so i'm working on a canvas that you can only drag a image from side to side and use the mouse wheel to re size the image by zooming in and out on it here is the code i have so far please feel free to ask any more details. I'm trying to find a way that's compact to do this and require minimum code.
<!DOCTYPE HTML>
<html>
<head>
<style>
body {
margin: 0px;
padding: 0px;
}
</style>
<script src="kinetic-v5.1.0.min.js" type="text/javascript"></script>
</head>
<body>
<div id="container"></div>
<script type="text/javascript">
function drawImage(imageObj) {
var stage = new Kinetic.Stage({
container: "container",
width: 1800,
height: 800
});
var layer = new Kinetic.Layer();
// image
var image1 = new Kinetic.Image({
image: imageObj,
x: stage.getWidth() / 2 - 896 / 1,
y: stage.getHeight() / 2 - 255 / 2,
width: 200,
height: 157,
draggable: true,
dragBoundFunc: function (pos) {
if (pos.x < this.minX) { }
this.minX = pos.x;
return {
x: pos.x,
y: this.getAbsolutePosition().y
}
}
});
// add cursor styling
image1.on('mouseover', function() {
document.body.style.cursor = 'pointer';
});
image1.on('mouseout', function() {
document.body.style.cursor = 'default';
});
layer.add(image1);
stage.add(layer);
}
var imageObj = new Image();
imageObj.onload = function() {
drawImage(this);
};
imageObj.src = 'image1.png';
</script>
</body>
</html>
One way would be to use a zoom helper. For example:
var zoomHelper = {
stage: null,
scale: 1,
zoomFactor: 1.1,
origin: {
x: 0,
y: 0
},
zoom: function(event) {
event.preventDefault();
var delta;
if (navigator.userAgent.toLowerCase().indexOf('firefox') > -1) {
if (event.originalEvent.detail > 0) {
//scroll down
delta = 0.2;
} else {
//scroll up
delta = 0;
}
} else {
if (event.originalEvent.wheelDelta < 0) {
//scroll down
delta = 0.2;
} else {
//scroll up
delta = 0;
}
}
var evt = event.originalEvent,
mx = evt.clientX - zoomHelper.stage.getX(),
my = evt.clientY - zoomHelper.stage.getY(),
zoom = (zoomHelper.zoomFactor - delta),
newscale = zoomHelper.scale * zoom;
zoomHelper.origin.x = mx / zoomHelper.scale + zoomHelper.origin
.x - mx / newscale;
zoomHelper.origin.y = my / zoomHelper.scale + zoomHelper.origin
.y - my / newscale;
zoomHelper.stage.setOffset({
x: zoomHelper.origin.x,
y: zoomHelper.origin.y
});
zoomHelper.stage.setScale({
x: newscale,
y: newscale
});
zoomHelper.stage.draw();
zoomHelper.scale *= zoom;
}
};
Here is a demo with code you provided in as an example slightly changed.
Try using this full javascript library.
Related
I am using Konva canvas framework and I want to implement zoom in and zoom out with mouse wheel.
The zoom in should be relative to my cursor pointer, but zoom out should always zoom out to the initial state.
<!DOCTYPE html>
<html>
<head>
<script src="https://unpkg.com/konva#7.2.2/konva.min.js"></script>
<meta charset="utf-8" />
<title>Konva Zoom Relative to Stage Demo</title>
<style>
body {
margin: 0;
padding: 0;
overflow: hidden;
background-color: #f0f0f0;
}
</style>
</head>
<body>
<div id="container"></div>
<script>
var width = window.innerWidth;
var height = window.innerHeight;
var stage = new Konva.Stage({
container: 'container',
width: width,
height: height,
});
var layer = new Konva.Layer();
stage.add(layer);
var circle = new Konva.Circle({
x: stage.width() / 2,
y: stage.height() / 2,
radius: 50,
fill: 'green',
});
layer.add(circle);
layer.draw();
var scaleBy = 0.95;
stage.on('wheel', (e) => {
e.evt.preventDefault();
var oldScale = stage.scaleX();
var pointer = stage.getPointerPosition();
var mousePointTo = {
x: (pointer.x - stage.x()) / oldScale,
y: (pointer.y - stage.y()) / oldScale,
};
var newScale =
e.evt.deltaY > 0 ? oldScale * scaleBy : oldScale / scaleBy;
stage.scale({ x: newScale, y: newScale });
var newPos = {
x: pointer.x - mousePointTo.x * newScale,
y: pointer.y - mousePointTo.y * newScale,
};
stage.position(newPos);
stage.batchDraw();
});
</script>
</body>
</html>
So, in the example you can see there is circle green in the center. When client zoom in, I want the zoom to be relative to pointer. But, when zooming out, the zoom won't be relative to pointer, but simply goes back to the initial state (green circle in the center).
