vignette.rb in rmagick-3.2.0

- old
+ new

@@ -49,12 +49,12 @@
 # according to the intensity of the composite image pixels. In this case, the
 # black pixels outside the oval become transparent and the white pixels inside
 # the oval remain opaque. Each gray pixel around the border of the oval has a
 # varying level of transparency depending on how dark or light it is.
 
-ballerina.matte = true  # Ensure the ballerina image's opacity channel is enabled.
-oval.matte = false      # Force the CopyOpacityCompositeOp to use pixel intensity
+ballerina.alpha(Magick::ActivateAlphaChannel)  # Ensure the ballerina image's opacity channel is enabled.
+oval.alpha(Magick::DeactivateAlphaChannel)     # Force the CopyOpacityCompositeOp to use pixel intensity
 # to determine how much transparency to add to the ballerina
 # pixels.
 
 ballerina = ballerina.composite(oval, CenterGravity, CopyOpacityCompositeOp)
 
@@ -72,7 +72,7 @@
 # supports 1`level of transparency. Therefore, composite the vignette over a
 # standard "checkerboard" background. The resulting image will be 100% opaque.
 
 checkerboard = Image.read('pattern:checkerboard') { self.size = "#{ballerina.columns}x#{ballerina.rows}" }
 vignette = checkerboard[0].composite(ballerina, CenterGravity, OverCompositeOp)
-vignette.display
+vignette.write('vignette.png')
 exit