【canvasモザイク効果】ロードされたピクチャに基づいて対応するモザイクピクチャ分類を動的に生成する:j...

/*!
 * Close Pixelate v2.0.00 beta
 * http://desandro.com/resources/close-pixelate/
 * 
 * Developed by
 * - David DeSandro  http://desandro.com
 * - John Schulz  http://twitter.com/jfsiii
 * 
 * Licensed under MIT license
 */

/*jshint asi: true, browser: true, eqeqeq: true, forin: false, immed: false, newcap: true, noempty: true, strict: true, undef: true */

( function( window, undefined ) {


// util vars
var TWO_PI = Math.PI * 2
var QUARTER_PI = Math.PI * 0.25

// utility functions
function isArray( obj ) {
  return Object.prototype.toString.call( obj ) === "[object Array]"
}

function isObject( obj ) {
  return Object.prototype.toString.call( obj ) === "[object Object]"
}

var console = window.console

// check for canvas support
var canvas = document.createElement('canvas')
var isCanvasSupported = canvas.getContext && canvas.getContext('2d')

// don't proceed if canvas is no supported
if ( !isCanvasSupported ) {
  return
}


function ClosePixelation( img, options ) {
  this.img = img
  // creat canvas
  var canvas = this.canvas = document.createElement('canvas')
  this.ctx = canvas.getContext('2d')
  // copy attributes from img to canvas
  canvas.className = img.className
  canvas.id = img.id

  this.render( options )

  // replace image with canvas
  img.parentNode.replaceChild( canvas, img )

}

ClosePixelation.prototype.render = function( options ) {
  this.options = options
  // set size

  var w0 = this.width0 = this.canvas.width = this.img.width;
  var h0 = this.height0 = this.canvas.height = this.img.height;
  
  var w1 = this.width1 = 274;
  var h1 = this.height1 = 274 * this.img.height / this.img.width;  
  
  // draw image on canvas
  this.ctx.drawImage( this.img, 0, 0, w1, h1 )//              ，   
	// this.ctx.drawImage( this.img, 0, 0 )//     

 // get imageData try {
	this.imgData = this.ctx.getImageData( 0, 0, w1, h1 ).data//              ，   
	// this.imgData = this.ctx.getImageData( 0, 0, w0, h0 ).data//     

 } catch ( error ) {
	if ( console ) {
		console.error( error ) 
	}
	return 
}
	this.ctx.clearRect( 0, 0, w1, h1 )
	for ( var i=0, len = options.length; i < len; i++ ) {
		this.renderClosePixels( options[i] ) 
	}
}

ClosePixelation.prototype.renderClosePixels = function( opts ) {

//              ，   


 var w = this.width1 var h = this.height1

//     

// var w = this.width0
//  var h = this.height0

   var ctx = this.ctx
  var imgData = this.imgData

  // option defaults
  
  var res = opts.resolution || 16
  var size = opts.size || res
  
  var alpha = opts.alpha || 1
  var offset = opts.offset || 0
  var offsetX = 0
  var offsetY = 0
  var cols = w / res + 1
  var rows = h / res + 1  
  var halfSize = size / 2
  var diamondSize = size / Math.SQRT2
  var halfDiamondSize = diamondSize / 2

  if ( isObject( offset ) ){ 
    offsetX = offset.x || 0
    offsetY = offset.y || 0
  } else if ( isArray( offset) ){
    offsetX = offset[0] || 0
    offsetY = offset[1] || 0
  } else {
    offsetX = offsetY = offset
  }

  var row, col, x, y, pixelY, pixelX, pixelIndex, red, green, blue, pixelAlpha

  for ( row = 0; row < rows; row++ ) {
    y = ( row - 0.5 ) * res + offsetY
    // normalize y so shapes around edges get color
    pixelY = Math.max( Math.min( y, h-1), 0)

    for ( col = 0; col < cols; col++ ) {
      x = ( col - 0.5 ) * res + offsetX
      // normalize y so shapes around edges get color
      pixelX = Math.max( Math.min( x, w-1), 0)
	  
      pixelIndex = ( pixelX + pixelY * w ) * 4
	  
      red   = imgData[ pixelIndex + 0 ]
      green = imgData[ pixelIndex + 1 ]
      blue  = imgData[ pixelIndex + 2 ]
      pixelAlpha = alpha * ( imgData[ pixelIndex + 3 ] / 255)

      ctx.fillStyle = 'rgba(' + red +','+ green +','+ blue +','+ pixelAlpha + ')'

      switch ( opts.shape ) {
        case 'circle' :
          ctx.beginPath()
            ctx.arc ( x, y, halfSize, 0, TWO_PI, true )
            ctx.fill()
          ctx.closePath()
          break
        case 'diamond' :
          ctx.save()
            ctx.translate( x, y )
            ctx.rotate( QUARTER_PI )
            ctx.fillRect( -halfDiamondSize, -halfDiamondSize, diamondSize, diamondSize )
          ctx.restore()
          break
        default :
          // square
          ctx.fillRect( x - halfSize, y - halfSize, size, size )
      } // switch
    } // col
  } // row
}

// enable img.closePixelate
HTMLImageElement.prototype.closePixelate = function ( options ) {
  return new ClosePixelation( this, options )
}

// put in global namespace
window.ClosePixelation = ClosePixelation

})( window );

 
    
   
然后html中
 
    
    
   
 


	window.onload = function() {
	  var dolly1 = document.getElementById('dolly1')
	  var pixelOpts = [ { resolution: 8 } ]//,shape:'diamond',shape:'circle' //          ，    （  ）        ，        8
	  var pixelDolly1 = dolly1.closePixelate( pixelOpts )
        }
 
  
転載先:https://www.cnblogs.com/snow-finland/p/4690159.html