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Flutter image preload
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I'm building a game with flutter. I have around 130-150mo of pictures. And some of them must be preloaded or else the user experience doesn't feels smooth.
I found by myself a way to preload images :
final asset = new ExactAssetImage(assetPath);
final stream = asset.resolve(createLocalImageConfiguration(context));
While this works, there's a huge drawback : The memory cost is about 6 times bigger then the actual image size.
Consequence ? My app end up consuming 800 MO of ram just by loading images, which is insane (especially considering it's a relatively simple app).
In fact the ram consumption is so big that I get tons of frame lost.
So in short :
What is the most ideal way to preload an image ? Is there something I missed ?
If you want the UX to feel smooth then you can use FadeInImage() and give it an asset image to use as placeholder until the final image loads, and if you want to fade in image from a transparent background then you can use the transparent_image package.
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I found many websites that switch from a content to another without letting the user watches the loading of many images and everything appears so light. Usually, I saw a sort of loading animation of 5, 10 or 15 seconds (without progress bar) that makes me think that it's the moment when the website renders all the initial content. I just came across a good use of progressive jpeg or they use a special framework? If not, what's the right development approach for fast loading images?
In these days of high-speed internet the advantage of progressive JPEG is that, with the right settings, you can get often get better compression than with sequential. In the days of dialup modems, progressive JPEG and interlaced GIF and PNG could allow to get a preview of what the image you were downloading looked like (and you could stop the download if it were bad).
Progressive JPEG does allow what you are describing. It takes more processing because the decoder has to decompress the image for each screen update. In order to see this effect on the screen, the decoder has to support re-decoding after scans and the application needs to interact with the decoder to update the display.
In summary, the fastest way to decode images is to process the entire JPEG stream. A progressive display take more processing but allows the user to see what is coming down.
I like the idea of Nodebox and Processing, and would like to generate movies to visualize some data/algorithms. However, Nodebox exports extremely bloated Quicktime files with frame by frame images, and Processing only exports Java applications. I want to be able to export movies that don't take a Gigabyte a minute of disk space. Perhaps something like SVG animations or Actionscript which stores the vector graphics definition of the animation rather than frame images would be better. Is there a framework that is as easy to program as Nodebox and Processing and can export "lean" movies?
Have you tried the MovieMaker library that ships with Processing ?
Also, it should be fairly simple to save multiple frames using saveFrame().
This is option have a couple of advantages:
If your sketch crashes at some point, you still have all the frames up to that point (unlike writing a .mov file)
It's fairly simple to put the frames back into a video file, but you also have control over playback speed and can easily do a bit of editing if needed.
You can try to a sequence of PDF file using createGraphics() to get vector output, but I'm not sure how stable/feasible this option is.
They are changing the way this works moving towards 2.0 too, as they are moving to GSVideo over Quicktime...
Daniel Shiffman posted about it recently on his blog, but it's the only place I've heard about any changes to post-2.0 tactics (though he IS part of the inner circle, I know)
You can find that post at
http://www.shiffman.net/2011/12/28/night-8-rendering-out-as-image-sequence/
Also, if you are on OSX, you can try Syphon ? See info here
https://forum.processing.org/topic/syphon-integration-with-processing
I am having a little issue here. I am a web development major and I am currently building this site for a project I am required to do. I wanted to make it look pretty with a background image. I created the image in Photoshop and saved it to web as a .jpg and it ended up being 58.8k in size.
I am all for websites that load quick for the user, but I am wondering if less than 60k is okay? I checked it on the yslow firefox extension and it loads for me in 96 ms (slightly poor test subject - http://www.speedtest.net/result/1146275377.png)
Is 60k too much, is it a best practice to have images only 10-20k? I HATE it when I see an image loading... it just.. isn't even worth the graphic at that point. Is there quicker ways to load a image of that size? CSS or tag? Or should I not even be worrying about it?
Most browsers load the background image last by default, so you shouldn't have a problem.
How large is too large depends on your hosting set up, the amount of traffic your site gets, and the typical transfer rate of your visitors.
