bringToFront and sendToBack

src/main/java/paintingcanvas/drawable/Drawable.java

@@ -585,10 +585,26 @@ public T setFilled(boolean filled) {
         return getThis();
     }
 
+    /**
+     * Gets the current layer of the object.
+     * By default, all objects are on layer 0.
+     * @see #setLayer(int)
+     * @see #bringToFront()
+     * @see #sendToBack()
+     * @return the original object to allow method chaining
+     */
     public int getLayer() {
         return this.layer;
     }
 
+    /**
+     * Puts the object on a specific layer.
+     * @see #getLayer()
+     * @see #bringToFront()
+     * @see #sendToBack()
+     * @param layer the layer to set the object to
+     * @return the original object to allow method chaining
+     */
     public T setLayer(int layer) {
         synchronized (Canvas.drawableSync) {
             this.layer = layer;
@@ -597,6 +613,28 @@ public T setLayer(int layer) {
         return getThis();
     }
 
+    /**
+     * Brings the object in front of all other objects.
+     * @see #getLayer()
+     * @see #setLayer(int)
+     * @see #sendToBack()
+     * @return the original object to allow method chaining
+     */
+    public T bringToFront() {
+        return this.setLayer(Canvas.getGlobalInstance().elements.getMaxLayer() + 1);
+    }
+
+    /**
+     * Puts the object behind all other objects.
+     * @see #getLayer()
+     * @see #setLayer(int)
+     * @see #bringToFront()
+     * @return the original object to allow method chaining
+     */
+    public T sendToBack() {
+        return this.setLayer(Canvas.getGlobalInstance().elements.getMinLayer() - 1);
+    }
+
     /**
      * Erase this object from the canvas. This object will be gone and cannot* be added back!
      * <p>

src/main/java/paintingcanvas/misc/ElementContainer.java

@@ -11,6 +11,8 @@
 public class ElementContainer {
     final List<Drawable<?>> elements = new Vector<>();
     boolean dirty = false;
+    int minLayer = 0;
+    int maxLayer = 0;
 
     public void foreach(DrawableConsumer consumer) {
         prepareRender();
@@ -22,7 +24,12 @@ public void foreach(DrawableConsumer consumer) {
     void prepareRender() {
         if (!dirty) return;
         synchronized (Canvas.drawableSync) {
-            elements.sort(Comparator.comparingInt(Drawable::getLayer));
+            elements.sort(Comparator.comparingInt(a -> {
+                int layer = a.getLayer();
+                minLayer = Math.min(minLayer, layer);
+                maxLayer = Math.max(maxLayer, layer);
+                return layer;
+            }));
         }
         dirty = false;
     }
@@ -31,6 +38,14 @@ public void setDirty() {
         this.dirty = true;
     }
 
+    public int getMinLayer() {
+        return minLayer;
+    }
+
+    public int getMaxLayer() {
+        return maxLayer;
+    }
+
     public int size() {
         return elements.size();
     }

src/test/java/examples/Test.java

@@ -22,11 +22,22 @@ public static void main(String[] args) {
         Image image = new Image(200, 200, "src/test/java/examples/flop.jpg")
                 .rotate(90);
 
-        int i = 0;
+        int i = -1;
+        Square[] squares = new Square[Hue.values().length];
         for (Hue h : Hue.values())
-            new Square(50 + (i % 8) * 100, 50 + (i++ / 8) * 100, 100, new Color(h.hex));
+            squares[++i] = new Square(50 + (i % 8) * 100, 50 + (i / 8) * 100, 100, new Color(h.hex));
 
         canvas.sleep(3);
-        image.setLayer(1);
+        image.bringToFront();
+
+        for (Square square : squares) {
+            square.bringToFront();
+            canvas.sleep(0.1);
+        }
+
+        for (Square square : squares) {
+            square.sendToBack();
+            canvas.sleep(0.1);
+        }
     }
 }