Allow full color tinting on grayscale template images. (#1629)

* Allow full color tinting on grayscale template images.

* Signing a commit with the correct email address.

* Add snapshot test for a grayscale image with ASExperimentalDrawingGlobal enabled.

Source/ASImageNode.mm

@@ -594,6 +594,14 @@ static ASWeakMap<ASImageNodeContentsKey *, UIImage *> *cache = nil;
   [self setNeedsDisplay];
 }
 
+- (void)tintColorDidChange
+{
+  [super tintColorDidChange];
+  if (_image.renderingMode == UIImageRenderingModeAlwaysTemplate) {
+    [self setNeedsDisplay];
+  }
+}
+
 #pragma mark Interface State
 
 - (void)clearContents

Source/Details/ASGraphicsContext.mm

@@ -47,7 +47,15 @@ UIImage *ASGraphicsCreateImageWithOptions(CGSize size, BOOL opaque, CGFloat scal
 
       UIGraphicsImageRendererFormat *format;
       if (sourceImage) {
-        format = sourceImage.imageRendererFormat;
+        if (sourceImage.renderingMode == UIImageRenderingModeAlwaysTemplate) {
+          // Template images will be black and transparent, so if we use
+          // 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;
+        } else {
+          format = sourceImage.imageRendererFormat;
+        }
         // We only want the private bits (color space and bits per component) from the image.
         // We have our own ideas about opacity and scale.
         format.opaque = opaque;

Tests/ASImageNodeSnapshotTests.mm

@@ -30,6 +30,14 @@
   return [UIImage imageWithContentsOfFile:path];
 }
 
+- (UIImage *)testGrayscaleImage
+{
+  NSString *path = [[NSBundle bundleForClass:[self class]] pathForResource:@"logo-square-black"
+                                                                    ofType:@"png"
+                                                               inDirectory:@"TestResources"];
+  return [UIImage imageWithContentsOfFile:path];
+}
+
 - (void)testRenderLogoSquare
 {
   // trivial test case to ensure ASSnapshotTestCase works
@@ -79,6 +87,25 @@
   ASSnapshotVerifyNode(node, @"blue_tint");
 }
 
+- (void)testTintColorOnGrayscaleNodePropertyAlwaysTemplate
+{
+  ASConfiguration *config = [ASConfiguration new];
+  config.experimentalFeatures = ASExperimentalDrawingGlobal;
+  [ASConfigurationManager test_resetWithConfiguration:config];
+
+  UIImage *test = [self testGrayscaleImage];
+  ASImageNode *node = [[ASImageNode alloc] init];
+  node.image = [test imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];
+  node.tintColor = UIColor.redColor;
+  ASDisplayNodeSizeToFitSize(node, test.size);
+  // Tint color should change view
+  ASSnapshotVerifyNode(node, @"red_tint");
+
+  node.tintColor = UIColor.blueColor;
+  // Tint color should change view
+  ASSnapshotVerifyNode(node, @"blue_tint");
+}
+
 - (void)testTintColorOnNodePropertyAutomatic
 {
   UIImage *test = [self testImage];