Fix issue where UIGraphicsRendererFormat is mutated

As part of #1629, we use the
preferred or default UIGraphicsRendererFormat. This was pointing to a
static variable which content scale was mutated across several graphic
render passes and lead to pixelated views.

Source/Details/ASGraphicsContext.mm

@@ -52,7 +52,11 @@ NS_INLINE void ASConfigureExtendedRange(UIGraphicsImageRendererFormat *format)
           // sourceImage.imageRenderFormat it will assume a grayscale color space.
           // This is not good because a template image should be able to tint to any color,
           // so we'll just use the default here.
-          format = defaultFormat;
+          if (AS_AVAILABLE_IOS_TVOS(11, 11)) {
+            format = [UIGraphicsImageRendererFormat preferredFormat];
+          } else {
+            format = [UIGraphicsImageRendererFormat defaultFormat];
+          }
         } else {
           format = sourceImage.imageRendererFormat;
         }

Tests/ASImageNodeSnapshotTests.mm

@@ -189,6 +189,19 @@ - (void)testRoundedCornerBlock
   ASSnapshotVerifyNode(node, nil);
 }
 
+- (void)testUIGraphicsRendererDrawingExperiment
+{
+  // Test to ensure that rendering with UIGraphicsRenderer don't regress
+  ASConfiguration *config = [ASConfiguration new];
+  config.experimentalFeatures = ASExperimentalDrawingGlobal;
+  [ASConfigurationManager test_resetWithConfiguration:config];
+
+  ASImageNode *imageNode = [[ASImageNode alloc] init];
+  imageNode.image = [self testImage];
+  ASDisplayNodeSizeToFitSize(imageNode, CGSizeMake(100, 100));
+  ASSnapshotVerifyNode(imageNode, nil);
+}
+
 #if AS_AT_LEAST_IOS13
 - (void)testDynamicAssetImage
 {

Tests/ASTextNodeSnapshotTests.mm

@@ -145,7 +145,22 @@ - (void)testFontPointSizeScaling
 }
 
 
+- (void)testUIGraphicsRendererDrawingExperiment
+{
+  // Test to ensure that rendering with UIGraphicsRenderer don't regress
+  ASConfiguration *config = [ASConfiguration new];
+  config.experimentalFeatures = ASExperimentalDrawingGlobal;
+  [ASConfigurationManager test_resetWithConfiguration:config];
+
+  // trivial test case to ensure ASSnapshotTestCase works
+  ASTextNode *textNode = [[ASTextNode alloc] init];
+  textNode.attributedText = [[NSAttributedString alloc] initWithString:@"judar"
+                                                            attributes:@{NSFontAttributeName : [UIFont italicSystemFontOfSize:24]}];
+  textNode.textContainerInset = UIEdgeInsetsMake(0, 2, 0, 2);
+  ASDisplayNodeSizeToFitSizeRange(textNode, ASSizeRangeMake(CGSizeZero, CGSizeMake(CGFLOAT_MAX, CGFLOAT_MAX)));
 
+  ASSnapshotVerifyNode(textNode, nil);
+}
 
 #if AS_AT_LEAST_IOS13