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HTML

              
                <main class="app-container">
  
  <h1>VueJS + HTML5 Canvas</h1>
  <span class="sub">Image upload, resize, crop, and base64 converter</span>
  
  <div id="app">
    <image-uploader 
      width="300px" 
      height="200px">
    </image-uploader>
    <section class="text-area-section">
      <textarea 
        v-model="sharedData.imageData">
      </textarea>
    </section>
  </div>
</main>

<!-- -->
<script type="text/x-template" id="image-uploader-template">
<div class="image-input__container image-uploader" 
	v-bind:style="containerStyles" 
  v-bind:class="{ 'image-loaded': isImageLoaded }">

    <!-- Hidden input we use to access file contents -->
    <form class="image-input__form" ref="form">
      <input @change="previewThumbnail" class="image-input__input" ref="fileInput" type="file" />
    </form>
    <div v-on:click="triggerInput" class="image-input__overlay"></div>
    <div class="image-input__control-buttons">
    	<button v-on:click="toBase64" type="button" class="to-base64">64</button>
      <button v-on:click="scaleUp" type="button" class="scale-up">+</button>
      <button v-on:click="scaleDown" type="button" class="scale-down">-</button>
      <button v-on:click="resetInput" type="button" class="reset-input">x</button>
    </div>

    <!-- Used in place of an image tag -->
    <canvas class="image-input__canvas"
      ref="canvas"
      v-bind:height="height"
      v-bind:width="width"
      v-bind:class="{ 'is-draggable': hoverIsDraggable }">
    </canvas>

  </div>
</script>
              
            
!

CSS

              
                /*******************************
 * HTML5 Canvas Image Uploader
 *******************************/
/* Trickery to allow hidden input, but get around safety checks by browsers */
.image-input__input 
{ 
  position: absolute;
  top: -10px; left: -10px;

  width: 9px;
  height: 9px;

  cursor: pointer;
}

.image-input__container {
  position: absolute;
  overflow: hidden;

  border: 1px dashed #FFF;
  
  box-sizing: border-box; /* display border inside */
  -moz-box-sizing: border-box;
  -webkit-box-sizing: border-box;

  &:hover {
    border: 1px solid #7FCC29;
    transition: 0.15s border;

    background: url("https://s3-us-west-2.amazonaws.com/s.cdpn.io/424395/camera.svg");
    background-size: 50px 41px;
    background-position: center;
    background-repeat: no-repeat;
  }
}

.image-input__overlay 
{
  position: absolute;
  top: 0; left: 0;

  width: 100%;
  height: 100%;

  cursor: pointer;

  .image-loaded & {
    display: none;
  }
}

.image-input__control-buttons 
{
  display: none;

  .image-loaded & { display: block; }

  position: absolute;
  top: 5px; left: 5px;

  button {
    margin: 0; padding: 0;
    width: 25px; height: 25px;
  }
}

.image-input__canvas {
  &.is-draggable {
    cursor: move;
  }
}

/*******************************
 * Demo Styles
 *******************************/

body { 
  color: #FFF;
  background-color: #533A71;
  font-family: 'Roboto', sans-serif;
}

h1 { margin-bottom: 0; }
.sub { 
  font-style: italic; 
  font-weight: 300;
}

.app-container { 
  margin: 0 auto; 
  min-width: 650px;
  max-width: 800px;
}
#app { position: relative; }

.image-uploader {
  position: absolute;
  margin: 20px 10px;
  left: 0;
}

.text-area-section {
  position: absolute;
  margin: 20px 10px;
  padding: 0;
  width: 300px;
  height: 200px;
  overflow: hidden;
  right: 0;
}

textarea {
  width: 100%;
  height: 100%;
}
              
            
!

JS

              
                var sharedData = {
  imageData: '',
  updateImageData: function(newData){
    this.imageData = newData;
  }
};

Vue.component('image-uploader', {
  template: '#image-uploader-template',
  props: ['id','width','height'],
  // Must be a function in component definition
  data: function () {
    return {
      isImageLoaded: false,
      hoverIsDraggable: false,
      // Image
      ctx: null, canvas: null,
      img: null, 
      // Properties
      scaleSteps: 0,
      imageX: 0, imageY: 0,
      scaledImageWidth: 0, scaledImageHeight: 0,
      imageWidth: 0, imageHeight: 0, imageRight: 0, imageBottom: 0,
      // State
      draggingImage: false,
      // Mouse 
      startX: 0, startY: 0,
      mouseX: 0, mouseY: 0,
      sharedData: window.sharedData
    }
  },
  computed: {
    containerStyles: function () {
      return {
        width: this.width,
        height: this.height
      };
    }
  },
  mounted: function(){
    this.$on('get-image-base64', function(){
      console.log("ON'ING");
      this.updateTemplateImage();
    });
    
    // Instantiate
    this.canvas = this.$refs.canvas;
    this.ctx = this.canvas.getContext("2d");
    this.img = document.createElement("img");
  },
  methods: {
    toBase64: function()
    {
      var imageData = this.canvas.toDataURL("image/png");
      imageData.replace('data:image/png;base64,', '');
      this.sharedData.updateImageData(imageData);
    },
    draw: function(withBorders) 
    {
      // clear the canvas
      this.ctx.clearRect(0, 0, this.canvas.width, this.canvas.height);

      // some maths
      var scaleFactor = 1 - (this.scaleSteps * .1) ;
      this.scaledImageWidth = this.img.width * scaleFactor;
      this.scaledImageHeight = this.scaledImageWidth * (this.img.height/this.img.width);

