KineticJs Canvas中用戶的圖像上傳器

Question

我正在嘗試為用戶添加圖像上傳器，以便他們可以將計算機中的圖像上傳到畫布上，並像其他圖像一樣將其移動/調整大小。 我沒有使用php的在線存儲，因此沒有一個可以做到這一點。 他們使用的這些圖像將不需要存儲在任何地方，只需在畫布中使用一次，然后便可以將畫布保存到計算機中（因此不需要在線存儲圖像）。 無論如何，我真的可以使用幫助，這是我不熟悉javascript的頁面，這是我到目前為止擁有的頁面...

    <style>
  canvas:active{
  cursor:pointer;
  }
.bg1{
  background-image:url('http://s23.postimg.org/bxtmsd2tn/boutiquebase.jpg');
  }
  .bg2{
  background-image:url('http://s4.postimg.org/bnevxi1y5/wall8.png');
  }

   .bg3{
  background-image:url('http://s13.postimg.org/6cgbaoblh/wall9.png');
  }
</style>

    <div id="container" class="bg1"></div>


  <img src="http://s23.postimg.org/bxtmsd2tn/boutiquebase.jpg" width="50px" id="wall1">
            <img src="http://s4.postimg.org/bnevxi1y5/wall8.png" width="50px" id="wall2">
  <img src="http://s13.postimg.org/6cgbaoblh/wall9.png" width="50px" id="wall3">


<table><tr>
  <td>
    <center> <img src="http://s29.postimg.org/yn6t21ah3/sidetable.png" id="shower" width="100px" style="cursor:pointer;">
   <br>
      <span id="hider1" class="sendingBut" style="cursor:pointer;">Remove </span>

      </center></td>
    </tr>
  </table>

    <script src="http://d3lp1msu2r81bx.cloudfront.net/kjs/js/lib/kinetic-v5.0.2.min.js"></script>

    <script>
         $('#wall2').click(function() {
    $('#container').removeClass('bg3').removeClass('bg1').addClass('bg2');
});    

            $('#wall1').click(function() {
    $('#container').removeClass('bg3').removeClass('bg2').addClass('bg1');
});   

            $('#wall3').click(function() {
    $('#container').removeClass('bg1').removeClass('bg2').addClass('bg3');
});   


              </script>
<script>


  function update(activeAnchor) {
        var group = activeAnchor.getParent();

        var topLeft = group.find('.topLeft')[0];
        var topRight = group.find('.topRight')[0];
        var bottomRight = group.find('.bottomRight')[0];
        var bottomLeft = group.find('.bottomLeft')[0];
        var image = group.find('.image')[0];

        var anchorX = activeAnchor.x();
        var anchorY = activeAnchor.y();

        // update anchor positions
        switch (activeAnchor.name()) {
          case 'topLeft':
            topRight.y(anchorY);
            bottomLeft.x(anchorX);
            break;
          case 'topRight':
            topLeft.y(anchorY);
            bottomRight.x(anchorX);
            break;
          case 'bottomRight':
            bottomLeft.y(anchorY);
            topRight.x(anchorX); 
            break;
          case 'bottomLeft':
            bottomRight.y(anchorY);
            topLeft.x(anchorX); 
            break;
        }

        image.setPosition(topLeft.getPosition());

        var width = topRight.x() - topLeft.x();
        var height = bottomLeft.y() - topLeft.y();
        if(width && height) {
          image.setSize({width:width, height: height});
        }
      }
      function addAnchor(group, x, y, name) {
        var stage = group.getStage();
        var layer = group.getLayer();

        var anchor = new Kinetic.Circle({
          x: x,
          y: y,
          stroke: '#666',
          fill: '#ddd',
          strokeWidth: 2,
          radius: 8,
          name: name,
          draggable: true,
          dragOnTop: false,
  opacity: .01
        });

    anchor.on('mouseout', function () {
        this.opacity(.01);
        layer.draw()
    });
    anchor.on('mouseenter', function () {
        this.opacity(1.00);
        layer.draw()
    });

        anchor.on('dragmove', function() {
          update(this);
          layer.draw();
        });
        anchor.on('mousedown touchstart', function() {
          group.setDraggable(false);
          this.moveToTop();
        });
        anchor.on('dragend', function() {
          group.setDraggable(true);
          layer.draw();
        });
        // add hover styling
        anchor.on('mouseover', function() {
          var layer = this.getLayer();
          document.body.style.cursor = 'pointer';
          this.setStrokeWidth(4);
          layer.draw();
        });
        anchor.on('mouseout', function() {
          var layer = this.getLayer();
          document.body.style.cursor = 'default';
          this.strokeWidth(2);
          layer.draw();
        });

