The rest server returns an image stream.

Assume that there is an image constantly changing at the backend of the rest server, and you want to provide a function to return the image stream, so that ASP. NET can be refreshed on a regular basis.

Rest server writes with Delphi Xe:

Function tremotediagnose. getviewpicturestream3 (aseesionid: string): tstream; <br/> begin <br/> result: = tmemorystream. create; <br/> try <br/> Inc (g_index); <br/> If (g_index mod 2) = 0 then <br/> tmemorystream (result ). loadfromfile ('C:/3s.png ') <br/> else <br/> tmemorystream (result ). loadfromfile ('C:/delphi-prism-mainlogo.png ') <br/> Reset T <br/> freeandnil (result); <br/> raise; <br/> end; <br/> end; </P> <p>

 

How can ASP. NET be displayed?

First, let's talk about Visual Studio 2010. I don't know what the previous version was like. This is really a huge memory-consuming tiger. I have 4 GB memory under windows7. After working for half a day, there will be insufficient memory, press Ctrl + C to display:

Check that the memory usage is 3.8gb.

 

To avoid refreshing the entire page, Ajax is required.

Assume that the web form has a webcontrols. Image component and sets its imageurl to myimage. aspx. The content of myimage. aspx is:

Write with Delphi Prism:

Namespace; </P> <p> interface </P> <p> uses <br/> system, <br/> system. data, <br/> system. configuration, <br/> system. web, <br/> system. web. security, <br/> system. web. sessionstate, <br/> system. web. UI, <br/> system. web. UI. webcontrols, <br/> system. web. UI. webcontrols. webparts, <br/> system. web. UI. htmlcontrols; </P> <p> type <br/> myimage = public partial class (system. web. UI. page) <br/> protected <br/> Method Page_load (Sender: object; E: eventargs); <br/> end; </P> <p> Implementation </P> <p> method myimage. page_load (Sender: object; E: eventargs); <br/> var <br/> MS: system. io. memorystream; <br/> O: tmyresult; <br/> S: string; <br/> vurl: string; <br/> VHC: remobjects. internetpack. HTTP. httpclient; <br/> vbytes: array of byte; <br/> vimage: image; <br/> vbmp: system. drawing. bitmap; <br/> FS: system. io. filestream; <br/> Vfilename: string; <br/> begin <br/> // you cannot use localhost ??!! <Br/> vurl: = 'HTTP: // 192.168.10.41: 8082/rest/restserver. dll/datasnap/rest/tremotediagnose/getviewpicturestream3/'; <br/> vurl: = vurl + system. uri. escapedatastring (Session. sessionid); <br/> VHC: = new remobjects. internetpack. HTTP. httpclient (); <br/> vbytes: = VHC. getbytes (vurl); <br/> // directly output the image <br/> response. clearcontent (); <br/> response. contenttype: = 'image/PNG '; <br/> response. binarywrite (vbytes); <br/> end; </P> <p> end. <br/>

Tick event of Ajax Timer:

VaR <br/> g_index: INTEGER: = 0; <br/> method _ default. timereffectick (Sender: system. object; E: system. eventargs); <br/> begin <br/> Inc (g_paramindex); <br/> image1.imageurl: = 'myimage. aspx? A = '+ g_paramindex.tostring (); <br/> end; <br/>

Here is a trick, that is, when you assign a value to image1.imageurl, the image will not be refreshed if the value remains the same. Therefore, you can give it a different parameter each time and let it think it has changed.

 

However, this effect is not satisfactory. Each time you refresh, there are two bad points:

1. the URL of the image will appear in the status bar, and the progress bar will also appear in the hour;

2. The mouse turns into an hourglass;

 

Can I solve this problem by using the server push method? How does image assign a byte stream to it?