So I changed some things, only for demo purpose - but the concept is the same:
<!DOCTYPE html>
<html>
<head>
<script src="https://unpkg.com/konva#7.2.2/konva.min.js"></script>
<meta charset="utf-8" />
<title>Konva Zoom Relative to Stage Demo</title>
<style>
body {
margin: 0;
padding: 0;
overflow: hidden;
background-color: #f0f0f0;
}
</style>
</head>
<body>
<div id="container"></div>
<script>
var width = window.innerWidth;
var height = window.innerHeight;
var stage = new Konva.Stage({
container: 'container',
width: width,
height: height,
});
var layer = new Konva.Layer();
stage.add(layer);
var circle = new Konva.Rect({
x: stage.width()/2,
y:stage.height()/2,
width: 50,
height: 50,
fill: 'green',
});
layer.add(circle);
layer.draw();
var scaleBy = 0.99;
stage.on('wheel', (e) => {
e.evt.preventDefault();
var oldScale = stage.scaleX();
var mousePointTo = {
x: stage.getPointerPosition().x / oldScale - stage.x() / oldScale,
y: stage.getPointerPosition().y / oldScale - stage.y() / oldScale
};
var newScale =
e.evt.deltaY > 0 ? oldScale * scaleBy : oldScale / scaleBy;
newScale = Math.max( newScale, 1 );
stage.scale({ x: newScale, y: newScale });
var newPos = {
x:
-(mousePointTo.x - stage.getPointerPosition().x / newScale) *
newScale,
y:
-(mousePointTo.y - stage.getPointerPosition().y / newScale) *
newScale
};
newPos.x = Math.min( newPos.x, 0 );
newPos.x = Math.max( newPos.x, width * ( 1 - newScale ) );
newPos.y = Math.min( newPos.y, 0 );
newPos.y = Math.max( newPos.y, height * ( 1 - newScale ) );
stage.position(newPos);
stage.batchDraw();
});
</script>
</body>
</html>
<!DOCTYPE html>
<html>
<head>
<title>Page Title</title>
<style>
body {
font-family: "Lato", sans-serif;
}
.sidenav {
height: 100%;
width: 0;
position: fixed;
z-index: 1;
top: 0;
left: 0;
background-color: #111;
overflow-x: hidden;
transition: 0.5s;
padding-top: 60px;
}
.sidenav a {
padding: 8px 8px 8px 32px;
text-decoration: none;
font-size: 25px;
color: #818181;
display: block;
transition: 0.3s;
}
.sidenav a:hover {
color: #f1f1f1;
}
.sidenav .closebtn {
position: absolute;
top: 0;
right: 25px;
font-size: 36px;
margin-left: 50px;
}
#main {
transition: margin-left .5s;
padding: 16px;
}
#media screen and (max-height: 450px) {
.sidenav {padding-top: 15px;}
.sidenav a {font-size: 18px;}
}
</style>
</head>
<body>
<div id="mySidenav" class="sidenav">
×
About
Services
Clients
Contact
</div>
<div id="main">
<span style="font-size:30px;cursor:pointer" onclick="openNav()">☰ Menu</span>
<canvas id="canvas" width="600" height="350" style="border:2px solid #d3d3d3;">></canvas>
</div>
<script>
var zoomIntensity = 0.1;
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
var width = 90;
var height = 50;
var scale = 1;
var originx = 0;
var originy = 0;
var visibleWidth = width;
var visibleHeight = height;
var c = document.getElementById("canvas");
var ctx = c.getContext("2d");
function draw(){
context.fillStyle = "white";
context.fillRect(originx,originy,1000/scale,800/scale);
context.fillStyle = "blue";
context.fillRect(170,50,50,50);
context.fillStyle = "white";
context.fillText('click here',175,70);
}
setInterval(draw, 1000/60);
canvas.onwheel = function (event){
event.preventDefault();
var mousex = event.clientX - canvas.offsetLeft;
var mousey = event.clientY - canvas.offsetTop;
var wheel = event.deltaY < 0 ? 1 : -1;
var zoom = Math.exp(wheel*zoomIntensity);
context.translate(originx, originy);
originx -= mousex/(scale*zoom) - mousex/scale;
originy -= mousey/(scale*zoom) - mousey/scale;
context.scale(zoom, zoom);
context.translate(-originx, -originy);
scale *= zoom;
visibleWidth = width / scale;
visibleHeight = height / scale;
}
function openNav() {
document.getElementById("mySidenav").style.width = "200px";
document.getElementById("main").style.marginLeft = "200px";
}
function closeNav() {
document.getElementById("mySidenav").style.width = "0";
document.getElementById("main").style.marginLeft= "0";
}
</script>
</body>
</html>
is there away to make a shape or object clickable on canvas frame or viewbox, even when i zoom in or out, cause all the examples i saw was just a fixed clickable location. for instance google map locations when i zoom in i can click more objects.
