Add UI for adding comments and ability to save them. Comments are represented in the document model as text annotations (annotations with Subtype Text). 

When there is no ToUnicode CMap, the text from the Simple Font instance (TrueType or Type1 font) should be extracted by mapping the glyph name to its corresponding charcode according to Adobe Glyph List. Additionally, the Differences array should be included in these calculations when there is custom encoding. The current implementation of RadPdfViewer makes ToString to the original char id byte value which leads to wrong characters. 

More information about this may be seen in the second point of section "5.9.1Mapping Character Codes to Unicode Values" on page 470 in PdfReference 1.7.

The rendering of images with size ~5000/6000 and BitsPerComponent is time-consuming. The scenario is optimized in terms of memory but would be nice to increase the performance as well.

RadPdfViewer partially supports CCITTFaxDecode (that is basically TIFF). There are some limitations that are not supported at this stage like EncodedByteAlign = true or Group 3, 2-D encoding.

Include support for layers

While the other annotations are drawn on top of the content, the highlight annotation is behind the text it highlights. In other words, it has to be inserted at a specific place in the ContentElementsUILayer. The pdf seems to mark the precise place where the highlight should be placed with the BDC, MCID and EMC operators in the content. At the moment, the read-only rendering of the highlight annotation has been implemented with an instance of the AnnotationUILayer called "HighlightUILayer" which is placed behind the ContentElementsUILayer. With this implementation, depending on the contents of the pdf, the highlight annotation might be visible or it might not be. 

To reproduce:
- Drop a RadPdfViewer on a blank form at design time. 

Some documents reqire this assembly as well. 

To reproduce:
Open a document that has highlighted areas.

One should be able to handle the annotations/hyperlinks clicking. 

Add a navigation pane to view attachments under a pdf. it is possible to have various attachments under a pdf file, such has another pdf. For example, when converting an email with attachments, the resulting pdf has attachments. 

RadPdfViewer has no possibility to view those right now. Could be an event and let the calling program manage this.

For our needs, I would like an event, because our attached files are also pdfs, so I could open them in a new tab

When Find Next is used multiple times fast, and pages are still loaded asynchronously, sometimes NullReferenceException is thrown with the following call stack:

System.NullReferenceException: Object reference not set to an instance of an object.
   at Telerik.Windows.Documents.Fixed.Text.TextRecognizer.GetLastCharacter()
   at Telerik.Windows.Documents.Fixed.Text.TextRecognizer.IsLineBreak(Glyph glyph)
   at Telerik.Windows.Documents.Fixed.Text.TextRecognizer.ProcessGlyph(Glyph glyph)
   at Telerik.Windows.Documents.Fixed.Text.TextRecognizer.CreateTextPage(RadFixedPageInternal page)
   at Telerik.Windows.Documents.Fixed.Text.TextDocument.GetTextPage(Int32 index)
   at Telerik.Windows.Documents.Fixed.Search.KMPTextSearch.FindNext(TextDocument document, TextPosition startPosition, String searchText, Boolean matchCase, Boolean wholeWordsOnly)
   at Telerik.Windows.Documents.Fixed.Search.TextSearch.Find(String text, TextSearchOptions options)

...

This exception seems to be related to AES algorithm PaddingMode property. 

 Currently, the first document is loaded. 

Workaround:
Wait for the document to load before loading the new document. 

This is reproducible for images with FlateDecode and predictor value in the range between 10 and 15. As an example you may take a look at the DecodeParms property in the following image PDF dictionary:

<< /BitsPerComponent 8 /ColorSpace /DeviceRGB /DecodeParms << /BitsPerComponent 8 /Colors 3 /Columns 1024 /Predictor 15 >> /Filter /FlateDecode /Height 2868 /Subtype /Image /Type /XObject /Width 1024 /Length 1236707 >>

Overprinting is option in the GraphicState that allows combining colors when drawing one object above another object.  It is briefly described on page 284 and page 565 in PdfReference 1.7. However, the result of overprinting is device dependent and there are no strict instructions how the result should look like. This feature also includes support for the different blending modes.