As the title says, I want to paint something with XOR mode because I want to clean it after a period of time.
I'm using C# (Window Form) with Visual Studio 2010.
Can anybody help me with this?
I made a nice extension for .net:
public static class XorDrawing
{
[DllImport("gdi32.dll", EntryPoint = "SetROP2", CallingConvention = CallingConvention.StdCall)]
private extern static int SetROP2(IntPtr hdc, int fnDrawMode);
[DllImport("gdi32.dll", EntryPoint = "MoveToEx", CallingConvention = CallingConvention.StdCall)]
private extern static bool MoveToEx(IntPtr hdc, int x, int y, IntPtr lpPoint);
[DllImport("gdi32.dll", EntryPoint = "LineTo", CallingConvention = CallingConvention.StdCall)]
private extern static bool LineTo(IntPtr hdc, int x, int y);
[DllImport("gdi32.dll", SetLastError = true)]
static extern IntPtr CreateCompatibleDC(IntPtr hdc);
[DllImport("gdi32.dll", EntryPoint = "SelectObject")]
public static extern IntPtr SelectObject([In] IntPtr hdc, [In] IntPtr hgdiobj);
[DllImport("gdi32.dll")]
static extern bool DeleteObject(IntPtr target);
[DllImport("gdi32.dll")]
static extern IntPtr CreatePen(PenStyle fnPenStyle, int nWidth, uint crColor);
[DllImport("gdi32.dll")]
static extern bool SetWorldTransform(IntPtr hdc, [In] ref XFORM lpXform);
[DllImport("gdi32.dll")]
public static extern int SetGraphicsMode(IntPtr hdc, int iMode);
/// <summary>
/// The XFORM structure specifies a world-space to page-space transformation.
/// </summary>
[StructLayout(LayoutKind.Sequential)]
public struct XFORM
{
public float eM11;
public float eM12;
public float eM21;
public float eM22;
public float eDx;
public float eDy;
public XFORM(float eM11, float eM12, float eM21, float eM22, float eDx, float eDy)
{
this.eM11 = eM11;
this.eM12 = eM12;
this.eM21 = eM21;
this.eM22 = eM22;
this.eDx = eDx;
this.eDy = eDy;
}
/// <summary>
/// Allows implicit converstion to a managed transformation matrix.
/// </summary>
public static implicit operator System.Drawing.Drawing2D.Matrix(XFORM xf)
{
return new System.Drawing.Drawing2D.Matrix(xf.eM11, xf.eM12, xf.eM21, xf.eM22, xf.eDx, xf.eDy);
}
/// <summary>
/// Allows implicit converstion from a managed transformation matrix.
/// </summary>
public static implicit operator XFORM(System.Drawing.Drawing2D.Matrix m)
{
float[] elems = m.Elements;
return new XFORM(elems[0], elems[1], elems[2], elems[3], elems[4], elems[5]);
}
}
public enum BinaryRasterOperations
{
R2_BLACK = 1,
R2_NOTMERGEPEN = 2,
R2_MASKNOTPEN = 3,
R2_NOTCOPYPEN = 4,
R2_MASKPENNOT = 5,
R2_NOT = 6,
R2_XORPEN = 7,
R2_NOTMASKPEN = 8,
R2_MASKPEN = 9,
R2_NOTXORPEN = 10,
R2_NOP = 11,
R2_MERGENOTPEN = 12,
R2_COPYPEN = 13,
R2_MERGEPENNOT = 14,
R2_MERGEPEN = 15,
R2_WHITE = 16
}
private enum PenStyle : int
{
PS_SOLID = 0, //The pen is solid.
PS_DASH = 1, //The pen is dashed.
PS_DOT = 2, //The pen is dotted.
PS_DASHDOT = 3, //The pen has alternating dashes and dots.
PS_DASHDOTDOT = 4, //The pen has alternating dashes and double dots.
PS_NULL = 5, //The pen is invisible.
PS_INSIDEFRAME = 6,// Normally when the edge is drawn, it’s centred on the outer edge meaning that half the width of the pen is drawn
// outside the shape’s edge, half is inside the shape’s edge. When PS_INSIDEFRAME is specified the edge is drawn
//completely inside the outer edge of the shape.