is there away to make a shape or object clickable on canvas frame or viewbox, even when i zoom in or out, cause all the examples i saw was just a fixed clickable location. for instance google map locations when i zoom in i can click more objects.
There are two spaces you have to account for, the actual canvas space and the translated space. This means you need to translate the mouse coordinates in order to know where in the space the object is actually located and map it back to the canvas coordinates so you can know if you are clicking on it. This is achieved by keeping track of the offset value you provided in the var originx, but the problem is that there is no way based on my trails at least for you to translate the mouse click location if you use the context.translate(originx, originy) if you both scale and pan the object space.
I have rewritten the code without the use of the translate function by making my own translate function that enables you to translate between the canvas space and object space in order to register a click event on the object regardless of the panned or zoomed in location.
This function also has a click to pan feature so you can click and drag the object screen to where ever you want to object to be positioned.
/*jshint esversion: 8 */
(function() {
const canvas = document.querySelector("canvas");
const context = canvas.getContext("2d");
let canvasWidth = 600;
let canvasHeight = 600;
let offset = {
x: 0,
y: 0
};
let pan = {
x: 0,
y: 0
};
var zoomIntensity = 0.1;
let scale = 1;
let mouse = {
x: 0,
y: 0
};
let dragging = false;
let square;
let shapes = [{
x: 170,
y: 50,
w: 50,
h: 50,
color: "blue"
},
{
x: 85,
y: 25,
w: 50,
h: 50,
color: "red"
},
{
x: 50,
y: 100,
w: 50,
h: 50,
color: "green"
},
];
function init() {
canvas.width = canvasWidth;
canvas.height = canvasHeight;
renderCanvas();
}
function drawSquare(x, y, width, height, color) {
context.fillStyle = color;
context.fillRect(x, y, width, height);
}
function objectsToCanvasScreen(x, y) {
const canvasScreenX = Math.floor((x - offset.x) * scale);
const canvasScreenY = Math.floor((y - offset.y) * scale);
return {
x: canvasScreenX,
y: canvasScreenY
};
}
function canvasToObjectsScreen(x, y) {
return {
x: x / scale + offset.x,
y: y / scale + offset.y
};
}
function renderCanvas() {
context.clearRect(0, 0, canvas.width, canvas.height);
shapes.forEach(({
x,
y,
w,
h,
color
}, index) => {
const {
x: csx,
y: csy
} = objectsToCanvasScreen(x, y);
shapes[index]._x = csx;
shapes[index]._y = csy;
shapes[index]._w = w * scale;
shapes[index]._h = h * scale;
drawSquare(csx, csy, w * scale, h * scale, color);
});
}
canvas.onwheel = function(e) {
const zoom = Math.exp((e.deltaY < 0 ? 1 : -1) * zoomIntensity);
const beforeZoom = canvasToObjectsScreen(mouse.x, mouse.y);
scale *= zoom;
const afterZoom = canvasToObjectsScreen(mouse.x, mouse.y);
offset.x += beforeZoom.x - afterZoom.x;
offset.y += beforeZoom.y - afterZoom.y;
renderCanvas();
};
canvas.onmousedown = function(e) {
if (e.button === 0) {
pan.x = mouse.x;
pan.y = mouse.y;
dragging = true;
}
};
canvas.onmouseup = (e) => (dragging = false);
canvas.onmousemove = function(e) {
mouse.x = e.offsetX;
mouse.y = e.offsetY;
if (dragging) {
offset.x -= (mouse.x - pan.x) / scale;
offset.y -= (mouse.y - pan.y) / scale;
pan.x = mouse.x;
pan.y = mouse.y;
renderCanvas();
}
};
canvas.onclick = function(e) {
shapes.forEach(({
_x,
_y,
_w,
_h,
color
}) => {
const {
x: mousex,
y: mousey
} = canvasToObjectsScreen(mouse.x, mouse.y);
