基于HTML5的Drag and Drop生成图片Base64信息

function init(){                                                                 
    dataModel = new ht.DataModel();                                                                             
    listView = new ht.widget.ListView(dataModel); 
    graphView = new ht.graph.GraphView(dataModel);
    splitView = new ht.widget.SplitView(listView, graphView);
    textArea = new ht.widget.TextArea(); 
    textArea.getElement().style.wordWrap = 'normal';
    textArea.getElement().style.color = '#777';
    textArea.setEditable(false);
    new ht.widget.SplitView(splitView, textArea, 'v').addToDOM();    
    new ht.layout.ForceLayout(graphView).start();                            
    listView.setRowHeight(50);   
    listView.drawRowBackground = function(g, data, selected, x, y, width, height){
        if(this.isSelected(data)){
            g.fillStyle = '#87A6CB';
        }
        else if(this.getRowIndex(data) % 2 === 0){
            g.fillStyle = '#F1F4F7';
        }
        else{
            g.fillStyle = '#FAFAFA';
        }
        g.beginPath();
        g.rect(x, y, width, height);
        g.fill();
    };

    ht.Default.setImage('icon', {
        width: 50,
        height: 50,
        clip: function(g, width, height) {   
            g.beginPath();
            g.arc(width/2, height/2, Math.min(width, height)/2-3, 0, Math.PI * 2, true);
            g.clip();                        
        },
        comps: [
            {
                type: 'image',
                stretch: 'uniform',
                rect: [0, 0, 50, 50],
                name: {func: 'getImage'}
            }
        ]
    });
    listView.setIndent(60);  
    listView.setVisibleFunc(function(data){
        return data instanceof ht.Node;
    });
    listView.getIcon = function(data){
        return 'icon';
    };                                  
    listView.getLabel = function(data){
        var name = data.getName(name);
        var image = ht.Default.getImage(name);
        if(image){
            name += ' ( ' + image.width + ' X ' + image.height + ' )';
        }
        return name;
    };
    window.addEventListener("dragenter", dragEnter, false);
    window.addEventListener("dragexit", dragExit, false);
    window.addEventListener("dragover", dragOver, false);
    window.addEventListener("drop", drop, false);                                             
}

function dragEnter(evt) {
    evt.stopPropagation();
    evt.preventDefault();
}

function dragExit(evt) {
    evt.stopPropagation();
    evt.preventDefault();
}

function dragOver(evt) {
    evt.stopPropagation();
    evt.preventDefault();
}

function drop(evt) {
    evt.stopPropagation();
    evt.preventDefault();

    dataModel.clear();
    textArea.setText("");
    lastNode = null;                

    var files = evt.dataTransfer.files;
    var count = files.length;                
    for (var i = 0; i < count; i++) {
        var file = files[i];
        var reader = new FileReader();
        reader.onloadend = handleReaderLoadEnd;
        reader.file = file;
        reader.readAsDataURL(file);
    }
}

function handleReaderLoadEnd(evt) {
    var reader = evt.target;  
    var file = reader.file;
    var name = file.name;
    name = name.substr(0, name.length - 4);
    var text = "ht.Default.setImage('" + name + "', '" + reader.result + "');\n";
    textArea.setText(textArea.getText() + text);                 
    ht.Default.setImage(name, reader.result); 

    var note = 'Date: ' + file.lastModifiedDate.toLocaleString() + '\n'
            + 'Name: ' + file.name + '\n'
            + 'Size: ' + file.size + '\n'
            + 'Type: ' + file.type;

    var node = new ht.Node();
    node.setName(name);
    node.setImage(name);
    node.s({
        'note': note,
        'note.position': 3
    });
    dataModel.add(node);

    if(lastNode){
        var edge = new ht.Edge(lastNode, node);
        dataModel.add(edge);                    
    }
    lastNode = node;                
}