The SVG Plugin for KUTE.js extends the core engine and enables animation for various SVG specific CSS properties, SVG morphing of path shapes and SVG transforms. We'll dig into this in great detail as well as provide valuable tips on how to configure your animation for best performance and visual aesthetics. The SVG Plugin is very light, maybe one of the lightest out there, still, you will find it to be very powerful and flexible.
Keep in mind that older browsers like Internet Explorer 8 and below as well as stock browser from Android 4.3 and below do not support inline SVG so make sure to fiter out your SVG tweens.
One of the most important parts of the plugin is the SVG morphing capability. It only applies to inline <path> and <glyph> SVG elements, with closed shapes (their d attribute ends with z). On initialization or animation start, depending on the chosen KUTE.js method, it will sample a number of points along the two paths based on a default / given sample size and will create two arrays with these points, the arrays that we need for interpolation. Further more, with a set of options we can then rearrange / reverse these arrays to optimize and / or maximize the visual effect of the morph:
true this option allows you to reverse the draw direction of the FIRST shape. By default this option is false.true this option allows you to reverse the draw direction of the SECOND shape. By default this option is also false.In the first morph example we are going to go through some basic steps on how to setup and how to improve the morph animation. Our demo is a morph from a rectangle into a star, so first let's create an SVG element with two paths, first is going to be visible, filled with color, while second is going to be hidden. The first path is the start shape and the second is the end shape, you guessed it, and we can also add some ID to the paths so we can easily target them with our code.
<svg id="morph-example" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 600 600">
<path id="rectangle" class="bg-lime" d="M38.01,5.653h526.531c17.905,0,32.422,14.516,32.422,32.422v526.531 c0,17.905-14.517,32.422-32.422,32.422H38.01c-17.906,0-32.422-14.517-32.422-32.422V38.075C5.588,20.169,20.104,5.653,38.01,5.653z"/>
<path id="star" style="visibility:hidden" d="M301.113,12.011l99.25,179.996l201.864,38.778L461.706,380.808 l25.508,203.958l-186.101-87.287L115.01,584.766l25.507-203.958L0,230.785l201.86-38.778L301.113,12.011"/>
</svg>
Now we can apply both .to() and fromTo() methods:
// the fromTo() method
var tween = KUTE.fromTo('#rectangle', {path: '#rectangle' }, { path: '#star' }).start();
// OR
// the to() method will take the path's d attribute value and use it as start value
var tween = KUTE.to('#rectangle', { path: '#star' }).start();
// OR
// simply pass in a valid path string without the need to have two paths in your SVG
var tween = KUTE.to('#rectangle', { path: 'M301.113,12.011l99.25,179.996l201.864,38.778L461.706,380.808l25.508,203.958l-186.101-87.287L115.01,584.766l25.507-203.958L0,230.785l201.86-38.778L301.113,12.011' }).start();
For all the above tween objects the animation should look like this:
As you can see, the animation could need some fine tunning. Let's go ahead and play with the new utility, it's gonna make your SVG morph work a breeze.
Well, we're going to set the morphIndex: 127 tween option and we will get an improved morph. Sometimes the recommended value isn't what we're looking for, so you just have to experience values around the recommended one. I also made a pen for you to play with.
Much better! You can play with the morphIndex value, maybe you can get a more interesting morph.
When your paths are only lineto, vertical-lineto and horizontal-lineto based shapes (the d attribute consists of L, V and H path commands), the SVG Plugin will work differently: it will use their points instead of sampling new ones. As a result, we boost the visual and maximize the performance. The morphPrecision option will not apply since the paths are already polygons, still you will have access to all the other options.
The plugin will try to convert paths to absolute values for polygons, but it might not find most accurate coordinates values for relative v and h path commands. I highly recommend using my utility converter to prepare your paths in that case.
// let's morph a triangle into a star
var tween1 = KUTE.to('#triangle', { path: '#star' }).start();
// or same path into a square
var tween2 = KUTE.to('#triangle', { path: '#square' }).start();
In the example below the triangle shape will morph into a square, then the square will morph into a star, so 2 tweens chained with a third that will morph back to the original triangle shape. For each tween the morph will use the number of points from the shape with most points as a sample size for the other shape. Let's have a look at the demo.
