[example/CustomCollectionView] Implement MosaicCollectionLayoutDelegate

examples/CustomCollectionView/Sample.xcodeproj/project.pbxproj

@@ -7,7 +7,7 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
-		25A1FA851C02F7AC00193875 /* MosaicCollectionViewLayout.m in Sources */ = {isa = PBXBuildFile; fileRef = 25A1FA841C02F7AC00193875 /* MosaicCollectionViewLayout.m */; };
+		25A1FA851C02F7AC00193875 /* MosaicCollectionLayoutDelegate.m in Sources */ = {isa = PBXBuildFile; fileRef = 25A1FA841C02F7AC00193875 /* MosaicCollectionLayoutDelegate.m */; };
 		25A1FA881C02FCB000193875 /* ImageCellNode.m in Sources */ = {isa = PBXBuildFile; fileRef = 25A1FA871C02FCB000193875 /* ImageCellNode.m */; };
 		576F970133B34DFD583D5CE4 /* libPods-Sample.a in Frameworks */ = {isa = PBXBuildFile; fileRef = 4CC0FB9EE0030992E8FBC0A0 /* libPods-Sample.a */; };
 		80364CCA1E3D95A90094400C /* ImageCollectionViewCell.m in Sources */ = {isa = PBXBuildFile; fileRef = 80364CC91E3D95A90094400C /* ImageCollectionViewCell.m */; };
@@ -19,8 +19,7 @@
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
-		25A1FA831C02F7AC00193875 /* MosaicCollectionViewLayout.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MosaicCollectionViewLayout.h; sourceTree = "<group>"; };
-		25A1FA841C02F7AC00193875 /* MosaicCollectionViewLayout.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MosaicCollectionViewLayout.m; sourceTree = "<group>"; };
+		25A1FA841C02F7AC00193875 /* MosaicCollectionLayoutDelegate.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MosaicCollectionLayoutDelegate.m; sourceTree = "<group>"; };
 		25A1FA861C02FCB000193875 /* ImageCellNode.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ImageCellNode.h; sourceTree = "<group>"; };
 		25A1FA871C02FCB000193875 /* ImageCellNode.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ImageCellNode.m; sourceTree = "<group>"; };
 		4CC0FB9EE0030992E8FBC0A0 /* libPods-Sample.a */ = {isa = PBXFileReference; explicitFileType = archive.ar; includeInIndex = 0; path = "libPods-Sample.a"; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -36,6 +35,7 @@
 		AC3C4A691A11F47200143C57 /* ViewController.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = ViewController.m; sourceTree = "<group>"; };
 		AC3C4A8D1A11F80C00143C57 /* Images.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = Images.xcassets; sourceTree = "<group>"; };
 		E2F287D91FFDEA2A747630CE /* Pods-Sample.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-Sample.release.xcconfig"; path = "Pods/Target Support Files/Pods-Sample/Pods-Sample.release.xcconfig"; sourceTree = "<group>"; };
+		E5D73A3A1EA6766B006418A8 /* MosaicCollectionLayoutDelegate.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = MosaicCollectionLayoutDelegate.h; sourceTree = "<group>"; };
 		F36BCD8EBAF79797AB5C6708 /* Pods-Sample.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-Sample.debug.xcconfig"; path = "Pods/Target Support Files/Pods-Sample/Pods-Sample.debug.xcconfig"; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
@@ -81,8 +81,8 @@
 		AC3C4A601A11F47200143C57 /* Sample */ = {
 			isa = PBXGroup;
 			children = (
-				25A1FA831C02F7AC00193875 /* MosaicCollectionViewLayout.h */,
-				25A1FA841C02F7AC00193875 /* MosaicCollectionViewLayout.m */,
+				E5D73A3A1EA6766B006418A8 /* MosaicCollectionLayoutDelegate.h */,
+				25A1FA841C02F7AC00193875 /* MosaicCollectionLayoutDelegate.m */,
 				AC3C4A651A11F47200143C57 /* AppDelegate.h */,
 				AC3C4A661A11F47200143C57 /* AppDelegate.m */,
 				AC3C4A681A11F47200143C57 /* ViewController.h */,
@@ -238,7 +238,7 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
-				25A1FA851C02F7AC00193875 /* MosaicCollectionViewLayout.m in Sources */,
+				25A1FA851C02F7AC00193875 /* MosaicCollectionLayoutDelegate.m in Sources */,
 				AC3C4A6A1A11F47200143C57 /* ViewController.m in Sources */,
 				AC3C4A671A11F47200143C57 /* AppDelegate.m in Sources */,
 				AC3C4A641A11F47200143C57 /* main.m in Sources */,

