... and have all of its internal dimensions and interactions remain relative to each other?
For example, with Flash, you can create a movie and publish a .swf file. Then, when you put that .swf file in a page, you can have that movie scale up or down and still maintain all of its functionality with it being none the wiser.
Is something similar with Canvas? I was directed by someone else to the WHATWG description of the scale property, but it was not helpful. Does the scale property do what I want and does anyone have an example?
Thanks!
I once solved this by wrapping the Canvas API with functions that used proportional coordinates (ie. 0.3, mapped to 0-1, fixed ratio and other axis relative to this).
Depending on how much work you want to do, you might want to either implement something like this yourself or use some pre-existing solution.
Related
So... I have some sets of 6 pictures, like these http://www.humus.name/index.php?page=Textures , and I basically want to render them on an html5 canvas like this: http://www.allforthecode.co.uk/aftc/forum/user/modules/forum/article.php?index=5&subindex=4&aid=303
But I'd rather not use any 3d library such as webgl or three.js, since that's the only 3d-related feature I need and I want the whole thing to be as lightweight as possible.
I thought, "c'mon, it's just a rotating cube, can't be that hard!"
WRONG.
My original planwas to keep the camera position fixed, ant then to keep track of the x and y offset (in radians) of each vertex, and then to project them on my canvas and to deform the context accordingly to render each face of the cube.
That approach doesn't seem to work, tho, so... can someone give me a pseudocode algorithm?
I think a good way to tackle this problem is to use CSS3 3d transformations. There's quite a few turorials to be found on the web giving details on how to build a 3d cube with CSS. Instead of using <div>s to build the cube's sides, you could use <img> or even <canvas> elements. By playing around with perspective attributes you should be able to place the 'camera' inside the cube looking out.
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/
I am reading this tutorial about making draggable and resizable rectangles
http://simonsarris.com/blog/225-canvas-selecting-resizing-shape
It is a good one and I want to create a similar one using images and this is what I had done
http://jsfiddle.net/LUhsK/2/
all i had done is to change the script that instead of drawing a square I draw an image given the image source, initial X, initial Y, width and height but as you can see it doesn't work. I really can't find what seems to be the problem
If I clearly understood what you are searching for I guess it can be easily resolved with
droppedElement = ui.helper.clone();
droppedElement.resizable();
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.
I wrote a paint application using the HTML5 canvas element.
Now I want to give the user an option to zoom in and out while painting.
How can I do this?
There are a few ways. It really depends on what you're looking for.
You could do it by scaling the entire context, as in ctx.scale(2,2), and then redrawing everything at this larger scale. Several things drawn, like paths and text, will scale gracefully. To accomplish this you will need to keep good track of everything drawn so far.
Another way is to take the entire canvas and draw it back to itself. This requires a temporary canvas because the operation is really: Draw to temp canvas, clear main, draw back to main scaled.
Another way is to use CSS transforms to merely zoom the canvas itself, which will make the image blurry (its zoomed!) but does not require changing any of the pixels already on the canvas.