Adds support for using UIGraphicsImageRenderer in ASTextNode. (#1384)

* Adds support for using UIGraphicsImageRenderer in ASTextNode.

In many cases this reduces the backing store of text nodes by 1/2.

* Guard for UIGraphicsRenderer availability.

* Comma

Schemas/configuration.json

@@ -26,7 +26,8 @@
                     "exp_skip_a11y_wait",
                     "exp_new_default_cell_layout_mode",
                     "exp_dispatch_apply",
-                    "exp_image_downloader_priority"
+                    "exp_image_downloader_priority",
+                    "exp_text_drawing"
                 ]
     		}
 		}

Source/ASExperimentalFeatures.h

@@ -32,6 +32,7 @@ typedef NS_OPTIONS(NSUInteger, ASExperimentalFeatures) {
   ASExperimentalNewDefaultCellLayoutMode = 1 << 11,         // exp_new_default_cell_layout_mode
   ASExperimentalDispatchApply = 1 << 12,                    // exp_dispatch_apply
   ASExperimentalImageDownloaderPriority = 1 << 13,          // exp_image_downloader_priority
+  ASExperimentalTextDrawing = 1 << 14,                      // exp_text_drawing
   ASExperimentalFeatureAll = 0xFFFFFFFF
 };
 

Source/ASExperimentalFeatures.mm

@@ -25,8 +25,8 @@ NSArray<NSString *> *ASExperimentalFeaturesGetNames(ASExperimentalFeatures flags
                                       @"exp_skip_a11y_wait",
                                       @"exp_new_default_cell_layout_mode",
                                       @"exp_dispatch_apply",
-                                      @"exp_image_downloader_priority"]));
-
+                                      @"exp_image_downloader_priority",
+                                      @"exp_text_drawing"]));
   if (flags == ASExperimentalFeatureAll) {
     return allNames;
   }

Source/ASTextNode.mm

@@ -18,6 +18,7 @@
 #import <mutex>
 #import <tgmath.h>
 
+#import <AsyncDisplayKit/ASAvailability.h>
 #import <AsyncDisplayKit/_ASDisplayLayer.h>
 #import <AsyncDisplayKit/ASDisplayNode+FrameworkPrivate.h>
 #import <AsyncDisplayKit/ASDisplayNode+Subclasses.h>
@@ -140,6 +141,9 @@ static ASTextKitRenderer *rendererForAttributes(ASTextKitAttributes attributes,
   ASTextKitAttributes _rendererAttributes;
   UIColor *_backgroundColor;
   UIEdgeInsets _textContainerInsets;
+  CGFloat _contentScale;
+  BOOL _opaque;
+  CGRect _bounds;
 }
 @end
 
@@ -148,12 +152,18 @@ static ASTextKitRenderer *rendererForAttributes(ASTextKitAttributes attributes,
 - (instancetype)initWithRendererAttributes:(ASTextKitAttributes)rendererAttributes
                            backgroundColor:(/*nullable*/ UIColor *)backgroundColor
                        textContainerInsets:(UIEdgeInsets)textContainerInsets
+                              contentScale:(CGFloat)contentScale
+                                    opaque:(BOOL)opaque
+                                    bounds:(CGRect)bounds
 {
   self = [super init];
   if (self != nil) {
     _rendererAttributes = rendererAttributes;
     _backgroundColor = backgroundColor;
     _textContainerInsets = textContainerInsets;
+    _contentScale = contentScale;
+    _opaque = opaque;
+    _bounds = bounds;
   }
   return self;
 }
@@ -526,31 +536,74 @@ static NSArray *DefaultLinkAttributeNames() {
   
   return [[ASTextNodeDrawParameter alloc] initWithRendererAttributes:[self _locked_rendererAttributes]
                                                      backgroundColor:self.backgroundColor
-                                                 textContainerInsets:_textContainerInset];
+                                                 textContainerInsets:_textContainerInset
+                                                        contentScale:_contentsScaleForDisplay
+                                                              opaque:self.isOpaque
+                                                              bounds:[self threadSafeBounds]];
 }
 
-+ (void)drawRect:(CGRect)bounds withParameters:(id)parameters isCancelled:(NS_NOESCAPE asdisplaynode_iscancelled_block_t)isCancelledBlock isRasterizing:(BOOL)isRasterizing
++ (UIImage *)displayWithParameters:(id<NSObject>)parameters isCancelled:(NS_NOESCAPE asdisplaynode_iscancelled_block_t)isCancelled
 {
   ASTextNodeDrawParameter *drawParameter = (ASTextNodeDrawParameter *)parameters;
-  UIColor *backgroundColor = (isRasterizing || drawParameter == nil) ? nil : drawParameter->_backgroundColor;
+  
+  if (drawParameter->_bounds.size.width <= 0 || drawParameter->_bounds.size.height <= 0) {
+    return nil;
+  }
+    
+  UIImage *result = nil;
+  UIColor *backgroundColor = drawParameter->_backgroundColor;
   UIEdgeInsets textContainerInsets = drawParameter ? drawParameter->_textContainerInsets : UIEdgeInsetsZero;
-  ASTextKitRenderer *renderer = [drawParameter rendererForBounds:bounds];
+  ASTextKitRenderer *renderer = [drawParameter rendererForBounds:drawParameter->_bounds];
+  BOOL renderedWithGraphicsRenderer = NO;
   