const {
x: squarex,
y: squarey
} = canvasToObjectsScreen(_x, _y);
if (
mousex >= squarex &&
mousex <= _w / scale + squarex &&
mousey >= squarey &&
mousey <= _h / scale + squarey
) {
alert(`${color} clicked!`);
}
});
};
init();
})();
body {
font-family: "Lato", sans-serif;
}
#canvas {
background: #E1BC8B;
}
<body>
<div id="main">
<canvas id="canvas" width="300" height="350"></canvas>
</div>
</body>
I am trying to keep text on image through kineticjs. But initially I am able to keep the text on image after dragging the image text is going under the image. Can anyone help me on this. Here is my fiddle,
JSFiddle
$(document).ready(function()
{
var startAngle = 0;
var minImgSize = 10;
function update(activeAnchor)
{
var group = activeAnchor.getParent();
var topLeft = group.get('.topLeft')[0];
var topRight = group.get('.topRight')[0];
var bottomRight = group.get('.bottomRight')[0];
var bottomLeft = group.get('.bottomLeft')[0];
var rotateAnchor = group.get('.rotateAnchor')[0];
var image = group.get('Image')[0];
var anchorX = activeAnchor.getX();
var anchorY = activeAnchor.getY();
var imageWidth = image.getWidth();
var imageHeight = image.getHeight();
// update anchor positions
switch (activeAnchor.getName()) {
case 'rotateAnchor':
break;
case 'topLeft':
topRight.setY(anchorY);
bottomLeft.setX(anchorX);
break;
case 'topRight':
topLeft.setY(anchorY);
bottomRight.setX(anchorX);
break;
case 'bottomRight':
topRight.setX(anchorX);
bottomLeft.setY(anchorY);
break;
case 'bottomLeft':
topLeft.setX(anchorX);
bottomRight.setY(anchorY);
break;
}
if (topRight.getX() < topLeft.getX() + minImgSize)
{
topRight.setX(topLeft.getX() + minImgSize);
}
if (bottomRight.getX() < topLeft.getX() + minImgSize)
{
bottomRight.setX(topLeft.getX() + minImgSize);
}
if (bottomRight.getY() < topLeft.getY() + minImgSize)
{
bottomRight.setY(topLeft.getY() + minImgSize);
}
if (bottomLeft.getY() < topLeft.getY() + minImgSize)
{
bottomLeft.setY(topLeft.getY() + minImgSize);
}
var width = topRight.getX() - topLeft.getX();
var height = bottomLeft.getY() - topLeft.getY();
image.setPosition({x : topLeft.getPosition().x, y:(topLeft.getPosition().y)});
image.setWidth(width);
image.setHeight(height);
rotateAnchor.setX(width / 2 + topLeft.getX());
rotateAnchor.setY(height / 2 + topLeft.getY());
}
function addAnchor(group, x, y, name, dragBound)
{
var stage = group.getStage();
var layer = group.getLayer();
var groupPos = group.getPosition();
var anchor = new Kinetic.Circle({
x: x,
y: y,
stroke: '#666',
fill: '#ddd',
strokeWidth: 2,
radius: 6,
name: name,
draggable: true,
dragOnTop: false
});
if (dragBound == 'rotate')
{
startAngle = angle(groupPos.x, groupPos.y, x + groupPos.x, y + groupPos.y);
anchor.setAttrs({
dragBoundFunc: function (pos) {
return getRotatingAnchorBounds(pos, group);
}
});
}
anchor.on('dragmove', function() {
update(this);
layer.draw();
});
anchor.on('mousedown touchstart', function() {
group.setDraggable(false);
this.moveToTop();
});
anchor.on('dragend', function() {
group.setDraggable(true);
layer.draw();
});
// add hover styling
anchor.on('mouseover', function() {
var layer = this.getLayer();
document.body.style.cursor = 'pointer';
this.setStrokeWidth(4);
layer.draw();
});
anchor.on('mouseout', function() {
var layer = this.getLayer();
document.body.style.cursor = 'default';
this.setStrokeWidth(2);
layer.draw();
});
group.add(anchor);
}
function loadImages(sources, callback)
{
var images = {};
var loadedImages = 0;
var numImages = 0;
