Add preliminary scroll direction support

JNWCollectionView/JNWCollectionViewFramework.m

@@ -99,9 +99,6 @@ static void JNWCollectionViewCommonInit(JNWCollectionView *collectionView) {
 
 	// Set the document view to a custom class that returns YES to -isFlipped.
 	collectionView.documentView = [[JNWCollectionViewDocumentView alloc] initWithFrame:CGRectZero];
-
-	collectionView.hasHorizontalScroller = NO;
-	collectionView.hasVerticalScroller = YES;
 
 	// We don't want to perform an initial layout pass until the user has called -reloadData.
 	collectionView->_collectionViewFlags.wantsLayout = NO;
@@ -591,11 +588,31 @@ - (void)performFullRelayoutForcingSubviewsReset:(BOOL)forceReset {
 - (void)layoutDocumentView {
 	if (!_collectionViewFlags.wantsLayout)
 		return;
+
+	[self updateScrollDirection];
 
 	NSView *documentView = self.documentView;
 	documentView.frameSize = self.data.encompassingSize;
 }
 
+- (void)updateScrollDirection {
+	switch (self.collectionViewLayout.scrollDirection) {
+		case JNWCollectionViewScrollDirectionVertical:
+			self.hasVerticalScroller = YES;
+			self.hasHorizontalScroller = NO;
+			break;
+		case JNWCollectionViewScrollDirectionHorizontal:
+			self.hasVerticalScroller = NO;
+			self.hasHorizontalScroller = YES;
+			break;
+		case JNWCollectionViewScrollDirectionBoth:
+		default:
+			self.hasVerticalScroller = YES;
+			self.hasHorizontalScroller = YES;
+			break;
+	}
+}
+
 - (CGSize)visibleSize {
 	return self.documentVisibleRect.size;
 }

JNWCollectionView/JNWCollectionViewLayout.h

@@ -27,6 +27,12 @@ typedef NS_ENUM(NSInteger, JNWCollectionViewDirection) {
 	JNWCollectionViewDirectionDown
 };
 
+typedef NS_ENUM(NSInteger, JNWCollectionViewScrollDirection) {
+	JNWCollectionViewScrollDirectionVertical,
+	JNWCollectionViewScrollDirectionHorizontal,
+	JNWCollectionViewScrollDirectionBoth
+};
+
 @interface JNWCollectionViewLayoutAttributes : NSObject
 @property (nonatomic, assign) CGRect frame;
 @property (nonatomic, assign) CGFloat alpha;
@@ -104,6 +110,18 @@ typedef NS_ENUM(NSInteger, JNWCollectionViewDirection) {
 /// Defaults to CGSizeZero, which means it will fit the collection view's frame.
 - (CGSize)contentSize;
 
+/// The scroll direction determines which way the collection view will show scroll indicators.
+///
+/// Subclasses should override this method to change the scroll direction.
+///
+/// Note that if the content view is larger than the bounds of the collection view, the content will
+/// still be scrollable, even if the scroll indicators do not show up. To prevent this, do not make
+/// the content view larger than the collection view itself in the direction in which you do not want
+/// scrolling.
+///
+/// Defaults to JNWCollectionViewScrollDirectionVertical.
+- (JNWCollectionViewScrollDirection)scrollDirection;
+
 /// Subclasses must implement this method for arrowed selection to work.
 - (NSIndexPath *)indexPathForNextItemInDirection:(JNWCollectionViewDirection)direction currentIndexPath:(NSIndexPath *)currentIndexPath;
 

JNWCollectionView/JNWCollectionViewLayout.m

@@ -60,6 +60,10 @@ - (CGSize)contentSize {
 	return CGSizeZero;
 }
 
+- (JNWCollectionViewScrollDirection)scrollDirection {
+	return JNWCollectionViewScrollDirectionVertical;
+}
+
 - (NSIndexPath *)indexPathForNextItemInDirection:(JNWCollectionViewDirection)direction currentIndexPath:(NSIndexPath *)currentIndexPath {
 	return currentIndexPath;
 }