Bitmap mybit=new Bitmap(100,100);//局部大小
Graphics g=Graphics.FromImage(mybit);
g.DrawImage(oldbit/*原圖*/,
new Rectangle(new Point(0,0),new Size(100,100)),//目标位置
new Rectangle(new Point(startX,startY),new Size(100,100)),//原圖位置
GraphicsUnit.Pixel);
Bitmap mybit=new Bitmap(100,100);//局部大小
Graphics g=Graphics.FromImage(mybit);
g.DrawImage(oldbit/*原圖*/,
new Rectangle(new Point(0,0),new Size(100,100)),//目标位置
new Rectangle(new Point(startX,startY),new Size(100,100)),//原圖位置
GraphicsUnit.Pixel);