Merge pull request #1356 from rcancro/textShrinkningOptimizations

[ASTextNode] More refinements to the new font size adjuster behavior.
facebookarchive · Mar 10, 2016 · 5fde235 · 5fde235
2 parents 0bc6060 + bcb1832
commit 5fde235
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Showing 2 changed files with 58 additions and 32 deletions.
diff --git a/AsyncDisplayKit/TextKit/ASTextKitFontSizeAdjuster.mm b/AsyncDisplayKit/TextKit/ASTextKitFontSizeAdjuster.mm
@@ -22,6 +22,8 @@ @implementation ASTextKitFontSizeAdjuster
   std::mutex _textKitMutex;
   BOOL _measured;
   CGFloat _scaleFactor;
+  NSLayoutManager *_sizingLayoutManager;
+  NSTextContainer *_sizingTextContainer;
 }
 
 - (instancetype)initWithContext:(ASTextKitContext *)context
@@ -78,30 +80,38 @@ + (void)adjustFontSizeForAttributeString:(NSMutableAttributedString *)attrString
 
 - (NSUInteger)lineCountForString:(NSAttributedString *)attributedString
 {
-  NSUInteger lineCount = 0;
-
-  static std::mutex __static_mutex;
-  std::lock_guard<std::mutex> l(__static_mutex);
-
-  NSTextStorage *textStorage = _attributes.textStorageCreationBlock ? _attributes.textStorageCreationBlock(attributedString) : [[NSTextStorage alloc] initWithAttributedString:attributedString];
-  NSLayoutManager *layoutManager = _attributes.layoutManagerCreationBlock ? _attributes.layoutManagerCreationBlock() : [[ASLayoutManager alloc] init];
-  layoutManager.usesFontLeading = NO;
-  [textStorage addLayoutManager:layoutManager];
-  NSTextContainer *textContainer = [[NSTextContainer alloc] initWithSize:CGSizeMake(_constrainedSize.width, FLT_MAX)];
-
-  textContainer.lineFragmentPadding = 0;
-  textContainer.lineBreakMode = _attributes.lineBreakMode;
-
-  // use 0 regardless of what is in the attributes so that we get an accurate line count
-  textContainer.maximumNumberOfLines = 0;
-  textContainer.exclusionPaths = _attributes.exclusionPaths;
-  [layoutManager addTextContainer:textContainer];
-
-  for (NSRange lineRange = { 0, 0 }; NSMaxRange(lineRange) < [layoutManager numberOfGlyphs] && lineCount <= _attributes.maximumNumberOfLines; lineCount++) {
-    [layoutManager lineFragmentRectForGlyphAtIndex:NSMaxRange(lineRange) effectiveRange:&lineRange];
-  }
-
-  return lineCount;
+    NSUInteger lineCount = 0;
+
+    static std::mutex __static_mutex;
+    std::lock_guard<std::mutex> l(__static_mutex);
+
+    NSTextStorage *textStorage = _attributes.textStorageCreationBlock ? _attributes.textStorageCreationBlock(attributedString) : [[NSTextStorage alloc] initWithAttributedString:attributedString];
+    if (_sizingLayoutManager == nil) {
+        _sizingLayoutManager = _attributes.layoutManagerCreationBlock ? _attributes.layoutManagerCreationBlock() : [[ASLayoutManager alloc] init];
+        _sizingLayoutManager.usesFontLeading = NO;
+    }
+    [textStorage addLayoutManager:_sizingLayoutManager];
+    if (_sizingTextContainer == nil) {
+        // make this text container unbounded in height so that the layout manager will compute the total
+        // number of lines and not stop counting when height runs out.
+        _sizingTextContainer = [[NSTextContainer alloc] initWithSize:CGSizeMake(_constrainedSize.width, FLT_MAX)];
+        _sizingTextContainer.lineFragmentPadding = 0;
+
+        // use 0 regardless of what is in the attributes so that we get an accurate line count
+        _sizingTextContainer.maximumNumberOfLines = 0;
+        [_sizingLayoutManager addTextContainer:_sizingTextContainer];
+    }
+
+    _sizingTextContainer.lineBreakMode = _attributes.lineBreakMode;
+    _sizingTextContainer.exclusionPaths = _attributes.exclusionPaths;
+
+
+    for (NSRange lineRange = { 0, 0 }; NSMaxRange(lineRange) < [_sizingLayoutManager numberOfGlyphs] && lineCount <= _attributes.maximumNumberOfLines; lineCount++) {
+        [_sizingLayoutManager lineFragmentRectForGlyphAtIndex:NSMaxRange(lineRange) effectiveRange:&lineRange];
+    }
+
+    [textStorage removeLayoutManager:_sizingLayoutManager];
+    return lineCount;
 }
 
