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HTML

              
                <script>
  // Copyright 2015 Owen Astrachan, Drew Hilton, Susan Rodger, Robert Duvall
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //    http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  // Created by Nick Parlante
  // Updated by Robert Duvall
  // Represents one pixel in a SimpleImage, supports rgb get/set.
  SimplePixel = function(simple_image, x, y) {
    __SimpleImageUtilities.funCheck('SimplePixel', 3, arguments.length);
    this.container = simple_image;
    this.x = x;
    this.y = y;
  };
  SimplePixel.prototype = {
    constructor: SimplePixel,
    getX: function() {
      __SimpleImageUtilities.funCheck('getX', 0, arguments.length);
      return this.x;
    },
    getY: function() {
      __SimpleImageUtilities.funCheck('getY', 0, arguments.length);
      return this.y;
    },
    getRed: function() {
      __SimpleImageUtilities.funCheck('getRed', 0, arguments.length);
      return this.container.getRed(this.x, this.y);
    },
    getGreen: function() {
      __SimpleImageUtilities.funCheck('getGreen', 0, arguments.length);
      return this.container.getGreen(this.x, this.y);
    },
    getBlue: function() {
      __SimpleImageUtilities.funCheck('getBlue', 0, arguments.length);
      return this.container.getBlue(this.x, this.y);
    },
    getAlpha: function() {
      __SimpleImageUtilities.funCheck('getAlpha', 0, arguments.length);
      return this.container.getAlpha(this.x, this.y);
    },
    setRed: function(val) {
      __SimpleImageUtilities.funCheck('setRed', 1, arguments.length);
      this.container.setRed(this.x, this.y, val);
    },
    setGreen: function(val) {
      __SimpleImageUtilities.funCheck('setGreen', 1, arguments.length);
      this.container.setGreen(this.x, this.y, val);
    },
    setBlue: function(val) {
      __SimpleImageUtilities.funCheck('setBlue', 1, arguments.length);
      this.container.setBlue(this.x, this.y, val);
    },
    setAlpha: function(val) {
      __SimpleImageUtilities.funCheck('setAlpha', 1, arguments.length);
      this.container.setAlpha(this.x, this.y, val);
    },
    setAllFrom: function(pixel) {
      __SimpleImageUtilities.funCheck('setAllFrom', 1, arguments.length);
      this.setRed(pixel.getRed());
      this.setGreen(pixel.getGreen());
      this.setBlue(pixel.getBlue());
      this.setAlpha(pixel.getAlpha());
    },
    toString: function() {
      return 'r:' + this.getRed() + ' g:' + this.getGreen() + ' b:' + this.getBlue();
    },
    // Render pixel as string
    getString: function() {
      return this.toString();
    }
  };
  // Note there is an Image built in, so don't use that name.
  // A SimpleImage can be created with a url, size, or an existing htmlImage or canvas
  SimpleImage = function() {
    if (arguments.length < 0 || arguments.length > 2) {
      __SimpleImageUtilities.funCheck('SimpleImage', 1, arguments.length);
      return null;
    }
    // function map for to support "overloaded constructor"
    var funMap = [
      function() {
        return __SimpleImageUtilities.EMPTY_IMAGE;
      },
      function(source) {
        if (source instanceof HTMLImageElement) {
          return source;
        } else if (typeof source == 'string') {
          return __SimpleImageUtilities.makeHTMLImageFromURL(source, this);
        } else if (source instanceof HTMLInputElement && source.type == 'file') {
          return __SimpleImageUtilities.makeHTMLImageFromInput(source.files[0], this);
        } else if (source instanceof SimpleImage) {
          return source.canvas;
        } else if (source instanceof HTMLCanvasElement) {
          return source;
        } else {
          __SimpleImageUtilities.throwError('Unrecognized value used to create a SimpleImage: ' + source);
        }
      },
      function(width, height) {
        if (width > 0 && height > 0) {
          return __SimpleImageUtilities.makeHTMLImageFromSize(width, height);
        } else {
          __SimpleImageUtilities.throwError('Unable to create a SimpleImage with a negative width or height [' + width + 'x' + height + ']');
        }
      }
    ];
    // call appropriate constructor
    var htmlImage = funMap[arguments.length].apply(this, arguments);
    // actual content is backed by an invisible canvas