for(var src in sources) {
numImages++;
}
for(var src in sources) {
images[src] = new Image();
images[src].onload = function() {
if(++loadedImages >= numImages) {
callback(images);
}
};
images[src].src = sources[src];
}
}
function radians (degrees) {return degrees * (Math.PI/180)}
function degrees (radians) {return radians * (180/Math.PI)}
function angle (cx, cy, px, py) {var x = cx - px; var y = cy - py; return Math.atan2 (-y, -x)}
function distance (p1x, p1y, p2x, p2y) {return Math.sqrt (Math.pow ((p2x - p1x), 2) + Math.pow ((p2y - p1y), 2))}
function getRotatingAnchorBounds(pos, group)
{
var groupPos = group.getPosition();
var rotation = degrees (angle (groupPos.x, groupPos.y, pos.x, pos.y) - startAngle);
var dis = distance (groupPos.x, groupPos.y, pos.x, pos.y);
console.log('x: ' + pos.x + '; y: ' + pos.y + '; rotation: ' + rotation + '; distance:' + dis);
group.setRotationDeg (rotation);
return pos;
}
function initStage(images)
{
var stage = new Kinetic.Stage({
container: 'container',
width: 578,
height: 400
});
var darthVaderGroup = new Kinetic.Group({
x: 270,
y: 100,
draggable: true,
fill: 'black'
});
var layer = new Kinetic.Layer();
var sw = stage.getWidth();
var sh = stage.getHeight();
var text = new Kinetic.Text({
x: 100,
y: 100,
text: "Gowtham",
fontSize: 32,
fontFamily: "Arial",
fill: "black",
stroke: "white",
strokeWidth: 1,
draggable: true,
dragBoundFunc: function (pos) {
var w = this.getWidth();
var h = this.getHeight();
if (pos.x < 0) {
pos.x = 0;
}
if (pos.x + w > sw) {
pos.x = sw - w;
}
if (pos.y < 0) {
pos.y = 0;
}
if (pos.y + h > sh) {
pos.y = sh - h;
}
return {
x: pos.x,
y: pos.y
}
}
});
layer.add(darthVaderGroup);
stage.add(layer);
layer.add(text);
layer.draw();
var darthVaderImg = new Kinetic.Image({
x: 0,
y: 0,
image: images.darthVader,
width: 200,
height: 138,
name: 'image'
});
darthVaderGroup.add(darthVaderImg);
addAnchor(darthVaderGroup, 0, 0, 'topLeft', 'none');
addAnchor(darthVaderGroup, darthVaderImg.getWidth(), 0, 'topRight', 'none');
addAnchor(darthVaderGroup, darthVaderImg.getWidth(), darthVaderImg.getHeight(), 'bottomRight', 'none');
addAnchor(darthVaderGroup, 0, darthVaderImg.getHeight(), 'bottomLeft', 'none');
addAnchor(darthVaderGroup, darthVaderImg.getWidth() / 2, darthVaderImg.getHeight() / 2, 'rotateAnchor','rotate');
darthVaderGroup.on('dragstart', function() {
this.moveToTop();
});
stage.draw();
}
var sources = {
darthVader: 'http://www.html5canvastutorials.com/demos/assets/darth-vader.jpg'
};
loadImages(sources, initStage);
});
canvas
{
border: 1px solid #aaa;
-moz-box-shadow: 3px 3px 8px #222;
-webkit-box-shadow: 3px 3px 8px #222;
box-shadow: 3px 3px 8px #222;
}
<script src="https://code.jquery.com/jquery-2.2.4.min.js"></script><script src="https://cdnjs.cloudflare.com/ajax/libs/kineticjs/5.2.0/kinetic.min.js"></script>
<div id="container"></div>
<button id="addImage">Add
</button>
I am using KonvaJs in my project. I need to implement drag bound to Konva.Layer. My layer has so many other shapes and images. I need to restrict the movement of layer up to 50% of it's width and height. The way I have done in this plunkr. The problem arises when user zoom-in or zoom-out the layer using mouse wheel. After the zoom, I don't know why the drag bound is behaving differently. Seems like I am not able to do the Math correctly. I need to have the same behavior i.e. the way movement of layer is restricted when user does not perform zoom. This is what I am doing:
//... a helper object for zooming