        group.add(anchor);
      }
      function loadImages(sources, callback) {
        var images = {};
        var loadedImages = 0;
        var numImages = 0;
        for(var src in sources) {
          numImages++;
        }



        for(var src in sources) {
          images[src] = new Image();
          images[src].onload = function() {
            if(++loadedImages >= numImages) {
              callback(images);
            }
          };
          images[src].src = sources[src];
        }
      }
      function initStage(images) {
        var stage = new Kinetic.Stage({
          container: 'container',
          width: 1000,
          height: 764
        });

    var layer = new Kinetic.Layer();


        var furniGroup = new Kinetic.Group({
          x: 270,
          y: 100,
          draggable: true
        });
        var yodaGroup = new Kinetic.Group({
          x: 100,
          y: 110,
          draggable: true
        });



        /*
         * go ahead and add the groups
         * to the layer and the layer to the
         * stage so that the groups have knowledge
         * of its layer and stage
         */

        layer.add(furniGroup);
        layer.add(yodaGroup);
        stage.add(layer);








   document.getElementById('shower').addEventListener('click', function() {
         furniImg.show();
layer.draw();
           }, false);


   document.getElementById('hider1').addEventListener('click', function() {
         furniImg.hide();
layer.draw();
           }, false);




        var furniImg = new Kinetic.Image({
          x: 0,
          y: 0,
  width: 338,
          height: 285,
          image: images.furni,
                    name: 'image'
        });

        furniGroup.add(furniImg);
   addAnchor(furniGroup, 0, 0, 'topLeft');
        addAnchor(furniGroup, 338, 0, 'topRight');
        addAnchor(furniGroup, 338, 285, 'bottomRight');
        addAnchor(furniGroup, 0, 285, 'bottomLeft');

        furniGroup.on('dragstart', function() {
          this.moveToTop();
        });

        var yodaImg = new Kinetic.Image({
          x: 0,
          y: 0,
          image: images.yoda,
          width: 93,
          height: 104,
          name: 'image'
        });

        yodaGroup.add(yodaImg);
        addAnchor(yodaGroup, 0, 0, 'topLeft');
        addAnchor(yodaGroup, 93, 0, 'topRight');
        addAnchor(yodaGroup, 93, 104, 'bottomRight');
        addAnchor(yodaGroup, 0, 104, 'bottomLeft');

        yodaGroup.on('dragstart', function() {
          this.moveToTop();
        });

        stage.draw();
      }



      var sources = {
        furni: 'http://s29.postimg.org/yn6t21ah3/sidetable.png',
        yoda: 'http://www.html5canvastutorials.com/demos/assets/yoda.jpg'
      };
      loadImages(sources, initStage);





    </script> 

Answer 1

您可以使用FileReader。

這具有跨域安全兼容的優點，因此您可以使用.toDataURL保存畫布。

<html>
<head>
  <script type="text/javascript" src="http://code.jquery.com/jquery.min.js"></script>
  <style>
    canvas {border: 1px solid #aaa;}
  </style>
  <script>
  $(function(){
        var canvas = document.getElementById("canvas");
        var ctx = canvas.getContext("2d");

        // drag image to canvas
        canvas.addEventListener("dragover", function(e){ e.preventDefault(); }, false);
        canvas.addEventListener("drop", function(e){
          var files = e.dataTransfer.files;
          if (files.length>0) {
              var file=files[0];
              if (typeof FileReader !== "undefined" && file.type.indexOf("image") != -1) {
                var reader=new FileReader();
                reader.onload=function (e) {
                    var dragImage=new Image();
                    dragImage.onload=function(){
                        newDraggedImage(dragImage);
                    };
                    dragImage.src=e.target.result;
                };
                reader.readAsDataURL(file);
              }
          }
          e.preventDefault();
        }, false);

        function newDraggedImage(img){
            ctx.drawImage(img,0,0);
        }

  }); // end $(function(){});
  </script>

</head>
<body>
    <p>Drag an image onto the canvas.</p>
    <canvas id="canvas" width="300" height="300"></canvas>
</body>
</html>