *)dataController constrainedSizeForNodeAtIndexPath:(NSIndexPath *)indexPath
 {
-  return ASSizeRangeMake(CGSizeMake(_nodesConstrainedWidth, 0),
-                         CGSizeMake(_nodesConstrainedWidth, FLT_MAX));
+  ASSizeRange constrainedSize = kInvalidSizeRange;
+  if (_asyncDelegateFlags.asyncDelegateTableViewConstrainedSizeForRowAtIndexPath) {
+    ASSizeRange delegateConstrainedSize = [_asyncDelegate tableView:self constrainedSizeForRowAtIndexPath:indexPath];
+    // ignore widths in the returned size range (for TableView)
+    constrainedSize = ASSizeRangeMake(CGSizeMake(_nodesConstrainedWidth, delegateConstrainedSize.min.height),
+                                      CGSizeMake(_nodesConstrainedWidth, delegateConstrainedSize.max.height));
+  } else {
+    constrainedSize = ASSizeRangeMake(CGSizeMake(_nodesConstrainedWidth, 0),
+                                      CGSizeMake(_nodesConstrainedWidth, FLT_MAX));
+  }
+  return constrainedSize;
 }
 
 - (NSUInteger)dataController:(ASDataController *)dataController rowsInSection:(NSUInteger)section

AsyncDisplayKitTests/ASTableViewTests.m

@@ -128,7 +128,6 @@
   return textCellNode;
 }
 
-
 - (ASCellNodeBlock)tableView:(ASTableView *)tableView nodeBlockForRowAtIndexPath:(NSIndexPath *)indexPath
 {
   return ^{
@@ -140,12 +139,52 @@
 
 @end
 
+@interface ASTableViewFilledDelegate : NSObject <ASTableViewDelegate>
+@end
+
+@implementation ASTableViewFilledDelegate
+
+- (ASSizeRange)tableView:(ASTableView *)tableView constrainedSizeForRowAtIndexPath:(NSIndexPath *)indexPath
+{
+  return ASSizeRangeMakeExactSize(CGSizeMake(10, 42));
+}
+
+@end
+
 @interface ASTableViewTests : XCTestCase
 @property (atomic, retain) ASTableView *testTableView;
 @end
 
 @implementation ASTableViewTests
 
+- (void)testConstrainedSizeForRowAtIndexPath
+{
+  // Initial width of the table view is non-zero and all nodes are measured with this size.
+  // Any subsequence size change must trigger a relayout.
+  // Width and height are swapped so that a later size change will simulate a rotation
+  ASTestTableView *tableView = [[ASTestTableView alloc] __initWithFrame:CGRectMake(0, 0, 100, 400)
+                                                                  style:UITableViewStylePlain];
+  
+  ASTableViewFilledDelegate *delegate = [ASTableViewFilledDelegate new];
+  ASTableViewFilledDataSource *dataSource = [ASTableViewFilledDataSource new];
+
+  tableView.asyncDelegate = delegate;
+  tableView.asyncDataSource = dataSource;
+  
+  [tableView reloadDataImmediately];
+  [tableView setNeedsLayout];
+  [tableView layoutIfNeeded];
+  
+  for (int section = 0; section < NumberOfSections; section++) {
+      for (int row = 0; row < NumberOfRowsPerSection; row++) {
+        NSIndexPath *indexPath = [NSIndexPath indexPathForRow:row inSection:section];
+        CGRect rect = [tableView rectForRowAtIndexPath:indexPath];
+        XCTAssertEqual(rect.size.width, 100);  // specified width should be ignored for table
+        XCTAssertEqual(rect.size.height, 42);
+      }
+  }
+}
+
 // TODO: Convert this to ARC.
 - (void)DISABLED_testTableViewDoesNotRetainItselfAndDelegate
 {