This demonstrates how to animate the position of an element along a curve.
Click the button or drag the dots to see the animation. You can use this example as a tool to find the right XY values for start, end, and control points that will give you the right shape path for your own animation on a curve.
The curved line shown here between points 0 and 3 is just for preview purposes, and is not part of animation on a curve. The draggable points 0 - 3 are displayed only for UI interactivity.
To see anim along a path, click the button above, or drag point 0, 1, 2, or 3.
The X and Y of point 0 is [92,103]
The X and Y of 1, 2, and 3, are the sub-arrays in array value of "curve:" in the anim.set()
anim.set('to', {curve: [
[147,317],
[532,179],
[538,288] ]});
First we add some HTML to animate.
<div class="example">
<button id="btn-animate" class='yui3-button'>Animate On Path</button>
<div id="demo">A</div>
</div>
Now we create an instance of Y.Anim, passing it a configuration object that includes the node we wish to animate.
var demoA = Y.one('#demo');
var anim = new Y.Anim({
node: demoA,
duration: 1.5,
easing: Y.Easing.easeOut
});
A click handler will set the to value before run is called.
var startAnim = function(e) {
anim.set('to', {
curve: [ [x1, y1], [x2, y2], [x3, y3] ] // Where 1 and 2 are curve control points, and 3 is the end point.
});
anim.run();
};
If the animation will be run multiple times, you'll need to reset the position of the animated element.
Finally we add an event handler to run the animation.
var resetToAnimStart = function(){
demoA.setStyles({'left': x0, 'top': y0}); // Where x0, y0 is the animation starting point
}
Y.one('#btn-animate').on('click', function(){
resetToAnimStart();
startAnim();
});
The code shown above does the basics. This example however, allows dragging the points, displays xy values for each point while you drag, and displays a path preview of the animation using YUI Graphics Utility. This adds some complexity.
<style>
.example {
position: relative;
padding: 0;
margin: 0;
width: 100%;
}
.example div, .example p, .example span{
padding: 0;
margin: 0;
}
#mygraphiccontainer {
width: 650px;
height: 400px;
}
.example #demo {
position: absolute;
left: 92px;
top: 103px;
background-color: #f00;
text-align: center;
line-height: 1.5em;
border: solid 1px #cc0000;
border-radius: 0;
-moz-box-shadow: 3px 3px 7px rgba(0,0,0,0.4);
-webkit-box-shadow: 3px 3px 7px rgba(0,0,0,0.4);
width: 20px;
height: 20px;
}
.dot {
position: absolute;
color: #396491;
font-size: 20px;
height: 0;
line-height: 12px;
opacity: 0.8;
width: 0;
cursor: move;
}
.dot .point {
background-color: #000;
position: absolute;
left: -3px;
top: -3px;
width: 6px;
height: 6px;
border-radius: 3px;
font-size: 0px;
}
.number-label {
position: absolute;
top: -1em;
left: -0.9em;
width: 1em;
height: 1em;
line-height: 1em;
}
/* Gives the points a larger target area to drag */
.dot .fat-finger {
position: absolute;
top: -30px; /* minus half the fat-finger height */
left: -30px;
width: 60px;
height: 60px;
-moz-border-radius: 30px;
-webkit-border-radius: 30px;
border-radius: 30px;
background-color: #abc;
opacity: 0.3;
filter: alpha (opacity = 30);
}
#dot-3 .fat-finger {
background-color: #f80;
opacity: 0.4;
}
#dot-0 .fat-finger {
background-color: #8DAA16;
opacity: 0.4;
}
#dot-0, #demo {
top: 103px;
left: 92px;
}
#dot-1 {
top: 317px;
left: 147px;
}
#dot-2 {
top: 179px;
left: 532px;
}
#dot-3 {
left: 538px;
top: 288px;
}
#info {
position: absolute;
width: 450px;
height: 15em;
right: 1em;
top: 1em;
}
code span {
color: #CC3300;
}
.point {
font-size: 24px;
left: 5px;
position: absolute;
top: -5px;
}
</style>
<!-- In order for the script to run, this HTML markup must be nested in a <div class="example"> -->
<div id="mygraphiccontainer"></div> <!-- Container for the preview of the curve line -->
<div id="info">
<button id="btn-animate" class='yui3-button'>Animate On Path</button>
<p>To see anim along a path, click the button above, or drag point 0, 1, 2, or 3.</p>
<p>The X and Y of point 0 is <code>[<span class="arr0">92,103</span>]</code></p>
<p>The X and Y of 1, 2, and 3, are the sub-arrays in array value of "curve:" in the anim.set()</p>
<p><code>anim.set('to', {curve: [
[<span class="arr1">147,317</span>],
[<span class="arr2">532,179</span>],
[<span class="arr3">538,288</span>] ]});</code></p>
