如何使用Dynamic Web TWAIN从网络摄像头捕获图像

元气小坏坏 提交于 2020-08-05 09:42:13

如何通过浏览器访问网络摄像头?

HTML5 为Web开发人员提供了JavaScript API MediaDevices.getUserMedia()。在本指南中,我们将使用Dynamic Web TWAIN SDK网络摄像头插件构建一个在线网络摄像头演示。

为什么选择Dynamic Web TWAIN网络摄像头附加组件

为什么有免费的选项时考虑付费选项?我们列出了HTML5不提供的网络摄像头附加组件的一些高级功能。

  • 浏览器兼容性 – HTML5与某些较旧的浏览器不兼容,例如Internet Explorer 8。
  • 精确控制网络摄像头 –您可以完全控制摄像机,例如摇摄,倾斜,滚动,变焦,曝光,光圈和自动对焦。
  • 分辨率设置 –使用GetResolution(),SetResolution()API获取和设置分辨率
  • 扫描仪质量的图像 – Dynamsoft提供了多种图像增强技术来帮助用户生成高质量的图像,包括自动边界检测,噪声消除和透视校正。
  • 上载到服务器 – SDK提供了内置方法,供用户将图像上载到服务器端。

如果您要构建一个健壮的,功能齐全的企业级应用程序,那么选择Dynamsoft的SDK这样的商业SDK将会为您带来巨大的投资回报。

关于Dynamic Web TWAIN网络摄像头附加组件

Dynamic Web TWAIN网络摄像头附加组件使Web开发人员可以使用JavaScript代码从网络摄像头捕获图像。网络摄像头SDK支持在Windows,macOS和Linux上的所有主流浏览器中嵌入视频流。Dynamic Web TWAIN还支持从移动相机捕获图像。

设备支持

  • 兼容UVC(USB视频类)的网络摄像头
  • 内置笔记本电脑摄像头
  • 文件相机

浏览器支持(跨平台)

  • Internet Explorer 8+
  • 边缘
  • 火狐浏览器

服务器端支持

  • Web服务器:Nginx,IIS,Tomcat,Apache等。
  • 操作系统:Linux,Windows等。
  • 语言:ASP.NET(C#/ VB.NET),PHP,JSP等

如何逐步使用网络摄像头附加组件

在这里,我们将向您展示如何使用SDK轻松地将HTML网页中的网络摄像头捕获和视频预览集成。首先,下载Dynamic Web TWAIN并将Resources文件夹复制到您的项目中。然后创建一个新的网页HelloWorld.html。

步骤1添加参考

<head>
    <script src="Resources/dynamsoft.webtwain.initiate.js"> </script>
    <script src="Resources/dynamsoft.webtwain.config.js"> </script>
    <script src="Resources/addon/dynamsoft.webtwain.addon.webcam.js"> </script>
</head>

步骤#2创建一个容器

<div id="dwtcontrolContainer"></div>

步骤#3输入一个下拉列表和两个按钮  

步骤#4通过调用Dynamsoft_OnReady()初始化对象

<script type="text/javascript">
        var DWObject;
        var isVideoOn = true;
 
        function Dynamsoft_OnReady() {
            DWObject = Dynamsoft.WebTwainEnv.GetWebTwain('dwtcontrolContainer'); // Get the Dynamic Web TWAIN object that is embedded in the div with id 'dwtcontrolContainer'
            if (DWObject) {
                DWObject.Width = 504;
                DWObject.Height = 600;
 
                var arySource = DWObject.Addon.Webcam.GetSourceList();
                for (var i = 0; i < arySource.length; i++)
                    document.getElementById("source").options.add(new Option(arySource[i], arySource[i]), i); // Get Webcam Source names and put them in a drop-down box
            }
            document.getElementById('source').onchange = function () {
          DWObject.Addon.Webcam.SelectSource(document.getElementById("source").options[document.getElementById("source").selectedIndex].value);
                SetIfWebcamPlayVideo(true);           
            }
            document.getElementById('source').onchange();
        }
    </script>

步骤#5控制网络摄像头

您可以使用以下API播放和停止视频流:DWObject.Addon.Webcam.StopVideo()和DWObject.Addon.Webcam.PlayVideo(DWObject,80,function(){})。

function enableButton(element) {
            element.style.backgroundColor = "";
            element.disabled = "";
        }
 
        function disableButton(element) {
            element.style.backgroundColor = "#aaa";
            element.disabled = "disabled";
        }
        
        function SetIfWebcamPlayVideo(bShow) {
            if (bShow) {
                DWObject.Addon.Webcam.StopVideo();
                DWObject.Addon.Webcam.PlayVideo(DWObject, 80, function () { });
                isVideoOn = true;
                enableButton(document.getElementById("btn-grab"));
                document.getElementById("btn-switch").value = "Hide Video";
            }
            else {
                DWObject.Addon.Webcam.StopVideo();
                isVideoOn = false;
                disableButton(document.getElementById("btn-grab"));
                document.getElementById("btn-switch").value = "Show Video";             
            }
        }
 
        function SwitchViews() {
            if (isVideoOn == false) {
                // continue the video
                SetIfWebcamPlayVideo(true);
            } else {
                // stop the video
                SetIfWebcamPlayVideo(false);
            }           
        }

