[Quote=引用 7 楼 zgke 的回复:]
Bitmap _Bitmap = new Bitmap(@"C:\1.bmp");
Graphics _Graphcis = Graphics.FromImage(_Bitmap);
Point _Left1 = new Point(0, 0);
Point _Left2 = new Point(_Bitmap.Width, 0);
Point _Left3 = new Point(_Bitmap.Width , _Bitmap.Height/2);
Point _Left4 = new Point(0, _Bitmap.Height/2);
Point[] _Point = new Point[] { _Left1, _Left2, _Left3, _Left4 };
PathGradientBrush _SetBruhs = new PathGradientBrush(_Point, WrapMode.TileFlipY);
_SetBruhs.CenterPoint = new PointF(0, 0);
_SetBruhs.FocusScales = new PointF(_Bitmap.Width/2, 0);
_SetBruhs.CenterColor = Color.FromArgb(250, 255, 255, 255);
_SetBruhs.SurroundColors=new Color[]{Color.FromArgb(100,255,255,255)};
_Graphcis.FillRectangle(_SetBruhs, new Rectangle(0, 0, _Bitmap.Width, _Bitmap.Height));
Point _Left1 = new Point(0, 0);
Point _Left2 = new Point(_Bitmap.Width, 0);
Point _Left3 = new Point(_Bitmap.Width , _Bitmap.Height/2);
Point _Left4 = new Point(0, _Bitmap.Height/2);
Point[] _Point = new Point[] { _Left1, _Left2, _Left3, _Left4 };
PathGradientBrush _SetBruhs = new PathGradientBrush(_Point, WrapMode.TileFlipY);
_SetBruhs.CenterPoint = new PointF(0, 0);
_SetBruhs.FocusScales = new PointF(_Bitmap.Width/2, 0);
_SetBruhs.CenterColor = Color.FromArgb(250, 255, 255, 255);
_SetBruhs.SurroundColors=new Color[]{Color.FromArgb(100,255,255,255)};
_Graphcis.FillRectangle(_SetBruhs, new Rectangle(0, 0, _Bitmap.Width, _Bitmap.Height));