I'm using my mouse click position to zoom and pan to a specific part of a map. Without scale the translate moves to the correct spot. However, if I scale and translate together it misses the click spot. I understand why but I don't understand how to compensate for it:
//get mouse interaction in svg path
let clickPoint = d3.mouse(this);
if (!d) {
//reset center and zoom level back to sart
projection.translate([width/2,height/2]).scale(scaleDefault);
centered = null;
scaleStartLevel = 1;
} else {
let translate = projection.translate();
//calc scale if the user hasn't zoomed to max zoom more
let getScale = scaleStartLevel < scaleMaxLevels ? projection.scale() + (scaleInc*scaleStartLevel) : projection.scale();
scaleStartLevel++;
//scale the map to the zoom level and translate to click point
projection.scale(getScale)
.translate([
translate[0] - clickPoint[0] + width / 2,
translate[1] - clickPoint[1] + height / 2
]);
centered = d;
}
//move the map
map.selectAll("path").transition()
.duration(750)
.attr("d", path);
I'm attempting to make an interactive pan/zoom SVG floorplan/map using the d3.behavior.zoom() functionality. I have based my code loosely on Zoom to Bounding Box II.
I am asynchronously loading a svg via $.get() then using a button.on('click') handler to get the .getBBox() of a specific <g> by element ID, #g-1101 (represented as a red circle on the svg). I then would like to center the viewport of the svg to the middle of #g-1101's bounding box.
As a cursory try I was just trying to translate the top-level svg > g by using g#1101's .getBBox().x && .getBBox().y. It seems to me my math is off.
I've tried incorporating the (svg.node().getBBox().width / 2) - scale * g.getBBox().x) to center the middle point of the bounding box to viewport but it's translation is not even in the ballpark.
Code
(function(){
var svg, g; $.get('http://layersofcomplexity.com/__fp.svg', function(svg){
$('body').append($(svg));
init();
},'text');
function init() {
console.log('init');
svg = d3.select('svg');
g = d3.select('svg > g');
var zoom = d3.behavior.zoom()
.translate([0, 0])
.scale(1)
.scaleExtent([1, 8])
.on("zoom", zoomed);
svg
.call(zoom)
.call(zoom.event);
$('.pan').on('click', function(){
// var id = '#g-1011';
var scale = 4;
var bbox = $('#g-1101')[0].getBBox();
// d3.select(id).node().getBBox();
var x = bbox.x;
var y = bbox.y;
// var scale = .9 / Math.max(dx / width, dy / height),
// var translate = [width / 2 - scale * x, height / 2 - scale * y];
var width = svg.node().getBBox().width;
var height = svg.node().getBBox().height;
var translate = [-scale*x,-scale*y];
g.transition().duration(750) .call(zoom.translate(translate).scale(scale).event);
});
}
function zoomed() {
g.attr("transform", "translate(" + d3.event.translate + ")scale(" + d3.event.scale + ")");
}
})();
-- EDIT JSBin was broken --
What am I missing? JSBin.
One small change in your code to center the marked in red g#g-1101
var bbox = $('#g-1101')[0].getBBox();
var x = bbox.x-((bbox.width));
var y = bbox.y-((bbox.height));
//scale should be 1 less
var translate = [-(x*(scale-1)),-(y*(scale-1))];
working code here
Hope this helps
On my D3 world map, i have a parent svg:g group called "main" which have two svg:g element, one for countries and another for popups.
I draw countries path under svg:g element called "countries". and under svg:g called "popups", i draw popups nodes using d3 force layout which show multiple callouts as rectangles.
Clicking on any country will to zoom that country to screen size. zoom to bounding box, Mike bostok. if am applying zoom on svg:g "countries" as i dont want the popups to zoom as they will get extra big.
Since Boundingbox for smaller country will have large scale and large countries will have small scale values.
Now how should i calculate the translate and scale for the Svg:g "popups", so that the popups rectangle size and fonts remain same.
It worked like a charm by using a formula:
[position after zoom has been applied ] * (1 - scalePopup).
See below for how to calculate the variable scalePopup
var bounds = path.bounds(d),
dx = bounds[1][0] - bounds[0][0],
dy = bounds[1][1] - bounds[0][1],
x = (bounds[0][0] + bounds[1][0]) / 2,
y = (bounds[0][1] + bounds[1][1]) / 2;
var scale = countryZoomScale(Math.max(dx, dy)) / Math.max(dx / width, dy / height),
translate = [width / 1.5 - scale * x, height / 2 - scale * y];
var scalePopup = map.zoomFactor / scale;
var popupLayer = d3.select('.popupLayer');
var centroid = path.centroid(d);
popupLayer.attr("transform", "translate(" + centroid[0] * (1 - scalePopup) + "," + centroid[1] * (1 - scalePopup) + ")scale(" + scalePopup + ")");
I am trying to implement a simple zoom in d3.js, simpler than all the examples I have gone through (I suppose) but it just doesn't wanna work. So, the functionality that I want to implement is: the user clicks on a section of the graph and that section zooms at a predefined fixed size in the centre of the chart; the user cannot zoom it any further, no panning either. And when the user clicks at any other section of the chart, the zoomed section translates back to its normal/original position.
var container = svg.append("g").classed("container-group", true);
container.attr({transform: "translate(" + 40*test_data.row + "," + 40*test_data.col + ")"});
container.call(d3.behavior.zoom().scaleExtent([1,5]).on("zoom", zoom));
function zoom() {
container.attr("transform","translate(" + d3.event.translate + ")scale(" + d3.event.scale + ")");
}
I have tried zoom.translate and zoom.size but couldn't get them right. And don't know how to reset the zoomed section either.