-  CGContextRef context = UIGraphicsGetCurrentContext();
-  ASDisplayNodeAssert(context, @"This is no good without a context.");
- 
-  CGContextSaveGState(context);
-  CGContextTranslateCTM(context, textContainerInsets.left, textContainerInsets.top);
-  
-  // Fill background
-  if (backgroundColor != nil) {
-    [backgroundColor setFill];
-    UIRectFillUsingBlendMode(CGContextGetClipBoundingBox(context), kCGBlendModeCopy);
+  if (AS_AVAILABLE_IOS_TVOS(10, 10)) {
+    if (ASActivateExperimentalFeature(ASExperimentalTextDrawing)) {
+      renderedWithGraphicsRenderer = YES;
+      UIGraphicsImageRenderer *graphicsRenderer = [[UIGraphicsImageRenderer alloc] initWithSize:CGSizeMake(drawParameter->_bounds.size.width, drawParameter->_bounds.size.height)];
+      result = [graphicsRenderer imageWithActions:^(UIGraphicsImageRendererContext * _Nonnull rendererContext) {
+        CGContextRef context = rendererContext.CGContext;
+        ASDisplayNodeAssert(context, @"This is no good without a context.");
+        
+        CGContextSaveGState(context);
+        CGContextTranslateCTM(context, textContainerInsets.left, textContainerInsets.top);
+        
+        // Fill background
+        if (backgroundColor != nil) {
+          [backgroundColor setFill];
+          UIRectFillUsingBlendMode(CGContextGetClipBoundingBox(context), kCGBlendModeCopy);
+        }
+        
+        // Draw text
+        [renderer drawInContext:context bounds:drawParameter->_bounds];
+        CGContextRestoreGState(context);
+      }];
+    }
   }
   
-  // Draw text
-  [renderer drawInContext:context bounds:bounds];
-  CGContextRestoreGState(context);
+  if (!renderedWithGraphicsRenderer) {
+    UIGraphicsBeginImageContextWithOptions(CGSizeMake(drawParameter->_bounds.size.width, drawParameter->_bounds.size.height), drawParameter->_opaque, drawParameter->_contentScale);
+      
+    CGContextRef context = UIGraphicsGetCurrentContext();
+    ASDisplayNodeAssert(context, @"This is no good without a context.");
+    
+    CGContextSaveGState(context);
+    CGContextTranslateCTM(context, textContainerInsets.left, textContainerInsets.top);
+    
+    // Fill background
+    if (backgroundColor != nil) {
+      [backgroundColor setFill];
+      UIRectFillUsingBlendMode(CGContextGetClipBoundingBox(context), kCGBlendModeCopy);
+    }
+    
+    // Draw text
+    [renderer drawInContext:context bounds:drawParameter->_bounds];
+    CGContextRestoreGState(context);
+    
+    result = UIGraphicsGetImageFromCurrentImageContext();
+    UIGraphicsEndImageContext();
+  }
+
+  return result;
 }
 
 #pragma mark - Attributes

Source/Details/_ASDisplayLayer.h

@@ -112,7 +112,7 @@ NS_ASSUME_NONNULL_BEGIN
  @summary Delegate override to provide new layer contents as a UIImage.
  @param parameters An object describing all of the properties you need to draw. Return this from -drawParametersForAsyncLayer:
  @param isCancelledBlock Execute this block to check whether the current drawing operation has been cancelled to avoid unnecessary work. A return value of YES means cancel drawing and return.
- @return A UIImage with contents that are ready to display on the main thread. Make sure that the image is already decoded before returning it here.
+ @return A UIImage (backed by a CGImage) with contents that are ready to display on the main thread. Make sure that the image is already decoded before returning it here.
  */
 + (UIImage *)displayWithParameters:(nullable id<NSObject>)parameters
                        isCancelled:(AS_NOESCAPE asdisplaynode_iscancelled_block_t)isCancelledBlock;

Tests/ASConfigurationTests.mm

@@ -31,7 +31,8 @@ static ASExperimentalFeatures features[] = {
   ASExperimentalSkipAccessibilityWait,
   ASExperimentalNewDefaultCellLayoutMode,
   ASExperimentalDispatchApply,
-  ASExperimentalImageDownloaderPriority
+  ASExperimentalImageDownloaderPriority,
+  ASExperimentalTextDrawing
 };
 
 @interface ASConfigurationTests : ASTestCase <ASConfigurationDelegate>
@@ -57,7 +58,8 @@ static ASExperimentalFeatures features[] = {
     @"exp_skip_a11y_wait",
     @"exp_new_default_cell_layout_mode",
     @"exp_dispatch_apply",
-    @"exp_image_downloader_priority"
+    @"exp_image_downloader_priority",
+    @"exp_text_drawing"
   ];
 }