Add support for textContainerInset to ASTextNode (ala UITextView) (#2062)

* Add support for textContainerInset to ASTextNode (ala UITextView)

* Better comment, parens to increase readability. Thanks @schneider!

* Add textContainerInset snapshot test.

AsyncDisplayKit/ASTextNode+Beta.h

@@ -31,6 +31,14 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @property (nullable, nonatomic, copy) NSTextStorage * (^textStorageCreationBlock)(NSAttributedString *_Nullable attributedString);
 
+/**
+ @abstract Text margins for text laid out in the text node.
+ @discussion defaults to UIEdgeInsetsZero.
+ This property can be useful for handling text which does not fit within the view by default. An example: like UILabel,
+ ASTextNode will clip the left and right of the string "judar" if it's rendered in an italicised font.
+ */
+@property (nonatomic, assign) UIEdgeInsets textContainerInset;
+
 @end
 
 NS_ASSUME_NONNULL_END

AsyncDisplayKit/ASTextNode.mm

@@ -49,6 +49,8 @@ struct ASTextNodeDrawParameter {
   CGFloat _shadowOpacity;
   CGFloat _shadowRadius;
   
+  UIEdgeInsets _textContainerInset;
+
   NSArray *_exclusionPaths;
 
   NSAttributedString *_composedTruncationText;
@@ -213,7 +215,15 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
   ASDN::MutexLocker l(__instanceLock__);
 
   if (_renderer == nil) {
-    CGSize constrainedSize = _constrainedSize.width != -INFINITY ? _constrainedSize : bounds.size;
+    CGSize constrainedSize;
+    if (_constrainedSize.width != -INFINITY) {
+      constrainedSize = _constrainedSize;
+    } else {
+      constrainedSize = bounds.size;
+      constrainedSize.width -= (_textContainerInset.left + _textContainerInset.right);
+      constrainedSize.height -= (_textContainerInset.top + _textContainerInset.bottom);
+    }
+    
     _renderer = [[ASTextKitRenderer alloc] initWithTextKitAttributes:[self _rendererAttributes]
                                                      constrainedSize:constrainedSize];
   }
@@ -279,6 +289,24 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
 #pragma mark - Layout and Sizing
 
+- (void)setTextContainerInset:(UIEdgeInsets)textContainerInset
+{
+  ASDN::MutexLocker l(__instanceLock__);
+  
+  BOOL needsUpdate = !UIEdgeInsetsEqualToEdgeInsets(textContainerInset, _textContainerInset);
+  if (needsUpdate) {
+    _textContainerInset = textContainerInset;
+    [self invalidateCalculatedLayout];
+    [self setNeedsLayout];
+  }
+}
+
+- (UIEdgeInsets)textContainerInset
+{
+  ASDN::MutexLocker l(__instanceLock__);
+  return _textContainerInset;
+}
+
 - (BOOL)_needInvalidateRendererForBoundsSize:(CGSize)boundsSize
 {
   ASDN::MutexLocker l(__instanceLock__);
@@ -291,6 +319,10 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
   // a new one.  However, there are common cases where the constrained size doesn't need to be the same as calculated.
   CGSize rendererConstrainedSize = _renderer.constrainedSize;
   
+  //inset bounds
+  boundsSize.width -= _textContainerInset.left + _textContainerInset.right;
+  boundsSize.height -= _textContainerInset.top + _textContainerInset.bottom;
+  
   if (CGSizeEqualToSize(boundsSize, rendererConstrainedSize)) {
     return NO;
   } else {
@@ -321,9 +353,14 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
   
   if (layout != nil) {
     ASDN::MutexLocker l(__instanceLock__);
-    if (CGSizeEqualToSize(_constrainedSize, layout.size) == NO) {
+    CGSize layoutSize = layout.size;
-      _constrainedSize = layout.size;
+    //Apply textContainerInset
-      _renderer.constrainedSize = layout.size;
+    layoutSize.width -= (_textContainerInset.left + _textContainerInset.right);
+    layoutSize.height -= (_textContainerInset.top + _textContainerInset.bottom);
+    
+    if (CGSizeEqualToSize(_constrainedSize, layoutSize) == NO) {
+      _constrainedSize = layoutSize;
+      _renderer.constrainedSize = layoutSize;
     }
   }
 }
@@ -335,6 +372,10 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
   
   ASDN::MutexLocker l(__instanceLock__);
   
+  //remove textContainerInset
+  constrainedSize.width -= (_textContainerInset.left + _textContainerInset.right);
+  constrainedSize.height -= (_textContainerInset.top + _textContainerInset.bottom);
+  
   _constrainedSize = constrainedSize;
   
   // Instead of invalidating the renderer, in case this is a new call with a different constrained size,
@@ -353,6 +394,11 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
       self.descender *= _renderer.currentScaleFactor;
     }
   }
+  
+  //add textContainerInset
+  size.width += (_textContainerInset.left + _textContainerInset.right);
+  size.height += (_textContainerInset.top + _textContainerInset.bottom);
+  
   return size;
 }
 
@@ -466,6 +512,8 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
   
   CGContextSaveGState(context);
   
+  CGContextTranslateCTM(context, _textContainerInset.left, _textContainerInset.top);
+  
   ASTextKitRenderer *renderer = [self _rendererWithBounds:drawParameterBounds];
   UIEdgeInsets shadowPadding = [self shadowPaddingWithRenderer:renderer];
   CGPoint boundsOrigin = drawParameterBounds.origin;

AsyncDisplayKitTests/ASTextNodeSnapshotTests.m

@@ -0,0 +1,35 @@
+//
+//  ASTextNodeSnapshotTests.m
+//  AsyncDisplayKit
+//
+//  Created by Garrett Moon on 8/12/16.
+//  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 "ASSnapshotTestCase.h"
+
+#import <AsyncDisplayKit/AsyncDisplayKit.h>
+
+@interface ASTextNodeSnapshotTests : ASSnapshotTestCase
+
+@end
+
+@implementation ASTextNodeSnapshotTests
+
+- (void)testTextContainerInset
+{
+  // trivial test case to ensure ASSnapshotTestCase works
+  ASTextNode *textNode = [[ASTextNode alloc] init];
+  textNode.attributedText = [[NSAttributedString alloc] initWithString:@"judar"
+                                                            attributes:@{NSFontAttributeName : [UIFont italicSystemFontOfSize:24]}];
+  [textNode measureWithSizeRange:ASSizeRangeMake(CGSizeZero, CGSizeMake(CGFLOAT_MAX, CGFLOAT_MAX))];
+  textNode.frame = CGRectMake(0, 0, textNode.calculatedSize.width, textNode.calculatedSize.height);
+  textNode.textContainerInset = UIEdgeInsetsMake(0, 2, 0, 2);
+  
+  ASSnapshotVerifyNode(textNode, nil);
+}
+
+@end