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//
// ASScrollNode.m
// AsyncDisplayKit
//
// 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.
//
#import "ASScrollNode.h"
#import "ASDisplayNodeExtras.h"
#import "ASDisplayNode+FrameworkPrivate.h"
#import "ASDisplayNode+FrameworkSubclasses.h"
#import "ASLayout.h"
#import "_ASDisplayLayer.h"
@interface ASScrollView : UIScrollView
@end
@implementation ASScrollView
// This special +layerClass allows ASScrollNode to get -layout calls from -layoutSublayers.
+ (Class)layerClass
{
return [_ASDisplayLayer class];
}
- (ASScrollNode *)scrollNode
{
return (ASScrollNode *)ASViewToDisplayNode(self);
}
#pragma mark - _ASDisplayView behavior substitutions
// Need these to drive interfaceState so we know when we are visible, if not nested in another range-managing element.
// Because our superclass is a true UIKit class, we cannot also subclass _ASDisplayView.
- (void)willMoveToWindow:(UIWindow *)newWindow
{
ASDisplayNode *node = self.scrollNode; // Create strong reference to weak ivar.
BOOL visible = (newWindow != nil);
if (visible && !node.inHierarchy) {
[node __enterHierarchy];
}
}
- (void)didMoveToWindow
{
ASDisplayNode *node = self.scrollNode; // Create strong reference to weak ivar.
BOOL visible = (self.window != nil);
if (!visible && node.inHierarchy) {
[node __exitHierarchy];
}
}
@end
@implementation ASScrollNode
{
BOOL _automaticallyManagesContentSize;
CGSize _contentCalculatedSizeFromLayout;
}
@dynamic view;
- (instancetype)init
{
return [super initWithViewBlock:^UIView *{ return [[ASScrollView alloc] init]; }];
}
- (ASLayout *)calculateLayoutThatFits:(ASSizeRange)constrainedSize
restrictedToSize:(ASLayoutElementSize)size
relativeToParentSize:(CGSize)parentSize
{
ASLayout *layout = [super calculateLayoutThatFits:constrainedSize
restrictedToSize:size
relativeToParentSize:parentSize];
ASDN::MutexLocker l(__instanceLock__); // Lock for using our two instance variables.
if (_automaticallyManagesContentSize) {
// To understand this code, imagine we're containing a horizontal stack set within a vertical table node.
// Our parentSize is fixed ~375pt width, but 0 - INF height. Our stack measures 1000pt width, 50pt height.
// In this case, we want our scrollNode.bounds to be 375pt wide, and 50pt high. ContentSize 1000pt, 50pt.
// We can achieve this behavior by: 1. Always set contentSize to layout.size. 2. Set bounds to parentSize,
// unless one dimension is not defined, in which case adopt the contentSize for that dimension.
_contentCalculatedSizeFromLayout = layout.size;
CGSize selfSize = parentSize;
if (ASPointsValidForLayout(selfSize.width) == NO) {
selfSize.width = _contentCalculatedSizeFromLayout.width;
}
if (ASPointsValidForLayout(selfSize.height) == NO) {
selfSize.height = _contentCalculatedSizeFromLayout.height;
}
// Don't provide a position, as that should be set by the parent.
layout = [ASLayout layoutWithLayoutElement:self
size:selfSize
sublayouts:layout.sublayouts];
}
return layout;
}
- (void)layout
{
[super layout];
ASDN::MutexLocker l(__instanceLock__); // Lock for using our two instance variables.
if (_automaticallyManagesContentSize) {
CGSize contentSize = _contentCalculatedSizeFromLayout;
if (ASIsCGSizeValidForLayout(contentSize) == NO) {
NSLog(@"%@ calculated a size in its layout spec that can't be applied to .contentSize: %@. Applying parentSize (scrollNode's bounds) instead: %@.", self, NSStringFromCGSize(contentSize), NSStringFromCGSize(self.calculatedSize));
contentSize = self.calculatedSize;
}
self.view.contentSize = contentSize;
}
}
- (BOOL)automaticallyManagesContentSize
{
ASDN::MutexLocker l(__instanceLock__);
return _automaticallyManagesContentSize;
}
- (void)setAutomaticallyManagesContentSize:(BOOL)automaticallyManagesContentSize
{
ASDN::MutexLocker l(__instanceLock__);
_automaticallyManagesContentSize = automaticallyManagesContentSize;
}
@end