How to get thumbnails from a file

Question

I have build a winform application which connects a technical drawing application (CAD - SolidEdge) and an ERP-system. This is working fine but I can't get the right thumbnails in the bomstructure.

When I click on a file in Windows (Windows 10) I see a nice preview image. How can I extract this image to my application?

I had found a similar question and solution (Extract thumbnail for any file in Windows) but this is won't work anymore (because of Windows 10 updates I guess).

Also this one (C# get thumbnail from file via windows api) doesn't work and gives: Example wrong thumbnail and Example wrong thumbnail.

Have you guys any idea how to solve this? Thanks!!

Yes, in my question I had mentioned this thread as non-working option (for me). — Marinus, Apr 23 '20 at 09:11

score 0 · Accepted Answer · answered Apr 28 '20 at 16:58

There are different types of thumbnails that can be retrieved from Windows.

Picture
Song Album Art
Document Icon
Folder
File Group
Single Item

Microsoft has a nice sample project called FileThumbnails that lets you play with each type. This project was updated for Windows10 and VS 2019 in March 2020. Although it's a universal windows project instead of winforms.

After playing with the different modes I found the one you are after for Solid Edge files is #6.

internal class FileExtensions
{
    public static readonly string[] SEfiles    = new string[] { ".dft", ".par", ".asm" };
}

FileOpenPicker openPicker = new FileOpenPicker();
foreach (string extension in FileExtensions.SEfiles)
{
    openPicker.FileTypeFilter.Add(extension);
}

StorageFile file = await openPicker.PickSingleFileAsync();
if (file != null)
{
    const ThumbnailMode thumbnailMode = ThumbnailMode.SingleItem;

    bool fastThumbnail = FastThumbnailCheckBox.IsChecked.Value;
    ThumbnailOptions thumbnailOptions = ThumbnailOptions.UseCurrentScale;
    if (fastThumbnail)
    {
        thumbnailOptions |= ThumbnailOptions.ReturnOnlyIfCached;
    }

    using (StorageItemThumbnail thumbnail = await file.GetScaledImageAsThumbnailAsync(thumbnailMode, size, thumbnailOptions))
    {
        if (thumbnail != null)
        {
            MainPage.DisplayResult(ThumbnailImage, OutputTextBlock, thumbnailMode.ToString(), size, file, thumbnail, false);
        }
        else
        {
            rootPage.NotifyUser(Errors.NoThumbnail, NotifyType.StatusMessage);
        }
    }
}

public static void DisplayResult(Image image, TextBlock textBlock, string thumbnailModeName, uint size, IStorageItem item, StorageItemThumbnail thumbnail, bool isGroup)
{
    BitmapImage bitmapImage = new BitmapImage();
    bitmapImage.SetSource(thumbnail);
    image.Source = bitmapImage;

    textBlock.Text = String.Format("ThumbnailMode.{0}\n"
                                       + "{1} used: {2}\n"
                                       + "Requested size: {3}\n"
                                       + "Returned size: {4}x{5}",
                                       thumbnailModeName,
                                       isGroup ? "Group" : item.IsOfType(StorageItemTypes.File) ? "File" : "Folder",
                                       item.Name,
                                       size,
                                       thumbnail.OriginalWidth,
                                       thumbnail.OriginalHeight);
    }

Result Example:

How to get thumbnails from a file

1 Answers1