C#生成图像

C#生成图像

private void button1_Click(object sender, EventArgs e)
        {

            //从内存解锁BcurBitmapitmap
            byte[] b = new byte[500 * 400];
            Random ra = new Random();
            for (int i = 0; i < 500; i++)
            {
                for (int j = 0; j < 400; j++)
                {
                    int r = ra.Next(1, 200);
                    b[i * 400 + j] = (byte)r;
                    //bitmap.SetPixel(i, j, Color.FromArgb(r, r, r));
                }
            }
            Bitmap bitmap = ToGrayBitmap(b,500,400);
            pictureBox1.Image = bitmap;
        }


        /// <summary>
        /// 像素点阵转换为bitmap
        /// </summary>
        /// <param name="rawValues">byte[]数组</param>
        /// <param name="width">图片的宽度</param>
        /// <param name="height">图片的高度</param>
        /// <returns>bitmap图片</returns>
        public Bitmap ToGrayBitmap(byte[] rawValues, int width, int height)
        {
            Bitmap bmp = new Bitmap(width, height, System.Drawing.Imaging.PixelFormat.Format8bppIndexed);
            BitmapData bmpData = bmp.LockBits(new System.Drawing.Rectangle(0, 0, width, height), ImageLockMode.WriteOnly, System.Drawing.Imaging.PixelFormat.Format8bppIndexed);

            //获取图像参数
            //bmpData.Stride = width;
            int stride = bmpData.Stride;  // 扫描线的宽度  
            int offset = stride - width;  // 显示宽度与扫描线宽度的间隙  
            IntPtr iptr = bmpData.Scan0;  // 获取bmpData的内存起始位置  
            int scanBytes = stride * height;// 用stride宽度，表示这是内存区域的大小  下面把原始的显示大小字节数组转换为内存中实际存放的字节数组
            int posScan = 0, posReal = 0;// 分别设置两个位置指针，指向源数组和目标数组  
            byte[] pixelValues = new byte[scanBytes];  //为目标数组分配内存  
            for (int x = 0; x < height; x++)
            {
                //下面的循环节是模拟行扫描
                for (int y = 0; y < width; y++)
                {
                    pixelValues[posScan++] = rawValues[posReal++];
                }
                posScan += offset;  //行扫描结束，要将目标位置指针移过那段“间隙”  
            }
            //用Marshal的Copy方法，将刚才得到的内存字节数组复制到BitmapData中
            System.Runtime.InteropServices.Marshal.Copy(pixelValues, 0, iptr, scanBytes);
            bmp.UnlockBits(bmpData);  // 解锁内存区域  
                                      //下面的代码是为了修改生成位图的索引表，从伪彩修改为灰度
            ColorPalette tempPalette;
            using (Bitmap tempBmp = new Bitmap(1, 1, System.Drawing.Imaging.PixelFormat.Format8bppIndexed))
            {
                tempPalette = tempBmp.Palette;
            }
            for (int i = 0; i < 256; i++)
            {
                tempPalette.Entries[i] = System.Drawing.Color.FromArgb(i, i, i);
            }

            bmp.Palette = tempPalette;

            //算法到此结束，返回结果
            return bmp;
        }