Swiftgram/AsyncDisplayKit/Details/_ASDisplayView.mm

/* 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 "_ASDisplayView.h"

#import <objc/runtime.h>

#import "_ASCoreAnimationExtras.h"
#import "_ASAsyncTransactionContainer.h"
#import "ASAssert.h"
#import "ASDisplayNodeExtras.h"
#import "ASDisplayNodeInternal.h"
#import "ASDisplayNode+Subclasses.h"

@interface _ASDisplayView ()
@property (nonatomic, assign, readwrite) ASDisplayNode *asyncdisplaykit_node;

// Keep the node alive while its view is active.  If you create a view, add its layer to a layer hierarchy, then release
// the view, the layer retains the view to prevent a crash.  This replicates this behaviour for the node abstraction.
@property (nonatomic, retain, readwrite) ASDisplayNode *keepalive_node;
@end

@implementation _ASDisplayView
{
  __unsafe_unretained ASDisplayNode *_node;  // Though UIView has a .node property added via category, since we can add an ivar to a subclass, use that for performance.
  BOOL _inHitTest;
  BOOL _inPointInside;
}

@synthesize asyncdisplaykit_node = _node;

+ (Class)layerClass
{
  return [_ASDisplayLayer class];
}

#pragma mark - NSObject Overrides
- (id)init
{
  return [self initWithFrame:CGRectZero];
}

- (NSString *)description
{
  // The standard UIView description is useless for debugging because all ASDisplayNode subclasses have _ASDisplayView-type views.
  // This allows us to at least see the name of the node subclass and get its pointer directly from [[UIWindow keyWindow] recursiveDescription].
  return [NSString stringWithFormat:@"<%@, view = %@>", _node, [super description]];
}

#pragma mark - UIView Overrides

- (id)initWithFrame:(CGRect)frame
{
  if (!(self = [super initWithFrame:frame]))
    return nil;

  return self;
}

- (void)willMoveToSuperview:(UIView *)newSuperview
{
  // Keep the node alive while the view is in a view hierarchy.  This helps ensure that async-drawing views can always
  // display their contents as long as they are visible somewhere, and aids in lifecycle management because the
  // lifecycle of the node can be treated as the same as the lifecycle of the view (let the view hierarchy own the
  // view).
  UIView *currentSuperview = self.superview;
  if (!currentSuperview && newSuperview) {
    self.keepalive_node = _node;
  }
  else if (currentSuperview && !newSuperview) {
    self.keepalive_node = nil;
  }
}

- (void)willMoveToWindow:(UIWindow *)newWindow
{
  BOOL visible = newWindow != nil;
  if (visible && !_node.inWindow) {
    [_node __enterHierarchy];
  } else if (!visible && _node.inWindow) {
    [_node __exitHierarchy];
  }
}

- (void)didMoveToSuperview
{
  // FIXME maybe move this logic into ASDisplayNode addSubnode/removeFromSupernode
  UIView *superview = self.superview;

  // If superview's node is different from supernode's view, fix it by setting supernode to the new superview's node.  Got that?
  if (!superview)
    [_node __setSupernode:nil];
  else if (superview != _node.supernode.view)
    [_node __setSupernode:superview.asyncdisplaykit_node];
}

- (void)setNeedsDisplay
{
  // Standard implementation does not actually get to the layer, at least for views that don't implement drawRect:.
  if (ASDisplayNodeThreadIsMain()) {
    [self.layer setNeedsDisplay];
  } else {
    dispatch_async(dispatch_get_main_queue(), ^ {
      [self.layer setNeedsDisplay];
    });
  }
}

- (void)setNeedsLayout
{
  if (ASDisplayNodeThreadIsMain()) {
    [super setNeedsLayout];
  } else {
    dispatch_async(dispatch_get_main_queue(), ^ {
      [super setNeedsLayout];
    });
  }
}

- (void)layoutSubviews
{
  if (ASDisplayNodeThreadIsMain()) {
    [_node __layout];
  } else {
    // FIXME: CRASH This should not be happening because of the way we gate -setNeedsLayout, but it has been seen.
    ASDisplayNodeFailAssert(@"not reached assertion");
    dispatch_async(dispatch_get_main_queue(), ^ {
      [_node __layout];
    });
  }
}

- (UIViewContentMode)contentMode
{
  return ASDisplayNodeUIContentModeFromCAContentsGravity(self.layer.contentsGravity);
}

- (void)setContentMode:(UIViewContentMode)contentMode
{
  ASDisplayNodeAssert(contentMode != UIViewContentModeRedraw, @"Don't do this. Use needsDisplayOnBoundsChange instead.");

  // Do our own mapping so as not to call super and muck up needsDisplayOnBoundsChange. If we're in a production build, fall back to resize if we see redraw
  self.layer.contentsGravity = (contentMode != UIViewContentModeRedraw) ? ASDisplayNodeCAContentsGravityFromUIContentMode(contentMode) : kCAGravityResize;
}

#pragma mark - Event Handling + UIResponder Overrides
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
  [_node touchesBegan:touches withEvent:event];
}

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
  [_node touchesMoved:touches withEvent:event];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
  [_node touchesEnded:touches withEvent:event];
}

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
  [_node touchesCancelled:touches withEvent:event];
}

- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
  // REVIEW: We should optimize these types of messages by setting a boolean in the associated ASDisplayNode subclass if
  // they actually override the method.  Same goes for -pointInside:withEvent: below.  Many UIKit classes use that
  // pattern for meaningful reductions of message send overhead in hot code (especially event handling).

  // Set boolean so this method can be re-entrant.  If the node subclass wants to default to / make use of UIView
  // hitTest:, it will call it on the view, which is _ASDisplayView.  After calling into the node, any additional calls
  // should use the UIView implementation of hitTest:
  if (!_inHitTest) {
    _inHitTest = YES;
    UIView *hitView = [_node hitTest:point withEvent:event];
    _inHitTest = NO;
    return hitView;
  } else {
    return [super hitTest:point withEvent:event];
  }
}

- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
{
  // See comments in -hitTest:withEvent: for the strategy here.
  if (!_inPointInside) {
    _inPointInside = YES;
    BOOL result = [_node pointInside:point withEvent:event];
    _inPointInside = NO;
    return result;
  } else {
    return [super pointInside:point withEvent:event];
  }
}

#if __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_6_0
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer
{
  return [_node gestureRecognizerShouldBegin:gestureRecognizer];
}
#endif

- (void)asyncdisplaykit_asyncTransactionContainerStateDidChange
{
  [_node asyncdisplaykit_asyncTransactionContainerStateDidChange];
}

@end