Passing computed SVG as a data URI to a SRC attribute - javascript

Have looked around the internet, and have not been able to find an answer to this.
I am building yet another custom image slider, but need to be able to handle arbitrary html in the div that is being animated.
Generally, this would be no problem... this certainly isn't the first slider I created, and, in general, if I require the pretty slice and dice effects, I use an empty div with the content as a background image like everyone else. If I do have to allow it to handle arbitrary html, I limit the effects, or simply fade in the html content once the slice-n-dice transition is completed.
In this case, however, I need the pretty effects AND the arbitrary HTML in the same sliders, and at the same time.
My best idea on how to do this was to convert the arbitrary HTML into an image.
I couldn't find a decent, client side solution anywhere... but eventually realized I could stuff the HTML into an SVG element, and can use SVG as a background image for the div.
(Just an FYI, this really only has to be handled by modern browsers, which can handle SVG and DATA-URLS and such)
The first part is actually kinda easy:
arbitraryHTML = "<style>div{padding:10px;border:5px solid red;border-radius:10px;width:500px;height:175px}p{text-align:justify;}img{height:50px;float:left;border-radius:5px;margin:10px;}</style><body><div><img src='steve.png'><h1>Arbitrary HTML</h1><p>This allows arbitrary HTML to be turned into an image, and the image is then able to be stuffed into a canvas. In this case, I will leave this image as an image so that I can set it as a background image of a div that will be visually sliced apart for a slider.</div></body>";
var stuff = document.createElement('svg');
stuff.innerHTML = "<foreignObject>"+arbitraryHTML+"</foreignObject>";
document.body.appendChild(stuff);
This works perfectly fine if I just want to stuff it directly into the DOM... but what I need to do is to use it as a background image for the div that I am slicing and dicing.
Since I already have the SVG code, I should be able to use it as a data uri to feed the image in.
I found an example like this on fiddle, and attempted to use this method on the code sample above to stuff the svg into the background-image...So far, I have completely failed to do so.
Example:
var i = document.createElement('div');
i.setAttribute("style","background-image:url('data:image/svg+xml,<svg>"+stuff.innerHTML+"</svg>);'");
document.body.appendChild(i);
Every time, I get the same problem; there are no errors or warnings thrown by Chrome console, but the div simply shows completely empty.
Using some methods (the code sample above, for example) the console shows the data uri in the code for the div properly, but still fails to show the background.
As part of bug testing, I had both side by side... the actual svg element (which displayed fine), and the div with the same code stuck as a background image (which would not display). Due to this, I am assuming that my problem is something about the way I am casting the svg into the data-url rather than the svg itself.
I really haven't been playing with either inline SVG or Data URL's very much before this... so it is quite possible that I am handling the data URL's or SVG improperly for the way that I am trying to use them.
Not really sure what I am doing wrong, but would really like to solve this.
Is there a better way of converting arbitrary HTML into an image that I missed?
Or is my idea of how to achieve this on the right track, but the implementation screwed up?
Any help would be greatly appreciated.

I guess Chrome still has this webkit bug. What your doing should work in Firefox or Opera 12. Note that IE9/10 doesn't support foreignObject at all, not sure about 11.

Related

Adding annotations on an image that can move in a canvas style tag

I'm trying to do something that seems simple, but I just can't do it.
I want to have an image that can be zoomed in and out, probably in a canvas (this I can do it).
But, I want to be able to put annotations on this image, like annotations on a map. I could also do this, with an html list positioned on the image.
Problem is, I have no idea how to merge these two concept into one, I know I can't really put html in the canvas, so forget about the li there.
Example of what I would like to be able to do (this is done in flash): http://www.digitalwanderer.net/darksun/
Any one has any ideas of the way to go to reproduce something like that in html?