examples/CustomCollectionView/Sample/ImageCellNode.m

@@ -1,20 +1,18 @@
 //
 //  ImageCellNode.m
-//  Sample
-//
-//  Created by McCallum, Levi on 11/22/15.
+//  Texture
 //
 //  Copyright (c) 2014-present, Facebook, Inc.  All rights reserved.
 //  This source code is licensed under the BSD-style license found in the
-//  LICENSE file in the root directory of this source tree. An additional grant
-//  of patent rights can be found in the PATENTS file in the same directory.
+//  LICENSE file in the /ASDK-Licenses directory of this source tree. An additional
+//  grant of patent rights can be found in the PATENTS file in the same directory.
+//
+//  Modifications to this file made after 4/13/2017 are: Copyright (c) 2017-present,
+//  Pinterest, Inc.  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
 //
-//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
-//  FACEBOOK BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
-//  ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
-//  CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+//      http://www.apache.org/licenses/LICENSE-2.0
 //
 
 #import "ImageCellNode.h"
@@ -36,7 +34,10 @@ - (id)initWithImage:(UIImage *)image
 
 - (ASLayoutSpec *)layoutSpecThatFits:(ASSizeRange)constrainedSize
 {
-  return [ASInsetLayoutSpec insetLayoutSpecWithInsets:UIEdgeInsetsZero child:_imageNode];
+  CGSize imageSize = self.image.size;
+  return [ASInsetLayoutSpec insetLayoutSpecWithInsets:UIEdgeInsetsZero
+                                                child:[ASRatioLayoutSpec ratioLayoutSpecWithRatio:imageSize.height/imageSize.width
+                                                                                            child:_imageNode]];
 }
 
 - (void)setImage:(UIImage *)image

examples/CustomCollectionView/Sample/MosaicCollectionLayoutDelegate.h

@@ -0,0 +1,20 @@
+//
+//  MosaicCollectionLayoutDelegate.h
+//  Texture
+//
+//  Copyright (c) 2017-present, Pinterest, Inc.  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
+//
+
+#import <UIKit/UIKit.h>
+#import <AsyncDisplayKit/AsyncDisplayKit.h>
+
+@interface MosaicCollectionLayoutDelegate : NSObject <ASCollectionLayoutDelegate>
+
+- (instancetype)initWithNumberOfColumns:(NSInteger)numberOfColumns headerHeight:(CGFloat)headerHeight;
+
+@end