The morph for polygon paths is the best morph in terms of performance so it's worth keeping that in mind. Also using paths with only L path command will make sure to prevent value processing and allow the animation to start as fast as possible.
In other cases, you may want to morph paths that have subpaths. Let's have a look at the following paths:
<svg id="multi-morph-example" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 600 600">
<path d="M206.115,255.957c-23.854-12.259-47.043-18.479-68.94-18.479c-2.978,0-5.976,0.09-8.974,0.354 c-27.94,2.312-53.461,9.684-69.875,15.414c-4.354,1.599-8.817,3.288-13.415,5.152L0,414.096 c30.851-11.416,58.146-16.969,83.135-16.969c40.423,0,69.764,15.104,93.996,30.652c11.481-38.959,39.022-133.045,47.241-161.162 C218.397,262.975,212.334,259.332,206.115,255.957z
M264.174,295.535l-45.223,157.074c13.416,7.686,58.549,32.024,93.105,32.024 c27.896,0,59.127-7.147,95.417-21.896l43.179-150.988c-29.316,9.461-57.438,14.26-83.732,14.26 C318.945,326.01,285.363,310.461,264.174,295.535z
M146.411,184.395c38.559,0.399,67.076,15.104,90.708,30.251l46.376-158.672c-9.772-5.598-35.403-19.547-53.929-24.3c-12.193-2.842-25.01-4.308-38.602-4.308c-25.898,0.488-54.194,6.973-86.444,19.9 L60.3,202.564c32.404-12.218,60.322-18.17,86.043-18.17C146.366,184.395,146.411,184.395,146.411,184.395L146.411,184.395z
M512,99.062c-29.407,11.416-58.104,17.233-85.514,17.233c-45.844,0-79.646-15.901-101.547-31.183L278.964,244.23 c30.873,19.854,64.146,29.939,99.062,29.939c28.474,0,57.97-6.84,87.73-20.344l-0.091-1.111l1.867-0.443L512,99.062z"/>
<path d="M0.175 256l-0.175-156.037 192-26.072v182.109z
M224 69.241l255.936-37.241v224h-255.936z
M479.999 288l-0.063 224-255.936-36.008v-187.992z
M192 471.918l-191.844-26.297-0.010-157.621h191.854z"/>
</svg>
As you can see, both these paths have subpaths, and KUTE.js will only animate the first of both in this case. To animate them all, we need to break them into multiple paths, so we can handle each path morph properly.
<svg id="multi-morph-example" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 600 600">
<path id="w11" d="M206.115,255.957c-23.854-12.259-47.043-18.479-68.94-18.479c-2.978,0-5.976,0.09-8.974,0.354 c-27.94,2.312-53.461,9.684-69.875,15.414c-4.354,1.599-8.817,3.288-13.415,5.152L0,414.096 c30.851-11.416,58.146-16.969,83.135-16.969c40.423,0,69.764,15.104,93.996,30.652c11.481-38.959,39.022-133.045,47.241-161.162 C218.397,262.975,212.334,259.332,206.115,255.957z"/>
<path id="w12" d="M264.174,295.535l-45.223,157.074c13.416,7.686,58.549,32.024,93.105,32.024 c27.896,0,59.127-7.147,95.417-21.896l43.179-150.988c-29.316,9.461-57.438,14.26-83.732,14.26 C318.945,326.01,285.363,310.461,264.174,295.535z"/>
<path id="w13" d="M146.411,184.395c38.559,0.399,67.076,15.104,90.708,30.251l46.376-158.672c-9.772-5.598-35.403-19.547-53.929-24.3c-12.193-2.842-25.01-4.308-38.602-4.308c-25.898,0.488-54.194,6.973-86.444,19.9 L60.3,202.564c32.404-12.218,60.322-18.17,86.043-18.17C146.366,184.395,146.411,184.395,146.411,184.395L146.411,184.395z"/>
<path id="w14" d="M512,99.062c-29.407,11.416-58.104,17.233-85.514,17.233c-45.844,0-79.646-15.901-101.547-31.183L278.964,244.23 c30.873,19.854,64.146,29.939,99.062,29.939c28.474,0,57.97-6.84,87.73-20.344l-0.091-1.111l1.867-0.443L512,99.062z"/>
<path id="w21" style="visibility:hidden" d="M0.175 256l-0.175-156.037 192-26.072v182.109z"/>
<path id="w22" style="visibility:hidden" d="M224 69.241l255.936-37.241v224h-255.936z"/>
<path id="w23" style="visibility:hidden" d="M479.999 288l-0.063 224-255.936-36.008v-187.992z"/>
<path id="w24" style="visibility:hidden" d="M192 471.918l-191.844-26.297-0.010-157.621h191.854z"/>
</svg>
After a close inspection we determined that paths are not ordered the same so it seems we need to tween the paths in a way that their points travel the least possible distance, as follows: #w11 to #w24, #w13 to #w21, #w14 to #w22 and #w12 to #w23.
