<script src="https://cdnjs.cloudflare.com/ajax/libs/konva/2.5.1/konva.min.js"></script>
<div>
<p> <input type='text' id='theText' value='BBB' /> <button id='st'>Change text</button> </p>
</div>
<div id='container1' style="width: 300px, height: 200px;"></div>
div
{
margin: 0 5px;
}
p
{
margin: 0 5px 5px 0;
}
// Set up the canvas / stage
var s1 = new Konva.Stage({container: 'container1', width: 300, height: 200});
// Add a layer for line
var layer = new Konva.Layer({draggable: false});
s1.add(layer);
// just a plain JS object to keep common variables in hand.
var cfg = { w: 300, h: 200, r: 80, txtSize: 520};
var group = new Konva.Group();
var circle = new Konva.Circle({x: cfg.w/2, y: cfg.h/2, radius: cfg.r, fill: 'DodgerBlue', stroke: 'DeepPink', strokeWidth: 5})
group.add(circle)
// make the text
var textValue = new Konva.Text({
id: "t1",
x: cfg.w/2,
y: cfg.h/2,
text: '',
fill: 'DeepPink ',
fontSize: cfg.txtSize
});
group.add(textValue);
textValue.offset({x: textValue.getWidth()/2, y: textValue.getHeight()/2});
layer.add(group)
// to spin a group about a point, set the offset to that point, then set the x & y to that point to !
var pos = group.getClientRect();
RotatePoint(group, {x: pos.x + pos.width/2, y: pos.y + pos.height/2});
// Everything is ready so draw the canvas objects set up so far.
s1.draw()
$('#st').on('click', function(){
group.scaleX(1);
var txt = $('#theText').val();
setValue(txt);
})
// set the offset for rotation to the given location and re-position the shape
function RotatePoint(shape, pos){ // where pos = {x: xpos, y: yPos}
var initialPos = shape.getAbsolutePosition();
var moveBy = {x: pos.x - initialPos.x, y: pos.y - initialPos.y};
// offset is relative to initial x,y of shape, so deduct x,y.
shape.offsetX(moveBy.x);
shape.offsetY(moveBy.y);
shape.x(initialPos.x + moveBy.x);
shape.y(initialPos.y + moveBy.y);
}
var setValue = function(newText){
// work out scaling to make text fit into the circle
var txt = this.layer.find('#t1')[0];
txt.text(newText).scale({x:1, y: 1})
var txtSize = txt.getClientRect();
var maxW = (cfg.r); // max allowed width of text
var txtScaleW = (txtSize.width > maxW ? ( maxW / txtSize.width) : 1);
var maxH = cfg.r; // max allowed height of text
var txtScaleH = (txtSize.height > maxH ? ( maxH / txtSize.height) : 1);
// finally decide which is the worst case and use that scaling
var txtScale = ( txtScaleW > txtScaleH ? txtScaleH : txtScaleW);
txt.scale({x: txtScale, y: txtScale});
txt.offset({x: txt.getWidth()/2, y: txt.getHeight()/2});
layer.draw()
}
// set initial text & spin !
setValue('BBB');
// The magin animation config.
var anim, pos = 0, frameCnt = 0
if (anim) {anim.stop(); }
anim = new Konva.Animation(function(frame) {
frameCnt = frameCnt + 1;
if (frameCnt % 2 === 0){
pos = pos + .2
var scaleX = Math.sin(pos);
textValue.visible(scaleX < 0 ? false : true);
group.scaleX(scaleX);
}
}, layer);
anim.start();
This Pen doesn't use any external CSS resources.