public IActionResult PreviewImage(string workbookId, string viewId)
{
if (!IsOnline)
{
return(null);
}
var etag = $"\"{TenantId}.{workbookId}.{viewId}\"";
var stringValues = this.Request.Headers.FindOrDefault(WebHelpers.HeaderStrings.IfNoneMatch);
if (stringValues.Count == 1 && stringValues[0] == etag)
{
return(StatusCode(System.Net.HttpStatusCode.NotModified));
}
stringValues = this.Request.Headers.FindOrDefault(WebHelpers.HeaderStrings.IfModifiedSince);
if (stringValues.Count == 1 && stringValues[0] == etag)
{
DateTime dt;
if (DateTime.TryParse(stringValues[0], out dt) && dt >= StartedAtUtc)
{
return(StatusCode(System.Net.HttpStatusCode.NotModified));
}
}
Response.Headers.Add(WebHelpers.HeaderStrings.ETag, etag);
if (Response.Headers.ContainsKey(WebHelpers.HeaderStrings.CacheControl))
{
Response.Headers.Remove(WebHelpers.HeaderStrings.CacheControl);
}
Response.Headers.Add(WebHelpers.HeaderStrings.LastModified, StartedAtUtc.ToRfc7231());
Response.Headers.Add(WebHelpers.HeaderStrings.CacheControl, "public");
var imageBytes = Cacher.FindOrCreate(Cache.CreateKey(workbookId, viewId), key =>
{
byte[] previewImagesBytes = ReportVisualService.DownloadPreviewImageForTableauVisual(workbookId, viewId);
if (previewImagesBytes != null)
{
//var fileResult = new FileContentResult(previewImagesBytes, "image/png");
return(new CacheEntry <byte[]>(previewImagesBytes));
}
else
{
return(null);
}
});
return(new FileContentResult(imageBytes.Value, "image/png"));
}