Now we can write the tween objects and get to working:
var multiMorph1 = KUTE.to('#w11', { path: '#w24' }).start();
var multiMorph2 = KUTE.to('#w13', { path: '#w21' }).start();
var multiMorph3 = KUTE.to('#w14', { path: '#w22' }).start();
var multiMorph3 = KUTE.to('#w12', { path: '#w23' }).start();
As you can imagine, it's quite hard if not impossible to code something that would do all this work automatically, so after a minute or two tweaking the options, here's what we should see:
Note that this final touch required using reverseSecondPath:true option for all tweens because each shape have a slightly different position from its corresponding shape, so make sure to check the svg.js for a full code review.
The last morph example is a bit more complex as the paths have subpaths with different positions and other important differences such as having different amounts of subpaths as well as significant differences of their positions. In this case you have to manually clone one or more paths in a way that the number of starting shapes is equal to the number of ending shapes, as well as making sure the starting shapes are close to their corresponding end shapes; at this point you should be just like in the previous example.
An important aspect of multi path morph is syncronization: since the .to() method will prepare the paths for interpolation at animation start, and this usually takes a bit of time, the problem can be easily solved as always using the .fromTo() method. So, let's get into it:
// complex multi morph, the paths should be self explanatory
var morph1 = KUTE.fromTo('#start-container', { path: '#start-container' }, { path: '#end-container' });
var morph2 = KUTE.fromTo('#startpath1', { path: '#startpath1' }, { path: '#endpath1' });
var morph3 = KUTE.fromTo('#startpath1-clone', { path: '#startpath1-clone' }, { path: '#endpath1' });
var morph4 = KUTE.fromTo('#startpath2', { path: '#startpath2' }, { path: '#endpath2' });
As with the previous example, you should change which path will morph to which path so that their points travel the least possible distance and the morph animation looks visually appealing. In the next example, we have used a mask where we included the subpaths of both start and end shape, just to get the same visual as the originals.
While there are other tools such as SVGMorpheus to enable this kind of multi-path morph, they lack in options to improve the visual and performance. The demos look acceptable in most cases, but the SVGs were manually prepared/optimized which makes it pretty much unusable on a broader scope. The SVG Plugin for KUTE.js uses approximatelly the same algorithm as D3.js for determining the coordinates for tween, it's super light, it's a better solution.
morphPrecision value (1-10) would be required, assuming performant hardware are powering the displays. For small displays you can get quite comfortable with almost any value, including the default value.lineto path commands are best for performance..to() and .fromTo() methods, but the ones that use the second method will start faster, because the values have been prepared already and for the first method the processing of the two paths happens on tween start delaying the animation, so keep that in mind when working with syncing multiple tweens, the .to() based morph will always start later. Of course this assumes the you cache the tween objects first and start the animation later, if not (you start the animation on object creation), both methods will be delayed.Next, we're going to animate the stroking of some elements. Starting with KUTE.js version 1.5.2, along with <path> shapes, <circle>, <ellipse>, <rect>, <line>, <polyline> and <polygon> shapes are also supported; the script uses the SVG standard .getTotalLength() method for <path> shapes, while the others use some helper methods. Here some code examples:
// draw the stroke from 0-10% to 90-100%
var tween1 = KUTE.fromTo('selector1',{draw:'0% 10%'}, {draw:'90% 100%'});
// draw the stroke from zero to full path length
var tween2 = KUTE.fromTo('selector1',{draw:'0% 0%'}, {draw:'0% 100%'});
// draw the stroke from full length to 50%
var tween3 = KUTE.fromTo('selector1',{draw:'0% 100%'}, {draw:'50% 50%'});
We're gonna chain these tweens and start the animation real quick.