    this.canvas = __SimpleImageUtilities.makeHTMLCanvas('SimpleImageCanvas');
    this.canvas.style.display = 'none';
    this.context = this.canvas.getContext('2d');
    // when image is loaded, it will fill this in
    this.imageData = null;
    // check to see if we can complete the constructor now instead of waiting
    if (htmlImage != null && (htmlImage instanceof HTMLCanvasElement || htmlImage.complete)) {
      this.__init(htmlImage);
    }
    this.ACCEPTED_FILES = 'image.*';
  }
  SimpleImage.prototype = {
    constructor: SimpleImage,
    complete: function() {
      return this.imageData != null;
    },
    getWidth: function() {
      __SimpleImageUtilities.funCheck('getWidth', 0, arguments.length);
      return this.width;
    },
    getHeight: function() {
      __SimpleImageUtilities.funCheck('getHeight', 0, arguments.length);
      return this.height;
    },
    getRed: function(x, y) {
      __SimpleImageUtilities.funCheck('getRed', 2, arguments.length);
      return this.imageData.data[this.__getIndex('getRed', x, y)];
    },
    getGreen: function(x, y) {
      __SimpleImageUtilities.funCheck('getGreen', 2, arguments.length);
      return this.imageData.data[this.__getIndex('getGreen', x, y) + 1];
    },
    getBlue: function(x, y) {
      __SimpleImageUtilities.funCheck('getBlue', 2, arguments.length);
      return this.imageData.data[this.__getIndex('getBlue', x, y) + 2];
    },
    getAlpha: function(x, y) {
      __SimpleImageUtilities.funCheck('getAlpha', 2, arguments.length);
      return this.imageData.data[this.__getIndex('getAlpha', x, y) + 3];
    },
    // Changes to the pixel write back to the image.
    getPixel: function(x, y) {
      __SimpleImageUtilities.funCheck('getPixel', 2, arguments.length);
      __SimpleImageUtilities.rangeCheck(x, 0, this.getWidth(), 'getPixel', 'x', 'wide');
      __SimpleImageUtilities.rangeCheck(y, 0, this.getHeight(), 'getPixel', 'y', 'tall');
      return new SimplePixel(this, x, y);
    },
    setRed: function(x, y, value) {
      __SimpleImageUtilities.funCheck('setRed', 3, arguments.length);
      this.imageData.data[this.__getIndex('getRed', x, y)] = __SimpleImageUtilities.clamp(value);
    },
    setGreen: function(x, y, value) {
      __SimpleImageUtilities.funCheck('setGreen', 3, arguments.length);
      this.imageData.data[this.__getIndex('getGreen', x, y) + 1] = __SimpleImageUtilities.clamp(value);
    },
    setBlue: function(x, y, value) {
      __SimpleImageUtilities.funCheck('setBlue', 3, arguments.length);
      this.imageData.data[this.__getIndex('getBlue', x, y) + 2] = __SimpleImageUtilities.clamp(value);
    },
    setAlpha: function(x, y, value) {
      __SimpleImageUtilities.funCheck('setAlpha', 3, arguments.length);
      this.imageData.data[this.__getIndex('getAlpha', x, y) + 3] = __SimpleImageUtilities.clamp(value);
    },
    setPixel: function(x, y, pixel) {
      __SimpleImageUtilities.funCheck('setPixel', 3, arguments.length);
      __SimpleImageUtilities.rangeCheck(x, 0, this.getWidth(), 'setPixel', 'x', 'wide');
      __SimpleImageUtilities.rangeCheck(y, 0, this.getHeight(), 'setPixel', 'y', 'tall');
      this.setRed(x, y, pixel.getRed());
      this.setBlue(x, y, pixel.getBlue());
      this.setGreen(x, y, pixel.getGreen());
      this.setAlpha(x, y, pixel.getAlpha());
    },
    // Scales contents of SimpleIage to the given size
    setSize: function(width, height) {
      __SimpleImageUtilities.funCheck('setSize', 2, arguments.length);
      width = Math.floor(width);
      height = Math.floor(height);
      if (width > 0 && height > 0) {
        // make sure we have the most current changes
        __SimpleImageUtilities.flush(this.context, this.imageData);
        this.imageData = __SimpleImageUtilities.changeSize(this.canvas, width, height);
        this.width = width;
        this.height = height;
        this.canvas.width = width;
        this.canvas.height = height;
      } else {
        __SimpleImageUtilities.throwError('You tried to set the size of a SimpleImage to a negative width or height [' + width + 'x' + height + ']');
      }
    },
    // Draws to the given canvas, setting its size to match SimpleImage's size
    drawTo: function(toCanvas) {
      if (this.imageData != null) {
        __SimpleImageUtilities.flush(this.context, this.imageData);
        toCanvas.width = this.getWidth();
