Получение изображения из System.Drawing.Graphics

{$reference System.dll}
{$reference System.Drawing.dll}
{$reference System.Windows.Forms.dll}
 
uses System, System.Drawing, System.Drawing.Drawing2D, System.Windows.Forms;
 
var
    f := new Form;
    g, gr: Graphics;
    m := new Matrix;
    b := new Bitmap('kartinka.png');
    bmp := new Bitmap(b.Size.Width, b.Size.Height);
 
function OnlineScreenshot: Bitmap;
begin
    gr := Graphics.FromImage(bmp);
    gr.CopyFromScreen(0, 0, 0, 0, bmp.Size, CopyPixelOperation.SourceCopy);
    Result := bmp;
end;
 
begin
    f.StartPosition := FormStartPosition.Manual;
    f.Location := new Point(0,0);
    f.BackColor := Color.FromArgb(0,0,0);
    f.Size := b.Size;
    f.FormBorderStyle := FormBorderStyle.None;
    f.Shown += procedure(sender, e) ->
    begin
        g := f.CreateGraphics;
        m.RotateAt(45, new Point(b.Size.Width div 2, b.Size.Height div 2));
        g.Transform := m;
        g.DrawImage(b, 0, 0, b.Size.Width, b.Size.Height);
        OnlineScreenShot;
        bmp.Save('out.png', System.Drawing.Imaging.ImageFormat.PNG);
        Halt;
    end;
    Application.Run(f);
end.