用指定颜色填充一个闭合区域

using System.Runtime.InteropServices;

 

[DllImport("gdi32.dll")]

public static extern IntPtr SelectObject(IntPtr hdc, IntPtr hgdiobj);

[DllImport("gdi32.dll")]

public static extern IntPtr CreateSolidBrush(int crColor);

[DllImport("gdi32.dll")]

public static extern bool ExtFloodFill(IntPtr hdc, int nXStart, int nYStart,

    int crColor, uint fuFillType);

[DllImport("gdi32.dll")]

public static extern bool DeleteObject(IntPtr hObject);

[DllImport("gdi32.dll")]

public static extern int GetPixel(IntPtr hdc, int x, int y);

public static uint FLOODFILLBORDER = 0;

public static uint FLOODFILLSURFACE = 1;

 

private void button1_Click(object sender, EventArgs e)

{

    Graphics vGraphics = Graphics.FromHwnd(Handle);

    vGraphics.DrawRectangle(Pens.Blue, new Rectangle(0, 0, 300, 300));

    vGraphics.DrawRectangle(Pens.Blue, new Rectangle(50, 70, 300, 300));

    IntPtr vDC = vGraphics.GetHdc();

    IntPtr vBrush = CreateSolidBrush(ColorTranslator.ToWin32(Color.Red));

    IntPtr vPreviouseBrush = SelectObject(vDC, vBrush);

    ExtFloodFill(vDC, 10, 10, GetPixel(vDC, 10, 10), FLOODFILLSURFACE);

    SelectObject(vDC, vPreviouseBrush);

    DeleteObject(vBrush);

    vGraphics.ReleaseHdc(vDC);

}