SVG dashoffset start angle - svg

I created simple circular progress bar with SVG, but I have some troubles with making progress bar starting from the top of the circle (clockwise), and not the right side as currently.
Here's the code:
http://www.webpackbin.com/4yxjPQgMb
I will really appreciate if you can provide some guidance on how can I fix this thing. Thank you.
// Edit:
I managed to do this via CSS, like this:
{
transform: rotateZ(-90deg);
transform-origin: center center;
}
But still looking how to do this via JS.

All non-path graphic shapes (like the <circle> you are using) have a defined "equivalent path". This is specified so that dash patterns behave consistently across all SVG renderers. In the case of a <circle> the equivalent path is defined to start at the 3 o'clock position and proceeds clockwise around the circle.
See: https://www.w3.org/TR/SVG/shapes.html#CircleElement
There is no way to alter that other than by rotating or otherwise transforming it. You can do that with CSS as you have done (doesn't currently work in all browsers) or with a transform attribute on the <circle>.

Related

How can I place a geo-referenced SVG over an openlayers map (not as image)

How can I place a complex SVG image (with css-styles!) geo-referenced over an openlayers map so that the document's CSS styles are used with rendering the SVG.
A regular ImageLayer does a fine job of showing the georeferenced svg on the map as an image. But because it is an image, the CSS of the document has no effect on the rendered SVG
The SVG Layer example on the other hand places the SVG into the DOM and makes it react to the document's CSS and reacts when you change the CSS. But it always maps the SVG over the whole planet and seems to hide any layer I place under it.
To give you an idea of the use case: we have an externally generated SVG with several 'groups or layers' in it representing different aspects of infrastructure. This svg has to be put correctly over a map (like we can do with the imagelayer), but we want to be able to selectively show/hide the different 'groups or layers' that are within the SVG.
I guess in the end we would be needing something similar to ol/layer/Image/ImageLayer to happen in the SVG-layer example.
Any suggestions about how to approach this would be very welcome, but working code is also OK ;-)
In the example the image width is 360 degrees and the center is at [0, 0]. For a smaller extent you would need to use the appropriate width and adjust the center used in the transform https://codesandbox.io/s/lucid-poitras-i1qyb?file=/main.js Use an opacity setting to avoid completely hiding the base layer.

svg elements - scroll to/ centering

I've an svg dynamically created on a page. As things "happen" (user clicks) the svg expands and collapses certain elements. It may fit in the viewport, it may not. In the case that its too big to fit on a page, the user must scroll to where s(he) wants to go/see. Now this is fine, however I have a requirement that the last element "selected" becomes the center of the page/viewport. i.e. If they click on an item, thats what they need to see without scrolling.
Could anybody tell me the best way to attack this. I've googled around but can't find what I'm looking for (though I'm not long at all this so I might have been searching the wrong stuff).
Is there a way to do this purely programmatically with javascript? Or am I obliged to pass by CSS to get the solution I want. Any tips/links/advice much appreciated.
thanks and have a nice day
G
I had a similar thing and I used the viewBox property to handle this. You could also use a wrapping <g> element, which you translate. However, from my point of view the basic approach is the same and you basically need to do two things:
keep track of the x and y offset and the dimensions of the viewport. (Using the viewBox will give you that »for free«)
Compute the center of the Element. Therefore I used the getBoundingClientRect()method which yields the AABB of of the Element in absolute coordinate space, relative to top-left edge of the whole page.
With these things, all that remains is to calculate the vector from the viewport center to the object's center.
Here you can find the reference of the viewBox and here a nice tutorial about it, because it can be a bit confusing at the beginning.
Another pro for the »viewBox« approach is: There is no dependency on special DOM elements, it just works on the root <svg> element. I once implemented both methods, I started out using a wrapping <g> element, what worked fine but gave me some performance issues. So I decided to change and use the viewBox, with the result, that the performance in Firefox grow, but slowed down in Chromium.
Edit
Here you can find a little fiddle, that outlines the approach. But be aware of the following: getBoundingClientRect() yields the position of the Element on the whole Page, so if your <svg> is not positioned at (0,0) (top: 0px; left: 0px), than that will include the offset of the svg itself. The offset of the viewBox must not include this offset, so you need to cancel that out somehow. For sake of simplicity I just used the client Bounding Rect of the SVG, what works because there are no transformations applied.