 - (CGFloat)scaleFactor

diff --git a/AsyncDisplayKit/TextKit/ASTextKitRenderer.mm b/AsyncDisplayKit/TextKit/ASTextKitRenderer.mm
@@ -142,28 +142,44 @@ - (void)_calculateSize
   if (isinf(_constrainedSize.width) == NO && [_attributes.pointSizeScaleFactors count] > 0) {
     _currentScaleFactor = [[self fontSizeAdjuster] scaleFactor];
   }
-
+  
   // Force glyph generation and layout, which may not have happened yet (and isn't triggered by
   // -usedRectForTextContainer:).
+  __block NSTextStorage *scaledTextStorage = nil;
+  BOOL isScaled = [self isScaled];
   [[self context] performBlockWithLockedTextKitComponents:^(NSLayoutManager *layoutManager, NSTextStorage *textStorage, NSTextContainer *textContainer) {
+    if (isScaled) {
+      NSMutableAttributedString *scaledString = [[NSMutableAttributedString alloc] initWithAttributedString:textStorage];
+      [ASTextKitFontSizeAdjuster adjustFontSizeForAttributeString:scaledString withScaleFactor:_currentScaleFactor];
+      scaledTextStorage = [[NSTextStorage alloc] initWithAttributedString:scaledString];
+
+      [textStorage removeLayoutManager:layoutManager];
+      [scaledTextStorage addLayoutManager:layoutManager];
+    }
     [layoutManager ensureLayoutForTextContainer:textContainer];
   }];
-
+  
   CGRect constrainedRect = {CGPointZero, _constrainedSize};
   __block CGRect boundingRect;
   [[self context] performBlockWithLockedTextKitComponents:^(NSLayoutManager *layoutManager, NSTextStorage *textStorage, NSTextContainer *textContainer) {
     boundingRect = [layoutManager usedRectForTextContainer:textContainer];
+    if (isScaled) {
+      // put the non-scaled version back
+      [scaledTextStorage removeLayoutManager:layoutManager];
+      [textStorage addLayoutManager:layoutManager];
+    }
   }];
-
+  
   // TextKit often returns incorrect glyph bounding rects in the horizontal direction, so we clip to our bounding rect
   // to make sure our width calculations aren't being offset by glyphs going beyond the constrained rect.
   boundingRect = CGRectIntersection(boundingRect, {.size = constrainedRect.size});
   CGSize boundingSize = [_shadower outsetSizeWithInsetSize:boundingRect.size];
   _calculatedSize = CGSizeMake(boundingSize.width, boundingSize.height);
-
-  if (_currentScaleFactor > 0.0 && _currentScaleFactor < 1.0) {
-    _calculatedSize.height = ceilf(_calculatedSize.height * _currentScaleFactor);
-  }
+}
+
+- (BOOL)isScaled
+{
+  return (self.currentScaleFactor > 0 && self.currentScaleFactor < 1.0);
 }
 
 #pragma mark - Drawing
@@ -189,7 +205,7 @@ - (void)drawInContext:(CGContextRef)context bounds:(CGRect)bounds;
   [[self context] performBlockWithLockedTextKitComponents:^(NSLayoutManager *layoutManager, NSTextStorage *textStorage, NSTextContainer *textContainer) {
 
     NSTextStorage *scaledTextStorage = nil;
-    BOOL isScaled = (self.currentScaleFactor > 0 && self.currentScaleFactor < 1.0);
+    BOOL isScaled = [self isScaled];
 
     if (isScaled) {
       // if we are going to scale the text, swap out the non-scaled text for the scaled version.