Graphics object to image file

Question

I would like to crop and resize my image. Here is my code:

Image image = Image.FromFile(AppDomain.CurrentDomain.BaseDirectory + \"Cropper/tests/castle.jpg\")         


        

Answer 1

This is not a direct answer to the OP's question, but it is an often-overlooked tool that can allow you to approach things in a different way, should that prove necessary.

It is often said that it's not possible to get at the content of a Graphics object. This is not true at all. With the right approach you can access data on a canvas using HDC and BitBlt. Here is one way to do it using C#:

    enum TernaryRasterOperations : uint
    {
        /// 
dest = source
        SRCCOPY = 0x00CC0020,
        /// 
dest = source OR dest
        SRCPAINT = 0x00EE0086,
        /// 
dest = source AND dest
        SRCAND = 0x008800C6,
        /// 
dest = source XOR dest
        SRCINVERT = 0x00660046,
        /// 
dest = source AND (NOT dest)
        SRCERASE = 0x00440328,
        /// 
dest = (NOT source)
        NOTSRCCOPY = 0x00330008,
        /// 
dest = (NOT src) AND (NOT dest)
        NOTSRCERASE = 0x001100A6,
        /// 
dest = (source AND pattern)
        MERGECOPY = 0x00C000CA,
        /// 
dest = (NOT source) OR dest
        MERGEPAINT = 0x00BB0226,
        /// 
dest = pattern
        PATCOPY = 0x00F00021,
        /// 
dest = DPSnoo
        PATPAINT = 0x00FB0A09,
        /// 
dest = pattern XOR dest
        PATINVERT = 0x005A0049,
        /// 
dest = (NOT dest)
        DSTINVERT = 0x00550009,
        /// 
dest = BLACK
        BLACKNESS = 0x00000042,
        /// 
dest = WHITE
        WHITENESS = 0x00FF0062,
        /// 

        /// Capture window as seen on screen.  This includes layered windows 
        /// such as WPF windows with AllowsTransparency="true"
        /// 
        CAPTUREBLT = 0x40000000
    }

    [DllImport("gdi32.dll", EntryPoint = "BitBlt", SetLastError = true)]
    [return: MarshalAs(UnmanagedType.Bool)]
    static extern bool BitBlt([In] IntPtr hdc, int nXDest, int nYDest, int nWidth, int nHeight, [In] IntPtr hdcSrc, int nXSrc, int nYSrc, TernaryRasterOperations dwRop);

    public static Bitmap CopyGraphicsContent(Graphics source, Rectangle rect)
    {
        Bitmap bmp = new Bitmap(rect.Width, rect.Height);

        using (Graphics dest = Graphics.FromImage(bmp))
        {
            IntPtr hdcSource = source.GetHdc();
            IntPtr hdcDest = dest.GetHdc();

            BitBlt(hdcDest, 0, 0, rect.Width, rect.Height, hdcSource, rect.X, rect.Y, TernaryRasterOperations.SRCCOPY);

            source.ReleaseHdc(hdcSource);
            dest.ReleaseHdc(hdcDest);
        }

        return bmp;
    }