Rearrange pages in PdfViewer via drag and drop

Question

Hi,I really like the PdfViewer control and how easy it is to display pdf files. However, I'd like to allow the users to visually arrange displayed pages via drag and drop. Is this feature included in the SfPdfViewer control?If not, it'd be better to create a List<Image> out of the pdf file and render that in a ListView. Therefore, I would be able to fully customize the pages' item template. How could this be achieved without loading the file in a dummy SfPdfViewer first and call GetPages() afterwards?Thanks and regards,Sebastian

Navaneetha Kannan Sudalai Muthu · Answer

Hi Sebastian,  

At present, PdfViewer does not support rearranging the pages of PDF. We have prepared a sample to load the PDF pages in a ListView and rearrange their order without using PdfViewer as you requested. Please find the sample in the link below.  

http://www.syncfusion.com/downloads/support/forum/137357/ze/RearrangePagesDemo-588030034  

However, we made use of Syncfusion’s PdfLoadedDocument to save the rearranged PDF. The rearranged file will be saved in the Application’s local folder.  

Please let us know if you need any further assistance.  

Best, 
Navaneetha Kannan

Sebastian · Answer

Thank you for the answer and the sample.

Unfortunately, the process of rendering every individual page as an image beforehand (!) is very slow and memory intensive. Maybe the PdfViewer is still the way to go? Is there a "base class" of the pdf rendering engine which could be used to show an individual page and could be put into a Listview?

Or do you have another idea to somehow virtualize the image rendering?

Navaneetha Kannan Sudalai Muthu · Answer

Hi Sebastian,  

There is no base class of PdfViewer’s rendering engine available. But it is possible to increase loading speed by updating the ListView items progressively as mentioned in the MSDN documentation below.  

https://docs.microsoft.com/en-us/windows/uwp/debug-test-perf/optimize-gridview-and-listview#update-listview-and-gridview-items-progressively  

We have achieved the same in the previously updated sample. The modified sample can be downloaded from the link below.   

http://www.syncfusion.com/downloads/support/forum/137357/ze/RearrangePagesDemo1196926774   

In the previously updated sample the pages will not appear for several minutes for a 55 pages PDF. But now in the attached sample first few pages will appear immediately, and the rest of the pages will be updated progressively in a seamless way.  

Please find more UI virtualization concepts in the documentation links below.  

https://docs.microsoft.com/en-us/windows/uwp/debug-test-perf/listview-and-gridview-data-optimization  

https://docs.microsoft.com/en-us/windows/uwp/debug-test-perf/optimize-gridview-and-listview  

Best, 
Navaneetha Kannan