C#实现网页加载后将页面截取成长图片

Posted 2021-04-14 dotNET跨平台

背景

最近再做一个需求，需要对网页生成预览图，如下图

但是网页千千万，总不能一个个打开，截图吧；于是想着能不能使用代码来实现网页的截图。其实要实现这个功能，无非就是要么实现一个仿真浏览器，要么调用系统浏览器，再进行截图操作。

代码实现

1、启用线程Thread

 void startPrintScreen(ScreenShotParam requestParam) { Thread thread = new Thread(new ParameterizedThreadStart(do_PrintScreen)); thread.SetApartmentState(ApartmentState.STA); thread.Start(requestParam); if (requestParam.Wait) { thread.Join(); FileInfo result = new FileInfo(requestParam.SavePath); long minSize = 1 * 1024;// 太小可能是空白圖，重抓 int maxRepeat = 2;  while ((!result.Exists || result.Length <= minSize) && maxRepeat > 0) { thread = new Thread(new ParameterizedThreadStart(do_PrintScreen)); thread.SetApartmentState(ApartmentState.STA); thread.Start(requestParam); thread.Join(); maxRepeat--; } } }

2、模拟浏览器WebBrowser

 void do_PrintScreen(object param) { try { ScreenShotParam screenShotParam = (ScreenShotParam)param; string requestUrl = screenShotParam.Url; string savePath = screenShotParam.SavePath; WebBrowser wb = new WebBrowser(); wb.ScrollBarsEnabled = false; wb.ScriptErrorsSuppressed = true; wb.Navigate(requestUrl); logger.Debug("wb.Navigate"); DateTime startTime = DateTime.Now; TimeSpan waitTime = new TimeSpan(0, 0, 0, 10, 0);// 10 second while (wb.ReadyState != WebBrowserReadyState.Complete) { Application.DoEvents(); if (DateTime.Now - startTime > waitTime) { wb.Dispose(); logger.Debug("wb.Dispose() timeout"); return; } }
 wb.Width = screenShotParam.Left + screenShotParam.Width + screenShotParam.Left; // wb.Document.Body.ScrollRectangle.Width (避掉左右側的邊線); wb.Height = screenShotParam.Top + screenShotParam.Height; // wb.Document.Body.ScrollRectangle.Height; wb.ScrollBarsEnabled = false; wb.Document.Body.Style = "overflow:hidden";//hide scroll bar var doc = (wb.Document.DomDocument) as mshtml.IHTMLDocument2; var style = doc.createStyleSheet("", 0); style.cssText = @"img { border-style: none; }";
 Bitmap bitmap = new Bitmap(wb.Width, wb.Height); wb.DrawToBitmap(bitmap, new Rectangle(0, 0, wb.Width, wb.Height)); wb.Dispose(); logger.Debug("wb.Dispose()");
 bitmap = CutImage(bitmap, new Rectangle(screenShotParam.Left, screenShotParam.Top, screenShotParam.Width, screenShotParam.Height)); bool needResize = screenShotParam.Width > screenShotParam.ResizeMaxWidth || screenShotParam.Height > screenShotParam.ResizeMaxWidth; if (needResize) { double greaterLength = bitmap.Width > bitmap.Height ? bitmap.Width : bitmap.Height; double ratio = screenShotParam.ResizeMaxWidth / greaterLength; bitmap = Resize(bitmap, ratio); }
 bitmap.Save(savePath, System.Drawing.Imaging.ImageFormat.Gif); bitmap.Dispose(); logger.Debug("bitmap.Dispose();"); logger.Debug("finish");
 } catch (Exception ex) { logger.Info($"exception: {ex.Message}"); } }

3、截图操作

 private static Bitmap CutImage(Bitmap source, Rectangle section) { // An empty bitmap which will hold the cropped image Bitmap bmp = new Bitmap(section.Width, section.Height); //using (Bitmap bmp = new Bitmap(section.Width, section.Height)) { Graphics g = Graphics.FromImage(bmp);
 // Draw the given area (section) of the source image // at location 0,0 on the empty bitmap (bmp) g.DrawImage(source, 0, 0, section, GraphicsUnit.Pixel);
 return bmp; } }
 private static Bitmap Resize(Bitmap originImage, Double times) { int width = Convert.ToInt32(originImage.Width * times); int height = Convert.ToInt32(originImage.Height * times);
 return ResizeProcess(originImage, originImage.Width, originImage.Height, width, height); }

完整代码

  public static string ScreenShotAndSaveAmazonS3(string account, string locale, Guid rule_ID, Guid template_ID) {  //新的Template var url = string.Format("https://xxxx/public/previewtemplate?showTemplateName=0&locale={0}&inputTemplateId={1}&inputThemeId=&Account={2}", locale, template_ID, account ); 
 var tempPath = Tools.GetAppSetting("TempPath");
 //路徑準備 var userPath = AmazonS3.GetS3UploadDirectory(account, locale, AmazonS3.S3SubFolder.Template); var fileName = string.Format("{0}.gif", template_ID); var fullFilePath = Path.Combine(userPath.LocalDirectoryPath, fileName); logger.Debug("userPath: {0}, fileName: {1}, fullFilePath: {2}, url:{3}", userPath, fileName, fullFilePath, url);  //開始截圖，並暫存在本機 var screen = new Screen(); screen.ScreenShot(url, fullFilePath);
 //將截圖，儲存到 Amazon S3 //var previewImageUrl = AmazonS3.UploadFile(fullFilePath, userPath.RemotePath + fileName);
 return string.Empty; }