Raphael.js image fill not updating constantly

I do have a Paper.path() in Raphael that is filled with a simple texture:
var fill = screen.path(Iso.topFacePath(top)).attr({
fill: 'url(http://www.example.com/mytexture.jpg)',
});
The path can be altered by the user via drag and drop. For this I use Element.drag() to bind the handlers.
The problem that I encouter now is that while the onmove-handler function is called the element in question will be recalculated and has to be drawn again. Apparently this is "too much" for raphael and the fill pattern will disappear randomly (flicker) and appear again some time later (at latest onend).
The actual code I use is a little too much to post here but I built a fiddle where you can see what's going on (you can drag the upper sides of the quadrangle).
Is there a simple fix to this?
I am used to canvas much more than raphael (actually this is the first time I really use raphael) so maybe my approach of redrawing everything everytime sth changes is plain wrong?
EDIT: I just found out that seems to be somehow browser-related as well. Chrome and Firefox will produce the flicker where Safari seems to do everything just fine.
This seems to be caching issue (raphael.js does not cache the bitmap fill and will reload it on every change) and is fixed (for me) by this pull request on GitHub that is (as of 08/14/2012) still pending.
Raphael is pretty hard / impossible to build oneself as the make file points to local and/or inexistent files, but you can either concatenate everything by hand, modify the build script or use the modified build that is used in the example to get hold of the fix.
Let's hope it will find its way into a future release of Raphael.

How would one create a triangle container for an image (x-browser)

How would I create a DIV containing an IMG where the DIV cuts the image into a triangle, thereby displaying only part of the image though a triangle.
so..
<div>
<img src='some_image' />
</div>
Where the image is a square, but the DIV containing the image is a triangle.
http://www.script-tutorials.com/creating-kaleidoscope-using-jquery-and-css/ solves this very well except this solution is not x-browser friendly (non-ie).
http://css3pie.com/ looks interesting, however this relies on PHP.
You can't create a non-rectangular DOM element.
There are a few ways to hack it.
Firstly, there is a method of using CSS borders with varying widths on each side of the element to make it look triangular. It will still be a rectangle, but it will look like a triangle.
There's a tutorial on this here: http://www.russellheimlich.com/blog/pure-css-shapes-triangles-delicious-logo-and-hearts/
The down-side of this approach is that it is limited to creating right-angled triangles. You can join several of them together to get around this, but then you don't have a single container for your image.
An alternative hacky way of doing it would be to place rotated elements on top of the main element so that they cover the appropriate parts of the image and make it look triangular. This works in all browsers, although IE does have some very nasty syntax to do rotation, and it's quite heavy on the browser, considering that you'd only be using it to make shapes.
Another option might be to use CSS transforms. However this is only supported by a minority of up-to-date browsers, so it won't work for most users.
A better approach might be to use a proper graphics library for this, rather than trying to shoe-horn it into a <div> element.
I'd recommend using Raphael. It's a Javascript library which can draw directly into the browser using SVG (or VML for IE). It's trivial to create triangles using it and to fill them with a graphic. See the examples on the Raphael home page to get you started.
Depending on what you want the outcome to be, as far as i'm aware you cant make a triangle DIV without Transform:; However one solution would be having a div positioned inside the div in question with a PNG cutting of half the image showing only the transparent part through. Not sure if this is a viable option for you though.

