displaying element but erasing everything on location/size change

src/Button.java

@@ -13,6 +13,6 @@ public class Button extends Visual {
     {
         Graphics g = imageBuffer.getGraphics();
         g.setColor(Color.BLUE);
-        g.fillRect(10, 33, 500, 500);
+        g.fillRect(0, 0, getWidth(), getHeight());
     }
 }

src/CustomFrame.java

@@ -7,16 +7,6 @@ public class CustomFrame extends Frame {
     public CustomFrame()
     {
         super();
-        this.addWindowStateListener(e -> {
-            imageBuffer = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_3BYTE_BGR);
-            imageBuffer.getGraphics().setColor(Color.WHITE);
-            imageBuffer.getGraphics().fillRect(0, 0, getWidth(), getHeight());
-            imageBuffer.getGraphics().setColor(Color.BLACK);
-        });
-    }
-
-    public BufferedImage getImageBuffer() {
-        return this.imageBuffer;
     }
 
     public CustomFrame(String name)
@@ -24,20 +14,8 @@ public class CustomFrame extends Frame {
         super(name);
     }
 
-    @Override
-    public void setSize(Dimension d)
-    {
-        this.setSize(d.width, d.height);
-    }
-
-    @Override
-    public void setSize(int width, int height)
-    {
-        super.setSize(width, height);
-        this.imageBuffer = new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR);
-        this.imageBuffer.getGraphics().setColor(Color.WHITE);
-        this.imageBuffer.getGraphics().fillRect(0, 0, this.getWidth(), this.getHeight());
-        this.imageBuffer.getGraphics().setColor(Color.BLACK);
+    public void setImageBuffer(BufferedImage imageBuffer) {
+        this.imageBuffer = imageBuffer;
     }
 
     @Override

src/Main.java

@@ -16,5 +16,23 @@ public class Main {
 
         Button button = new Button();
         win.addVisual(button);
+        int x = 20;
+        int y = 20;
+        while(true){
+            if(x > win.getWidth()){
+                x = 0;
+                y+=20;
+            }
+            if(y > win.getHeight()){
+                y = 0;
+            }
+            button.setLocation(x, y);
+            x+=10;
+            try {
+                Thread.sleep(10);
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        }
     }
 }

src/Visual.java

@@ -1,23 +1,45 @@
+import java.awt.*;
 import java.awt.image.BufferedImage;
 import java.util.ArrayList;
 import java.util.List;
 
 public class Visual {
+
+    /*--------------------------------------------------------------------
+                            Tree Elements
+    ---------------------------------------------------------------------*/
     private List<Visual> children;
     private Visual parent;
     private BufferedImage imageBuffer;
+
+
+    /*--------------------------------------------------------------------
+                        Attributes
+    ---------------------------------------------------------------------*/
     private int width;
     private int height;
     private int locationX;
     private int locationY;
+    private Color backgroundColor;
+    private Color foregroundColor;
+    private Boolean valid;
 
 
+    /*--------------------------------------------------------------------
+                        Constructors
+    ---------------------------------------------------------------------*/
     public Visual() {
         this.children = new ArrayList<>();
         this.parent = null;
-        this.imageBuffer = new BufferedImage(0, 0, BufferedImage.TYPE_3BYTE_BGR);
+        this.backgroundColor = Color.WHITE;
+        this.foregroundColor = Color.BLACK;
+        valid = false;
     }
 
+
+    /*--------------------------------------------------------------------
+                    Attributes Methods
+    ---------------------------------------------------------------------*/
     public int getWidth()
     {
         return this.width;
@@ -31,17 +53,51 @@ public class Visual {
     public void setSize(int width, int height){
         this.width = width;
         this.height = height;
-        
-//        if(this.parent != null) {
-//            this.imageBuffer = this.parent.getImageBuffer();
-//        }
-        this.repaint();
+
+        initializeImageBuffer(width, height);
+
+        this.valid = false;
+        this.revalidate();
+    }
+
+    public int getLocationX(){
+        return this.locationX;
+    }
+
+    public int getLocationY(){
+        return this.locationY;
+    }
+
+    public void setLocation(int x, int y){
+        this.locationX = x;
+        this.locationY = y;
+        this.valid = false;
+        this.revalidate();
+    }
+
+    public Color getBackgroundColor() {
+        return backgroundColor;
+    }
+
+    public void setBackgroundColor(Color backgroundColor) {
+        this.backgroundColor = backgroundColor;
+        this.valid = false;
+        this.revalidate();
+    }
+
+    public Color getForegroundColor() {
+        return foregroundColor;
+    }
+
+    public void setForegroundColor(Color foregroundColor) {
+        this.foregroundColor = foregroundColor;
+        this.valid = false;
+        this.revalidate();
     }
 
     private void calculateInitialSize() {
-        this.width = this.parent.getWidth() - this.getLocationX();
-        this.height = this.parent.getHeight() - this.getLocationY();
-        this.imageBuffer = this.parent.getImageBuffer().getSubimage(this.locationX, this.locationY, this.width, this.height);
+        this.width = 20;
+        this.height = 20;
     }
 
     private void calculateInitialLocation(){
@@ -49,13 +105,20 @@ public class Visual {
         this.locationY = 200;
     }
 
