c# - How does this code work? [HARD] -


link: http://www.codeproject.com/kb/dotnet/twaindotnet.aspx

i'm trying create wrapper class open source .net implementation of twain , i'm having trouble understand how gets image.

i've downloaded source code , in gui there button called acquire. when click button go it's event handler find code assume gets image:

private void menuitemscan_click(object sender, system.eventargs e) {     if (!msgfilter)     {         this.enabled = false;         msgfilter = true;         application.addmessagefilter(this);     }     tw.acquire(); }

if follow acquire() method see it's contents, see this:

public void acquire() {     twrc rc;     closesrc();     if (appid.id == intptr.zero)     {         init(hwnd);         if (appid.id == intptr.zero)             return;     }     rc = dsmident(appid, intptr.zero, twdg.control, twdat.identity, twmsg.opends, srcds);     if (rc != twrc.success)         return;      twcapability cap = new twcapability(twcap.xfercount, 1);     rc = dscap(appid, srcds, twdg.control, twdat.capability, twmsg.set, cap);     if (rc != twrc.success)     {         closesrc();         return;     }      twuserinterface guif = new twuserinterface();     guif.showui = 1;     guif.modalui = 1;     guif.parenthand = hwnd;     rc = dsuserif(appid, srcds, twdg.control, twdat.userinterface, twmsg.enableds, guif);     if (rc != twrc.success)     {         closesrc();         return;     } }

what don't understand how method 'void' return type can have return statement. also, acquiring , returning image?

can out?

i'm trying create useful wrapper , open source it, because stands there no easy drag , drop solution scanning images in c#.

thanks help!

edit: regarding returns. til! i'm curious how application gets images display on form.

any guidance?

"void" means returns nothing, not doesn't return. return statement terminates function , returns caller

for other question, there few other relevant stack overflow questions

the dscap line seeing if there multiple images. capture happens part of call dsuserif


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