C# - How to print aspect ratio / full page

Question

I am printing the CHART control on button click:

chart1.SaveImage(ms, ChartImageFormat.Bmp);
Bitmap bm = new Bitmap(ms);

PrintDocument doc = new PrintDocument();
doc.PrintPage += (s, ev) =>
{
    ev.Graphics.DrawImage(bm, Point.Empty); // adjust this to put the image elsewhere
    ev.HasMorePages = false;
};
doc.DefaultPageSettings.Landscape = true;

doc.Print();

How do I force it to print the control so that it fits to the size of the page (preserving the aspect ratio)?

Answer 1

There are at least two different ways to do it, both include scaling the image to be printed to fit the page size of the selected printer:

1) using .NET facilities (haven't tested it myself, lifted from this post):

    private void printDocument1_PrintPage(object sender, System.Drawing.Printing.PrintPageEventArgs e)
    {
        Image i = pictureBox1.Image;

        float newWidth = i.Width * 100 / i.HorizontalResolution;
        float newHeight = i.Height * 100 / i.VerticalResolution;

        float widthFactor = newWidth / e.MarginBounds.Width;
        float heightFactor = newHeight / e.MarginBounds.Height;

        if(widthFactor>1 | heightFactor > 1)
        {
            if(widthFactor > heightFactor)
            {
                newWidth = newWidth / widthFactor;
                newHeight = newHeight / widthFactor;
            }
            else
            {
                newWidth = newWidth / heightFactor;
                newHeight = newHeight / heightFactor;
            }
        }
        e.Graphics.DrawImage(i, 0, 0, (int)newWidth, (int)newHeight);
    }
}

2) P/Invoke'ing Windows API calls from the GDI and flat GDI (this is much more complex but faster and you can pass a plain byte array of a bitmap file (read file as byte[]), provide an email to me if need this code):

  private static extern bool ClosePrinter(IntPtr hPrinter);
  private static extern bool OpenPrinter([MarshalAs(UnmanagedType.LPStr)] string szPrinter, out IntPtr hPrinter, IntPtr pd);
  private static extern int SetJob(IntPtr hPrinter, int JobId, int Level, ref byte pJob, int Command_Renamed);
  private static extern int GdiplusStartup(out IntPtr token, ref StartupInput input, out StartupOutput output);
  private static extern int GdiplusShutdown(IntPtr token);
  internal static extern int GdipLoadImageFromStream([In, MarshalAs(UnmanagedType.Interface)]IStream stream, out IntPtr image);
  internal static extern int GdipDisposeImage(IntPtr image);
  static internal extern int GdipCreateFromHDC2(IntPtr hDC, IntPtr hDevice, out IntPtr graphics);
  static internal extern int GdipDeleteGraphics(IntPtr graphics);
  static internal extern int GdipReleaseDC(IntPtr graphics, IntPtr hdc);
  internal static extern int GdipGetImageDimension(IntPtr image, out float width, out float height);
  internal static extern int GdipGetDpiX(IntPtr graphics, out float dpi);
  internal static extern int GdipGetDpiY(IntPtr graphics, out float dpi);
  static internal extern int GdipDrawImageRectI(IntPtr graphics, IntPtr image, int x, int y, int width, int height);
  private static extern IntPtr CreateDC([MarshalAs(UnmanagedType.LPStr)] string lpszDriver, [MarshalAs(UnmanagedType.LPStr)] string lpszDevice, [MarshalAs(UnmanagedType.LPStr)] string lpszOutput, IntPtr lpInitData);
  private static extern bool DeleteDC(IntPtr hdc);
  private static extern int StartDoc(IntPtr hdc, DOCINFO lpdi);
  private static extern int EndDoc(IntPtr hdc);
  private static extern int StartPage(IntPtr hdc);
  private static extern int EndPage(IntPtr hdc);
  private static extern int GetDeviceCaps(IntPtr hdc, int nIndex);