+
+    /*--------------------------------------------------------------------
+                            Tree Methods
+    ---------------------------------------------------------------------*/
+
     public void addVisual(Visual child) {
         this.children.add(child);
         child.setParent(this);
         child.calculateInitialLocation();
         child.calculateInitialSize();
+        child.imageBuffer = new BufferedImage(child.getWidth(), child.getHeight(), BufferedImage.TYPE_3BYTE_BGR);
+        child.valid = false;
 
-        this.repaint();
+        this.revalidate();
     }
 
     private void setParent(Visual parent)
@@ -72,56 +135,44 @@ public class Visual {
         this.parent.handleNotification();
     }
 
-    public void repaint() {
-        if(this instanceof Window)
-        {
-            for(Visual v: children)
-            {
-                v.paint(this.imageBuffer);
-            }
-        }
-        else{
-            this.parent.repaint();
-        }
-    }
-
     public void callRepaint()
     {
-        this.repaint();
+        this.paint(this.imageBuffer);
+        this.parent.revalidate();
     }
 
-    public int getLocationX(){
-        return this.locationX;
-    }
-
-    public int getLocationY(){
-        return this.locationY;
-    }
-
-    public void setLocationX(int locationX){
-        this.locationX = locationX;
-    }
-
-    public void setLocationY(int locationY){
-        this.locationY = locationY;
+    public void revalidate() {
+        initializeImageBuffer(width, height);
+        this.paint(imageBuffer);
+        for(Visual v:children){
+            if(!v.valid){
+                v.paint(v.imageBuffer);
+            }
+            this.imageBuffer.getGraphics().drawImage(v.imageBuffer, v.locationX, v.locationY, null);
+            v.valid = true;
+        }
+        this.valid = true;
+        if(!(this instanceof Window)){
+            this.parent.revalidate();
+        }
+        else{
+            Window window = (Window)this;
+            window.setFrameImageBuffer(this.imageBuffer);
+        }
     }
 
     public void paint(BufferedImage imageBuffer) {
 
     }
 
-    public void setImageBuffer(BufferedImage imageBuffer){
-        this.imageBuffer = imageBuffer;
-    }
+    /*--------------------------------------------------------------------
+                            Helper Methods
+    ---------------------------------------------------------------------*/
 
-    private BufferedImage getImageBuffer() {
-        return this.imageBuffer;
-    }
-
-    public void triggerBufferChange() {
-        for(Visual v: children){
-            v.imageBuffer = this.imageBuffer;
-            v.triggerBufferChange();
-        }
+    private void initializeImageBuffer(int width, int height){
+        this.imageBuffer = new BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR);
+        this.imageBuffer.getGraphics().setColor(backgroundColor);
+        this.imageBuffer.getGraphics().fillRect(0, 0, width, height);
+        this.imageBuffer.getGraphics().setColor(foregroundColor);
     }
 }

src/Window.java

@@ -1,6 +1,7 @@
 import java.awt.*;
 import java.awt.event.WindowListener;
 import java.awt.event.WindowStateListener;
+import java.awt.image.BufferedImage;
 
 public class Window extends Visual {
     public CustomFrame frame;
@@ -10,9 +11,8 @@ public class Window extends Visual {
         super();
         this.frame = new CustomFrame();
         this.addWindowStateListener(e -> {
-            setImageBuffer(frame.getImageBuffer());
-            triggerBufferChange();
-            repaint();
+            this.setSize(getWidth(), getHeight());
+            revalidate();
         });
     }
 
@@ -20,8 +20,12 @@ public class Window extends Visual {
     public void setSize(int width, int height)
     {
         this.frame.setSize(width, height);
-        this.setImageBuffer(this.frame.getImageBuffer());
         super.setSize(width, height);
+        revalidate();
+    }
+
+    public void setFrameImageBuffer(BufferedImage imageBuffer){
+        this.frame.setImageBuffer(imageBuffer);
     }
 
     public void setSize(Dimension dimension) {