Develop Reference

Javascript/HTML5 Image Viewer with Labels

I am reconstructing a massive collection of medical modules that were created in Flash. All of the modules are being redesigned for cross platform enjoyment (js and HTML5). I have been searching for a library or plugin that will add arrows(with rollover capabilities) and text above an image when the user clicks a button. I have had little luck.
The closest package I have found is Zoomify, but it's still not what I am looking for. They are asking for too much money for maximum development capabilities. I was really hoping to find a JQuery plugin or javascript library that would allow me to fully customize the interface. Here is a screenshot of an OLD FLASH module:
The red arrow corresponds to the link selected on the left. The new design is much more appealing but the underlying idea is the same, click buttons point to the objects.
If there is no such library or plugin should I create a simple javascript image viewer and store overlay coordinates in a database? Or is that overkill? I have hunderds of these things to do... maybe thousands :( Any help/direction would be greatly appreciated.

What you are asking for is provided by CSS, which enables one to place text directly on top of an image or other rendered HTML. The key CSS properties to investigate are:
position set to 'absolute'
values for at least two of top, right, bottom or left
use z-index to specifying layering/order

Lightbox is a good option "Lightbox is a simple, unobtrusive script used to overlay images on top of the current page. It's a snap to setup and works on all modern browsers."

JavaScript image zoom and pan (drag)

Any recommendations on zooming a large image and panning around? ideally inline on the page.
I've been using PanoJS (aka GSV2), but now more people are using iPhone/iPad/Android type devices, this library is either too slow, or the older versions do not support dragging (the one I'm using at the moment).
http://code.google.com/p/panojs/
http://www.dimin.net/software/panojs/
My current thought is that using the tiled images approach is too much for these little processors (at maximum zoom trying to drag 144 individual images, from a 3000 x 3000px original image, where each tile is 250x250px).
So probably looking more at loading the original image in an with a set width/height... and either writing my own JS to zoom/drag, or using another library (which I can't seem to find at the moment)... then there is the question of using jQuery (with jQuery UI for draggable support), or just writing the raw JS myself to keep the amount of code down.

More so answering my own question, as the standard libraries don't seem to work as well as I needed, I ended up creating my own solution:
https://github.com/craigfrancis/zoomify
The intention is that you can copy this code and then customise it to your own particular requirements... so ideally you should be able to read/understand the code, rather than just dropping it into your project and hoping for the best.

I would suggest making a viewport for mobile devices of screen width.
set all the images that are outside the viewport for more than one tile to display:none.
Then when the user pans just update the display property.
That way the browser will mainly compute a large element moving with a few images, and then compute the on and off state of some images.
a lot less graphics intensive than to recalculate a graphics heavy div element.

After looking around for this too, I decided to use OpenSeadragon (New BSD licence), an open-source, web-based viewer for high-resolution zoomable images (desktop and mobile). I needed it for the Image Pyramid sources with Multi-Image support and filtering capabilities (via one of a multitude of plugins)
Another strong contender was OpenLayers (2-Clause BSD). Here's a simple example with a static image, and here's the complete list of examples.

A way to create random-noise background image (png) with javascript?

The new layout of YouTube added a background random-noise which I like very much, having seen almost exactely the same effect on other sites, so I plan to use the same technique in my webpage prototypes, or at least have this "trick" in my toolbox for future use.
The image is like this (taken from http://g.raphaeljs.com/barchart.html):
Now Youtube accomplishes the (embarrassingly identical) same effect by embedding the image in source code:
(on Youtube main page, right click background to display it, then right click the image and "display image properties" [ffox]):
data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAJUAAACVCAAAAAB0....lotsofdata
I tried to discover where this line of code is in the source code, but due to the dynamic creation, I couldn't.
So, my question is:
"Is there a way to apply a tiled background to a page, using a png image generated algorithmically CLIENT-SIDE?" (preferrably with javascript)
I am very beginner in webdev and javascript, but I like to base my learning around defined problems to be solved, so this would be a nice way to learn something
Thanks for reading!
UPDATE:
For anyone interested in tile texture generation using javascript, I found this, which seems very interesting:
http://somethinghitme.com/projects/canvasterrain/
http://somethinghitme.com/projects/canvasterrain/js/canvasTerrain.js

To generate image client-side, I suggest you to have a look to HTML5 canvas element.
You can draw on a canvas with Javascript (even if the canvas element is hidden), and so generate anything you want (including a simple noise tile).
Resource to learn Canvas drawing : https://developer.mozilla.org/en/Drawing_Graphics_with_Canvas
After that, you can export your canvas as URL with the method toDataURL (a string like "data:image/png;base64....") which is interpreted by browsers like a traditionnal url for an image, so you can set it as css background for your body element.
Warning 1 : Canvas is supported by all modern browsers and you can emulate it on IE with ExplorerCanvas - but I don't know if ExplorerCanvas support .toDataURL()
Warning 2 : Canvas is resolution-dependant, so I suggest you to generate a little tile (32*32, or 64*64) and repeat it
Edit : An example of tiled background : http://jsfiddle.net/SfzPc/12/
Edit 2 : An completed example with a noisy background : http://jsfiddle.net/SfzPc/14/