Any help would be much appreciated !
I´ll give an example of zooming some circles. Clicking on the red rectangle will zoom out to 50%, clicking on the blue one will return to a 100% scale. The exact functions you are looking for are zoomOut() and initialZoom()
var zoomListener = d3.behavior.zoom().scaleExtent([0.1, 3]);
width = 200 ;
height = 200 ;
//svg
var svg = d3.select("body").append("svg").attr("id","vis")
.attr("width", width )
.attr("height", height );
//transition listener group
var svgGroup = svg.append("g").call(zoomListener);
//zoom in and zoom out buttons
svg.append("rect").attr("x",0).attr("y",0).attr("width",50).attr("height",50).style("fill","red").on("click",zoomOut);
svg.append("rect").attr("x",0).attr("y",50).attr("width",50).attr("height",50).style("fill","blue").on("click",initialZoom);
var i,k;
for(i=90;i<width-20;i+=20){
for( k=20;k<height-20;k+=20){
svgGroup.append("circle").attr("cx", i).attr("cy", k).attr("r", 10);
}
}
function zoomOut(){
//fix transition to center of canvas
x = (width/2) * 0.5;
y = (height/2) * 0.5;
//zoom transition- scale value 150%
svgGroup.transition().duration(500).attr("transform", "translate("+x+","+y+")scale(0.5)" );
}
function initialZoom(){
//fix transition to center of canvas
x = (width/2) ;
y = (height/2) ;
//zoom transition- scale value 100%
svgGroup.transition().duration(500).attr("transform", "scale(1)" );
}
I'm programming a HTML5 < canvas > project that involves zooming in and out of images using the scroll wheel.
I want to zoom towards the cursor like google maps does but I'm completely lost on how to calculate the movements.
What I have: image x and y (top-left corner); image width and height; cursor x and y relative to the center of the canvas.
In short, you want to translate() the canvas context by your offset, scale() it to zoom in or out, and then translate() back by the opposite of the mouse offset. Note that you need to transform the cursor position from screen space into the transformed canvas context.
ctx.translate(pt.x,pt.y);
ctx.scale(factor,factor);
ctx.translate(-pt.x,-pt.y);
Demo: http://phrogz.net/tmp/canvas_zoom_to_cursor.html
I've put up a full working example on my website for you to examine, supporting dragging, click to zoom in, shift-click to out, or scroll wheel up/down.
The only (current) issue is that Safari zooms too fast compared to Chrome or Firefox.
I hope, these JS libraries will help you:
(HTML5, JS)
Loupe
http://www.netzgesta.de/loupe/
CanvasZoom
https://github.com/akademy/CanvasZoom
Scroller
https://github.com/zynga/scroller
As for me, I'm using loupe. It's awesome!
For you the best case - scroller.
I recently needed to archive same results as Phrogz had already done but instead of using context.scale(), I calculated each object size based on ratio.
This is what I came up with. Logic behind it is very simple. Before scaling, I calculate point distance from edge in percentages and later adjust viewport to correct place.
It took me quite a while to come up with it, hope it saves someones time.
$(function () {
var canvas = $('canvas.main').get(0)
var canvasContext = canvas.getContext('2d')
var ratio = 1
var vpx = 0
var vpy = 0
var vpw = window.innerWidth
var vph = window.innerHeight
var orig_width = 4000
var orig_height = 4000
var width = 4000
var height = 4000
$(window).on('resize', function () {
$(canvas).prop({
width: window.innerWidth,
height: window.innerHeight,
})
}).trigger('resize')
$(canvas).on('wheel', function (ev) {
ev.preventDefault() // for stackoverflow
var step
if (ev.originalEvent.wheelDelta) {
step = (ev.originalEvent.wheelDelta > 0) ? 0.05 : -0.05
}
if (ev.originalEvent.deltaY) {
step = (ev.originalEvent.deltaY > 0) ? 0.05 : -0.05
}
if (!step) return false // yea..
