Gave CoreControl the ability to shatter parent backgrounds

elements/core/core.go

@@ -5,6 +5,7 @@ import "image/color"
 import "git.tebibyte.media/sashakoshka/tomo"
 import "git.tebibyte.media/sashakoshka/tomo/canvas"
 import "git.tebibyte.media/sashakoshka/tomo/artist"
+import "git.tebibyte.media/sashakoshka/tomo/shatter"
 
 // Core is a struct that implements some core functionality common to most
 // widgets. It is meant to be embedded directly into a struct.
@@ -144,6 +145,19 @@ func (control CoreControl) DrawBackgroundBounds (
 	}
 }
 
+// DrawBackgroundBoundsShatter is like DrawBackgroundBounds, but uses the
+// shattering algorithm to avoid drawing in areas specified by rocks.
+func (control CoreControl) DrawBackgroundBoundsShatter (
+	fallback artist.Pattern,
+	bounds image.Rectangle,
+	rocks ...image.Rectangle,
+) {
+	tiles := shatter.Shatter(bounds, rocks...)
+	for _, tile := range tiles {
+		control.DrawBackgroundBounds(fallback, tile)
+	}
+}
+
 // Window returns the window containing the element.
 func (control CoreControl) Window () tomo.Window {
 	parent := control.Parent()