Rotating a circle image shifts it's position

I am trying to rotate a circle image using jquery rotate plugin. But, I observe that the circle image appears to be oscillating about it's center while rotating. Something like a linear movement.
In IE7, it's pretty much observable. In Chrome/Firefox, if you zoom a bit, this wobbling issue can be observed.
I tried to rotate the image using Raphael library too. But still, the circle was wobbling.
Then I rotated the image with a c# program to see if the problem is with the browsers' graphic engine. But even here this issue is observed. I even took various images to see if the circle was imperfect. But, all the images show this behavior.
Can this be happening because of anti aliasing? Or, is it just an optical illusion?
If not, then what else can be the reason?
I am using jqueryrotate plugin rotate method to do this. $('#circleimg').rotate(Position);
Check this jsFiddle. Btw, this is the kind of source code you can include yourself in your question to make answering it easier for others.
http://jsfiddle.net/KyJzQ/
I used this rotate plugin since you did not specify which one you used.
HTML
<img id="circleimg" src="http://i.imgur.com/KgUDClr.png">
<img id="circleimg2" src="http://i.imgur.com/sK4qP6z.png">
JAVASCRIPT
var rot = 0;
window.setInterval(function() {
$('#circleimg').rotate(rot);
$('#circleimg2').rotate(rot);
rot += 1;
},
5
);
I think the circle you've provided is not actually a perfect circle, hence the tiny "oscillations" you see.
I added another circle that I rendered myself. If you zoom in closely enough you will see jagged pixels moving around the edge of my circle, but I don't see any way around this since the jQuery plugin is not actually re-rendering the image. I don't see any of the "oscillating" you mention in my circle.
This issue is more about vector art than it is about programming. Get a nice vector graphics program and render the nicest circle you can. Even the one I made is not really that good. Or use HTML5 and canvas to draw dynamically, rather than moving a static image around.

javascript raphael - how to stroke individual paths?

I am trying to make a tool for my website which traces over Japanese characters, showing the stroke order etc.. something like this: http://www.chinesehideout.com/tools/strokeorder.php?c=5pel
I have made a bunch of SVG files in inkscape, which are made up of just curves, one for each stroke of the character. I have then imported these into Raphael using the raphael-svg-import: https://github.com/wout/raphael-svg-import
The SVGs are displaying perfectly, however I want to animate them.
My question is: Is there a way to take each path from the SVG in turn in Raphael, and then animate/stroke them? If so..how??
If you need any more info please say!
Thanks
EDIT: Perhaps I should clarify, when I say stroke I mean progressively draw the line, starting from the first point and ending at the last. At the moment it draws all paths simultaneously and draws the whole of each path at once.
The technique people use in svg for doing this is outlined in this answer. It's probably possible to adapt that to Raphaël, though the Raphaël documentation doesn't list stroke-dashoffset.
Raphaël has a method Element.getSubpath(from, to) that can be used to get only part of a path, that should probably also be an option.

Rollover overlays with SVG

i want to acheive the effect on this page using SVG. As you can see it uses a series of PNG transparent overlays when the user mouses over a polygonal hotspot drawn on a product.
What i want to achieve is the same thing with SVG, but without messing about with creating a load of PNGs, so that when the user mouses over an area the transparent shape (with link on it) appears over the top. The SVG shape would be built from a set of coordinates exactly as a polygonal hotspot would on an image map.
So i guess my first question is, can this be done with plain old SVG or do i need to use something like Raphael to achieve this? Never seen this effect before with SVG so if anyone has an example like that would be very useful.
Thanks in advance.
There are several ways to get this effect with plain old SVG. Probably the simplest is to use CSS within the SVG. For example:
<style>
.overlay:hover
{
opacity: 0.5;
}
</style>
<svg>
<a xlink:href="http://www.wherever/you/want/to/link/to.com">
<path class="overlay" d="Coordinates of your shape..." />
</a>
</svg>
I've written about various other methods at:
http://www.petercollingridge.co.uk/data-visualisation/mouseover-effects-svgs
Yes it can be done with SVG only, with or without javascript.
One way to get the effect would be to overlay a white semi-transparent path on top of the image that you want to whiten. Another way would be to use an SVG filter to process the image directly, similar to what I've done here or here to recolor a PNG (view page source and feel free to reuse that in any way you like).
You'll want to make use of the 'pointer-events' property most likely. Here's an example showing how to detect mouse-events on the fill and/or stroke of an svg shape, even if the shape is invisible.

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