Gave CoreControl the ability to shatter parent backgrounds

elements/containers/container.go

@@ -4,7 +4,6 @@ import "image"
 import "git.tebibyte.media/sashakoshka/tomo"
 import "git.tebibyte.media/sashakoshka/tomo/input"
 import "git.tebibyte.media/sashakoshka/tomo/canvas"
-import "git.tebibyte.media/sashakoshka/tomo/artist"
 import "git.tebibyte.media/sashakoshka/tomo/elements/core"
 import "git.tebibyte.media/sashakoshka/tomo/default/theme"
 import "git.tebibyte.media/sashakoshka/tomo/default/config"
@@ -189,10 +188,11 @@ func (element *Container) redoAll () {
 	for index, entry := range element.children {
 		rocks[index] = entry.Bounds
 	}
-	pattern := element.theme.Pattern (
-		tomo.PatternBackground,
-		tomo.State { })
-	artist.DrawShatter(element.core, pattern, element.Bounds(), rocks...)
+	
+	element.core.DrawBackgroundBoundsShatter (
+		element.theme.Pattern(tomo.PatternBackground, tomo.State { }),
+		element.Bounds(),
+		rocks...)
 
 	// cut our canvas up and give peices to child elements
 	for _, entry := range element.children {

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()