Well, I know prefetch is working to some extent (at least, in Chrome and Firefox), as I can watch it prefetching rather large volumes of images that arnt used in the html at all. All of those images must have been triggered by the prefetch loop.
Still, I'll read over the Mozzilla doc, maybe things have changed a little since javascript has been more widely used. On Feb 6, 3:12 pm, gregor <greg.power...@googlemail.com> wrote: > @Litty: yes, I think you are right, my ignorance. Image.prefetch() > will causes the image to be loaded into browser cache. You then use > the same URL to instantiate an Image object later in code, and > hopefully the image binary will be already downloaded. This old > Mozzilla doc describes the process: > > http://devedge-temp.mozilla.org/viewsource/2003/link-prefetching/inde... > > The doc suggests the behavior darkflame described in OP, namely, > browser is busy downloading all the prefetches it finds in the page. > > @darkflame: > > > > > b) If I do have to load, say, upto 10 images that have to be seperate, > > is it better to just loop over a list of them prefetching and leave it > > upto the browser....or should I put a timer and trigger a load every, > > say, 5 seconds ? > > (or dosnt it make much difference). > > My reading of the Mozzilla doc is that the browser will notice all the > prefetch tags when it loads the page, and it will then get busy > downloading them. So I have doubts whether where you put the > Image.prefetch(url) in execution logic makes any difference, i.e. you > do not have fine tune programmatic control over prefetch so you can't > code to prefetch first 10, then later trigger prefetching next 10. For > example the Mozzilla doc states "The link tag has to be inside the > head tag to make prefetching work" etc. > > > > > On Feb 6, 9:14 am, Litty Preeth <preeth.h...@gmail.com> wrote: > > > > > > "You are thinking of loading 20MB of images into the DHTML DOM of you > > > > > application" > > > > > > Am I? Does the DOM keep them there even when not displayed? > > > > > These images certainly wouldnt be displayed all at once. 1 or 2 at a > > > > > time at most. > > > > > I'm not absolutely sure, but I think if you load an image it is > > > > basically attached to a document, whether the browser caches it or > > > > not, and whether it is currently visible of not. You don't control the > > > > browser cache, I mean I don't think you can tell it to conveniently > > > > download all your images and store them neatly on disk until you need > > > > to display them for example. > > > > ah, pig. > > > I thought that was exactly that prefetch was doing -sigh- > > > I thought it loaded it to ram first, then the browser keeps a copy in > > > its cache for reloading if needed. > > > -sigh- > > > That does change things indeed then. > > > > AFAIK the prefetch creates an IMG element but its not attached to the DOM. > > > > - Litty > > > > On Fri, Feb 6, 2009 at 1:03 PM, darkflame <darkfl...@gmail.com> wrote: > > > > > > > "You are thinking of loading 20MB of images into the DHTML DOM of > > > > > > you > > > > > > application" > > > > > > > Am I? Does the DOM keep them there even when not displayed? > > > > > > These images certainly wouldnt be displayed all at once. 1 or 2 at a > > > > > > time at most. > > > > > > I'm not absolutely sure, but I think if you load an image it is > > > > > basically attached to a document, whether the browser caches it or > > > > > not, and whether it is currently visible of not. You don't control the > > > > > browser cache, I mean I don't think you can tell it to conveniently > > > > > download all your images and store them neatly on disk until you need > > > > > to display them for example. > > > > > ah, pig. > > > > I thought that was exactly that prefetch was doing -sigh- > > > > I thought it loaded it to ram first, then the browser keeps a copy in > > > > its cache for reloading if needed. > > > > -sigh- > > > > That does change things indeed then. > > > > > > > Again, not at once. > > > > > > Surely a staggered download they wouldnt have a problem with? > > > > > > Emulating, say, what it would expect from a user browseing > > > > > > DeviantArt? > > > > > > yeah, the staggered download is basically the idea of the maze - each > > > > > time you move to next location you've only got one locations worth of > > > > > images to fetch. Or if it worked fast enough you could fetch all the > > > > > required images for the adjoining locations so they would be ready to > > > > > go instantly. It depends entirely on no of image bytes per location. > > > > > Yes, I looks like I'll be switching to a as-you-go-along-it-loads-the- > > > > next-rooms approach. > > > > Allthough... > > > > > > Point is doing it this way old images are thrown away and can be > > > > > garbage collected as you go, so you are not accumulating images in > > > > > memory. It's stable. (assuming I'm right about the how this works of > > > > > course). > > > > > ...I'm not sure there will be much that can be chucked away in this > > > > game. > > > > My engine is able to remove items easily enough, but for this game > > > > items from the start of the game are still usefull at the end, so > > > > theres only a few case's when images can be removed never to be > > > > recalled. > > > > > > > ". The point of > > > > > > the composite image strip is to fetch several images in one request > > > > > > since they come in a single binary file. " > > > > > > > Yes, I understand the point of them, and I think image bundles are a > > > > > > great idea. > > > > > > (In fact, online in general, theres probably a lot of wasted > > > > > > bandwidth > > > > > > used on little UI elements on webpages..like 5kb gifs etc....) > > > > > > In this specific case though they arnt approperate. > > > > > > Not unless I got the server to dynamically splice the images > > > > > > together > > > > > > and the client to cut them up. > > > > > > But thats beyond the scope of the projects timeframe. > > > > > > This is exactly what the GWT ImageBundle does (and what has been best > > > > > practice in web design for years). Annoyingly for you GWT only does > > > > > this once per module because Bruce says they can't think of a single > > > > > use case for needing separate ImageBundles! My bet is that if you > > > > > just start loading all the images as you are suggesting, you will have > > > > > to attach them to the DOM somewhere, so ultimately what you will be > > > > > doing is building the entire game at the same time as the player is > > > > > trying to play the first locations. So my betting is three to one on > > > > > a) whilst this build is going on the game play will be badly affected > > > > > at precisely the time you least want it to, and b) once you've loaded > > > > > it all it will run like a dog anyway. > > > > > Yes, I think your right there. > > > > But I think cutting up 30MB of images client side might actualy raise > > > > the required specs of the game :P > > > > > > I may well be wrong, but if I'm not, and you looked at the maze idea > > > > > as plan B, then using image strips a la ImageBundle will make the game > > > > > run much faster and smoother, so the effort might well be critical in > > > > > the end. This is after all the heart of your technical challenge. This > > > > > has been done so many times I expect you will find some javascript > > > > > code that cuts them up (or maybe CSS stuff) to crib from somewhere and > > > > > some server side tools to pack the image strips as well. > > > > > I may have miss-understoof how image bundles worked completely here > > > > though, as I originaly thought they were fixed at compile-time. > > > > From the perspective of people editing the game content (images/text), > > > > what would they have to do? > > > > Run a script file of some sort every time they changed an image in the > > > > game? > > > > Or would the image be spliced together server-side for each user as > > > > they request the javascript? (which would surely increase sever load > > > > and load time too) > > > > > I'm thinking strongly of going for the maze-techique now, but still > > > > need the best method/approach for loading within it. > > > > (Basicaly ; "I know theres these 10 large images to be loaded for the > > > > next area, whats the best way to do it so the client dosnt notice the > > > > loading") --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group. To post to this group, send email to Google-Web-Toolkit@googlegroups.com To unsubscribe from this group, send email to google-web-toolkit+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/Google-Web-Toolkit?hl=en -~----------~----~----~----~------~----~------~--~---
