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How do you use Capability Negotiation?

This feature is only available for TWAIN scanners.

A: Capability Negotiation is the way a TWAIN application communicates with a TWAIN source. This is how Dynamic Web TWAIN communicates with a scanner. The process looks something like this:

  • [Dynamic Web TWAIN] Are you capable of ***?
  • [Scanner] Yes, and here is what I can do…
  • [Dynamic Web TWAIN] Great, here is what I want done…
  • [Scanner] Consider it done

Dynamic Web TWAIN provides two methods, getCapabilities() and setCapabilities() , for negotiation. The following shows how to ask for supported page sizes and set it to A4 using Capability Negotiation.

Ask for supported sizes
DWObject.getCapabilities(function(result) {
    for (var i = 0; i < result.length; i++) {
        if (result[i].capability.value === Dynamsoft.DWT.EnumDWT_Cap.ICAP_SUPPORTEDSIZES)
            sizes = result[i].values;
}, function(error) {
Set page size to A4
        exception: "ignore",
        capabilities: [{
            capability: Dynamsoft.DWT.EnumDWT_Cap.ICAP_SUPPORTEDSIZES,
            curValue: 1, // 1 means 'A4' in our case
            exception: "fail"
    function(result) {
    function(error) {

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