PS_USERSTYLE = 7,
PS_ALTERNATE = 8,
PS_STYLE_MASK = 0x0000000F,
PS_ENDCAP_ROUND = 0x00000000,
PS_ENDCAP_SQUARE = 0x00000100,
PS_ENDCAP_FLAT = 0x00000200,
PS_ENDCAP_MASK = 0x00000F00,
PS_JOIN_ROUND = 0x00000000,
PS_JOIN_BEVEL = 0x00001000,
PS_JOIN_MITER = 0x00002000,
PS_JOIN_MASK = 0x0000F000,
PS_COSMETIC = 0x00000000,
PS_GEOMETRIC = 0x00010000,
PS_TYPE_MASK = 0x000F0000
};
public enum GraphicsMode : int
{
GM_COMPATIBLE = 1,
GM_ADVANCED = 2,
}
private static IntPtr BeginDraw(System.Drawing.Bitmap bmp, System.Drawing.Graphics graphics, int x1, int y1, int x2, int y2, bool dash, out int oldRop, out IntPtr img, out IntPtr oldpen)
{
var gHdc = graphics.GetHdc();
var hdc = CreateCompatibleDC(gHdc);
graphics.ReleaseHdc(hdc);
img = bmp.GetHbitmap();
SelectObject(hdc, img);
oldpen = IntPtr.Zero;
if (dash)
{
var pen = CreatePen(PenStyle.PS_DASH, 1, 0);
oldpen = SelectObject(hdc, pen);
}
oldRop = SetROP2(hdc, (int)BinaryRasterOperations.R2_NOTXORPEN); // Switch to inverted mode. (XOR)
SetGraphicsMode(hdc, (int)GraphicsMode.GM_ADVANCED);
XFORM transform = graphics.Transform;
SetWorldTransform(hdc, ref transform);
return hdc;
}
private static void FinishDraw(System.Drawing.Bitmap bmp, System.Drawing.Graphics graphics, IntPtr hdc, IntPtr oldpen, int oldRop, IntPtr img, bool dash)
{
SetROP2(hdc, oldRop);
var transform = graphics.Transform;
graphics.ResetTransform(); //in case there is transform
var outBmp = System.Drawing.Image.FromHbitmap(img);
//CopyChannel(bmp, outBmp, ChannelARGB.Alpha, ChannelARGB.Alpha);
graphics.Clear(Color.Transparent);
graphics.DrawImage(outBmp, 0, 0); //draw the xored image on the bitmap
graphics.Transform = transform;
if (dash) DeleteObject(SelectObject(hdc, oldpen)); //delete new pen (switch to oldpen)
DeleteObject(img); // Delete the GDI bitmap (important).
DeleteObject(hdc);
}
public static void DrawXorLine(this System.Drawing.Graphics graphics, System.Drawing.Bitmap bmp, int x1, int y1, int x2, int y2, bool dash = true)
{
int oldRop;
IntPtr oldpen, img;
var hdc = BeginDraw(bmp, graphics, x1, y1, x2, y2, dash, out oldRop, out img, out oldpen);
MoveToEx(hdc, x1, y1, IntPtr.Zero);
LineTo(hdc, x2, y2);
FinishDraw(bmp, graphics, hdc, oldpen, oldRop, img, dash);
}
public static void DrawXorRectangle(this System.Drawing.Graphics graphics, System.Drawing.Bitmap bmp, int x1, int y1, int x2, int y2, bool dash = true)
{
int oldRop;
IntPtr oldpen, img;
var hdc = BeginDraw(bmp, graphics, x1, y1, x2, y2, dash, out oldRop, out img, out oldpen);
MoveToEx(hdc, x1, y1, IntPtr.Zero); //clockwise
LineTo(hdc, x2, y1);
LineTo(hdc, x2, y2);
LineTo(hdc, x1, y2);
LineTo(hdc, x1, y1);
FinishDraw(bmp, graphics, hdc, oldpen, oldRop, img, dash);
}
}
Usage
g.DrawXorRectangle(bmp, outRect.Left, outRect.Top, outRect.Left + outRect.Width, outRect.Top + outRect.Height);
Or
g.DrawXorLine(bmp, x1, y1, x2, y2);