c# - How to override maximum 32x32 mouse size in Windows like this program can

Question

I'd like for my program to be able to override the maximum imposed mouse size of 32x32 much like the program in the picture attached does, the cursor pictured is 72x72. This is a capture from ProcMon showing what's going on when the cursors change.

However, if I try to change the registry values for the cursor files myself and then push the changes using

SystemParametersInfo(SPI.SPI_SETCURSORS, 0, IntPtr.Zero, SPIF.SPIF_SENDCHANGE);

then the cursor will change, but it's still limited to the 32x32 maximum size. How was this program able to get around that restriction? Also, the cursors remain after the program ends, so it can't be something it's doing while running, but must override a setting somewhere.

Thanks for your help, I haven't been able to find ANYTHING like this on the net, so I don't even know if anyone will have the answer.

EDIT: I see some access to a file called C:WindowsSysWOW64Imageres.dll. They're only reads, but maybe these cursors are stored in here, or they modified this file somehow. But I figured it might get someone with more experience than myself off on the right track.

EDIT 2: I believe the sizes are dictated by the SM_CXCURSOR and SM_CYCURSOR variables. If I could find a way to set these, I might be in business. Going to write a quick program to get me those values on the PC with the program running and huge mouse cursor and see what it returns...

EDIT 3: No luck; the PC with the huge cursor returns 32x32 for it's SM_CXCURSOR and SM_CYCURSOR.

Answer 1

Using SetSystemCursor it is possible to set a cursor to an image of much larger size than the standard cursor.

Here is a class I have for resizing the system cursors:

using System;
using System.Drawing;
using System.Reflection;
using System.Runtime.InteropServices;

namespace WindowsFormsApplication1
{
    class SystemCursors
    {
        [DllImport("user32.dll")]
        static extern bool SetSystemCursor(IntPtr hcur, uint id);

        enum CursorShift
        {
            Centered,
            LowerRight,
        }

        public static void SetSystemCursorsSize(int newSize)
        {
            ResizeCursor(System.Windows.Forms.Cursors.AppStarting, newSize, CursorShift.LowerRight);
            ResizeCursor(System.Windows.Forms.Cursors.Arrow, newSize, CursorShift.LowerRight);
            ResizeCursor(System.Windows.Forms.Cursors.Cross, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.Hand, newSize, CursorShift.LowerRight);
            ResizeCursor(System.Windows.Forms.Cursors.Help, newSize, CursorShift.LowerRight);
            ResizeCursor(System.Windows.Forms.Cursors.HSplit, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.IBeam, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.No, newSize, CursorShift.LowerRight);
            ResizeCursor(System.Windows.Forms.Cursors.NoMove2D, newSize, CursorShift.LowerRight);
            ResizeCursor(System.Windows.Forms.Cursors.NoMoveHoriz, newSize, CursorShift.LowerRight);
            ResizeCursor(System.Windows.Forms.Cursors.NoMoveVert, newSize, CursorShift.LowerRight);
            ResizeCursor(System.Windows.Forms.Cursors.PanEast, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.PanNE, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.PanNorth, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.PanNW, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.PanSE, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.PanSouth, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.PanSW, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.PanWest, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.SizeAll, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.SizeNESW, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.SizeNS, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.SizeNWSE, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.SizeWE, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.UpArrow, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.VSplit, newSize, CursorShift.Centered);
            ResizeCursor(System.Windows.Forms.Cursors.WaitCursor, newSize, CursorShift.LowerRight);
        }

        private static void ResizeCursor(System.Windows.Forms.Cursor cursor, 
            int newSize, CursorShift cursorShift)
        {
            Bitmap cursorImage = GetSystemCursorBitmap(cursor);
            cursorImage = ResizeCursorBitmap(cursorImage, new Size(newSize, newSize), cursorShift);
            SetCursor(cursorImage, getResourceId(cursor));
        }

        public static Bitmap GetSystemCursorBitmap(System.Windows.Forms.Cursor cursor)
        {
            Bitmap bitmap = new Bitmap(
                cursor.Size.Width, cursor.Size.Height,
                System.Drawing.Imaging.PixelFormat.Format32bppArgb);

            Graphics graphics = Graphics.FromImage(bitmap);

            cursor.Draw(graphics,
                new Rectangle(new Point(0, 0), cursor.Size));

            bitmap = Crop(bitmap);

            return bitmap;
        }

        private static Bitmap Crop(Bitmap bmp)
        {
            //code from http://stackoverflow.com/a/10392379/935052

            int w = bmp.Width;
            int h = bmp.Height;

            Func<int, bool> allWhiteRow = row =>
            {
                for (int i = 0; i < w; ++i)
                    if (bmp.GetPixel(i, row).A != 0)
                        return false;
                return true;
            };

