Notification is displayed too late.

[Jakub Ś]

Steps to reproduce

1. Drop large file into editor e.g. 30MB image (large file size is used to increase time before notification is displayed)
2. Observe

Expected result

CKEditor should display notification once file is dropped.

It would be perfect if this was something like "Preparing file for upload" but from what I have talked with my colleague, it will be easier to just display "Upload 0%"

Actual result

CKEditor displays notification once it receives information about package size (file size with headers, control sums etc. which is greater than sole file size).

For few seconds there is no information and CKEditor is not responding. This can make users think that editor has hung and not that it is processing the file.

In fact CKEditor is processing base64 string for the image to preview it. For larger files we could intorduce configurable maximum file size for which preview should be shown. Antying above that property will not be using preview. Reported here: #13825

Other details (browser, OS, CKEditor version, installed plugins)

This behaviour has been introduced in CKEditor 4.5.4. In CKEditor 4.5.3 we were using file size (smaller than whole package size) thus notification was displayed at once. In CKEditor we display real upload size but we get that information only after first progress event is fired.