Рисование в PictureBox

Unit Unit1;
 
interface
 
uses System, System.Drawing, System.Windows.Forms;
 
type
  Form1 = class(Form)
    
    procedure pictureBox1_Paint(sender: Object; e: PaintEventArgs);
    procedure pictureBox2_Paint(sender: Object; e: PaintEventArgs);
    procedure pictureBox3_Paint(sender: Object; e: PaintEventArgs);
    procedure pictureBox1_MouseDown(sender: Object; e: MouseEventArgs);
    procedure pictureBox1_MouseMove(sender: Object; e: MouseEventArgs);
    procedure pictureBox1_MouseUp(sender: Object; e: MouseEventArgs);
    procedure button1_Click(sender: Object; e: EventArgs);
    procedure button2_Click(sender: Object; e: EventArgs);
    procedure checkBox1_CheckedChanged(sender: Object; e: EventArgs);
    procedure pictureBox2_MouseDown(sender: Object; e: MouseEventArgs);
    procedure pictureBox2_MouseMove(sender: Object; e: MouseEventArgs);
    procedure pictureBox2_MouseUp(sender: Object; e: MouseEventArgs);
    procedure button4_Click(sender: Object; e: EventArgs);
    procedure button3_Click(sender: Object; e: EventArgs);
    procedure button5_Click(sender: Object; e: EventArgs);
  {$region FormDesigner}
  private
    {$resource Unit1.Form1.resources}
    pictureBox2: PictureBox;
    pictureBox3: PictureBox;
    button1: Button;
    button2: Button;
    checkBox1: CheckBox;
    button3: Button;
    button4: Button;
    button5: Button;
    label1: &Label;
    pictureBox1: PictureBox;
    {$include Unit1.Form1.inc}
  {$endregion FormDesigner}
  public
    constructor;
    begin
      InitializeComponent;
    end;
  end;
 
implementation
var
  flagKvadr, flagEllips: Boolean;
  X1, X2: Integer;
   
   
procedure Form1.pictureBox1_Paint(sender: Object; e: PaintEventArgs); //синий квадрат
begin
  var g:=e.Graphics;
  g.FillRectangle(System.Drawing.Brushes.Blue,0,0,pictureBox1.width, pictureBox1.height);
end;
 
procedure Form1.pictureBox2_Paint(sender: Object; e: PaintEventArgs); // желтый круг
begin
 
  SetStyle(ControlStyles.SupportsTransparentBackColor, true);
  pictureBox2.BackColor := Color.Transparent;
 
  var g:=e.Graphics;
  g.FillEllipse(System.Drawing.Brushes.Yellow,0,0,pictureBox2.width, pictureBox2.height); 
 
 
end;
 
procedure Form1.pictureBox3_Paint(sender: Object; e: PaintEventArgs);
begin
  var g:=e.Graphics;
  g.FillRectangle(System.Drawing.Brushes.white,0,0,pictureBox3.width, pictureBox3.height); 
end;