/*
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* jQuery.eraser v0.4.2
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* makes any image or canvas erasable by the user, using touch or mouse input
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* https://github.com/boblemarin/jQuery.eraser
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*
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* Usage:
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*
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* $('#myImage').eraser(); // simple way
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*
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* $(#canvas').eraser( {
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* size: 20, // define brush size (default value is 40)
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* completeRatio: .65, // allows to call function when a erased ratio is reached (between 0 and 1, default is .7 )
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* completeFunction: myFunction // callback function when complete ratio is reached
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* } );
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*
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* $('#image').eraser( 'clear' ); // erases all canvas content
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*
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* $('#image').eraser( 'reset' ); // revert back to original content
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*
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* $('#image').eraser( 'size', 80 ); // change the eraser size
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*
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*
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* https://github.com/boblemarin/jQuery.eraser
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* http://minimal.be/lab/jQuery.eraser/
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*
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* Copyright (c) 2010 boblemarin emeric@minimal.be http://www.minimal.be
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use,
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* copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following
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* conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*/
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(function( $ ){
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var methods = {
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init : function( options ) {
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return this.each(function(){
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var $this = $(this),
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data = $this.data('eraser');
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if ( !data ) {
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var width = $this.width(),
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height = $this.height(),
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pos = $this.offset(),
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$canvas = $("<canvas/>"),
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canvas = $canvas.get(0),
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size = ( options && options.size )?options.size:40,
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completeRatio = ( options && options.completeRatio )?options.completeRatio:.7,
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completeFunction = ( options && options.completeFunction )?options.completeFunction:null,
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parts = [],
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colParts = Math.floor( width / size ),
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numParts = colParts * Math.floor( height / size ),
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n = numParts,
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ctx = canvas.getContext("2d");
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// replace target with canvas
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$this.after( $canvas );
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canvas.id = this.id;
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canvas.className = this.className;
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canvas.width = width;
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canvas.height = height;
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ctx.drawImage( this, 0, 0 );
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$this.remove();
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// prepare context for drawing operations
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ctx.globalCompositeOperation = "destination-out";
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ctx.strokeStyle = 'rgba(255,0,0,255)';
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ctx.lineWidth = size;
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ctx.lineCap = "round";
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// bind events
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$canvas.bind('mousedown.eraser', methods.mouseDown);
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$canvas.bind('touchstart.eraser', methods.touchStart);
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$canvas.bind('touchmove.eraser', methods.touchMove);
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$canvas.bind('touchend.eraser', methods.touchEnd);
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// reset parts
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while( n-- ) parts.push(1);
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// store values
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data = {
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posX:pos.left,
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posY:pos.top,
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touchDown: false,
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touchID:-999,
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touchX: 0,
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touchY: 0,
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ptouchX: 0,
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ptouchY: 0,
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canvas: $canvas,
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ctx: ctx,
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w:width,
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h:height,
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source: this,
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size: size,
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parts: parts,
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colParts: colParts,
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numParts: numParts,
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ratio: 0,
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complete: false,
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completeRatio: completeRatio,
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completeFunction: completeFunction
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};
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$canvas.data('eraser', data);
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// listen for resize event to update offset values
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$(window).resize( function() {
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var pos = $canvas.offset();
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data.posX = pos.left;
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data.posY = pos.top;
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});
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}
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});
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},
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touchStart: function( event ) {
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var $this = $(this),
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data = $this.data('eraser');
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if ( !data.touchDown ) {
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var t = event.originalEvent.changedTouches[0],
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tx = t.pageX - data.posX,
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ty = t.pageY - data.posY;
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methods.evaluatePoint( data, tx, ty );
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data.touchDown = true;
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data.touchID = t.identifier;
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data.touchX = tx;
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data.touchY = ty;
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event.preventDefault();
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}
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},
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touchMove: function( event ) {
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var $this = $(this),
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data = $this.data('eraser');
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if ( data.touchDown ) {
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var ta = event.originalEvent.changedTouches,
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n = ta.length;
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while( n-- )
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if ( ta[n].identifier == data.touchID ) {