examples/CustomCollectionView/Sample/MosaicCollectionLayoutDelegate.m

@@ -0,0 +1,165 @@
+//
+//  MosaicCollectionLayoutDelegate.m
+//  Texture
+//
+//  Copyright (c) 2017-present, Pinterest, Inc.  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
+//
+
+#import "MosaicCollectionLayoutDelegate.h"
+#import "ImageCellNode.h"
+
+#import <AsyncDisplayKit/ASCollectionElement.h>
+
+@implementation MosaicCollectionLayoutDelegate {
+  // Read-only properties
+  NSInteger _numberOfColumns;
+  CGFloat _headerHeight;
+  CGFloat _columnSpacing;
+  UIEdgeInsets _sectionInset;
+  UIEdgeInsets _interItemSpacing;
+}
+
+- (instancetype)initWithNumberOfColumns:(NSInteger)numberOfColumns headerHeight:(CGFloat)headerHeight
+{
+  self = [super init];
+  if (self != nil) {
+    _numberOfColumns = numberOfColumns;
+    _headerHeight = headerHeight;
+    _columnSpacing = 10.0;
+    _sectionInset = UIEdgeInsetsMake(10.0, 10.0, 10.0, 10.0);
+    _interItemSpacing = UIEdgeInsetsMake(10.0, 0, 10.0, 0);
+  }
+  return self;
+}
+
+- (id)additionalInfoForLayoutWithElements:(ASElementMap *)elements
+{
+  return nil;
+}
+
+- (ASCollectionLayoutState *)calculateLayoutWithContext:(ASCollectionLayoutContext *)context
+{
+  CGFloat layoutWidth = context.viewportSize.width;
+  ASElementMap *elements = context.elements;
+  CGFloat top = 0;
+
+  // TODO use +[NSMapTable elementToLayoutAttributesTable]
+  NSMapTable<ASCollectionElement *, UICollectionViewLayoutAttributes *> *attrsMap = [NSMapTable mapTableWithKeyOptions:(NSMapTableObjectPointerPersonality | NSMapTableWeakMemory) valueOptions:NSMapTableStrongMemory];
+  NSMutableArray *columnHeights = [NSMutableArray array];
+
+  NSInteger numberOfSections = [elements numberOfSections];
+  for (NSUInteger section = 0; section < numberOfSections; section++) {
+    NSInteger numberOfItems = [elements numberOfItemsInSection:section];
+
+    top += _sectionInset.top;
+
+    if (_headerHeight > 0) {
+      NSIndexPath *indexPath = [NSIndexPath indexPathForItem:0 inSection:section];
+      ASCollectionElement *element = [elements supplementaryElementOfKind:UICollectionElementKindSectionHeader
+                                                              atIndexPath:indexPath];
+      UICollectionViewLayoutAttributes *attrs = [UICollectionViewLayoutAttributes layoutAttributesForSupplementaryViewOfKind:UICollectionElementKindSectionHeader
+                                                                                                                     withIndexPath:indexPath];
+
+      ASSizeRange sizeRange = [self sizeRangeForHeaderOfSection:section withLayoutWidth:layoutWidth];
+      CGSize size = [element.node layoutThatFits:sizeRange].size;
+      CGRect frame = CGRectMake(_sectionInset.left, top, size.width, size.height);
+
+      attrs.frame = frame;
+      [attrsMap setObject:attrs forKey:element];
+      top = CGRectGetMaxY(frame);
+    }
+
+    [columnHeights addObject:[NSMutableArray array]];
+    for (NSUInteger idx = 0; idx < _numberOfColumns; idx++) {
+      [columnHeights[section] addObject:@(top)];
+    }
+
+    CGFloat columnWidth = [self _columnWidthForSection:section withLayoutWidth:layoutWidth];
+    for (NSUInteger idx = 0; idx < numberOfItems; idx++) {
+      NSUInteger columnIndex = [self _shortestColumnIndexInSection:section withColumnHeights:columnHeights];
+      NSIndexPath *indexPath = [NSIndexPath indexPathForItem:idx inSection:section];
+      ASCollectionElement *element = [elements elementForItemAtIndexPath:indexPath];
