HTML overlapping images - html

I have to place on a web page a cylinder that looks like this:
it is composed by small images that overlaps to draw the curves on the surface. Every one of them is places on the page with a different img tag enveloped in an anchor with its own href. The z-index property of the img is used to make them overlap in the right way.
The cylinder has to be composed because it is dynamically created, as you can see from the image, its faces can have different colors.
What i need to do is to make all the faces clickable and each one has to point to a different URL.
My problem is, of course, that the cylinder has curves. And i have to be sure that the clicks points to the correct URL especially near the curves, it hasn't to be precise at pixel level, but at least acceptable.
I've tried to use a map with a single area for each of the images that composes the cylinder, but of course it didn't work, as i saw from the specifications, in such cases only the first declared map in the DOM works.
I'm thinking about to solve this via Javascript, but i think it wouldn't be an easy job, so i would be happy if someone can give me some advice on what should i try.
Oh, i cannot use HTML5 features to solve this.

Neat application of older technology to solve a challenging puzzle.
I can think of two ways forward for you. One is to put a transparent (rectangular) image on top of the cylinder and create an HTML image map, using the shape="poly" attribute. For resources, search for the HTML elements map and area for reference, especially the shape attribute. There should be many good tutorials online. Nowadays this technique isn't used that much any more, but it was really popular in the late 90s.
Another way is to use event delegation in javascript, attaching an event listener to the primary container. On each of your image "pixels" apply a CSS class for the appropriate portion of the cylinder it is in. In your event handler, you can do something differently depending on the class of the clicked on image, and you can do this without the massive overhead of attaching an event on each individual "pixel". In JQuery this would be something like:
$("#cylinder").on("click", ".green", function() { location.href = "green_url"; }
$("#cylinder").on("click", ".red", function() { location.href = "red url"; }
assuming you put class="green" on your green pixels and class="red" on your red pixels. (You can do this by quadrant or other technique; color is just an example).

Your best luck SVG ! https://developer.mozilla.org/en-US/docs/SVG/Tutorial
It is almost impossible with html dom elements to do this, you will have to bend it with CSS compatible all browsers.
There is also Canvas but you will have a hard time dealing with the clicks.
Only problem with SVG is that it's not supported in < IE8, and hardly in IE8. But bending a DOM element is also not available < IE9.
EDIT:
I saw that you can't use HTML5, so your only chance is generating the whole image in GD2 for example and trying to map the points. But what is the reason you can't use HTML5 ?

You might also try doing it using javascript / canvas via getImageData() function. This canvas function will rgba values of the given point. Using the alpha value you can check if mouse is over or clicking on the correct area or if it is a transparent area and nothing should happen.
I also made jquery plugin exactly for this purpose. Maybe it might help. http://www.cw-internetdienste.de/pixelselection/

Related

Can i turn an HTML <map> <area> grayscale with CSS? [duplicate]

I'm created a very large map with many poly areas (over 20 coordinates each) for regions within the map. However, you can't add css to the AREA tag as I was told it's not a visible element. What I want to do is when the user hovers over an area on the map, I want it to be "highlighted" by applying a 1px border to the specific AREA element. Is there a way of doing this? No, I'm not going to resort using rectangles.
Not possible with CSS.
You might check out the Map Hilight jQuery plugin, though.
EDIT 10.2011
ImageMapster is a more recent, and more powerful plugin you should also check out.
If you want to be able to use arbitrary shapes and still use styles, have you considered trying SVG?
I'm not an SVG master but here's an example I whipped up: http://jsfiddle.net/tZKuv/3/. For production you may want to replace the default stroke with none, I used gray so you can see where it is.
The disadvantage is that you'd lose the ease-of-use area/map gives you, but I imagine you can accomplish your goal if you go this route. I added cursor: pointer to the polygon and you can add onclick handlers to simulate the href of <area>.
An obvious caveat is browser support. This seems to be working in Chrome, and I am pretty sure it should work in IE9 (jsfiddle's not working in IE9 at the moment), but previous versions of IE don't support SVG.
Update: Made a quick test page to test IE9. It does indeed work as expected. Here's the source.
Update again: This would also solve the zooming problem you asked about in another question.
Nope, there is no way to do this as you describe. I've researched it and tried. What you can do is set up mouseover events on the various segments and swap some overlay image that is shaded in the same area.

html area tag with holes

The problem I have about using the map & area tag is that I havent been able to find out a solution to having "holes" in the area, for example imagine a lake on map, you dont want that area to be clickable.
Example code:
http://jsfiddle.net/WbKqS/
In this example I have placed 3 lakes on the map but I dont want the lakes to have the hovereffect/being clickable, is this possible? Maybe with another technique?
HTML areas don't support having holes or multiple sets of coords, so you'll need to go with a workaround.
How about a solution based on the approach illustrated below?
I don't think this is a good idea to develope this using area map. I would use Raphael instead. a map example with Raphael
You could position other 'hidden' (div) elements over the lakes, preventing the hover effect from being triggered. Disadvantage is shape of the elements (square). Using canvas could be a solution for that, but not all browsers support it.
I wish it worked that way, but it does not as of right now. Try using SVG format instead. That's Scalable Vector Graphics technology. SVGs support holes and multiple shapes or islands if you will.
Hope this helps, it helped me in Firefox.
If that method fails, I'll look into using <canvas> tag.