Hover effects on irregular polygons in CSS

I'm wondering how to go about marking up and coding hover effects for a map similar to this image.
When each district (or section) is moused over/touched/clicked I need to change the colour of it without affecting any other section. The boundaries on each section must be representative of the image and shouldn't be squares. The solution can't use canvas since the site I'm working on has to be usable in older browsers (I'm gutted, personally.)
Ideally I want to do this with CSS without using too much JavaScript or loads of images. Has anyone done this before?
Edit: I know people are suggesting the <area> tag, but AFAIK, it doesn't accept the :hover pseudo class.
Edit 2: I might use this: http://www.netzgesta.de/mapper/
Another self answer...
A few months ago I came across a library called Raphael JS - http://raphaeljs.com/. For those of you unfamiliar with it, it's an SVG DOM library first and foremost. If you know a thing or two about SVG, you'll know that IE doesn't support it, but it does support VML. Raphael caters for this as well. Awesome, right?
Anyway, I ended up saving the AI file for the map as an SVG file and importing the paths into a JSON block, basically doing the same thing as this code: http://raphaeljs.com/australia.html
The only issue I came across:
I wanted the map background to be transparent. Setting fill to transparent whilst allowing the section to accept mouseover worked in Firefox, but in IE, it failed. I instead opted for filling the path with white, then setting the opacity to 0.01. After that I duplicated the path and didn't fill it to create the border.
You can use HTML <area> Tag
If you use jQuery you can use the maphilight plugin. documented at http://davidlynch.org/projects/maphilight/docs/ and available from github at https://github.com/kemayo/maphilight
I see what the problem here is: making let's say a world map the usual way is quite a load. If I get it right, what you want is to have a territory map image and put hover effects making hover area match country borders exactly. SVG can be used for the map (the drawing part is already done) but the problem is how to generate HTML area map using SVG map coordinates. There's a solution (I've tried it, looks good at least with the demo provided) which translates SVG into Raphael (generates the coords) using PHP. But again you need raphael.js for that... well if you change your mind: https://github.com/atirip/svg2raphael. And if you're not familiar with Raphael it will take a time to get used to it, documentation is not so good -for me-.
Edit: I can confirm that translation from SVG->rapahel.js works but SVG files needs some tweaks. For what I see in the example SVG provided in svg2raphael the files were made with Adobe Illustrator. I've tried with SVG (plain) from Inkscape and it didn't work properly, but I could manage to fix the issues, for example:
svg2raphael won't translate Inkscape generated <path style="fill:#ff0000" ...></path> (will set fill="none"!!! so the result is invisible, but will translate correctly <path fill="#ff0000" ...></path> Seems like it will ignore everything inside style="".
svg2raphael misreads the alignments from Inkscape SVG, so you need to either move the illustration inside Inkscape or edit the SVG file with text editor and change the M value to M0,0.
svg2raphael can translate multiple svg elements, but looks at the main tag which Inkscape generates to align groups of illustrations, sometimes the whole illustration moves away from the render area and you see nothing. Hope this helps!
Edit 2: You can use Inkscape's style="" for creating CSS rules to apply to the SVG, that works great ang keeps style outside SVG/Raphael!

Dynamically pixelate an html image element

I'm to take an image on a webpage, and then use javascript (or whatever would be best suited) to dynamically 'pixelate' it (e.g. into 20px squares). Then, as the user scrolls down the page, I need the image to gradually increase in resolution, till it is no longer pixelated.
Any ideas how I could go about doing this? I realise I could use php to resize an image and several times and just switch out the image, but that would require loading several extra images. Also, I know I could probably do the effect with flash & pixelbender, but I want to achieve it within the limitations of HTML5, CSS & Javascript if possible.
Appreciate any thoughts!
Update: Something like this, but with Javascript instead of Flash? http://www.reflektions.com/miniml/template_permalink.asp?id=390
You could render the picture in a hidden <canvas> element. Then use a derivation of the technique described here http://dev.opera.com/articles/view/html-5-canvas-the-basics/#pixelbasedmanipulation . To create a pixelated version of the image in a second <canvas> element using ever decreasing fillRect's. This way you even buffer the orginal image data.
edit: I would use 2 <canvas> elements so that you only have to fetch and draw the original image once. Perhaps you could buffer/cache this image in the same <canvas> element but by drawing it outside of the view port i am not sure if this is possible though.
I would use a calculation where you get the width in pixels divided by the square width and then the height divided by the square height. This would give you the lower resolution your looking for.
Then you can find a way to change the resolution to the result or grab the color of every pixel at position (height and width)/2 of the square your looking for. Then generate them into div tags or table with the appropriate color and size eventually resulting in the image its self.
I have a probably faster idea where you can have multiple versions of the image and change their z-index or their visibility as you scroll. Basically each image would have the different resolutions. If you have to do that to many images then this solution wont be as efficient as there would be lots of image editing but you can always do a batch edit.
Let me see If I can think of more ideas then I will edit.
Have a look at http://close-pixelate.desandro.com/
Explanation here: https://stackoverflow.com/a/8372981/22470
Not in a portable way.
That might be doable in Flash. Firefox JS extensions allow it to read images as JS arrays, Base64 strings etc. You might experiment with "1 DIV=1 pixel" hack, but it's hard to get any reasonable size of the image at any reasonable speed. If you feel really hyper, you could try creating base64-encoded images on the fly using the data: URI... many ways but none good...

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