Loading thumbnails in ThumbnailEx control
Posted: Thu Oct 11, 2012 8:36 pm
We're currently using GdPicture v9 - mainly the PDF portion of the library. In one of our applications, we have a ThumbnailEx control that loads its data from a GdViewer.
The question I have is regarding the PreloadAllItems property of the ThumbnailEx control. If I set that to False, then my 100-page PDF document comes up instantly, and all of the thumbnails that are visible without scrolling are shown. The issue is that none of the other thumbnails are fetched until you physically scroll down in the ThumbnailEx control. So if I load a document, wait 30 minutes, and then scroll to the last pages in the ThumbnailEx control, it still pauses to load those thumbnails.
Conversely, if I set PreloadAllItems to true, it takes about 12 seconds to load, but as soon as it comes up, I can scroll all the way to the bottom of the ThumbnailEx control and all the thumbnails are there without any waiting.
What we're looking for is a hybrid of both behaviors. We don't want to have to wait until all 100 pages are loaded before showing the document, but the thumbnails would get generated without the user needing to scroll through everything. Obviously if the user opens the document and scrolls straight to the bottom they're going to have to wait, but it would be much more efficient than waiting for the user to scroll to a point to start loading the thumbnails for that point.
Can you explain if that's possible by using the functionality that already exists? Or is that something that you'd need to add in a future version?
The question I have is regarding the PreloadAllItems property of the ThumbnailEx control. If I set that to False, then my 100-page PDF document comes up instantly, and all of the thumbnails that are visible without scrolling are shown. The issue is that none of the other thumbnails are fetched until you physically scroll down in the ThumbnailEx control. So if I load a document, wait 30 minutes, and then scroll to the last pages in the ThumbnailEx control, it still pauses to load those thumbnails.
Conversely, if I set PreloadAllItems to true, it takes about 12 seconds to load, but as soon as it comes up, I can scroll all the way to the bottom of the ThumbnailEx control and all the thumbnails are there without any waiting.
What we're looking for is a hybrid of both behaviors. We don't want to have to wait until all 100 pages are loaded before showing the document, but the thumbnails would get generated without the user needing to scroll through everything. Obviously if the user opens the document and scrolls straight to the bottom they're going to have to wait, but it would be much more efficient than waiting for the user to scroll to a point to start loading the thumbnails for that point.
Can you explain if that's possible by using the functionality that already exists? Or is that something that you'd need to add in a future version?