            Func<int, bool> allWhiteColumn = col =>
            {
                for (int i = 0; i < h; ++i)
                    if (bmp.GetPixel(col, i).A != 0)
                        return false;
                return true;
            };

            int topmost = 0;
            for (int row = 0; row < h; ++row)
            {
                if (allWhiteRow(row))
                    topmost = row;
                else break;
            }

            int bottommost = 0;
            for (int row = h - 1; row >= 0; --row)
            {
                if (allWhiteRow(row))
                    bottommost = row;
                else break;
            }

            int leftmost = 0, rightmost = 0;
            for (int col = 0; col < w; ++col)
            {
                if (allWhiteColumn(col))
                    leftmost = col;
                else
                    break;
            }

            for (int col = w - 1; col >= 0; --col)
            {
                if (allWhiteColumn(col))
                    rightmost = col;
                else
                    break;
            }

            if (rightmost == 0) rightmost = w; // As reached left
            if (bottommost == 0) bottommost = h; // As reached top.

            int croppedWidth = rightmost - leftmost;
            int croppedHeight = bottommost - topmost;

            if (croppedWidth == 0) // No border on left or right
            {
                leftmost = 0;
                croppedWidth = w;
            }

            if (croppedHeight == 0) // No border on top or bottom
            {
                topmost = 0;
                croppedHeight = h;
            }

            try
            {
                var target = new Bitmap(croppedWidth, croppedHeight);
                using (Graphics g = Graphics.FromImage(target))
                {
                    g.DrawImage(bmp,
                      new RectangleF(0, 0, croppedWidth, croppedHeight),
                      new RectangleF(leftmost, topmost, croppedWidth, croppedHeight),
                      GraphicsUnit.Pixel);
                }
                return target;
            }
            catch (Exception ex)
            {
                throw new Exception(
                  string.Format("Values are topmost={0} btm={1} left={2} right={3} croppedWidth={4} croppedHeight={5}", topmost, bottommost, leftmost, rightmost, croppedWidth, croppedHeight),
                  ex);
            }
        }

        private static Bitmap ResizeCursorBitmap(Bitmap bitmap, Size size, CursorShift cursorShift)
        {
            if (size.Width > 32)
            {
                //shifting must occur
                Bitmap intermediateBitmap = new Bitmap(64, 64);
                Graphics intermediateGraphics = Graphics.FromImage(intermediateBitmap);
                if (cursorShift == CursorShift.LowerRight)
                    //place the mouse cursor in the lower right hand quadrant of the bitmap
                    intermediateGraphics.DrawImage(bitmap,
                        intermediateBitmap.Width / 2, intermediateBitmap.Height / 2);
                else if (cursorShift == CursorShift.Centered)
                    intermediateGraphics.DrawImage(bitmap,
                        intermediateBitmap.Width / 2 - bitmap.Width / 2,
                        intermediateBitmap.Height / 2 - bitmap.Height / 2);

                //now we have a shifted bitmap; use it to draw the resized cursor
                //Bitmap finalBitmap = new Bitmap(intermediateBitmap, size);    //normal quality
                Bitmap finalBitmap = new Bitmap(size.Width, size.Height);
                Graphics finalGraphics = Graphics.FromImage(finalBitmap);
                finalGraphics.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
                finalGraphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                finalGraphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                finalGraphics.DrawImage(intermediateBitmap, 0, 0, finalBitmap.Width, finalBitmap.Height);
                return finalBitmap;
            }
            else
            {
                Bitmap newBitmap = new Bitmap(bitmap, size);
                return newBitmap;
            }
        }

        private static uint getResourceId(System.Windows.Forms.Cursor cursor)
        {
            FieldInfo fi = typeof(System.Windows.Forms.Cursor).GetField(
                "resourceId", BindingFlags.NonPublic | BindingFlags.Instance);
            object obj = fi.GetValue(cursor);
            return Convert.ToUInt32((int)obj);
        }

        private static void SetCursor(Bitmap bitmap, uint whichCursor)
        {
            IntPtr ptr = bitmap.GetHicon();
            bool retval = SetSystemCursor(ptr, whichCursor);
        }

    }
}

It works by getting the current system cursor as provided in System.Windows.Forms.Cursors and making an image from it with Cursor.Draw. The image is then resized to the desired size. This requires shifting the cursor image, either to the lower right hand corner (like for arrow pointers) or centering the cursor image inside the larger image (like for Cross and IBeam).

You can use your own image for the cursor if desired, bypassing all the resizing code. Just supply the Bitmap to SetCursor.

Once the new cursor image is ready, the last piece of data needed is the ID of the cursor we are trying to replace. Each System.Windows.Forms.Cursor does contain this information, but in a private variable, so reflection is used to get the value. If you prefer to avoid reflection, you could build a table of these values instead. See MSDN SetSystemCursor for a list of values.

To use the class just call

SystemCursors.SetSystemCursorsSize(128);