        toCanvas.height = this.getHeight();
        toCanvas.getContext('2d').drawImage(this.canvas, 0, 0, toCanvas.width, toCanvas.height);
      } else {
        var myself = this;
        setTimeout(function() {
          myself.drawTo(toCanvas);
        }, 100);
      }
    },
    // Export an image as an linear array of pixels that can be iterated over
    toArray: function() {
      __SimpleImageUtilities.funCheck('toArray', 0, arguments.length);
      var array = new Array();
      // nip 2012-7
      // 1. simple-way (this is as good or faster in various browser tests)
      // var array = new Array(this.getWidth() * this.getHeight());
      // 2. change to cache-friendly y/x ordering
      // Non-firefox browsers may benefit
      for (var y = 0; y < this.getHeight(); y++) {
        for (var x = 0; x < this.getWidth(); x++) {
          //array[i++] = new SimplePixel(this, x, y);  // 2.
          array.push(new SimplePixel(this, x, y)); // 1.
        }
      }
      return array;
    },
    // Support iterator within for loops (eventually)
    values: function() {
      __SimpleImageUtilities.funCheck('values', 0, arguments.length);
      return this.toArray();
    },
    // Better name than values if we have to use it
    pixels: function() {
      return this.values();
    },
    // Private methods: should not be called publicly, but it should not hurt if it is
    // Completes the construction of this object once the htmlImage is loaded
    __init: function(img) {
      try {
        this.id = img.id;
        // this is a hack to make three different cases work together:
        // - small empty image, thumbnail images, and canvases
        this.width = ('naturalWidth' in img) ? Math.max(img.naturalWidth, img.width) : img.width;
        this.height = ('naturalHeight' in img) ? Math.max(img.naturalHeight, img.height) : img.height;
        this.canvas.width = this.width;
        this.canvas.height = this.height;
        // are we copying an already loaded image or drawing it fresh
        if (img instanceof HTMLCanvasElement) {
          var canvasData = img.getContext('2d').getImageData(0, 0, this.width, this.height);
          this.context.putImageData(canvasData, 0, 0);
        } else {
          this.context.drawImage(img, 0, 0, this.width, this.height);
        }
        this.imageData = this.context.getImageData(0, 0, this.width, this.height);
      } catch (err) {
        console.log(err);
        __SimpleImageUtilities.throwError('The name you used to create a SimpleImage was not correct: ' + img.id);
      }
    },
    // computes index into 1-d array, and checks correctness of x,y values
    __getIndex: function(funName, x, y) {
      __SimpleImageUtilities.rangeCheck(x, 0, this.getWidth(), funName, 'x', 'wide');
      __SimpleImageUtilities.rangeCheck(y, 0, this.getHeight(), funName, 'y', 'tall');
      return (Math.floor(x) + Math.floor(y) * this.getWidth()) * 4;
    }
  };
  // Private helper functions, add __ to reduce chance they will conflict with anyone else's method names
  var __SimpleImageUtilities = (function() {
    // private globals
    // image needed to seed "sized" image
    var EMPTY_IMAGE_DATA = 'data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAQAAAAnZu5uAAAAAXNSR0IArs4c6QAAABVJREFUeJxiYPgPhyQwAQAAAP//AwCgshjoJhZxhgAAAABJRU5ErkJggg==';
    // number of canvases created to hold images
    var globalCanvasCount = 0;
    // load image by wrapping it in an HTML element
    function makeHTMLImage(url, name, simpleImage, loadFunc) {
      if (loadFunc == null) {
        loadFunc = function() {
          simpleImage.__init(this);
          console.log('loaded image: ' + simpleImage.id);
        }
      }
      var img = new Image();
      img.onload = loadFunc;
      img.src = url;
      img.id = name;
      img.style.display = 'none';
      return img;
    }
    // public utility functions
    return {
      // make a blank image so it is cached for future uses
      EMPTY_IMAGE: makeHTMLImage(EMPTY_IMAGE_DATA, 'EMPTY', null, function() {}),
      // create a canvas element
      makeHTMLCanvas: function(prefix) {
        var canvas = document.createElement('canvas');
        canvas.id = prefix + globalCanvasCount;
        canvas.style.display = 'none';
        canvas.innerHTML = 'Your browser does not support HTML5.'
        globalCanvasCount++;
        return canvas;
