Start implementing the canvas to draw graphs.

fx/src/main/kotlin/org/nwapw/abacus/fx/graphing/GraphCanvas.kt

@@ -0,0 +1,39 @@
+package org.nwapw.abacus.fx.graphing
+
+import javafx.beans.value.ChangeListener
+import javafx.scene.canvas.Canvas
+
+/**
+ * A canvas that renders a graph.
+ *
+ * The GraphCanvas uses the provided [Graph] instance in order to draw the outputs on itself.
+ * @param graph the graph used to render.
+ */
+class GraphCanvas(graph: Graph): Canvas() {
+
+    /**
+     * The graph that is currently being used to generate inputs / outputs.
+     * The redraw is triggered if this graph is reset.
+     */
+    var graph: Graph = graph
+        set(value) {
+            field = value
+            redraw()
+        }
+
+    init {
+        val redrawListener = ChangeListener<Number> { _, _, _ -> redraw() }
+        widthProperty().addListener(redrawListener)
+        heightProperty().addListener(redrawListener)
+        redraw()
+    }
+
+    /**
+     * Redraws the graph onto the canvas.
+     */
+    fun redraw() {
+        val graphicsContext = graphicsContext2D
+        val outputs = graph.generateOutputs(graph.generateInputs())
+    }
+
+}