Remember: the draw property also accepts absolute values, eg. draw: '0 150'; the .to() method takes 0% 100% as start value for your tweens when stroke-dasharray and stroke-dashoffset are not set.
Starting with KUTE.js 1.5.2, the SVG Plugin features a new tween property for cross browser SVG transforms, but was coded as a separate set of methods for SVG only, to keep performance tight. A very simple roadmap was described here; in brief we needed to find a way to enable transforms for SVG in a reliable and cross-browser supported fashion.
While you can still use regular CSS3 transforms for SVGs on browsers like Google Chrome and Firefox, to animate SVG shapes on all browsers, we use the transform presentation attribute and the svgTransform tween property with a special notation:
// regular CSS3 transforms apply to SVG elements, but not working in IE and some older Opera versions
var tween1 = KUTE.to('shape', { translate: [150,100], rotate: 45, skewX: 15, skewY: 20, scale: 1.5 }, {transformOrigin: "50% 50%"});
// using the svgTransform property, working in all browsers
// the Y translation as well as rotate transform-origin are provided
var tween2 = KUTE.to('shape', {svgTransform: { translate: [120,100], rotate: [45,0,0], skewX: 15, skewY: 20, scale: 1.2 }});
// OR using shorthand notations
// we understand the Y translation is 0 and the rotation transform-origin is 50% 50%,
// the center of the shape and not the parent SVG's center
var tween2 = KUTE.to('shape', {svgTransform: { translate: 120, rotate: 45, scale: 1.2 }});
As you can see we have some familiar notation as well as new notation. One thing to know is that this feature may not support and wasn't tested for SVG specific chained/nested transformations. Perhaps the most important thing to remember is the fact that SVG tranformations always use SVG coordinates system, and the transform attribute requires no degree or pixel as measurement units. Let's break it down.
In our first example we'll have a look at rotations. For instance setting rotate: [45,0,0], the first value is the angle to which the shape will rotate to and the other two values are coordinates for the transform-origin. When rotate: 45 notation is used, the script will calculate the coordinates of the shape's central point, as if your transform-origin default value is 50% 50%, something you would expect from regular HTML elements. However keep in mind that the transform-origin coordinates are relative to the parent <svg> element. Let's have a look at a quick demo:
The first tween uses the CSS3 transform notation and the animation clearly shows the shape rotating around it's center coordinate, as we've set transformOrigin option to 50% 50%, but this animation doesn't work in all browsers. The second tween uses the rotate: 360 notation and the animation shows the shape rotating around it's own central point, an animation that DO WORK in all SVG enabled browsers.
When for CSS3 transforms we could have used values such as center bottom as transform-origin (also not supported in all modern browsers), the entire processing was basically in/by the browser, however when it comes to SVG we need to make use of the SVG API functions to determine the proper value. But stay cool, here comes .getBBox() to the rescue! Here's how to rotate an element around it's 25% 75% coordinate:
// rotate around element's "25% 75%"" coordinate as transform-origin
// get the bounding box
// returns an object like {x:0, y:20, width:200, height: 200} for any type of SVG shape
// x is the distance from top, y is the distance from left, width and height are just that
var bb = element.getBBox();
// determine the X point of transform-origin for 25%
var shapeOriginX = bb.x + (25 * bb.width / 100);
// determine the Y point of transform-origin for 75%
var shapeOriginY = bb.y + (75 * bb.height / 100);
// set your rotation tween with "25% 75%" transform-origin
var rotationTween = KUTE.to(element, {svgTransform: {rotate: [45, shapeOriginX, shapeOriginY]}});
Or you can rotate an element around the parent's <svg> 50% 50% coordinate:
// rotate around parent svg's "50% 50%" coordinate as transform-origin
// get the bounding box
var svgBB = element.ownerSVGElement.getBBox(); // returns same object but it's for the parent <svg> element
// determine the X point of transform-origin for 50%
var svgOriginX = svgBB.x + (50 * svgBB.width / 100);
// determine the Y point of transform-origin for 50%
var svgOriginY = svgBB.y + (50 * svgBB.height / 100);
// set your rotation tween with "50% 50%" transform-origin of the parent <svg> element
var rotationTween = KUTE.to(element, {svgTransform: {rotate: [150, svgOriginX, svgOriginY]}});
In this example we'll have a look at translations, so when setting translate: [150,0], the first value is X (horizontal) coordinate to which the shape will translate to and the second value is Y (vertical) coordinate for translation. When translate: 150 notation is used, the script will understand that's the X value and the Y value is 0 just like for the regular HTML elements transformation. Let's have a look at a quick demo:
The first tween uses the CSS3 translate: 580 notation and the second tween uses the translate: [0,0] as svgTransform value. For the second example the values are unitless and are relative to the viewBox attribute.
