最经遇到一个很棘手的问题，写出来大家探讨一下。
工作流系统中存在很多自定义的表单，由于是老系统，这些表单只能支持IE。现在做移动应用，需要将这些自定义的aspx表单展示在mobile safari浏览器中。
这些自定义表单用了大量的htc、只支持ie的javascript。而现在的任务是需要将这些表单展示在mobile safari浏览器中。
想了很多办法感觉都不好。昨天突然想到一个办法就是根据Url将表单转换成图片，然后展示到移动客户端。大致流程是：在服务端创建一个WebBrowser实例，在这个WebBrowser加载这个表单Url。由于WebBrowser内置的是IE内核，所以htc，javascript、css都能很好的运行，然后将通过ActiveX 将这个WebBrowser转换成图片。代码如下：
IViewObject.cs
[ComVisible(true), ComImport()]
[GuidAttribute("0000010d-0000-0000-C000-000000000046")]
[InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)]
public interface IViewObject
{
[return: MarshalAs(UnmanagedType.I4)]
[PreserveSig]
int Draw(
[MarshalAs(UnmanagedType.U4)] UInt32 dwDrawAspect,
int lindex,
IntPtr pvAspect,
[In] IntPtr ptd,
IntPtr hdcTargetDev,
IntPtr hdcDraw,
[MarshalAs(UnmanagedType.Struct)] ref Rectangle lprcBounds,
[MarshalAs(UnmanagedType.Struct)] ref Rectangle lprcWBounds,
IntPtr pfnContinue,
[MarshalAs(UnmanagedType.U4)] UInt32 dwContinue);
[PreserveSig]
int GetColorSet([In, MarshalAs(UnmanagedType.U4)] int dwDrawAspect,
int lindex, IntPtr pvAspect, [In] IntPtr ptd,
IntPtr hicTargetDev, [Out] IntPtr ppColorSet);
[PreserveSig]
int Freeze([In, MarshalAs(UnmanagedType.U4)] int dwDrawAspect,
int lindex, IntPtr pvAspect, [Out] IntPtr pdwFreeze);
[PreserveSig]
int Unfreeze([In, MarshalAs(UnmanagedType.U4)] int dwFreeze);
void SetAdvise([In, MarshalAs(UnmanagedType.U4)] int aspects,
[In, MarshalAs(UnmanagedType.U4)] int advf,
[In, MarshalAs(UnmanagedType.Interface)] IAdviseSink pAdvSink);
void GetAdvise([In, Out, MarshalAs(UnmanagedType.LPArray)] int[] paspects,
[In, Out, MarshalAs(UnmanagedType.LPArray)] int[] advf,
[In, Out, MarshalAs(UnmanagedType.LPArray)] IAdviseSink[] pAdvSink);
}
HtmlCapture.cs
publicclass HtmlCapture
{
private WebBrowser web;
private Timer tready;
private Rectangle screen;
private Size? imgsize =null;
//an event that triggers when the html document is captured
publicdelegatevoid HtmlCaptureEvent(object sender,
Uri url, Bitmap image);
publicevent HtmlCaptureEvent HtmlImageCapture;
//class constructor
public HtmlCapture()
{
//initialise the webbrowser and the timer
web =new WebBrowser();
tready =new Timer();
tready.Interval =2000;
screen = Screen.PrimaryScreen.Bounds;
//set the webbrowser width and hight
web.Width = screen.Width;
web.Height = screen.Height;
//suppress script errors and hide scroll bars
web.ScriptErrorsSuppressed =true;
web.ScrollBarsEnabled =false;
//attached events
web.Navigating +=
new WebBrowserNavigatingEventHandler(web_Navigating);
web.DocumentCompleted +=new
WebBrowserDocumentCompletedEventHandler(web_DocumentCompleted);
tready.Tick +=new EventHandler(tready_Tick);
}
#region Public methods
publicvoid Create(string url)
{
imgsize =null;
web.Navigate(url);
}
publicvoid Create(string url, Size imgsz)
{
this.imgsize = imgsz;
web.Navigate(url);
}
#endregion
#region Events
void web_DocumentCompleted(object sender,
WebBrowserDocumentCompletedEventArgs e)
{
//start the timer
tready.Start();
// string s = web.Document.GetElementById("").InnerHtml;
}
void web_Navigating(object sender, WebBrowserNavigatingEventArgs e)
{
//stop the timer
tready.Stop();
}
void tready_Tick(object sender, EventArgs e)
{
//stop the timer
tready.Stop();
//get the size of the document's body
Rectangle body = web.Document.Body.ScrollRectangle;
//check if the document width/height is greater than screen width/height
Rectangle docRectangle =new Rectangle()
{
Location =new Point(0, 0),
Size =new Size(body.Width > screen.Width ? body.Width : screen.Width,
body.Height > screen.Height ? body.Height : screen.Height)
};
//set the width and height of the WebBrowser object
web.Width = docRectangle.Width;
web.Height = docRectangle.Height;
//if the imgsize is null, the size of the image will
//be the same as the size of webbrowser object
//otherwise set the image size to imgsize
Rectangle imgRectangle;
if (imgsize ==null)
imgRectangle = docRectangle;
else
imgRectangle =new Rectangle()
{
Location =new Point(0, 0),
Size = imgsize.Value
};
//create a bitmap object
Bitmap bitmap =new Bitmap(imgRectangle.Width, imgRectangle.Height);
//get the viewobject of the WebBrowser
IViewObject ivo = web.Document.DomDocument as IViewObject;
ivo.ToString();
using (Graphics g = Graphics.FromImage(bitmap))
{
//get the handle to the device context and draw
IntPtr hdc = g.GetHdc();
ivo.Draw(1, -1, IntPtr.Zero, IntPtr.Zero,
IntPtr.Zero, hdc, ref imgRectangle,
ref docRectangle, IntPtr.Zero, 0);
g.ReleaseHdc(hdc);
}
//invoke the HtmlImageCapture event
HtmlImageCapture(this, web.Url, bitmap);
}
#endregion
}
}
下面我们使用上面代码可以截图工作流表单的图片了：
void hc_HtmlImageCapture(object sender, Uri url, Bitmap image)
{
image.Save("C:/test.bmp");
}
private void button1_Click(object sender, EventArgs e)
{
HtmlCapture hc = new HtmlCapture();
hc.HtmlImageCapture += new HtmlCapture.HtmlCaptureEvent(hc_HtmlImageCapture);
hc.Create("http://10.5.23.117:8011/Recipe1.aspx");
}
这样效果和PC端展示一样。
截取百度快照：
获取的图片：
尽管展示和pc端一样，但是图片存在的问题主要有：
1、不支持复制粘贴
2、不支持多标签页的切换（移动端不需要支持表单编辑功能）
3、不支持超链接点击
总结：由于WebBrowser支持htc、已经写好的javascript代码，而js和htc做了不少业务逻辑处理，所以在服务端使用WebBrowser去处理表单的思路是正确的。但是进一步如何解决上面的三个问题。需要进一步探讨。在不大量修改之前存在的工作流表单的前提下，如果你有更好的想法，期待你的告诉我。
（全文完）
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