Swiftgram/AsyncDisplayKit/Layout/ASRelativeLayoutSpec.mm
Hannah Troisi c857e809f4 Clean up header comments (for consistent Facebook licensing info) (#1741)
[Licensing] Clean up header comments (for consistent Facebook licensing info)
2016-06-11 23:31:39 -07:00

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//
// ASRelativeLayoutSpec.mm
// AsyncDisplayKit
//
// Created by Samuel Stow on 12/31/15.
//
// 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 "ASRelativeLayoutSpec.h"
#import "ASInternalHelpers.h"
#import "ASLayout.h"
@implementation ASRelativeLayoutSpec
- (instancetype)initWithHorizontalPosition:(ASRelativeLayoutSpecPosition)horizontalPosition verticalPosition:(ASRelativeLayoutSpecPosition)verticalPosition sizingOption:(ASRelativeLayoutSpecSizingOption)sizingOption child:(id<ASLayoutable>)child
{
if (!(self = [super init])) {
return nil;
}
ASDisplayNodeAssertNotNil(child, @"Child cannot be nil");
_horizontalPosition = horizontalPosition;
_verticalPosition = verticalPosition;
_sizingOption = sizingOption;
[self setChild:child];
return self;
}
+ (instancetype)relativePositionLayoutSpecWithHorizontalPosition:(ASRelativeLayoutSpecPosition)horizontalPosition verticalPosition:(ASRelativeLayoutSpecPosition)verticalPosition sizingOption:(ASRelativeLayoutSpecSizingOption)sizingOption child:(id<ASLayoutable>)child
{
return [[self alloc] initWithHorizontalPosition:horizontalPosition verticalPosition:verticalPosition sizingOption:sizingOption child:child];
}
- (void)setHorizontalPosition:(ASRelativeLayoutSpecPosition)horizontalPosition
{
ASDisplayNodeAssert(self.isMutable, @"Cannot set properties when layout spec is not mutable");
_horizontalPosition = horizontalPosition;
}
- (void)setVerticalPosition:(ASRelativeLayoutSpecPosition)verticalPosition {
ASDisplayNodeAssert(self.isMutable, @"Cannot set properties when layout spec is not mutable");
_verticalPosition = verticalPosition;
}
- (void)setSizingOption:(ASRelativeLayoutSpecSizingOption)sizingOption
{
ASDisplayNodeAssert(self.isMutable, @"Cannot set properties when layout spec is not mutable");
_sizingOption = sizingOption;
}
- (ASLayout *)measureWithSizeRange:(ASSizeRange)constrainedSize
{
CGSize size = {
constrainedSize.max.width,
constrainedSize.max.height
};
BOOL reduceWidth = (_horizontalPosition & ASRelativeLayoutSpecPositionCenter) != 0 ||
(_horizontalPosition & ASRelativeLayoutSpecPositionEnd) != 0;
BOOL reduceHeight = (_verticalPosition & ASRelativeLayoutSpecPositionCenter) != 0 ||
(_verticalPosition & ASRelativeLayoutSpecPositionEnd) != 0;
// Layout the child
const CGSize minChildSize = {
reduceWidth ? 0 : constrainedSize.min.width,
reduceHeight ? 0 : constrainedSize.min.height,
};
ASLayout *sublayout = [self.child measureWithSizeRange:ASSizeRangeMake(minChildSize, constrainedSize.max)];
// If we have an undetermined height or width, use the child size to define the layout
// size
size = ASSizeRangeClamp(constrainedSize, {
isfinite(size.width) == NO ? sublayout.size.width : size.width,
isfinite(size.height) == NO ? sublayout.size.height : size.height
});
// If minimum size options are set, attempt to shrink the size to the size of the child
size = ASSizeRangeClamp(constrainedSize, {
MIN(size.width, (_sizingOption & ASRelativeLayoutSpecSizingOptionMinimumWidth) != 0 ? sublayout.size.width : size.width),
MIN(size.height, (_sizingOption & ASRelativeLayoutSpecSizingOptionMinimumHeight) != 0 ? sublayout.size.height : size.height)
});
// Compute the position for the child on each axis according to layout parameters
CGFloat xPosition = [self proportionOfAxisForAxisPosition:_horizontalPosition];
CGFloat yPosition = [self proportionOfAxisForAxisPosition:_verticalPosition];
sublayout.position = {
ASRoundPixelValue((size.width - sublayout.size.width) * xPosition),
ASRoundPixelValue((size.height - sublayout.size.height) * yPosition)
};
return [ASLayout layoutWithLayoutableObject:self
constrainedSizeRange:constrainedSize
size:size
sublayouts:@[sublayout]];
}
- (CGFloat)proportionOfAxisForAxisPosition:(ASRelativeLayoutSpecPosition)position
{
if ((position & ASRelativeLayoutSpecPositionCenter) != 0) {
return 0.5f;
} else if ((position & ASRelativeLayoutSpecPositionEnd) != 0) {
return 1.0f;
} else {
return 0.0f;
}
}
@end