/// <summary>
/// Returns null if the file is null, the file is not an image, or there is no thumbnail resource info creator.
/// </summary>
internal static IEnumerable <Control> GetThumbnailControl(BlobFile file, Func <decimal, ResourceInfo> thumbnailResourceInfoCreator)
{
// NOTE: We'd like to check here whether the file is a renderable image or not. But we can't because we don't have the file contents.
// So, we'll have to make sure that all ThumbnailPageInfoCreators provide a page that knows how to handle NEF files (ideally we'd want
// it to behave as if there was no thumbnail at all if there is an unrenderable image file).
// The only alternative to this that I can think of is creating a new file table field called "IsRenderable" that we store when
// we first save the image.
if (file == null || !ContentTypes.IsImageType(file.ContentType) || thumbnailResourceInfoCreator == null)
{
return(Enumerable.Empty <Control>());
}
return(new EwfImage(new ImageSetup(null, sizesToAvailableWidth: true), thumbnailResourceInfoCreator(file.FileId)).ToCollection().GetControls());
}
/// <summary>
/// Uploaded file cannot be null. But if uploadedFile.HasFile is false, this will be a no-op.
/// Pass null for acceptableFileExtensions if there is no restriction on file extension.
/// PerformAdditionalImageValidation cannot be null but may be an empty delegate.
/// </summary>
public static void ValidateUploadedFile(
Validator validator, EwfFileUpload uploadedFile, string[] acceptableFileExtensions, Action <Validator, System.Drawing.Image> performAdditionalImageValidation,
bool mustBeRenderableImage)
{
var file = uploadedFile.GetPostBackValue(AppRequestState.Instance.EwfPageRequestState.PostBackValues);
if (file == null)
{
return;
}
// Perform generic file validation.
if (acceptableFileExtensions != null && !FileExtensions.MatchesAGivenExtension(file.FileName, acceptableFileExtensions))
{
validator.NoteErrorAndAddMessage(Translation.UnacceptableFileExtension + " " + acceptableFileExtensions.GetCommaDelimitedStringFromCollection());
// Don't bother trying to see if it's an image and parse the image. The file extension message be more detailed than the messages those errors produce.
return;
}
// Perform image-specific validation if necessary.
if (mustBeRenderableImage)
{
// Make sure it is an image according to its content type.
if (!ContentTypes.IsImageType(GetContentTypeForPostedFile(file)))
{
validator.NoteErrorAndAddMessage("Please upload a valid image file.");
}
else
{
// Make sure it is an image type that we understand. Also perform optional custom validation.
try {
using (var stream = new MemoryStream(file.Contents)) {
var image = System.Drawing.Image.FromStream(stream);
performAdditionalImageValidation(validator, image);
}
}
catch (ArgumentException) {
// If we end up in this catch block, it means that System.Drawing.Image does not understand our image. Since we already know that our content type
// is image at this point, this usually means that the file is some sort of unsupported image format, like NEF.
validator.NoteErrorAndAddMessage("The uploaded image file is in an unsupported format.");
}
}
}
}