      },
      // get image from uploaded file input
      makeHTMLImageFromInput: function(file, simpleImage) {
        console.log('creating image: ' + file.name);
        var reader = new FileReader();
        reader.onload = function() {
          makeHTMLImage(this.result, file.name.substr(file.name.lastIndexOf('/') + 1), simpleImage);
        }
        reader.readAsDataURL(file);
        return null;
      },
      // get image from a relative URL
      makeHTMLImageFromURL: function(url, simpleImage) {
        var name = url.substr(0, url.indexOf(';'));
        console.log('creating image: ' + name);
        if (url.substr(0, 4) != 'http') {
          return makeHTMLImage(url, name, simpleImage);
        } else {
          // does not work --- loading image from URL taints the canvas so we cannot use it :(
          __SimpleImageUtilities.throwError('Unfortunately you cannot create a SimpleImage directly from a URL: ' + url);
        }
      },
      // create an empty image of the given size
      makeHTMLImageFromSize: function(width, height) {
        console.log('creating image: ' + width + 'x' + height);
        var img = __SimpleImageUtilities.EMPTY_IMAGE.cloneNode(true);
        img.width = width;
        img.height = height;
        return img;
      },
      // set size of the image to the given values, scaling the pixels
      changeSize: function(canvasOld, newWidth, newHeight) {
        var canvasNew = __SimpleImageUtilities.makeHTMLCanvas('setSize_');
        canvasNew.width = newWidth;
        canvasNew.height = newHeight;
        // draw old canvas to new canvas
        var contextNew = canvasNew.getContext('2d');
        contextNew.drawImage(canvasOld, 0, 0, newWidth, newHeight);
        return contextNew.getImageData(0, 0, newWidth, newHeight);
      },
      // clamp values to be in the range 0..255
      clamp: function(value) {
        return Math.max(0, Math.min(Math.floor(value), 255));
      },
      // push accumulated local changes out to the screen
      flush: function(context, imageData) {
        if (imageData != null) {
          context.putImageData(imageData, 0, 0, 0, 0, imageData.width, imageData.height);
        }
      },
      // call this to abort with a message
      throwError: function(message) {
        throw new Error(message);
      },
      // called from user-facing functions to check number of arguments
      funCheck: function(funcName, expectedLen, actualLen) {
        if (expectedLen != actualLen) {
          var s1 = (actualLen == 1) ? '' : 's'; // pluralize correctly
          var s2 = (expectedLen == 1) ? '' : 's';
          var message = 'You tried to call ' + funcName + ' with ' + actualLen + ' value' + s1 +
            ', but it expects ' + expectedLen + ' value' + s2 + '.';
          // someday: think about "values" vs. "arguments" here
          __SimpleImageUtilities.throwError(message);
        }
      },
      // called from user-facing functions to check if given value is valid
      rangeCheck: function(value, low, high, funName, coordName, size) {
        if (value < low || value >= high) {
          var message = 'You tried to call ' + funName + ' for a pixel with ' + coordName + '-coordinate of ' + value +
            ' in an image that is only ' + high + ' pixels ' + size +
            ' (valid ' + coordName + ' coordinates are ' + low + ' to ' + (high - 1) + ').';
          __SimpleImageUtilities.throwError(message);
        }
      }
    };
  })();
</script>

<h1>Javascript image Upload</h1>

<canvas id="can">
</canvas>
<p>
  filename:
  <input type="file" multiple="false" accept="image/*" id="finput" onchange="upload()">
  <input type="text" id="tinput">
</p>
              
            
!

CSS

              
                canvas {
  height: 200px;
  border: 1px solid lightgray;
  margin: 10px;
}
h1 {
  font-family: verdana;
  font-color: Red;
}
input {
  font-size: 14pt;
}

              
            
!

JS

              
                function upload() {
  var imgcanvas = document.getElementById("can");
  var fileinput = document.getElementById("finput");
  var image = new SimpleImage(fileinput);
  //Draw image on canvas
  image.drawTo(imgcanvas);
}

function getInput() {
  var textinput = document.getElementById("tinput");
  var userinput = textinput.value;
}

              
            
!
999px

Console