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insert-image-after-selected-image.md

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title How can I insert an image after a selected image in the viewer?
keywords Dynamic Web TWAIN, Image Viewer, insert after selected image, insert
breadcrumbText How can I insert an image after a selected image in the viewer?
description How can I insert an image after a selected image in the viewer?
date 2021-12-09 11:34:50 +0800
last_modified 2024-09-19 08:47:35 +0800

Image Viewer

How can I insert an image after a selected image in the viewer?

By default, when you scan or load images, they are appended to the end of the image array in buffer. However, in some business scenarios, the user may want to insert these new images to a specified index. Unfortunately, Dynamic Web Twain does not provide a native method for that. The following code snippet shows how this functionality can be implemented.

1. Insert when acquiring

function acquireToIndex(index) {
  DWTObject.IfAppendImage = false;
  DWTObject.CurrentImageIndexInBuffer = index;
  DWTObject.RegisterEvent("OnPostTransfer", function () {
    DWTObject.CurrentImageIndexInBuffer++;
  });
  DWTObject.RegisterEvent("OnPostAllTransfers", function () {
    DWTObject.IfAppendImage = true;
  });
  DWTObject.AcquireImage();
}

2. Insert when loading

function loadToIndex(index) {
  var oldCount = DWTObject.HowManyImagesInBuffer;
  DWTObject.RegisterEvent("OnPostLoad", function () {
    var newCount = DWTObject.HowManyImagesInBuffer;
    for (var j = 0; j < newCount - oldCount; j++)
      DWTObject.MoveImage(oldCount + j, index + j);
  });
  DWTObject.LoadImageEx("", 5);
}