+      UICollectionViewLayoutAttributes *attrs = [UICollectionViewLayoutAttributes layoutAttributesForCellWithIndexPath:indexPath];
+
+      ASSizeRange sizeRange = [self sizeRangeForItem:element.node atIndexPath:indexPath withLayoutWidth:layoutWidth];
+      CGSize size = [element.node layoutThatFits:sizeRange].size;
+      CGPoint position = CGPointMake(_sectionInset.left + (columnWidth + _columnSpacing) * columnIndex,
+                                         [columnHeights[section][columnIndex] floatValue]);
+      CGRect frame = CGRectMake(position.x, position.y, size.width, size.height);
+
+      attrs.frame = frame;
+      [attrsMap setObject:attrs forKey:element];
+      // TODO Profile and avoid boxing if there are significant retain/release overheads
+      columnHeights[section][columnIndex] = @(CGRectGetMaxY(frame) + _interItemSpacing.bottom);
+    }
+
+    NSUInteger columnIndex = [self _tallestColumnIndexInSection:section withColumnHeights:columnHeights];
+    top = [columnHeights[section][columnIndex] floatValue] - _interItemSpacing.bottom + _sectionInset.bottom;
+
+    for (NSUInteger idx = 0; idx < [columnHeights[section] count]; idx++) {
+      columnHeights[section][idx] = @(top);
+    }
+  }
+
+  CGFloat contentHeight = [[[columnHeights lastObject] firstObject] floatValue];
+  CGSize contentSize = CGSizeMake(layoutWidth, contentHeight);
+  return [[ASCollectionLayoutState alloc] initWithElements:elements contentSize:contentSize elementToLayoutArrtibutesMap:attrsMap];
+}
+
+- (CGFloat)_widthForSection:(NSUInteger)section withLayoutWidth:(CGFloat)layoutWidth
+{
+  return layoutWidth - _sectionInset.left - _sectionInset.right;
+}
+
+- (CGFloat)_columnWidthForSection:(NSUInteger)section withLayoutWidth:(CGFloat)layoutWidth
+{
+  return ([self _widthForSection:section withLayoutWidth:layoutWidth] - ((_numberOfColumns - 1) * _columnSpacing)) / _numberOfColumns;
+}
+
+- (ASSizeRange)sizeRangeForItem:(ASCellNode *)item atIndexPath:(NSIndexPath *)indexPath withLayoutWidth:(CGFloat)layoutWidth;
+{
+  CGFloat itemWidth = [self _columnWidthForSection:indexPath.section withLayoutWidth:layoutWidth];
+  if ([item isKindOfClass:[ImageCellNode class]]) {
+    return ASSizeRangeMake(CGSizeMake(itemWidth, 0), CGSizeMake(itemWidth, CGFLOAT_MAX));
+  } else {
+    return ASSizeRangeMake(CGSizeMake(itemWidth, itemWidth)); // In kShowUICollectionViewCells = YES mode, make those cells itemWidth x itemWidth.
+  }
+}
+
+- (ASSizeRange)sizeRangeForHeaderOfSection:(NSInteger)section withLayoutWidth:(CGFloat)layoutWidth
+{
+  return ASSizeRangeMake(CGSizeMake(0, _headerHeight), CGSizeMake([self _widthForSection:section withLayoutWidth:layoutWidth], _headerHeight));
+}
+
+- (NSUInteger)_tallestColumnIndexInSection:(NSUInteger)section withColumnHeights:(NSArray *)columnHeights
+{
+  __block NSUInteger index = 0;
+  __block CGFloat tallestHeight = 0;
+  [columnHeights[section] enumerateObjectsUsingBlock:^(NSNumber *height, NSUInteger idx, BOOL *stop) {
+    if (height.floatValue > tallestHeight) {
+      index = idx;
+      tallestHeight = height.floatValue;
+    }
+  }];
+  return index;
+}
+
+- (NSUInteger)_shortestColumnIndexInSection:(NSUInteger)section withColumnHeights:(NSArray *)columnHeights
+{
+  __block NSUInteger index = 0;
+  __block CGFloat shortestHeight = CGFLOAT_MAX;
+  [columnHeights[section] enumerateObjectsUsingBlock:^(NSNumber *height, NSUInteger idx, BOOL *stop) {
+    if (height.floatValue < shortestHeight) {
+      index = idx;
+      shortestHeight = height.floatValue;
+    }
+  }];
+  return index;
+}
+
+@end