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.
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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.
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/
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.
I'm trying to create a pure css Venn diagram like this
Where the circle gets highlighted on mouse hover. But the problem is: using the border-radius property if I mouse over the corner of the circle (outside the circle) , it triggers hover as well.
for a demo see this jsfiddle link and hover over the red area
is there any CSS solution to avoid this or am I ganna have to calculate it using javascript?
EDIT: Thanks to all for the responses.
I should have posted the browser information as well. I'm using Chrome 12
So far it seems this bug exists in chrome. I will update this page with any further findings.
UPDATE Aug 2013: Just tested this again on Chrome 28 and the issue no longer exists.
I know it's possible to draw circles with border-radius:50%, but it really is a bit of a hack. And it doesn't work in IE8 or lower, without using even more hacks, like CSS3Pie.
So while I accept that you've produced a good-looking Venn diagram in your fiddle example, I don't think it's the best way to do this.
A much better solution would be to use a proper graphics library to draw the diagram using either Canvas or SVG.
For Canvas, you could try this library: http://www.canvasxpress.org/venn.html
For SVG, I would recommend Raphael, which will produce hover-able Venn diagrams in about four lines of code.
I know that neither Canvas nor SVG are supported by IE8, but then neither is border-radius, so I assume that isn't a criteria for you.
In any case, Raphael does actually work in all versions of IE, as it detects the browser and renders VML instead of SVG if it's running in IE. Canvas support can also be hacked into older IEs if you really need it.
I use a screenshot tool like SnagIt and this tool is able to make a screenshot of a specific element inside a website. I tried this feature with firefox, safari and ie, all runs fine. When I use the mouse pointer to aim an element, SnagIt shows a red box around the hovered element in the browser. For example, this tool knows the exact coordinates of a div or img element.
What is the technique behind this feature? Is there a common way for every browser? I've already used Spy++ to get the window handles, unfortunately this isn't the resolution.
I'm in a project in which I need this feature for different browsers.
Thank you very much,
Mark
If you want to know the x,y coordinates of any element in javascript, Then I suggest you use jquery [http://jquery.com] on your page and use its offset function.