抓取网页图片问题

Question

请问怎么用C#程序实现抓取网页上的图片？
然后把该图片保存为相应格式（jpg、gif…)？
可以的话麻烦给出代码～多谢啦！！！

Answer 1

http://blog.csdn.net/hertcloud/archive/2007/03/14/1528971.aspx通过HttpWebResponse和HttpWebRequest 获取http地址上的图片

Answer 2

主要思想：
使用IE控件先显示网页，然后使用API函数将其绘画内容写入image对象，然后保存。
主要函数，传入IE控件
public static Image Capture(Control control, ImageSettingInfo imageInfo)codeproject有个示例，可以拍摄一个很大的网页的图片，我这个只能拍摄当前显示的内容，但可以拍摄任何控件。以下是代码：using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Text;
using System.Runtime.InteropServices;
using System.Diagnostics;
using System.IO;
using System.Drawing.Imaging;using BaseFrame.ShareFunction;namespace BaseFrame.Images
{
    /// <summary>
    /// 捕获窗口的影响
    /// </summary>
    public sealed class CaptureImage
    {
        // Violates rule: StaticHolderTypesShouldNotHaveConstructors.
        // Uncomment the following line to correct the violation.
        private CaptureImage() { }        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        private static extern Boolean PrintWindow(IntPtr hwnd, IntPtr hdcBlt, uint nFlags);        #region 常量
        /// <summary>
        /// 画图开始X坐标
        /// </summary>
        public const int BRWTOP = 0;
        /// <summary>
        /// Y坐标
        /// </summary>
        public const int BRWLEFT = 0;
        /// <summary>
        /// 图片质量
        /// </summary>
        public const long QUALITY = 100;
        /// <summary>
        /// 原图大小
        /// </summary>
        public const double RESOLUTION = 1.0;
        #endregion        //public delegate void CaptureHandler();        //public static event CaptureHandler CaptureImageEvent;        //public delegate void ThumbnailHandler();        //public static event ThumbnailHandler ThumbnailImageEvent;        public static Image Capture(Control control, ImageSettingInfo imageInfo)
        {
            Debug.Assert(control != null);
            if (control == null)
            {
                throw new ArgumentNullException("control is null");
            }
            Debug.Assert(imageInfo != null);
            if (imageInfo == null)
            {
                throw new ArgumentNullException("imageInfo is null");
            }            IntPtr hwnd = control.Handle;
            //Get bitmap to hold screen fragment.
            Bitmap bm = null;            Graphics g = null;
            IntPtr hdc;
            //Image screenfrag = null;            Bitmap finalImage = null;            Image originalImage = null;
            try
            {
                // 计算最终图片大小
                int finalWidth = (int)((imageInfo.ImageWidth) * RESOLUTION);
                int finalHeight = (int)((imageInfo.ImageHeight) * RESOLUTION);                bm = new Bitmap(finalWidth, finalHeight, System.Drawing.Imaging.PixelFormat.Format32bppRgb);                g = Graphics.FromImage(bm);                hdc = g.GetHdc();                // 绘画目标窗口到 hdc
                PrintWindow(hwnd, hdc, 0);                g.ReleaseHdc(hdc);                g.Flush();                g.DrawImage(bm, BRWLEFT, BRWTOP, finalWidth, finalHeight);                //Write Image.
                EncoderParameters eps = new EncoderParameters(1);                eps.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, QUALITY);                ImageCodecInfo ici = GetEncoderInfo("image/" + imageInfo.ImageFormat.ToString().ToLower());                // 确保保存路径存在
                if (!Directory.Exists(Path.GetDirectoryName(imageInfo.ImageSavePath)))
                {
                    Directory.CreateDirectory(Path.GetDirectoryName(imageInfo.ImageSavePath));
                }                // 保存图片
                bm.Save(imageInfo.ImageSavePath, ici, eps);                // 返回最终图片
                originalImage = Image.FromHbitmap(bm.GetHbitmap());
            }
            catch (ExternalException ex)
            {
                LogInfo.Log(ex);
            }
            catch (IOException ex)
            {
                LogInfo.Log(ex);
            }
            catch (Exception ex)
            {
                LogInfo.Log(ex);
            }
            finally
            {
                if (g != null)
                    g.Dispose();
                if (bm != null)
                    bm.Dispose();
                if (finalImage != null)
                    finalImage.Dispose();
            }            return originalImage;
        }        private static ImageCodecInfo GetEncoderInfo(String mimeType)
        {
            ImageCodecInfo[] encoders;
            encoders = ImageCodecInfo.GetImageEncoders();
            for (int j = 0; j < encoders.Length; ++j)
            {
                if (encoders[j].MimeType == mimeType)
                    return encoders[j];
            }
            return null;
        }
    }
}