Merge pull request #265 from andyscott/ASTextNode-max-line-count

Add maximumLineCount to ASTextNode

AsyncDisplayKit/ASTextNode.h

@@ -64,6 +64,12 @@ typedef NS_ENUM(NSUInteger, ASTextNodeHighlightStyle) {
  */
 @property (nonatomic, readonly, assign, getter=isTruncated) BOOL truncated;
 
+/**
+ @abstract The maximum number of lines to render of the text before truncation.
+ @default 0 (No limit)
+ */
+@property (nonatomic, assign) NSUInteger maximumLineCount;
+
 /**
  @abstract The number of lines in the text. Text must have been sized first.
  */

AsyncDisplayKit/ASTextNode.mm

@@ -243,6 +243,7 @@ ASDISPLAYNODE_INLINE CGFloat ceilPixelValue(CGFloat f)
     _renderer = [[ASTextNodeRenderer alloc] initWithAttributedString:_attributedString
                                                         truncationString:_composedTruncationString
                                                           truncationMode:_truncationMode
+                                                        maximumLineCount:_maximumLineCount
                                                          constrainedSize:constrainedSize];
   }
   return _renderer;
@@ -905,6 +906,15 @@ ASDISPLAYNODE_INLINE CGFloat ceilPixelValue(CGFloat f)
   return [[self _renderer] truncationStringCharacterRange].location != NSNotFound;
 }
 
+- (void)setMaximumLineCount:(NSUInteger)maximumLineCount
+{
+    if (_maximumLineCount != maximumLineCount) {
+        _maximumLineCount = maximumLineCount;
+        [self _invalidateRenderer];
+        [self setNeedsDisplay];
+    }
+}
+
 - (NSUInteger)lineCount
 {
   return [[self _renderer] lineCount];

AsyncDisplayKit/Details/ASTextNodeRenderer.h

@@ -54,6 +54,7 @@ typedef NS_ENUM(NSUInteger, ASTextNodeRendererMeasureOption) {
 - (instancetype)initWithAttributedString:(NSAttributedString *)attributedString
                         truncationString:(NSAttributedString *)truncationString
                           truncationMode:(NSLineBreakMode)truncationMode
+                        maximumLineCount:(NSUInteger)maximumLineCount
                          constrainedSize:(CGSize)constrainedSize;
 #pragma mark - Drawing
 /*

AsyncDisplayKit/Details/ASTextNodeRenderer.mm

@@ -29,6 +29,7 @@ static const CGFloat ASTextNodeRendererTextCapHeightPadding = 1.3;
   NSAttributedString *_attributedString;
   NSAttributedString *_truncationString;
   NSLineBreakMode _truncationMode;
+  NSUInteger _maximumLineCount;
   NSRange _truncationCharacterRange;
   NSRange _visibleRange;
 
@@ -45,6 +46,7 @@ static const CGFloat ASTextNodeRendererTextCapHeightPadding = 1.3;
 - (instancetype)initWithAttributedString:(NSAttributedString *)attributedString
                         truncationString:(NSAttributedString *)truncationString
                           truncationMode:(NSLineBreakMode)truncationMode
+                        maximumLineCount:(NSUInteger)maximumLineCount
                          constrainedSize:(CGSize)constrainedSize
 {
   if (self = [super init]) {
@@ -53,6 +55,8 @@ static const CGFloat ASTextNodeRendererTextCapHeightPadding = 1.3;
     _truncationMode = truncationMode;
     _truncationCharacterRange = NSMakeRange(NSNotFound, truncationString.length);
     
+    _maximumLineCount = maximumLineCount;
+
     _constrainedSize = constrainedSize;
   }
   return self;
@@ -90,6 +94,8 @@ static const CGFloat ASTextNodeRendererTextCapHeightPadding = 1.3;
   _textContainer.lineFragmentPadding = 0;
   // Translate our truncation mode into a line break mode on the container
   _textContainer.lineBreakMode = _truncationMode;
+  // Set maximum number of lines
+  _textContainer.maximumNumberOfLines = _maximumLineCount;
 
   [_layoutManager addTextContainer:_textContainer];
 

AsyncDisplayKitTests/ASTextNodeRendererTests.m

@@ -18,6 +18,7 @@
 @property (nonatomic, copy, readwrite) NSAttributedString *attributedString;
 @property (nonatomic, copy, readwrite) NSAttributedString *truncationString;
 @property (nonatomic, readwrite, assign) NSLineBreakMode truncationMode;
+@property (nonatomic, readwrite, assign) NSUInteger maximumLineCount;
 @property (nonatomic, readwrite, assign) CGFloat lineSpacing;
 
 @property (nonatomic, readwrite, assign) CGSize constrainedSize;
@@ -50,6 +51,7 @@
   _renderer = [[ASTextNodeRenderer alloc] initWithAttributedString:_attributedString
                                                       truncationString:_truncationString
                                                         truncationMode:_truncationMode
+                                                      maximumLineCount:_maximumLineCount
                                                        constrainedSize:_constrainedSize];
 
 }
@@ -71,6 +73,19 @@
   XCTAssertTrue(numberOfLines == 1 , @"If constrained height (%f) is float max, then there should only be one line of text. Size %@", _constrainedSize.width, NSStringFromCGSize(size));
 }
 
+- (void)testMaximumLineCount
+{
+    NSArray *lines = [NSArray arrayWithObjects:@"Hello!", @"world!", @"foo", @"bar", @"baz", nil];
+    _maximumLineCount = 2;
+    for (int i = 0; i <= [lines count]; i++) {
+        NSString *line = [[lines subarrayWithRange:NSMakeRange(0, i)] componentsJoinedByString:@"\n"];
+        _attributedString   = [[NSAttributedString alloc] initWithString:line];
+        [self setUpRenderer];
+        [_renderer size];
+        XCTAssertTrue(_renderer.lineCount <= _maximumLineCount, @"The line count %tu after rendering should be no larger than the maximum line count %tu", _renderer.lineCount, _maximumLineCount);
+    }
+}
+
 - (void)testNoTruncationIfEnoughSpace
 {
   [self setUpRenderer];
@@ -124,7 +139,6 @@
   [_renderer enumerateTextIndexesAtPosition:CGPointZero usingBlock:^(NSUInteger characterIndex, CGRect glyphBoundingRect, BOOL *stop) {
     XCTFail(@"Shouldn't be any text indexes to enumerate");
   }];
-
 }
 
 @end