60k seems reasonable to me for an average site with not too many simultaneous visitors. However, bandwidth costs money and this is the reason that you rarely see background images of that size on big sites. On the other hand, youtube regularly streams videos that are thousands of times larger than the background image that you propose. It's impossible to give you precise advice without knowing much more about your site, its hosting solution and it's usage statistics.
Chances are, if you're asking this question, 60k is perfectly fine.
If you want to guarantee that your background image loads first or last you can do:
<script type="text/javascript">
bgimage = new Image();
bgimage.src = "http://www.olhovsky.com/img/cdf97/256fwt1_eg.png";
</script>
Place that code above the body tag to preload the background image. Place it lower in your html document to load it later (e.g. after the </body> tag to load the background last).
And then in the body tag:
<body onload="document.body.background=bgimage.src;">
I don't think 60k is too large although you probably want to look at your likely users and think about what their connection speeds will be like. If you wanted to try and squeeze the file size down as much as possible, try smushing it as well and you might see it drop a little further.
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I've been a web developer for quite some time, and I am used to transforming all my designs into the png file format in order to build my webpages. Despite the fact that png, contrary to jpg, allows transparency in the images, is it a better solution?
The question regards page loading time and best webdesign practices, as well as file size versus quality of the images.
What do you think is the best solution to use?
It depends.
PNG is better for crisp images with a low number of colours,
JPG is better for a low-bandwidth image - however it is not as crisp and therefore not very good for GUI.
Generally, JPG is for photos and pictures, whereas PNG (or GIF) is for layout.
You may find this page interesting, as it goes over the basics of PNG vs GIF.
Google has written about it very well. From Selecting the right image format, you can find a flow-chart to make the decision:
Given the ever-rising speed of the average net connection I don't tend to think that page loading time is much of a concern any more [ducks!]; It's really far more useful to think about what you are trying to achieve with the resources you have at your end: For example is bandwidth limited? Then tending towards heavier compression is a no-brainer. Is the graphic content of the site going to expand, ensuring that the cost of server space will increase over time? Then tending towards heavier compression will delay that cost. Is it an art portfolio site? Then -- aha! -- compression artefacts in the sampler work may actually be desirable! Are you trying to flog a game? Then the screenshots should probably be ultra-crisp.
Generally, then, I would repeat what has been said, although perhaps in slightly different language: For site furnishings, which tend to be computer-generated and will be cached for re-use between pages, tend towards png; For site content, which will often be page-specific and likely large and complex enough to mask lossy compression, tend towards jpg.
With specific reference to switching to png where you decide it is appropriate, run everything through PNGCrush as a matter of course -- otherwise they won't get displayed with the colours you expect in every browser and the overall quality of your design will be diminished.
"Given the ever-rising speed of the average net connection I don't tend to think that page loading time is much of a concern any more "
According to the website SEO optimisation, Google rank your website worse if page load time is above 2 seconds, so compression is necessary, especially on new website designs heavy on graphics.
jpg is usually preferred for photographic images that have a lot of subtly different colors. png works well with computer generated graphics.
That's my rule of thumb.
I am a starter and mostly what I do is if the image is too big I make small unless it's a background image. And if it is for layout I choose PNG and JPG for pictures.
Can anyone tell me how i can parse a png image into many png images in J2ME ? I want to write a code that take a image and give many images that have equal pixels.
You mean you want to cut it into smaller images?
Load the image.
Convert to a bitmap.
Encode arbitrary rectangles as PNG.
Save the PNGs.
Unfortunately, I don't know anything about image processing usinf J2ME libraries.
Here's what I googled as far as loading a PNG in J2ME.
Using that, you'll be able to see the API calls used, and following the import list, you'll get to the classes used. Look at those class's methods, and yu'll probably come up with what you need.
I did this mostly because you're having an emergency, but frankly, you could have googled this yourself, or composed a question that was clearer, which would have led to someone more knowledgeable about J2ME image processing helping you.
Just don't panic, take a breath, google for what you need, you'll be fine.