</div>
<div id="dot-0" class="dot zero">
<div class="point"></div>
<div class="fat-finger" title="Drag to change start point"></div> <!-- Gives the points a larger target area to drag -->
<div class="number-label">0</div>
</div>
<div id="dot-1" class="dot one">
<div class="point"></div>
<div class="fat-finger" title="Drag to change path"></div>
<div class="number-label">1</div>
</div>
<div id="dot-2" class="dot two">
<div class="point"></div>
<div class="fat-finger" title="Drag to change path"></div>
<div class="number-label">2</div>
</div>
<div id="dot-3" class="dot three">
<div class="point"></div>
<div class="fat-finger" title="Drag to change end point"></div>
<div class="number-label">3</div>
</div>
<div id="demo">A</div>
<script>
YUI().use('anim', 'dd-drag', 'graphics', 'cssbutton', function(Y){
var mygraphic = new Y.Graphic({render:"#mygraphiccontainer"}),
origin = Y.one('.example'), // The XY values for the animation are based on the upper-left corner of this element
demoA = Y.one('#demo'), // The animated element
dotList = Y.all('.dot');
// Draggable points
dot0 = Y.one('#dot-0'), dot1 = Y.one('#dot-1'), dot2 = Y.one('#dot-2'), dot3 = Y.one('#dot-3'),
// Array of XY arrays of draggable points
arrDot = [
[parseInt(dotList.item(0).getStyle('left'), 10), parseInt(dotList.item(0).getStyle('top'), 10)],
[parseInt(dotList.item(1).getStyle('left'), 10), parseInt(dotList.item(1).getStyle('top'), 10)],
[parseInt(dotList.item(2).getStyle('left'), 10), parseInt(dotList.item(2).getStyle('top'), 10)],
[parseInt(dotList.item(3).getStyle('left'), 10), parseInt(dotList.item(3).getStyle('top'), 10)]
],
// Make points draggable
dd0 = new Y.DD.Drag({
node: '#dot-0'
}),
dd1 = new Y.DD.Drag({
node: '#dot-1'
}),
dd2 = new Y.DD.Drag({
node: '#dot-2'
}),
dd3 = new Y.DD.Drag({
node: '#dot-3'
});
// Puts current XY values of points into displayed code snippet
var updateCodeSnippetValues = function(){
Y.one('.arr0').setHTML(arrDot[0][0] + ',' + arrDot[0][1]); // Start
Y.one('.arr1').setHTML(arrDot[1][0] + ',' + arrDot[1][1]); // Control point 1
Y.one('.arr2').setHTML(arrDot[2][0] + ',' + arrDot[2][1]); // Control point 2
Y.one('.arr3').setHTML(arrDot[3][0] + ',' + arrDot[3][1]); // End
}
/**
* Stops the animation
* Updates the array of point XY values
* Updates the curve preview
* Updates displayed XY point values in code snippet
*/
var dotDragHandler = function(dot){
Y.Anim.stop();
arrDot[dotList.indexOf(dot)] = [parseInt(dot.getStyle('left'), 10), parseInt(dot.getStyle('top'), 10)];
drawCurve();
updateCodeSnippetValues();
}
dd0.on('drag:drag', function(e){
dotDragHandler(this.get('dragNode'));
});
dd1.on('drag:drag', function(e){
dotDragHandler(this.get('dragNode'));
});
dd2.on('drag:drag', function(e){
dotDragHandler(this.get('dragNode'));
});
dd3.on('drag:drag', function(e){
dotDragHandler(this.get('dragNode'));
});
// button handler
Y.one('#btn-animate').on('click', function(){
Y.Anim.stop();
setTimeout(startAnim, 500);
});
Y.all('.dot').on('mouseup', function(e){
setTimeout(startAnim, 500);
});
// Create the animation instance
var anim = new Y.Anim({
node: demoA,
duration: 1.5,
easing: Y.Easing.easeOut
});
/**
* Sets the anim curve values with the XY values from the arrDot array
* Adds the origin offset values because anim works off page coordinates
*/
var startAnim = function(e){
var oX = origin.getX(),
oY = origin.getY();
// Reset the animated element to the start position.
// This is needed for running the animation multiple times
demoA.setStyles({'left':arrDot[0][0], 'top':arrDot[0][1]});
anim.set('to', {
curve: [ [(arrDot[1][0] + oX), (arrDot[1][1] + oY)], [ (arrDot[2][0] + oX), (arrDot[2][1] + oY) ], [ (arrDot[3][0] + oX), (arrDot[3][1] + oY) ] ]
});
anim.run();
};
// Adds a YUI Graphics path shape to the Graphics instance mygraphic
var animPath = mygraphic.addShape({
type: "path",
stroke: {
weight: 4,
color: "#aabbcc"
}
});
// Draw a preview curve with the Graphics animPath shape to match the Anim curve
var drawCurve = function(){
animPath.clear();
animPath.moveTo(arrDot[0][0],arrDot[0][1]);
animPath.curveTo(arrDot[1][0],arrDot[1][1], arrDot[2][0],arrDot[2][1], arrDot[3][0],arrDot[3][1]);
animPath.end();
}
drawCurve(); // Initial drawing of the preview curve
updateCodeSnippetValues(); // Initial setting of code snippet XY values
});
</script>