How to mark up speedometer/gauge in HTML/CSS?

As a front-end developer, I've been given a mock-up design to implement. This design features several tachograph-style icons, which have me stumped as to the best way to mark them up in HTML and CSS.
The images look like the following:
Obviously these assets represent the empty state and the full state respectively.
My issue is this: how can I mark-up these images so that I can show varying levels of completion, i.e. 10% full, 60% full etc?
Waiting in anticipation to hear your answers.
I would seriously recommend looking into the Raphael javascript library. You can knock something like this up in just a few lines of code.
See also this question: Drawing a half gauge/speedometer (JavaScript Canvas or Java Swing Example needed) where I gave an answer including a four-line code sample using Raphael, which provides an animated fuel gauge. You'll need to tweak it for your design, but even then it's only going to be a few lines of code.
The great thing about using Raphael to draw things like this is that it is fully compatible with older browsers, even IE (as far back as IE6 if you need it), without you having to do any special code to support it. It's a great little library.
Hope that helps.
Given that the image reprisents actual data and isn't purely a design mechanism, I'd mark the image up as an HTML image.
<img ... alt="10%">
If your concern is about showing portions of the image, one way you could do this would be to set the image as a background to some container and use width and height to identify the amount of the image to show.
i'm not an expert on html5 /css3, but would you not use the html5 arc command to create a mask to reveal the full state.
As you have a 270 degree rotation from empty to full, you'd just map the value as percentage of 270 to create the value of the arc that would mask the appropriate value.
I believe that there is a java script Math.PI that might help to.

Apply css to AREA MAP

I'm created a very large map with many poly areas (over 20 coordinates each) for regions within the map. However, you can't add css to the AREA tag as I was told it's not a visible element. What I want to do is when the user hovers over an area on the map, I want it to be "highlighted" by applying a 1px border to the specific AREA element. Is there a way of doing this? No, I'm not going to resort using rectangles.
Not possible with CSS.
You might check out the Map Hilight jQuery plugin, though.
EDIT 10.2011
ImageMapster is a more recent, and more powerful plugin you should also check out.
If you want to be able to use arbitrary shapes and still use styles, have you considered trying SVG?
I'm not an SVG master but here's an example I whipped up: http://jsfiddle.net/tZKuv/3/. For production you may want to replace the default stroke with none, I used gray so you can see where it is.
The disadvantage is that you'd lose the ease-of-use area/map gives you, but I imagine you can accomplish your goal if you go this route. I added cursor: pointer to the polygon and you can add onclick handlers to simulate the href of <area>.
An obvious caveat is browser support. This seems to be working in Chrome, and I am pretty sure it should work in IE9 (jsfiddle's not working in IE9 at the moment), but previous versions of IE don't support SVG.
Update: Made a quick test page to test IE9. It does indeed work as expected. Here's the source.
Update again: This would also solve the zooming problem you asked about in another question.
Nope, there is no way to do this as you describe. I've researched it and tried. What you can do is set up mouseover events on the various segments and swap some overlay image that is shaded in the same area.

Clickable lines and circles with HTML Canvas

I'm thinking of making an application where at some points a graph is displayed that maps people over time and space. The vertical access is location, the horizontal access is time, and each person is identified by a line. At any point where the person did something of significance, there is a bigger dot on their line. Conceptually, clicking the dot brings up data about that particular dot, but clicking anywhere else on the line brings you to a detail on that person. Hypothetically, when you hover over the line the line should change color, and when you hover over a dot, just the dot should change color.
I know that I could do this pretty easily with flash, but I was wondering if these days there is any way to do this using only html and javascript. Is it possible? (Compatibility is not an issue, the only machine I am targeting is my own.)
Thanks!
You can do this with canvas, but it might be simpler to use SVG.
Since SVG uses DOM, you get builtin methods for handling events like clicking etc., instead of having to write your own handling code like you would need with canvas.
There are a few libraries that make working with SVG simpler and cross-browser compatible, such as Raphael and Dojo's dojox.gfx library.
You could create the dots as overlaid divs, so you can easily handle clicks etc. You'd have to sort out positioning quite neatly, of course.
However, highlighting the line will involve calculating the point-to-line distance manually and redrawing.