var zoomHelper = {
stage: null,
scale: 1,
zoomFactor: 1.1,
origin: {
x: 0,
y: 0
},
zoom: function(event) {
event.preventDefault();
var delta;
if (navigator.userAgent.toLowerCase().indexOf('firefox') > -1) {
if (event.originalEvent.detail > 0) {
//scroll down
delta = 0.2;
} else {
//scroll up
delta = 0;
}
} else {
if (event.originalEvent.wheelDelta < 0) {
//scroll down
delta = 0.2;
} else {
//scroll up
delta = 0;
}
}
var evt = event.originalEvent,
mx = evt.clientX - zoomHelper.stage.getX(),
my = evt.clientY - zoomHelper.stage.getY(),
zoom = (zoomHelper.zoomFactor - delta),
newscale = zoomHelper.scale * zoom;
zoomHelper.origin.x = mx / zoomHelper.scale + zoomHelper.origin
.x - mx / newscale;
zoomHelper.origin.y = my / zoomHelper.scale + zoomHelper.origin
.y - my / newscale;
zoomHelper.stage.setOffset({
x: zoomHelper.origin.x,
y: zoomHelper.origin.y
});
zoomHelper.stage.setScale({
x: newscale,
y: newscale
});
zoomHelper.stage.draw();
zoomHelper.scale *= zoom;
preCalculation();
}
};
// Code goes here
var w = window.innerWidth;
var h = window.innerHeight;
var height, minX, minY, maxX, maxY;
var stage = new Konva.Stage({
container: 'container',
width: w,
height: h
});
zoomHelper.stage =stage;
var layer = new Konva.Layer({
draggable: true,
dragBoundFunc: function(pos) {
console.log('called');
var X = pos.x;
var Y = pos.y;
if (X < minX) {
X = minX;
}
if (X > maxX) {
X = maxX;
}
if (Y < minY) {
Y = minY;
}
if (Y > maxY) {
Y = maxY;
}
return ({
x: X,
y: Y
});
}
});
stage.add(layer);
function preCalculation(){
// pre-calc some bounds so dragBoundFunc has less calc's to do
height = layer.getHeight();
minX = stage.getX() - layer.getWidth() / 2;
maxX = stage.getX() + stage.getWidth() - layer.getWidth() / 2;
minY = stage.getY() - layer.getHeight() / 2;
maxY = stage.getY() + stage.getHeight() - layer.getHeight() / 2;
console.log(height, minX, minY, maxX, maxY);
}
preCalculation();
var img = new Image();
img.onload = function() {
var floorImage = new Konva.Image({
image: img,
width: w,
height: h
});
layer.add(floorImage);
layer.draw();
};
img.src = 'https://s.yimg.com/pw/images/coverphoto02_h.jpg.v3';
$(stage.container).on('mousewheel DOMMouseScroll', zoomHelper.zoom);
While using dragBoundFunc you have to return absolute position of layer. As you are changing attributes of top node (stage) it can be hard to maintain absolute position. So you can try to set bound function inside 'dragmove' event:
layer.on('dragmove', function() {
var x = Math.max(minX, Math.min(maxX, layer.x()));
var y = Math.max(minY, Math.min(maxY, layer.y()));
layer.x(x);
layer.y(y);
});
http://plnkr.co/edit/31MUmOjXBUVuaHVJsL3c?p=preview
I'm having some problems with scaling a container to a fixed point.
In my case I'm trying to scale (zoom) a stage to the mouse cursor.
Here is a way to do with pure canvas:
http://phrogz.net/tmp/canvas_zoom_to_cursor.html (as discussed at Zoom Canvas to Mouse Cursor)
I just can't get figure out how to apply the same logic while using the KineticJS API.
Sample code:
var position = this.stage.getUserPosition();
var scale = Math.max(this.stage.getScale().x + (0.05 * (scaleUp ? 1 : -1)), 0);
this.stage.setScale(scale);
// Adjust scale to position...?
this.stage.draw();
After a lot of struggling and searching and trying, using the tip provided by #Eric Rowell and the code posted in the SO question Zoom in on a point (using scale and translate) I finally got the zooming in and out of a fixed point working using KineticJS.
Here's a working DEMO.
