c# - Populate ItemsControl from a Collection which is incomplete -


i need create pdf previewer in wpf , want display pages in itemscontrol bound observablecollection of rendered pages (each page bitmapsource instance). itemscontrol inside scrollviewer. now, don't want render pages @ once because there can hundred of them , eat memory fast. want render ones visible in app window. but, @ same time want itemscontrol big number of pages in pdf document scrollviewer's scrollbar adequately small , shows how more there scroll.

so question is, how make itemscontrol big number of pages not make observablecollection have pages?

i considered replacing itemscontrol grid , add dummy items height set height of page , replace actual page when it's visible user seems lot of work.

instead of having observablecollection<bitmapsource> (which seemingly have) should have observablecollection<page>, page class bitmapsource property implements inotifypropertychanged interface, e.g.

public class page : inotifypropertychanged {     public event propertychangedeventhandler propertychanged;      private bitmapsource image;      public bitmapsource image     {         { return image; }         set         {             image = value;             propertychanged?.invoke(this,                 new propertychangedeventargs(nameof(image)));         }     } }

you create many page instances there pages in document , put them observablecollection. when page loaded, assign image property, trigger binding in itemtemplate:

<itemssource.itemtemplate>     <datatemplate>         <image source="{binding image}"/>     <datatemplate> </itemssource.itemtemplate>

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