[orx-fx] Add fade to Contour and CannyEdgeDetector

orx-fx/src/jvmDemo/kotlin/DemoContour01.kt

@@ -0,0 +1,56 @@
+/**
+ * Demonstrate the Contour filter
+ * @author Edwin Jakobs
+ */
+
+import org.openrndr.application
+import org.openrndr.color.ColorRGBa
+import org.openrndr.draw.createEquivalent
+import org.openrndr.draw.loadImage
+import org.openrndr.extra.fx.edges.Contour
+import org.openrndr.extra.imageFit.imageFit
+import org.openrndr.extra.shapes.primitives.grid
+
+fun main() = application {
+    configure {
+        width = 720
+        height = 720
+    }
+    program {
+        val image = loadImage("demo-data/images/image-001.png")
+        val contour = Contour()
+        contour.levels = 4.0
+        contour.window = 1
+        contour.outputBands = true
+        contour.contourColor = ColorRGBa.PINK
+        contour.backgroundOpacity = 0.0
+
+        val edges = image.createEquivalent()
+        extend {
+            val cells = drawer.bounds.grid(2, 2).flatten()
+            val actions = listOf(
+                {
+                    contour.outputBands = true
+                    contour.levels = 2.0
+                },
+                {
+                    contour.outputBands = false
+                    contour.levels = 2.0
+                },
+                {
+                    contour.outputBands = false
+                    contour.levels = 8.0
+                },
+                {
+                    contour.outputBands = true
+                    contour.levels = 8.0
+                },
+            )
+            for ((cell, action) in cells zip actions) {
+                action()
+                contour.apply(image, edges)
+                drawer.imageFit(edges, cell)
+            }
+        }
+    }
+}