using System;using System.Collections.Generic;using System.Drawing;using System.IO;using System.Linq;using System.Text;using System.Threading;using System.Threading.Tasks;using System.Windows.Forms;
namespace PrintScreen.Common{ public class Screen { protected static NLog.Logger logger = NLog.LogManager.GetCurrentClassLogger();
 public void ScreenShot(string url, string path , int width = 400, int height = 300 , int left = 50, int top = 50 , int resizeMaxWidth = 200, int wait = 1) { if (!string.IsNullOrEmpty(url) && !string.IsNullOrEmpty(path)) { ScreenShotParam requestParam = new ScreenShotParam { Url = url, SavePath = path, Width = width, Height = height, Left = left, Top = top, ResizeMaxWidth = resizeMaxWidth, Wait = wait != 0 }; startPrintScreen(requestParam); } }
 void startPrintScreen(ScreenShotParam requestParam) { Thread thread = new Thread(new ParameterizedThreadStart(do_PrintScreen)); thread.SetApartmentState(ApartmentState.STA); thread.Start(requestParam); if (requestParam.Wait) { thread.Join(); FileInfo result = new FileInfo(requestParam.SavePath); long minSize = 1 * 1024;// 太小可能是空白圖，重抓 int maxRepeat = 2;  while ((!result.Exists || result.Length <= minSize) && maxRepeat > 0) { thread = new Thread(new ParameterizedThreadStart(do_PrintScreen)); thread.SetApartmentState(ApartmentState.STA); thread.Start(requestParam); thread.Join(); maxRepeat--; } } }
 void do_PrintScreen(object param) { try { ScreenShotParam screenShotParam = (ScreenShotParam)param; string requestUrl = screenShotParam.Url; string savePath = screenShotParam.SavePath; WebBrowser wb = new WebBrowser(); wb.ScrollBarsEnabled = false; wb.ScriptErrorsSuppressed = true; wb.Navigate(requestUrl); logger.Debug("wb.Navigate"); DateTime startTime = DateTime.Now; TimeSpan waitTime = new TimeSpan(0, 0, 0, 10, 0);// 10 second while (wb.ReadyState != WebBrowserReadyState.Complete) { Application.DoEvents(); if (DateTime.Now - startTime > waitTime) { wb.Dispose(); logger.Debug("wb.Dispose() timeout"); return; } }
 wb.Width = screenShotParam.Left + screenShotParam.Width + screenShotParam.Left; // wb.Document.Body.ScrollRectangle.Width (避掉左右側的邊線); wb.Height = screenShotParam.Top + screenShotParam.Height; // wb.Document.Body.ScrollRectangle.Height; wb.ScrollBarsEnabled = false; wb.Document.Body.Style = "overflow:hidden";//hide scroll bar var doc = (wb.Document.DomDocument) as mshtml.IHTMLDocument2; var style = doc.createStyleSheet("", 0); style.cssText = @"img { border-style: none; }";
 Bitmap bitmap = new Bitmap(wb.Width, wb.Height); wb.DrawToBitmap(bitmap, new Rectangle(0, 0, wb.Width, wb.Height)); wb.Dispose(); logger.Debug("wb.Dispose()");
 bitmap = CutImage(bitmap, new Rectangle(screenShotParam.Left, screenShotParam.Top, screenShotParam.Width, screenShotParam.Height)); bool needResize = screenShotParam.Width > screenShotParam.ResizeMaxWidth || screenShotParam.Height > screenShotParam.ResizeMaxWidth; if (needResize) { double greaterLength = bitmap.Width > bitmap.Height ? bitmap.Width : bitmap.Height; double ratio = screenShotParam.ResizeMaxWidth / greaterLength; bitmap = Resize(bitmap, ratio); }
 bitmap.Save(savePath, System.Drawing.Imaging.ImageFormat.Gif); bitmap.Dispose(); logger.Debug("bitmap.Dispose();"); logger.Debug("finish");
 } catch (Exception ex) { logger.Info($"exception: {ex.Message}"); } }
 private static Bitmap CutImage(Bitmap source, Rectangle section) { // An empty bitmap which will hold the cropped image Bitmap bmp = new Bitmap(section.Width, section.Height); //using (Bitmap bmp = new Bitmap(section.Width, section.Height)) { Graphics g = Graphics.FromImage(bmp);
 // Draw the given area (section) of the source image // at location 0,0 on the empty bitmap (bmp) g.DrawImage(source, 0, 0, section, GraphicsUnit.Pixel);
 return bmp; } }
 private static Bitmap Resize(Bitmap originImage, Double times) { int width = Convert.ToInt32(originImage.Width * times); int height = Convert.ToInt32(originImage.Height * times);
 return ResizeProcess(originImage, originImage.Width, originImage.Height, width, height); }
 private static Bitmap ResizeProcess(Bitmap originImage, int oriwidth, int oriheight, int width, int height) { Bitmap resizedbitmap = new Bitmap(width, height); //using (Bitmap resizedbitmap = new Bitmap(width, height)) { Graphics g = Graphics.FromImage(resizedbitmap); g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; g.Clear(Color.Transparent); g.DrawImage(originImage, new Rectangle(0, 0, width, height), new Rectangle(0, 0, oriwidth, oriheight), GraphicsUnit.Pixel); return resizedbitmap; } }
 }
 class ScreenShotParam { public string Url { get; set; } public string SavePath { get; set; } public int Width { get; set; } public int Height { get; set; } public int Left { get; set; } public int Top { get; set; } /// <summary> /// 長邊縮到指定長度 /// </summary> public int ResizeMaxWidth { get; set; } public bool Wait { get; set; } }
}

效果

完成，达到预期的效果。