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Universal pan and zoom library
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README.md

panzoom Build Status

Extensible, mobile friendly pan and zoom framework (supports DOM and SVG).

Demo

Usage

Grab it from npm and use with your favorite bundler:

npm install panzoom --save

Or download from CDN:

<script src='https://unpkg.com/panzoom@7.1.2/dist/panzoom.min.js'></script>

If you download from CDN the library will be available under panzoom global name.

Pan and zoom DOM subtree

// just grab any DOM element
var area = document.querySelector('.zoomable')

// And pass it to panzoom
panzoom(area)

SVG panzoom example

<!-- this is your html file with svg -->
<body>
  <svg>
    <!-- this is the draggable root -->
    <g id='scene'> 
      <circle cx='10' cy='10' r='5' fill='pink'></circle>
    </g>
  </svg>
</body>
// In the browser panzoom is already on the
// window. If you are in common.js world, then 
// var panzoom = require('panzoom')

// grab the DOM SVG element that you want to be draggable/zoomable:
var scene = document.getElementById('scene')

// and forward it it to panzoom.
panzoom(scene)

If your use case requires dynamic behavior (i.e. you want to make a scene not draggable anymore, or even completely delete an SVG element) make sure to call dispose() method:

var instance = panzoom(scene)
// do work
// ...
// then at some point you decide you don't need this anymore:
instance.dispose()

This will make sure that all event handlers are cleared and you are not leaking memory

Events notification

The library allows to subscribe to transformation changing events. E.g. when user starts/ends dragging the scene, the scene will fire panstart/panend events. Here is example of all supported events:

var instance = panzoom(scene);
instance.on('panstart', function(e) {
  console.log('Fired when pan is just started ', e);
  // Note: e === instance.
});

instance.on('pan', function(e) {
  console.log('Fired when the scene is being panned', e);
});

instance.on('panend', function(e) {
  console.log('Fired when pan ended', e);
});

instance.on('zoom', function(e) {
  console.log('Fired when scene is zoomed', e);
});

instance.on('transform', function(e) {
  // This event will be called along with events above.
  console.log('Fired when any transformation has happened', e);
});

See JSFiddle console for a demo.

Ignore mouse wheel

Sometimes zooming interferes with scrolling. If you want to alleviate it you can provide a custom filter, which will allow zooming only when modifier key is down. E.g.

panzoom(document.getElementById('g4'), {
  beforeWheel: function(e) {
    // allow wheel-zoom only if altKey is down. Otherwise - ignore
    var shouldIgnore = !e.altKey;
    return shouldIgnore;
  }
});

See JSFiddle for the demo. The tiger will be zoomable only when Alt key is down.

Ignore keyboard events

By default, panzoom will listen to keyboard events, so that users can navigate the scene with arrow keys and +, - signs to zoom out. If you don't want this behavior you can pass the filterKey() predicate that returns truthy value to prevent panzoom's default behavior:

panzoom(document.getElementById('g4'), {
  filterKey: function(/* e, dx, dy, dz */) {
    // don't let panzoom handle this event:
    return true;
  }
});

Zoom Speed

You can adjust how fast it zooms, by passing optional zoomSpeed argument:

panzoom(document.getElementById('g4'), {
  zoomSpeed: 0.065 // 6.5% per mouse wheel event
});

Min Max Zoom

You can set min and max zoom, by passing optional minZoom and maxZoom argument:

panzoom(document.getElementById('g4'), {
  maxZoom: 1,
  minZoom: 0.1
});

Disable Smooth Scroll

You can disable smooth scroll, by passing optional smoothScroll argument:

panzoom(document.getElementById('g4'), {
  smoothScroll: false
});

With this setting the momentum is disabled.

Pause/resume the panzoom

You can pause and resume the panzoom by calling the following methods:

var controller = panzoom(document.getElementById('g4'));

controller.isPaused(); //  returns false
controller.pause();    //  Pauses event handling
controller.isPaused(); //  returns true now
controller.resume();   //  Resume panzoom
controller.isPaused(); //  returns false again

Script attachment

If you want to quickly play with panzoom without using javascript, you can configure it via script tag:

<!-- this is your html file -->
<!DOCTYPE html>
<html>
<head>
  <script src='https://unpkg.com/panzoom@7.1.2/dist/panzoom.min.js'
    query='#scene' name='pz'></script>
</head>
<body>
  <svg>
    <!-- this is the draggable root -->
    <g id='scene'> 
      <circle cx='10' cy='10' r='5' fill='pink'></circle>
    </g>
  </svg>
</body>
</html>

Most importantly, you can see query attribute that points to CSS selector. Once the element is found panzoom is attached to this element. The controller will become available under window.pz name. And you can pass additional options to the panzoom via attributes prefixed with pz-.

Here is a demo: Script based attributes

Adjust Double Click Zoom

You can adjust the double click zoom multiplier, by passing optional zoomDoubleClickSpeed argument.

When double clicking, zoom is multiplied by zoomDoubleClickSpeed, which means that a value of 1 will disable double click zoom completely.

panzoom(document.getElementById('g4'), {
  zoomDoubleClickSpeed: 1, 
});

Set Initial Position And Zoom

You can set the initial position and zoom, by chaining the zoomAbs function with x position, y position and zoom as arguments:

panzoom(document.getElementById('g4'), {
  maxZoom: 1,
  minZoom: 0.1
}).zoomAbs(
  300, // initial x position
  500, // initial y position
  0.1  // initial zoom 
);

Handling touch events

The library will handle ontouch events very aggressively, it will preventDefault, and stopPropagation for the touch events inside container. Sometimes this is not a desirable behavior.

If you want to take care about this yourself, you can pass onTouch callback to the options object:

panzoom(document.getElementById('g4'), {
  onTouch: function(e) {
    // `e` - is current touch event.

    return false; // tells the library to not preventDefault.
  }
});

Note: if you don't preventDefault yourself - make sure you test the page behavior on iOS devices. Sometimes this may cause page to bounce undesirably.

Handling double click events

By default panzoom will prevent default action on double click events - this is done to avoid accidental text selection (which is default browser action on double click). If you prefer to allow default action, you can pass onDoubleClick() callback to options. If this callback returns false, then the library will not prevent default action:

panzoom(document.getElementById('g4'), {
  onDoubleClick: function(e) {
    // `e` - is current double click event.

    return false; // tells the library to not preventDefault, and not stop propagation
  }
});

license

MIT

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