jQuery Knob

• canvas based ; no png or jpg sprites.
• touch, mouse and mousewheel, keyboard events implemented.
• downward compatible ; overloads an input element.

Example

<input type="text" value="75" class="dial">

<script>
$(function() {
    $(".dial").knob();
});
</script>

Options

Options are provided as attributes 'data-option':

<input type="text" class="dial" data-min="-50" data-max="50">

... or in the "knob()" call :

$(".dial").knob({
                'min':-50
                ,'max':50
                });

The following options are supported :

Behaviors :

• min : min value | default=0.
• max : max value | default=100.
• step : step size | default=1.
• angleOffset : starting angle in degrees | default=0.
• angleArc : arc size in degrees | default=360.
• stopper : stop at min & max on keydown/mousewheel | default=true.
• readOnly : disable input and events | default=false.

UI :

• cursor : display mode "cursor", cursor size could be changed passing a numeric value to the option, default width is used when passing boolean value "true" | default=gauge.
• thickness : gauge thickness.
• lineCap : gauge stroke endings. | default=butt, round=rounded line endings
• width : dial width.
• displayInput : default=true | false=hide input.
• displayPrevious : default=false | true=displays the previous value with transparency.
• fgColor : foreground color.
• inputColor : input value (number) color.
• font : font family.
• fontWeight : font weight.
• bgColor : background color.
• unit: unit option for value inside knob e.g. '%', 'px', 'pt' etc.

Hooks

<script>
$(".dial").knob({
                    'release' : function (v) { /*make something*/ }
                });
</script>

• 'release' : executed on release

  Parameters :

  • value : int, current value

• 'change' : executed at each change of the value

  Parameters :

  • value : int, current value

• 'draw' : when drawing the canvas

  Context :

  • this.g : canvas context 2D (see Canvas documentation)
  • this.$ : jQuery wrapped element
  • this.o : options
  • this.i : input
  • ... console.log(this);

• 'cancel' : triggered on [esc] keydown

• 'error' : called if the browser doesn't support canvases and the plugin didn't initialize as a result

The scope (this) of each hook function is the current Knob instance (refer to the demo code).

Example

<input type="text" value="75" class="dial">

<script>
$(".dial").knob({
                 'change' : function (v) { console.log(v); }
                });
</script>

Dynamically configure

<script>
$('.dial')
    .trigger(
        'configure',
        {
        "min":10,
        "max":40,
        "fgColor":"#FF0000",
        "skin":"tron",
        "cursor":true
        }
    );
</script>

Set the value

<script>
$('.dial')
    .val(27)
    .trigger('change');
</script>

Supported browser

Tested on Chrome, Safari, Firefox, IE 8.0.