Swiftgram/AsyncDisplayKit/Layout/ASInsetLayoutNode.mm
Huy Nguyen f8531f467d Add Layout nodes.
- The code is forked from LayoutComponents in ComponentKit.
- Public interfaces are modified to be strictly Objective-C. As a result, users are not forced to switch to Objective-C++, the linker can happily compile and Swift fans can continue using the mighty ASDK.
2015-06-25 11:32:30 +07:00

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/*
* 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 "ASInsetLayoutNode.h"
#import "ASAssert.h"
#import "ASBaseDefines.h"
#import "ASInternalHelpers.h"
#import "ASLayoutNodeSubclass.h"
@interface ASInsetLayoutNode ()
{
UIEdgeInsets _insets;
ASLayoutNode *_node;
}
@end
/* Returns f if f is finite, substitute otherwise */
static CGFloat finite(CGFloat f, CGFloat substitute)
{
return isinf(f) ? substitute : f;
}
/* Returns f if f is finite, 0 otherwise */
static CGFloat finiteOrZero(CGFloat f)
{
return finite(f, 0);
}
/* Returns the inset required to center 'inner' in 'outer' */
static CGFloat centerInset(CGFloat outer, CGFloat inner)
{
return ASRoundPixelValue((outer - inner) / 2);
}
@implementation ASInsetLayoutNode
+ (instancetype)newWithInsets:(UIEdgeInsets)insets
node:(ASLayoutNode *)node
{
if (node == nil) {
return nil;
}
ASInsetLayoutNode *n = [super newWithSize:{}];
if (n) {
n->_insets = insets;
n->_node = node;
}
return n;
}
+ (instancetype)newWithSize:(ASLayoutNodeSize)size
{
ASDISPLAYNODE_NOT_DESIGNATED_INITIALIZER();
}
/**
Inset will compute a new constrained size for it's child after applying insets and re-positioning
the child to respect the inset.
*/
- (ASLayout *)computeLayoutThatFits:(ASSizeRange)constrainedSize
restrictedToSize:(ASLayoutNodeSize)size
relativeToParentSize:(CGSize)parentSize
{
ASDisplayNodeAssert(ASLayoutNodeSizeEqualToNodeSize(size, ASLayoutNodeSizeZero),
@"ASInsetLayoutNode only passes size {} to the super class initializer, but received size %@ "
"(node=%@)", NSStringFromASLayoutNodeSize(size), _node);
const CGFloat insetsX = (finiteOrZero(_insets.left) + finiteOrZero(_insets.right));
const CGFloat insetsY = (finiteOrZero(_insets.top) + finiteOrZero(_insets.bottom));
// if either x-axis inset is infinite, let child be intrinsic width
const CGFloat minWidth = (isinf(_insets.left) || isinf(_insets.right)) ? 0 : constrainedSize.min.width;
// if either y-axis inset is infinite, let child be intrinsic height
const CGFloat minHeight = (isinf(_insets.top) || isinf(_insets.bottom)) ? 0 : constrainedSize.min.height;
const ASSizeRange insetConstrainedSize = {
{
MAX(0, minWidth - insetsX),
MAX(0, minHeight - insetsY),
},
{
MAX(0, constrainedSize.max.width - insetsX),
MAX(0, constrainedSize.max.height - insetsY),
}
};
const CGSize insetParentSize = {
MAX(0, parentSize.width - insetsX),
MAX(0, parentSize.height - insetsY)
};
ASLayout *childLayout = [_node layoutThatFits:insetConstrainedSize parentSize:insetParentSize];
const CGSize computedSize = ASSizeRangeClamp(constrainedSize, {
finite(childLayout.size.width + _insets.left + _insets.right, parentSize.width),
finite(childLayout.size.height + _insets.top + _insets.bottom, parentSize.height),
});
ASDisplayNodeAssert(!isnan(computedSize.width) && !isnan(computedSize.height),
@"Inset node computed size is NaN; you may not specify infinite insets against a NaN parent size\n"
"parentSize = %@, insets = %@", NSStringFromCGSize(parentSize), NSStringFromUIEdgeInsets(_insets));
const CGFloat x = finite(_insets.left, constrainedSize.max.width -
(finite(_insets.right,
centerInset(constrainedSize.max.width, childLayout.size.width)) + childLayout.size.width));
const CGFloat y = finite(_insets.top,
constrainedSize.max.height -
(finite(_insets.bottom,
centerInset(constrainedSize.max.height, childLayout.size.height)) + childLayout.size.height));
return [ASLayout newWithNode:self
size:computedSize
children:@[[ASLayoutChild newWithPosition:{x,y} layout:childLayout]]];
}
@end