For skews for SVGs we have a very simple notation: skewX: 25 or skewY: -25 as SVGs don't support the skew: [X,Y] function. Here's a quick demo:
The first tween skews the shape on both X and Y axis in a chain via regular CSS3 transforms and the second tween skews the shape on X and Y axis via the svgTransform tween property. The example also showcases the fact that chain transformations for SVGs via transform attribute works just as for the CSS3 transformations and you really have to check the example code here to learn how to master this technique.
For this particular example we've set transformOrigin option to "0px 0px" for the first shape (the default value for SVGs' transform-origin on most browsers) because we cannot set anything similar for the skews of the transform attribute for the second shape. Generally skews are hard to handle for SVGs because they are independent of any transform-origin. We can only compensate with translation, a very complicated story.
Another transform example for SVGs is the scale. Unlike translations, for scale animation the plugin only accepts single value like scale: 1.5, for both X (horizontal) axis and Y (vertical) axis, to keep it simple and even if SVGs do support scale(X,Y). But because the scaling on SVGs depends very much on the shape's position, the script will always try to adjust the translation to make the animation look as we would expect. A quick demo:
The first tween scales the shape at scale: 1.5 via regular CSS3 transforms, and the second tween scales down the shape at scale: 0.5 value via svgTransform. If you inspect the elements, you will notice for the second shape translation is involved, and this is to keep transform-origin at an expected 50% 50% value. A similar case as with the skews.
Our last transform example for SVGs is the mixed transformation. Similar with scale animation the plugin will try to adjust the rotation transform-origin to make it look as you would expect it from regular HTML elements. Let's combine 3 functions at the same time and see what happens:
Both shapes are scaled at scale: 1.5, translated to translate: 250 and skewed at skewX: -15. If you inspect the elements, you will notice the second shape's translation is different from what we've set in the tween object, and this is to keep transform-origin at an expected 50% 50% value. This means that the plugin will also compensate rotation transform origin when skews are used, so that both CSS3 transform property and SVG transform attribute have an identical animation.
translate, scale, rotate, skewX and skewY. All this to make sure the animation looks like we would expect from regular HTML elements transformations. Maybe future versions will feature .matrix() transformations to handle all possible transform function combinations, but I'm going to need help with implementation and testing..getBBox() method, it's really useful to set custom transform-origin.overflow: hidden for <svg> so child elements are partialy/completely hidden while animating. You might want to set overflow: visible or some browser specific tricks if that is the case.viewBox="0 0 500 500" attribute for <svg> and no width and/or height attribute(s), means that you expect the SVG to be scalable and most Internet Explorer versions simply don't work. You might want to check this tutorial.svgTransform property DOES stack transform functions for chained tween objects created with the .to() method, you will have to provide only values for the functions that will change and the plugin will try to keep the unchanged values. However, there's a catch: you need to follow the properties that change and I highly recommend checking the example code for skews in the svg.js file..fromTo() method with all proper values.svgTransform feature does not support 3D transforms, because they are not supported in all browsers.The SVG Plugin can be combined with the Attributes Plugin to enable even more advanced/complex animations for SVG elements.
Since SVG morph scripting works only with path or glyph elements, I'm also considering a very light convertToPath feature, but there are some already out there.