步骤#6通过使用CaptureImage()捕获图像

function CaptureImage() {
            if (DWObject) {
                var funCaptureImage = function () {
                    SetIfWebcamPlayVideo(false);
                };
                DWObject.Addon.Webcam.CaptureImage(funCaptureImage, funCaptureImage);
            }
        }

如何同时从扫描仪和网络摄像头捕获图像

文档/记录管理应用程序通常需要通过Web浏览器从扫描仪和网络摄像机捕获图像。您可以使用Dynamic Web TWAIN核心SDK和网络摄像头附加组件轻松实现此目的。 

网络摄像头和扫描仪捕获JavaScript

让我们继续在HelloWorld.html网页上进行工作。

步骤#1重写函数Dynamsoft_OnReady()

要控制TWAIN扫描器,请调用API:DWObject = Dynamsoft.WebTwainEnv.GetWebTwain('dwtcontrolContainer')

Dynamsoft.WebTwainEnv.AutoLoad = false;
        Dynamsoft.WebTwainEnv.RegisterEvent('OnWebTwainReady', Dynamsoft_OnReady); // Register OnWebTwainReady event. This event fires as soon as Dynamic Web TWAIN is initialized and ready to be used
 
        var webCamStartingIndex;//This is used to separate scanners and webcams
        var DWObject;
        var isVideoOn = true;
 
        function Dynamsoft_OnReady() {
            DWObject = Dynamsoft.WebTwainEnv.GetWebTwain('dwtcontrolContainer'); // Get the Dynamic Web TWAIN object that is embedded in the div with id 'dwtcontrolContainer'
            if (DWObject) {
                DWObject.Width = 504;
                DWObject.Height = 600;
 
                document.getElementById('source').options.length = 0;
                var count = DWObject.SourceCount;
                for (var i = 0; i < count; i++) { document.getElementById('source').options.add(new Option(DWObject.GetSourceNameItems(i), i)); } webCamStartingIndex = i; var arySource = DWObject.Addon.Webcam.GetSourceList(); for (var i = 0; i < arySource.length; i++) document.getElementById("source").options.add(new Option(arySource[i], arySource[i]), i + webCamStartingIndex); // Get Webcam Source names and put them in a drop-down box } document.getElementById('source').onchange = function () { if (document.getElementById('source').selectedIndex < webCamStartingIndex) { if (arySource.length > 0) 
                        DWObject.Addon.Webcam.StopVideo();
                    isVideoOn = false;
                    document.getElementById("btn-grab").style.backgroundColor = "";
                    document.getElementById('btn-grab').value = 'Acquire From a Scanner';
                    document.getElementById("btn-switch").style.display = 'none';
                }
                else {
                    DWObject.Addon.Webcam.SelectSource(document.getElementById("source").options[document.getElementById("source").selectedIndex].value);
 
                    SetIfWebcamPlayVideo(true);
 
                    document.getElementById('btn-grab').value = 'Acquire From a Webcam';
                    document.getElementById("btn-switch").style.display = '';
                }
                document.getElementById("btn-grab").disabled = "";
            }
 
            document.getElementById('source').onchange();
        }

步骤#2捕获图像

function CaptureImage() {
            if (DWObject) {
                if (document.getElementById('source').selectedIndex < webCamStartingIndex) { DWObject.IfShowUI = true; DWObject.IfDisableSourceAfterAcquire = true; DWObject.SelectSourceByIndex(document.getElementById('source').selectedIndex); DWObject.CloseSource(); DWObject.OpenSource(); DWObject.AcquireImage(); } else { var funCaptureImage = function () { SetIfWebcamPlayVideo(false); }; DWObject.Addon.Webcam.CaptureImage(funCaptureImage, funCaptureImage); } } }

如何将扫描的图像上传到服务器端

步骤#1添加用于上传的按钮


 

步骤#2上传图片
准备好图像后,您可以通过调用HTTPUploadThroughPost()将其上传到Web服务器。

function upload() {
            if (DWObject) {
                // If no image in buffer, return the function
                if (DWObject.HowManyImagesInBuffer == 0)
                    return;
 
                var strHTTPServer = location.hostname; //The name of the HTTP server. For example: "www.dynamsoft.com";
                var CurrentPathName = unescape(location.pathname);
                var CurrentPath = CurrentPathName.substring(0, CurrentPathName.lastIndexOf("/") + 1);
                var strActionPage = CurrentPath + "filename"; // Action page
                DWObject.IfSSL = false; // Set whether SSL is used
                DWObject.HTTPPort = location.port == "" ? 80 : location.port;
 
                var Digital = new Date();
                var uploadfilename = Digital.getMilliseconds(); // Uses milliseconds according to local time as the file name
 
