C# 截取图片的方法

1、C#截取图片的方法

方法一、

一个像素一个像素的画，遍历每一个像素，速度慢

 /// <summary>
        /// 截取一张图片的制定部分
        /// </summary>
        /// <param name="bitmapPathAndName">原始图片路径名称</param>
        /// <param name="width">截取图片的宽度</param>
        /// <param name="height">截取图片的高度</param>
        /// <param name="offsetX">开始截取图片的X坐标</param>
        /// <param name="offsetY">开始截取图片的Y坐标</param>
        /// <returns></returns>
        public Bitmap GetPartOfImage(string bitmapPahtAndName, int width, int height, int offsetX, int offsetY)
        {
            Bitmap sourceBitmap = new Bitmap(bitmapPahtAndName);
            Bitmap resultBitmap = new Bitmap(width, height);
            for (int x = 0; x < width; x++)
            {
                for (int y = 0; y < height; y++)
                {
                    if (offsetX + x < sourceBitmap.Size.Width & offsetY + y < sourceBitmap.Size.Height)
                    {
                        resultBitmap.SetPixel(x, y, sourceBitmap.GetPixel(offsetX + x, offsetY + y));
                    }
                }
            }
            return resultBitmap;
        }

方法二、在一个知道位置画一个要截取的图像

 

 /// <summary>
        /// 截取一张图片的制定部分
        /// </summary>
        /// <param name="bitmapPathAndName">原始图片路径名称</param>
        /// <param name="width">截取图片的宽度</param>
        /// <param name="height">截取图片的高度</param>
        /// <param name="offsetX">开始截取图片的X坐标</param>
        /// <param name="offsetY">开始截取图片的Y坐标</param>
        /// <returns></returns>
        public Bitmap GetPartOfImageRec(string bitmapPathAndName, int width, int height, int offsetX, int offsetY)
        {
            Bitmap sourceBitmap = new Bitmap(bitmapPathAndName);
            Bitmap resultBitmap = new Bitmap(width, height);
            using (Graphics g = Graphics.FromImage(resultBitmap))
            {
                Rectangle resultRectangle = new Rectangle(0,0,width,height);
                Rectangle sourceRectangle = new Rectangle(0 + offsetX, 0 + offsetY, width, height);
                g.DrawImage(sourceBitmap, resultRectangle, sourceRectangle, GraphicsUnit.Pixel);
            }
            return resultBitmap;
        }