      // draw the image
      // this.ctx.drawImage(
      // this.img, (top left coords of source to use (x,y)), 
      // width & height of source to use (width, height)
      // (x,y) on canvas
      // width & height on canvas
      this.ctx.drawImage(this.img, 0, 0, this.img.width, this.img.height, this.imageX, this.imageY, this.scaledImageWidth, this.scaledImageHeight);

      this.imageRight = this.imageX + this.scaledImageWidth;
      this.imageBottom = this.imageY + this.scaledImageHeight;

      // optionally draw a box around the image (indicates "selected")
      if (withBorders) {
          this.ctx.beginPath();
          this.ctx.moveTo(this.imageX, this.imageY);
          this.ctx.lineTo(this.imageRight, this.imageY);
          this.ctx.lineTo(this.imageRight, this.imageBottom);
          this.ctx.lineTo(this.imageX, this.imageBottom);
          this.ctx.closePath();
          this.ctx.stroke();
      }
    },
    resetInput: function(){
      // clear the canvas
      this.ctx.clearRect(0, 0, this.canvas.width, this.canvas.height);
      // Reset state
      this.$refs.form.reset();
      this.isImageLoaded = false;
    },
    scaleUp: function(){
      this.scaleSteps--;
      this.draw(false);
    },
    scaleDown: function(){
      this.scaleSteps++;
      this.draw(false);
    },
    getMousePos: function(evt){
        var rect = this.canvas.getBoundingClientRect(), // abs. size of element
            scaleX = this.canvas.width / rect.width,    // relationship bitmap vs. element for X
            scaleY = this.canvas.height / rect.height;  // relationship bitmap vs. element for Y

        return {
          x: (evt.clientX - rect.left) * scaleX,   // scale mouse coordinates after they have
          y: (evt.clientY - rect.top) * scaleY     // been adjusted to be relative to element
        }
    },
    isImageHit: function(x, y){
      return (x > this.imageX && x < this.imageX + this.imageWidth && y > this.imageY && y < this.imageY + this.imageHeight);
    },
    triggerInput: function(event)
    {
      event.preventDefault();
      this.$refs.fileInput.click();
    },
    previewThumbnail: function (event) 
    {
      var vm = this;
      var input = event.target;

      if (input.files && input.files[0]) 
      {
        var reader = new FileReader();

        // Set as source
        reader.onload = function (e) {
          vm.img.src = e.target.result;
        }

        reader.readAsDataURL(input.files[0]);

        vm.img.onload = function() 
        {
          // Draw
          vm.ctx.drawImage(vm.img, 0, 0);

          // Grab position info
          vm.imageWidth = vm.img.width;
          vm.imageHeight = vm.img.height;
          vm.imageRight = vm.imageX + vm.imageWidth;
          vm.imageBottom = vm.imageY + vm.imageHeight
          
          // Update CTX
          vm.draw(false);

          // Notify component
          vm.isImageLoaded = true;
        }
      }

      function handleMouseDown(e) {
        var pos = vm.getMousePos(e);
        vm.startX = pos.x;
        vm.startY = pos.y;
        vm.draggingImage = vm.hoverIsDraggable;
      }

      function handleMouseUp(e) {
        vm.draggingImage = false;
        vm.draw(false);
      }

      function handleMouseOut(e) {
        handleMouseUp(e);
      }

      function handleMouseMove(e) 
      {
        // Update cursor property var (;
        var pos = vm.getMousePos(e);
        vm.hoverIsDraggable = vm.isImageHit(pos.x, pos.y);

        if (vm.draggingImage) 
        {
          //
          vm.mouseX = pos.x;
          vm.mouseY = pos.y;

          // move the image by the amount of the latest drag
          var dx = vm.mouseX - vm.startX;
          var dy = vm.mouseY - vm.startY;
          
          // Lock image to canvas viewport
          var collidedOnLeft = vm.imageX > 0 && dx > 0;
          var collidedOnRight = vm.imageRight < vm.canvas.width && dx < 0;
          var collidedOnTop = vm.imageY > 0 && dy > 0;
          var collidedOnBottom = vm.imageBottom < vm.canvas.height && dy < 0;

          if(collidedOnLeft) {
            vm.imageX = 0;
            vm.imageRight = vm.scaledImageWidth;
          }
          else if(collidedOnRight) {
            vm.imageX = vm.canvas.width - vm.scaledImageWidth;
            vm.imageRight = vm.canvas.width;
          } else {
            vm.imageX += dx;
            vm.imageRight += dx;
          }
          
          if(collidedOnTop) {
            vm.imageY = 0;
            vm.imageBottom = vm.scaledImageHeight;
          }
          else if(collidedOnBottom) {
            vm.imageY = vm.canvas.height - vm.scaledImageHeight;
            vm.imageBottom = vm.canvas.height;
          } else {
            vm.imageY += dy;
            vm.imageBottom += dy;
          }

          // Reset the startXY for next time
          vm.startX = vm.mouseX;
          vm.startY = vm.mouseY;

          // Redraw the image with border
          vm.draw(true);
        }
      } // END MOUSEMOVE

      // LISTEN (:
      vm.canvas.addEventListener('mousedown', handleMouseDown, false);
      vm.canvas.addEventListener('mousemove', handleMouseMove, false);
      vm.canvas.addEventListener('mouseup', handleMouseUp, false);
      vm.canvas.addEventListener('mouseout', handleMouseOut, false);
    }
  }
});

var app = new Vue({
  el: '#app',
  data: {
    sharedData: window.sharedData
  },
  methods: {}
});
              
            
!
999px

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