Using GWT I am loading images from a server I do not control. Currently, I use GWT new Image( url) and then use ImageHandlers and ErrorHandlers to catch what happened and put the images in my buffer and the DOM. Then I make the images visible sequently to animate the process. But now I need a bit more, I need to know the error code, e.g.304 that the server returned for the image and also I need to get at the header response attribute, 'Last-modified'. For 304, I know I need to resubmit the request later when the server will have created a new version ( with exactly the same url ) which I think I can manage, but it will then have a new 'Last-modified' and I need to know that DateTime.
By using new Image(url), I am letting the browser do the loading, but I don't know how to get at the details of the load.
Q1:Is there a way to pull more info from an image? GWT Image just seeems to wrap a JS object. I look in Firefox Console-Network, but don't see much detail there either. Is Last-modified and error code forgotten by the time it gets (or doesn't) in the DOM tree.
If the answer to Q1 is no the information is gone or inaccessible, ..
Q2: Do I need to stop using the browser to fetch images and do it with an XmlHttpRequest and then presumably I have access to the response codes and the header attributes. SOP is not an issue. But how then do I get from say the Response OutputStream to an Image? Do I have to Base64 encode it or is there a better way? Will one of the other non-url constructors for image help, say Image(Element) or Image(ImageResource). Then the issue becomes how to make a response stream into a Element or ImageResource?
Note: This other question 'How to print error message of why image failed to load?' is related, but doesn't get to an answer.