You can use CSS to display this image:
#someimageselector {
background: white url('data:image/png;base64,iVBOR...lots of data') repeat scroll left top;
}
You can change the initial color of your background by editing the value white.
To set CSS with JavaScript, set the background property of an element:
document.getElementByID("someimageselector").background = 'white url(data:image/png....';

There are two jQuery plugin libraries that do exactly what you are looking for: NoiseGen and Noisy. Haven't used either yet but they both look pretty good.
NoiseGen
Project: http://primegap.net/2011/10/20/noisegen-generate-background-noise-with-jquery/
Demo: http://www.lucaongaro.eu/demos/noisegen/
Noisy
Project: https://github.com/DanielRapp/Noisy
Demo: http://rappdaniel.com/other/noisy-sample/

Fyi: Base64 is binary data represented as a string.
Most likely the original image still came out of Photoshop and was later encoded into Base64.
This technique helps having less http-requests per page view, as the actual image data can be saved and cached inside the css or html document.

How can I manipulate an image on a website?

I am creating a website where a user is able to upload an image and then rotate or move it around on a background. The final position of the image is then recorded in some way (bitmap?) and sent with some form results.
I'm a bit lost as to how to do this, the website is built using asp.net, I presume what I am trying to do could be done in Silverlight, javascript, flash, flex or maybe html5?
If anyone knows the best way of doing this or can link to a resource or tutorial I would be grateful. I would prefer not to do it in flash or flex as I am unfamiliar with them and do not have the tools installed to edit them. I would prefer Silverlight or javascript solution.
Thanks,
nl

I'd recommend doing this in javascript. At a high level, you just need an element on the page to contain your image, some basic code to allow the user to drag the container around (much of this is available prebuilt through frameworks like mootools), and some logic to save the final element position after the user is done positioning it.
I'm not sure what you mean by saving it as a bitmap, but I'd recommend just saving the element's x and y offset coordinates from the top-left corner of its container. Again, there are readily available frameworks that will do pretty much all of the positioning computations for you.
Here is an example site that implements draggable images with persistent state between sessions: http://webcomix.no-ip.org

You can do this with html5.
Have a look at canvas tag along with this javascript.
where logo is the image, context is the canvas tag context.
context.clearRect(0, 0, width, height);
context.setTransform(_m11, _m12, _m21, _m22, _dx, _dy);
context.drawImage(logo, 0, 0);
Have a look at this example - http://jsfiddle.net/prowla/Kj3UL/ best viewed in Chrome to use the new Range input types, if in FF or IE, change values in text boxes to manipulate the image.
You could save the 6 parameters of the setTransform function to save the state of the image manipulation.

animated board game for web - not Flash - what is possible?

What is the best cross-browser way to get a flat mouse coordinate input data and simple callback for mouse events for my rectangular game area on my web page, even when it has loads of larger and smaller images and text string overlaid haphazard onto it?
And what is the best way to insert or remove a text string or semi-transparent image overlay at an arbitrary location (and Z order, specified relative to existing objects) in a board game rectangle with cross-browser DHTML?
And how can I stop the user selecting part or all of my montage of images (I just want them to interact with it as if it was Flash), and can I stop the right click menus coming up in IE, FF etc?
I want to do this without Flash because I want something that will work both on desktops and on iPhone and potentially other mobile platforms too.
I appreciate there are serious limitations (eg less image scaling capabilities, not vector, no rotation capability) to what I can do if I'm not using Flash but I'm very interested to know what capabilities are available.
Are there perhaps any frameworks available to make it easier than coding from scratch?
Would J/Query be a good match for some of the requirements? What else do I need?

I would recommend Google Web Toolkit. It lets you program in Java, which gives you all the type-safety and nice IDE functionality that Java entails, but compiles to Javascript so that you can just run it in a browser. It also does a ton of optimization and supports tons of features.

jQuery is excellent at doing this. I used jQuery's UI and Ajax functionality to implement the frontend for a game of chess.
I made it a little easier by creating an 8-by-8 table with unique div names for each tile, so Javascript can access them by getting the elements by id. If you can't create something like that, you do have the option of placing elements anywhere on the page (either absolute or relative to a given element). You can also easily change the z-index, including when the use is dragging a piece or when they have dropped it.
As far as disable right click and item selection goes, that's something that I didn't figure out how to do. You might want to take a look at some other Ajax games like Grand Strategy, which are much more polished than my experiment and may have figured out how to do this.

There are two main APIs for working with arbitrary drawing and positioning on the web, Canvas and SVG.
Take a look at Chrome Canvas Experiments and the Raphael Javascript toolkit to see some examples and Javascript abstractions.

The key is element.style.position = 'absolute'. To illustrate just what's possible here's how far I've managed to push javascript (and from scratch at that!):
http://slebetman.110mb.com/tank3.html - RTS in DOM! Click on units/squads then click somewhere else to tell them where to go. You can control both sides.