Rob said:I have a servlet that loads images, which are usually big. I want
to show the message "loading image" when retrieving the image,
..and automatically shows the image once it is done. Any suggestions
here?
If you put a thin but obvious border around the space the image
will occupy, images (at least JPGs and GIFs) are pretty efficient
at showing their own 'load progress'. And they will demonstrate
the progress with something much more interesting than an
'hourglass'.
KISS.
Andrew, I'm not quite sure I understand you clearly.
What I want to show is dynamic loading image like http://www.ajaxload.info/
and automatically switches to the image once it has been loaded.
Rob wrote:
..
I am also relatively confident that is the case. My
take is that you are over-thinking this, and as a result,
are about to make (yet) a(nother) crappy web. app.
Ughh. Now that is pointless and stupid. Instead of
an image that is scanning down the page line by line
as it is loading*, I get to watch a sickening little 'twirly
thing' that shows no indication of the % progress?
One step forward, two steps back.
* I am thinking JPEG there, as opposed to GIFs,
which have a much smarter way to show 'some part'
of the image early on.
BTW -
What format are the images?
How big are the images (in px and bytes)?
The images are dynamically generated, in PNG format.
..Size varies.
I'm thinking of going AJAX for that purpose. But not sure how
to, any hint?
Andrew said:Rob wrote:
...
Smack 'em out to JPEG. That should reduce the size to
at least a third.
How *much?* What is the frigging *minimum* and *maximum*?
(Sheesh) Getting information from some people is like
pulling teeth, from a chook.
Don't.
Lew said:There's a standard idiom for showing images in web apps - have a servlet
serve'em up. Then Andrew's placeholder trick can work.
<img src="/Imager?name=foo.jpg" />
I use this for, say, when images are stored in a database instead of a
relative directory of the web app. Also useful for images created on
the fly.
The images are dynamically generated, in PNG format. Size varies.
I'm thinking of going AJAX for that purpose. But not sure how
to, any hint?
Andrew said:Rob wrote:
..
Smack 'em out to JPEG. That should reduce the size to
at least a third.
RedGrittyBrick said:IME that depends entirely on the image content.
...For images with
continuously varying tone and high levels of detail, JPEG will give
better compression (assuming you use lossy compression, as you know, you
can set JPEG quality to 100% for effectively lossless compression).
In other cases PNG can give better compression than JPEG.
To achieve high compression with JPEG involves a tradeoff in quality
which can lead to very noticable muddiness and ringing effects on images
with flat-colour backgrounds.
I'd try both.
Roger said:Or map Imager/* to your servlet so you can write <img
src="Imager/foo.jpg"> if you want all browsers to understand that the
image name is foo.jpg (should the user try to save the image). This
specially applies to SonyEricsson mobiles if I remember correctly.
Lew said:Nice tip. I can make immediate use of that - in fact, for a client's
project.
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