i am working on an application which require Zoom In, Zoom out and Panning. I have achieved all these functionality using viewBox property of svg.
My current Zoom In works fine but it zoom toward the center of screen. I want to add additional functionality of Zoom in toward a selected element. I know i can set viewBox to the selected element bbox values, but i want sequential/smooth zoom in which does not conflict with my current/default zoom in.
how i can achieve this?
here is jsfiddle for the sample code:- http://jsfiddle.net/55G9c/
HTML Code
<div onclick="zoomin()" style="display: block;float: left;border: 1px solid;cursor: pointer">
ZoomIn
</div>
<div onclick="zoomout()" style="display: block;float: left;border: 1px solid;cursor: pointer;margin-left: 10px">
ZoomOut
</div>
<svg id="mainsvg" width="600px" height="500px" viewBox="0 0 600 500">
<g id="gnode">
<rect id="boundry" x="0" y="0" width="599" height="499" fill="none" stroke='black'/>
<circle id="centernode" cx="300" cy="250" r="5" fill="red" stroke="none" />
<rect id="selected" x="450" y="100" width="50" height="50" fill="blue" stroke='none'/>
</g>
</svg>
Javascript Code
var svg=document.getElementById('mainsvg');
var gnode=document.getElementById('gnode');
var zoomPercentage=0.25;
var MAXIMUM_ZOOM_HEIGHT = 1400;
var baseBox={};
var level=0;
var widthRatio,heightRatio;
var clientheight = document.documentElement.clientHeight;
var clientwidth = document.documentElement.clientWidth;
function setup(){
var
baseX,
baseY,
baseWidth,
baseHeight,
percentageDifference,
heightDifference;
svg.setAttribute('height', clientheight);
svg.setAttribute('width', clientwidth);
var boundry=document.getElementById('boundry');
boundry.setAttribute('height', clientheight-1);
boundry.setAttribute('width', clientwidth-1);
var centernode=document.getElementById('centernode');
centernode.setAttribute('cy', clientheight/2);
centernode.setAttribute('cx', clientwidth/2);
if (svg.height.baseVal.value >= MAXIMUM_ZOOM_HEIGHT)
baseHeight = MAXIMUM_ZOOM_HEIGHT;
else
baseHeight = Math.round(gnode.getBBox().height) + 60;
baseY = (svg.height.baseVal.value - baseHeight) / 2;
percentageDifference = baseHeight / svg.height.baseVal.value;
baseWidth = percentageDifference * svg.width.baseVal.value;
baseX = (svg.width.baseVal.value - baseWidth) / 2;
baseBox.x = baseX;
baseBox.y = baseY;
baseBox.width = baseWidth;
baseBox.height = baseHeight;
level = 0;
heightDifference = MAXIMUM_ZOOM_HEIGHT - baseHeight;
zoomPercentage = (heightDifference / 10) / heightDifference;
setViewBox(baseBox);
}
function setViewBox(viewBox) {
svg.viewBox.baseVal.x = Math.round(viewBox.x);
svg.viewBox.baseVal.y = Math.round(viewBox.y);
svg.viewBox.baseVal.width = Math.round(viewBox.width);
svg.viewBox.baseVal.height = Math.round(viewBox.height);
setRatios();
}
function setRatios () {
widthRatio = svg.viewBox.baseVal.width / svg.width.baseVal.value;
heightRatio = svg.viewBox.baseVal.height / svg.height.baseVal.value;
}
function calculateViewBox(level) {
var
height = baseBox.height - (zoomPercentage * level * baseBox.height),
y = baseBox.y + (baseBox.height - height) / 2,
width = baseBox.width - (zoomPercentage * level * baseBox.width),
x = baseBox.x + (baseBox.width - width) / 2,
viewBox = {
x: x,
y: y,
width: width,
height: height
}
return viewBox;
}
function zoomin(){
level++;
if(level>5)
level=5;
var
x,
y,
paperViewBox = svg.viewBox.baseVal,
previousViewBox = calculateViewBox(level - 1),
newViewBox = calculateViewBox(level);
//callback = this.afterZoom;
if (Math.round(paperViewBox.x) > Math.round(newViewBox.x))
/**
* is panned left
*/
x = paperViewBox.x - (previousViewBox.width - newViewBox.width) / 2;
else if (Math.round(paperViewBox.x) < Math.round(previousViewBox.x) - (Math.round(newViewBox.x) - Math.round(previousViewBox.x)))
/**
* is panned right
*/
x = paperViewBox.x + (previousViewBox.width - newViewBox.width) + (previousViewBox.width - newViewBox.width) / 2;
else
x = newViewBox.x;
if (Math.round(paperViewBox.y) > Math.round(newViewBox.y))
/**
* is panned up
*/
y = paperViewBox.y - (previousViewBox.height - newViewBox.height) / 2;
else if (Math.round(paperViewBox.y) < Math.round(previousViewBox.y) - (Math.round(newViewBox.y) - Math.round(previousViewBox.y)))
/**
* is panned down
*/
y = paperViewBox.y + (previousViewBox.height - newViewBox.height) + (previousViewBox.height - newViewBox.height) / 2;
else
y = newViewBox.y;
var data = {
viewBox: {
x: x,
y: y,
width: newViewBox.width,
height: newViewBox.height
}
}
SetZoomViewBox(data);
}
function SetZoomViewBox(data){
var viewBox = data.viewBox;
svg.viewBox.baseVal.x = Math.round(viewBox.x);
svg.viewBox.baseVal.y = Math.round(viewBox.y);
svg.viewBox.baseVal.width = Math.round(viewBox.width);
svg.viewBox.baseVal.height = Math.round(viewBox.height);
setRatios();
}
function zoomout(){
level--;
if(level<0)
level=0;
var
x,
y,
paperViewBox = svg.viewBox.baseVal,
previousViewBox = calculateViewBox(level + 1),
newViewBox = calculateViewBox(level);
if (Math.round(paperViewBox.x) > Math.round(previousViewBox.x) + (Math.round(previousViewBox.x) - Math.round(newViewBox.x)))
/**
* is panned left
*/
x = paperViewBox.x - (newViewBox.width - previousViewBox.width);
else if (Math.round(paperViewBox.x) < Math.round(previousViewBox.x))
/**
* is panned right
*/
x = paperViewBox.x;
else
x = newViewBox.x;
if (Math.round(paperViewBox.y) > Math.round(previousViewBox.y) + (Math.round(previousViewBox.y) - Math.round(newViewBox.y)))
/**
* is panned up
*/
y = paperViewBox.y - (newViewBox.height - previousViewBox.height);
else if (Math.round(paperViewBox.y) < Math.round(previousViewBox.y))
/**
* is panned down
*/
y = paperViewBox.y;
else
y = newViewBox.y;
var data = {
viewBox: {
x: x,
y: y,
width: newViewBox.width,
height: newViewBox.height
}
}
SetZoomViewBox(data);
}
setup();