And here's the code:
var ui = {
stage: null,
scale: 1,
zoomFactor: 1.1,
origin: {
x: 0,
y: 0
},
zoom: function(event) {
event.preventDefault();
var evt = event.originalEvent,
mx = evt.clientX /* - canvas.offsetLeft */,
my = evt.clientY /* - canvas.offsetTop */,
wheel = evt.wheelDelta / 120;
var zoom = (ui.zoomFactor - (evt.wheelDelta < 0 ? 0.2 : 0));
var newscale = ui.scale * zoom;
ui.origin.x = mx / ui.scale + ui.origin.x - mx / newscale;
ui.origin.y = my / ui.scale + ui.origin.y - my / newscale;
ui.stage.setOffset(ui.origin.x, ui.origin.y);
ui.stage.setScale(newscale);
ui.stage.draw();
ui.scale *= zoom;
}
};
$(function() {
var width = $(document).width() - 2,
height = $(document).height() - 5;
var stage = ui.stage = new Kinetic.Stage({
container: 'container',
width: width,
height: height
});
var layer = new Kinetic.Layer({
draggable: true
});
var rectX = stage.getWidth() / 2 - 50;
var rectY = stage.getHeight() / 2 - 25;
var box = new Kinetic.Circle({
x: 100,
y: 100,
radius: 50,
fill: '#00D200',
stroke: 'black',
strokeWidth: 2,
});
// add cursor styling
box.on('mouseover', function() {
document.body.style.cursor = 'pointer';
});
box.on('mouseout', function() {
document.body.style.cursor = 'default';
});
layer.add(box);
stage.add(layer);
$(stage.content).on('mousewheel', ui.zoom);
});
You need to offset the stage such that it's center point is positioned at the fixed point. Here's an example, because the center point of the stage is defaulted to the upper left corner of the canvas. Let's say that your stage is 600px wide and 400px tall, and you want the stage to zoom from the center. You would need to do this:
var stage = new Kinetic.Stage({
container: 'container',
width: 600,
height: 400,
offset: [300, 200]
};
updated #juan.facorro's demo to scale shape instead of stage
jsFiddle
var ui = {
stage: null,
box: null,
scale: 1,
zoomFactor: 1.1,
zoom: function(event) {
event.preventDefault();
var evt = event.originalEvent,
mx = evt.offsetX,
my = evt.offsetY,
wheel = evt.wheelDelta / 120; //n or -n
var zoom = (ui.zoomFactor - (evt.wheelDelta < 0 ? 0.2 : 0));
var newscale = ui.scale * zoom;
var origin = ui.box.getPosition();
origin.x = mx - (mx - origin.x) * zoom;
origin.y = my - (my - origin.y) * zoom;
ui.box.setPosition(origin.x, origin.y);
ui.box.setScale(newscale);
ui.stage.draw();
ui.scale *= zoom;
}
};
$(function() {
var width = $(document).width() - 2,
height = $(document).height() - 5;
var stage = ui.stage = new Kinetic.Stage({
container: 'container',
width: width,
height: height
});
var layer = new Kinetic.Layer();
var rectX = stage.getWidth() / 2 - 50;
var rectY = stage.getHeight() / 2 - 25;
var box = ui.box = new Kinetic.Circle({
x: 100,
y: 100,
radius: 50,
fill: '#00D200',
stroke: 'black',
strokeWidth: 2,
draggable: true
});
// add cursor styling
box.on('mouseover', function() {
document.body.style.cursor = 'pointer';
});
box.on('mouseout', function() {
document.body.style.cursor = 'default';
});
layer.add(box);
stage.add(layer);
$(stage.content).on('mousewheel', ui.zoom);
});
The demo above only works if the x and y coordinates of the stage are 0. If e.g. the stage is draggable it will change these coordinates while dragging so they need to be included in the offset calculation. This can be achieved by subtracting them from the canvas offsets:
jsfiddle
zoom: function(event) {
event.preventDefault();
var evt = event.originalEvent,
mx = evt.offsetX - ui.scale.getX(),
my = evt.offsetY - ui.scale.getY(),
var zoom = (ui.zoomFactor - (evt.wheelDelta < 0 ? 0.2 : 0));
var newscale = ui.scale * zoom;
var origin = ui.box.getPosition();
origin.x = mx - (mx - origin.x) * zoom;
origin.y = my - (my - origin.y) * zoom;
ui.box.setPosition(origin.x, origin.y);
ui.box.setScale(newscale);
ui.stage.draw();
ui.scale *= zoom;
}