Stopped trying to cache the currentScaleFactor

Was running into issues where the scale factor would get cleared when setting a new atributedString on a textNode.

I was clearing out the currentScaleFactor when setting an attributedString into a textNode. It appears that `_calculateSize` isn't always called when setting a new string into a ASTextNode. It can be the case that only `drawInContext:bounds:` is called. With _currentScaleFactor cleared out the renderer that calls`drawInContext...` was being called with a scaleFactor of 0.

It could be the case that the fix could be to remove the clearing of `currentScaleFactor` from `setAttributedString`, but this seems like a safer fix to me. It does, however, require an extra run through the font adjuster when enabled.

AsyncDisplayKit/ASTextNode+Beta.h

@@ -15,9 +15,4 @@
  */
 @property (nonatomic, copy) NSArray *pointSizeScaleFactors;
 
-/**
- @abstract The currently applied scale factor, or 0 if the text node is not being scaled.
- */
-@property (nonatomic, assign, readonly) CGFloat currentScaleFactor;
-
 @end

AsyncDisplayKit/ASTextNode.mm

@@ -244,7 +244,6 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
     .maximumNumberOfLines = _maximumNumberOfLines,
     .exclusionPaths = _exclusionPaths,
     .pointSizeScaleFactors = _pointSizeScaleFactors,
-    .currentScaleFactor = self.currentScaleFactor,
     .layoutManagerCreationBlock = self.layoutManagerCreationBlock,
     .textStorageCreationBlock = self.textStorageCreationBlock,
   };
@@ -338,10 +337,7 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
 
   [self setNeedsDisplay];
   
-  CGSize size = [[self _renderer] size];
-  // the renderer computes the current scale factor during sizing, so let's grab it here
-  _currentScaleFactor = _renderer.currentScaleFactor;
-  return size;
+  return [[self _renderer] size];
 }
 
 #pragma mark - Modifying User Text
@@ -380,8 +376,6 @@ static NSArray *DefaultLinkAttributeNames = @[ NSLinkAttributeName ];
     self.isAccessibilityElement = YES;
   }
 
-  // reset the scale factor if we get a new string.
-  _currentScaleFactor = 0;
   if (attributedString.length > 0) {
     CGFloat screenScale = ASScreenScale();
     self.ascender = round([[attributedString attribute:NSFontAttributeName atIndex:0 effectiveRange:NULL] ascender] * screenScale)/screenScale;

AsyncDisplayKit/TextKit/ASTextKitAttributes.h

@@ -86,10 +86,6 @@ struct ASTextKitAttributes {
    An array of scale factors in descending order to apply to the text to try to make it fit into a constrained size.
    */
   NSArray *pointSizeScaleFactors;
-  /**
-   The currently applied scale factor. Only valid if pointSizeScaleFactors are provided. Defaults to 0 (no scaling)
-   */
-  CGFloat currentScaleFactor;
   /**
    An optional block that returns a custom layout manager subclass. If nil, defaults to NSLayoutManager.
    */
@@ -123,7 +119,6 @@ struct ASTextKitAttributes {
       shadowOpacity,
       shadowRadius,
       pointSizeScaleFactors,
-      currentScaleFactor,
       layoutManagerCreationBlock,
       layoutManagerDelegate,
       textStorageCreationBlock,
@@ -138,7 +133,6 @@ struct ASTextKitAttributes {
     && shadowOpacity == other.shadowOpacity
     && shadowRadius == other.shadowRadius
     && [pointSizeScaleFactors isEqualToArray:other.pointSizeScaleFactors]
-    && currentScaleFactor == currentScaleFactor
     && layoutManagerCreationBlock == other.layoutManagerCreationBlock
     && textStorageCreationBlock == other.textStorageCreationBlock
     && CGSizeEqualToSize(shadowOffset, other.shadowOffset)

AsyncDisplayKit/TextKit/ASTextKitRenderer.mm

@@ -49,9 +49,6 @@ static NSCharacterSet *_defaultAvoidTruncationCharacterSet()
     _constrainedSize = constrainedSize;
     _attributes = attributes;
     _sizeIsCalculated = NO;
-    if ([attributes.pointSizeScaleFactors count] > 0) {
-      _currentScaleFactor = attributes.currentScaleFactor;
-    }
   }
   return self;
 }
@@ -141,7 +138,8 @@ static NSCharacterSet *_defaultAvoidTruncationCharacterSet()
 - (void)_calculateSize
 {
   [self truncater];
-  if ([_attributes.pointSizeScaleFactors count] > 0) {
+  // if we have no scale factors or an unconstrained width, there is no reason to try to adjust the font size
+  if ([_attributes.pointSizeScaleFactors count] > 0 && isinf(_constrainedSize.width) == NO) {
     _currentScaleFactor = [[self fontSizeAdjuster] scaleFactor];
   }
 
@@ -175,6 +173,11 @@ static NSCharacterSet *_defaultAvoidTruncationCharacterSet()
   // We add an assertion so we can track the rare conditions where a graphics context is not present
   ASDisplayNodeAssertNotNil(context, @"This is no good without a context.");
   
+  // This renderer may not be the one that did the sizing. If that is the case its _currentScaleFactor will not be set, so we should compute it now
+  if ([_attributes.pointSizeScaleFactors count] > 0 && isinf(_constrainedSize.width) == NO && _sizeIsCalculated == NO) {
+    _currentScaleFactor = [[self fontSizeAdjuster] scaleFactor];
+  }
+
   CGRect shadowInsetBounds = [[self shadower] insetRectWithConstrainedRect:bounds];
 
   CGContextSaveGState(context);