                //Upload image in JPEG
                DWObject.HTTPUploadThroughPost(strHTTPServer, DWObject.CurrentImageIndexInBuffer, strActionPage, uploadfilename + ".jpg", OnHttpUploadSuccess, OnHttpUploadFailure);
            }
        }

该SDK支持ASP.NET(C#/ VB.NET),PHP,JSP,ASP等,以在服务器端接收图像数据。

PHP代码

 


 

 

php网络摄像头应用程序

JSP代码

<%@page import="java.util.*,java.io.File,java.io.FileOutputStream,org.apache.commons.fileupload.FileUpload,org.apache.commons.fileupload.FileItem,org.apache.commons.fileupload.disk.DiskFileItemFactory,org.apache.commons.fileupload.servlet.ServletFileUpload,sun.misc.BASE64Decoder"%>
<%@page contentType="application/json; charset=utf-8" %>
<%@page language="java" %>
<% String strJson = "{\"success\":false}"; try{ // get more info from: http://commons.apache.org/proper/commons-fileupload/ DiskFileItemFactory factory = new DiskFileItemFactory(); ServletContext servletContext = this.getServletConfig().getServletContext(); File repository = (File) servletContext.getAttribute("javax.servlet.context.tempdir"); factory.setRepository(repository); ServletFileUpload upload = new ServletFileUpload(factory); List items = upload.parseRequest(request);
        Iterator iter = items.iterator();
 
        String fileName = null;
        String tempFileName = null;
        String contentType = null;
        FileItem fileItem = null;
 
        while (iter.hasNext()) {
            FileItem item = iter.next();
            String fieldName = item.getFieldName();
 
            if(fieldName.equals("fileName")){
                fileName = item.getString();
            }else if(fieldName.equals("RemoteFile")){
                tempFileName = item.getName();
                contentType = item.getContentType();
                fileItem = item;
            }
        }
 
        if(fileName == null || fileName.isEmpty()){
            fileName = tempFileName;
        }
        String path = application.getRealPath(request.getServletPath());
        String dir = new java.io.File(path).getParent();
        String filePath = dir + "/UploadedImages/" + fileName;
 
        File file = new File(filePath);
 
        if(!file.getParentFile().exists()){
            file.getParentFile().mkdir();
        }
        if(!file.exists()){
            file.createNewFile();
        }
        if(!contentType.contains("text/plain")){
            fileItem.write(file);
        }else{
            String base64Str = fileItem.getString();
            byte[] b = null;
            b = (new BASE64Decoder()).decodeBuffer(base64Str);
            FileOutputStream fileOutStream = new FileOutputStream(file);
            fileOutStream.write(b);
            fileOutStream.flush();
            fileOutStream.close();
        }
 
        strJson = "{\"success\":true, \"fileName\":\"" + fileName + "\"}";
    }
    catch(Exception ex){
        strJson = "{\"success\":false, \"error\": \"" + ex.getMessage().replace("\\", "\\\\") + "\"}";
    }
 
    out.clear();
    out.write(strJson);
    out.close();
%>

ASP.NET(C#)代码

<%@ Page Language="C#" %>
<%@ Import Namespace="System.IO" %>
<% string strJson = "{\"success\":false}"; try { HttpPostedFile file = Request.Files["RemoteFile"]; string fileName = Request.Form["fileName"]; if (string.IsNullOrEmpty(fileName)) fileName = file.FileName; string filePath = Server.MapPath(".") + "\\UploadedImages\\" + fileName; if (!file.ContentType.Contains("text/plain")) { file.SaveAs(filePath); } else { Stream fs = file.InputStream; byte[] base64Bytes = new byte[fs.Length]; fs.Read(base64Bytes, 0, (int) fs.Length); StringBuilder base64Str = new StringBuilder(); foreach (byte b in base64Bytes) { base64Str.Append((char) b); } File.WriteAllBytes(filePath, Convert.FromBase64String(base64Str.ToString())); } strJson = "{\"success\":true, \"fileName\":\"" + fileName + "\"}"; } catch (Exception ex) { strJson = "{\"success\":false, \"error\": \"" + ex.Message.Replace("\\", "\\\\") + "\"}"; } Response.Clear(); Response.ContentType = "application/json; charset=utf-8"; Response.Write(strJson); Response.End(); %>
本文转载自【慧都科技】。欢迎任何形式的转载,但请务必注明出处、不得修改原文相关链接,尊重他人劳动成果
易学教程内所有资源均来自网络或用户发布的内容,如有违反法律规定的内容欢迎反馈
该文章没有解决你所遇到的问题?点击提问,说说你的问题,让更多的人一起探讨吧!