var new_ratio = ratio + step
var min_ratio = Math.max(vpw / orig_width, vph / orig_height)
var max_ratio = 3.0
if (new_ratio < min_ratio) {
new_ratio = min_ratio
}
if (new_ratio > max_ratio) {
new_ratio = max_ratio
}
// zoom center point
var targetX = ev.originalEvent.clientX || (vpw / 2)
var targetY = ev.originalEvent.clientY || (vph / 2)
// percentages from side
var pX = ((vpx * -1) + targetX) * 100 / width
var pY = ((vpy * -1) + targetY) * 100 / height
// update ratio and dimentsions
ratio = new_ratio
width = orig_width * new_ratio
height = orig_height * new_ratio
// translate view back to center point
var x = ((width * pX / 100) - targetX)
var y = ((height * pY / 100) - targetY)
// don't let viewport go over edges
if (x < 0) {
x = 0
}
if (x + vpw > width) {
x = width - vpw
}
if (y < 0) {
y = 0
}
if (y + vph > height) {
y = height - vph
}
vpx = x * -1
vpy = y * -1
})
var is_down, is_drag, last_drag
$(canvas).on('mousedown', function (ev) {
is_down = true
is_drag = false
last_drag = { x: ev.clientX, y: ev.clientY }
})
$(canvas).on('mousemove', function (ev) {
is_drag = true
if (is_down) {
var x = vpx - (last_drag.x - ev.clientX)
var y = vpy - (last_drag.y - ev.clientY)
if (x <= 0 && vpw < x + width) {
vpx = x
}
if (y <= 0 && vph < y + height) {
vpy = y
}
last_drag = { x: ev.clientX, y: ev.clientY }
}
})
$(canvas).on('mouseup', function (ev) {
is_down = false
last_drag = null
var was_click = !is_drag
is_drag = false
if (was_click) {
}
})
$(canvas).css({ position: 'absolute', top: 0, left: 0 }).appendTo(document.body)
function animate () {
window.requestAnimationFrame(animate)
canvasContext.clearRect(0, 0, canvas.width, canvas.height)
canvasContext.lineWidth = 1
canvasContext.strokeStyle = '#ccc'
var step = 100 * ratio
for (var x = vpx; x < width + vpx; x += step) {
canvasContext.beginPath()
canvasContext.moveTo(x, vpy)
canvasContext.lineTo(x, vpy + height)
canvasContext.stroke()
}
for (var y = vpy; y < height + vpy; y += step) {
canvasContext.beginPath()
canvasContext.moveTo(vpx, y)
canvasContext.lineTo(vpx + width, y)
canvasContext.stroke()
}
canvasContext.strokeRect(vpx, vpy, width, height)
canvasContext.beginPath()
canvasContext.moveTo(vpx, vpy)
canvasContext.lineTo(vpx + width, vpy + height)
canvasContext.stroke()
canvasContext.beginPath()
canvasContext.moveTo(vpx + width, vpy)
canvasContext.lineTo(vpx, vpy + height)
canvasContext.stroke()
canvasContext.restore()
}
animate()
})
<!DOCTYPE html>
<html>
<head>
<title></title>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
</head>
<body>
<canvas class="main"></canvas>
</body>
</html>
I took #Phrogz's answer as a basis and made a small library that enables canvas with dragging, zooming and rotating.
Here is the example.
var canvas = document.getElementById('canvas')
//assuming that #param draw is a function where you do your main drawing.
var control = new CanvasManipulation(canvas, draw)
control.init()
control.layout()
//now you can drag, zoom and rotate in canvas
You can find more detailed examples and documentation on the project's page
Faster
Using ctx.setTransform gives you more performance than multiple matrix calls ctx.translate, ctx.scale, ctx.translate.
No need for complex transformation inversions as and expensive DOM matrix calls tp converts point between zoomed and screen coordinate systems.
Flexible
Flexibility as you don't need to use ctx.save and ctx.restore if you are rendering content at using different transforms. Returning to the transform with ctx.setTransform rather than the potentially frame rate wreaking ctx.restorecall
Easy to invert the transform and get the world coordinates of a (screen) pixel position and the other way round.
Examples
Using mouse and mouse wheel to zoom in and out at mouse position
An example using this method to scale page content at a point (mouse) via CSS transform CSS Demo at bottom of answer also has a copy of the demo from the next example.
And an example of this method used to scale canvas content at a point using setTransform
How
Given a scale and pixel position you can get the new scale as follow...
const origin = {x:0, y:0}; // canvas origin
var scale = 1; // current scale
function scaleAt(x, y, scaleBy) { // at pixel coords x, y scale by scaleBy
scale *= scaleBy;
origin.x = x - (x - origin.x) * scaleBy;
origin.y = y - (y - origin.y) * scaleBy;
}
To position the canvas and draw content
ctx.setTransform(scale, 0, 0, scale, origin.x, origin.y);
ctx.drawImage(img, 0, 0);
To use if you have the mouse coordinates
const zoomBy = 1.1; // zoom in amount
scaleAt(mouse.x, mouse.y, zoomBy); // will zoom in at mouse x, y
scaleAt(mouse.x, mouse.y, 1 / zoomBy); // will zoom out by same amount at mouse x,y
To restore the default transform
ctx.setTransform(1,0,0,1,0,0);
The inversions
To get the coordinates of a point in the zoomed coordinate system and the screen position of a point in the zoomed coordinate system
Screen to world
function toWorld(x, y) { // convert to world coordinates
x = (x - origin.x) / scale;
y = (y - origin.y) / scale;
return {x, y};
}
World to screen
function toScreen(x, y) {
x = x * scale + origin.x;
y = y * scale + origin.y;
return {x, y};
}