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var tx = ta[n].pageX - data.posX,
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ty = ta[n].pageY - data.posY;
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methods.evaluatePoint( data, tx, ty );
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data.ctx.beginPath();
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data.ctx.moveTo( data.touchX, data.touchY );
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data.touchX = tx;
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data.touchY = ty;
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data.ctx.lineTo( data.touchX, data.touchY );
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data.ctx.stroke();
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event.preventDefault();
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break;
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}
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}
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},
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touchEnd: function( event ) {
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var $this = $(this),
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data = $this.data('eraser');
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if ( data.touchDown ) {
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var ta = event.originalEvent.changedTouches,
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n = ta.length;
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while( n-- )
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if ( ta[n].identifier == data.touchID ) {
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data.touchDown = false;
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event.preventDefault();
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break;
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}
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}
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},
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evaluatePoint: function( data, tx, ty ) {
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var p = Math.floor(tx/data.size) + Math.floor( ty / data.size ) * data.colParts;
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if ( p >= 0 && p < data.numParts ) {
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data.ratio += data.parts[p];
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data.parts[p] = 0;
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if ( !data.complete) {
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if ( data.ratio/data.numParts >= data.completeRatio ) {
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data.complete = true;
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if ( data.completeFunction != null ) data.completeFunction();
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}
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}
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}
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},
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mouseDown: function( event ) {
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var $this = $(this),
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data = $this.data('eraser'),
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tx = event.pageX - data.posX,
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ty = event.pageY - data.posY;
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methods.evaluatePoint( data, tx, ty );
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data.touchDown = true;
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data.touchX = tx;
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data.touchY = ty;
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data.ctx.beginPath();
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data.ctx.moveTo( data.touchX-1, data.touchY );
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data.ctx.lineTo( data.touchX, data.touchY );
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data.ctx.stroke();
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$this.bind('mousemove.eraser', methods.mouseMove);
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$(document).bind('mouseup.eraser', data, methods.mouseUp);
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event.preventDefault();
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},
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mouseMove: function( event ) {
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var $this = $(this),
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data = $this.data('eraser'),
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tx = event.pageX - data.posX,
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ty = event.pageY - data.posY;
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methods.evaluatePoint( data, tx, ty );
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data.ctx.beginPath();
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data.ctx.moveTo( data.touchX, data.touchY );
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data.touchX = tx;
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data.touchY = ty;
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data.ctx.lineTo( data.touchX, data.touchY );
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data.ctx.stroke();
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event.preventDefault();
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},
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mouseUp: function( event ) {
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var data = event.data,
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$this = data.canvas;
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data.touchDown = false;
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$this.unbind('mousemove.eraser');
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$(document).unbind('mouseup.eraser');
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event.preventDefault();
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},
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clear: function() {
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var $this = $(this),
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data = $this.data('eraser');
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if ( data )
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{
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data.ctx.clearRect( 0, 0, data.w, data.h );
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var n = data.numParts;
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while( n-- ) data.parts[n] = 0;
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data.ratio = data.numParts;
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data.complete = true;
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if ( data.completeFunction != null ) data.completeFunction();
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}
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},
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size: function(value) {
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var $this = $(this),
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data = $this.data('eraser');
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if ( data && value )
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{
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data.size = value;
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data.ctx.lineWidth = value;
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}
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},
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reset: function() {
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var $this = $(this),
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data = $this.data('eraser');
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if ( data )
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{
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data.ctx.globalCompositeOperation = "source-over";
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data.ctx.drawImage( data.source, 0, 0 );
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data.ctx.globalCompositeOperation = "destination-out";
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var n = data.numParts;
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while( n-- ) data.parts[n] = 1;
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data.ratio = 0;
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data.complete = false;
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}
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}
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};
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$.fn.eraser = function( method ) {
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if ( methods[method] ) {
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return methods[method].apply( this, Array.prototype.slice.call( arguments, 1 ));
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} else if ( typeof method === 'object' || ! method ) {
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return methods.init.apply( this, arguments );
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} else {
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$.error( 'Method ' + method + ' does not yet exist on jQuery.eraser' );
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}
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};
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})( jQuery );
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