Html5 drag and drop on svg element

2019-01-18 11:27发布

站内问答 / jQuery
627 2 5

I am trying to follow the html5 drag and drop tutorial here. I could not get the dragstart event to be registered on rect element. If I change the event from draggable to mousedown it calls the handleDragStart handler. Please ignore the additional blank registration in the code.

JSFiddle here

<!DOCTYPE html>
<html><head>
  <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1/jquery.min.js"></script>
  <style type="text/css" media="screen">
    svg rect { cursor: move; }
  </style>
</head><body>
  <h1>SVG/HTML 5 Example</h1>
  <svg id="cvs">
    <rect draggable="true" x="0" y="10" width="100" height="80" fill="#69c" />
    <rect x="50" y="50" width="90" height="50" fill="#c66" />        
  </svg>
  <script type="text/javascript" src="loc.js"></script>
</body></html>

loc.js

$(document).ready(function() {    
    function handleDragStart(e) {
        log("handleDragStart");                
          this.style.opacity = '0.4';  // this ==> e.target is the source node.
    };

    var registercb = function () {
            $("#cvs > rect").each(function() {
                  $(this).attr('draggable', 'true');
              });
            $("#cvs > rect").bind('dragstart', handleDragStart);    
            $(window).mousedown(function (e) {        

            });    
            $(window).mousemove(function (e) {                
            });
            $(window).mouseup(function (e) {
                log("mouseup");                
            });
        };

    function log() {
      if (window.console && window.console.log)
        window.console.log('[XXX] ' + Array.prototype.join.call(arguments, ' '));
    };

    registercb();
});

2条回答
祖国的老花朵
2楼-- · 2019-01-18 12:10

I know this is an old question, I arrived here from this other question that was marked as a duplicate of this one, and wanted to add a possible solution that doesn't require jQuery or any libraries, and that works in all major browsers. It is based on this tutorial recommended by @AmirHossein Mehrvarzi.

This small solution doesn't use the drag events, just the mousedown, mouseup and mousemove. This is how it works:

  • When the mouse is down on the rectangle, it saves the mouse position and the active element.
  • When the mouse moves, the rectangle coordinates are updated with the new mouse position.
  • When the mouse is up, it resets the active element.

From the code in the question above:

var selectedElement = null;
var currentX = 0;
var currentY = 0;

$(document).ready(function() {
    
    function handleDragStart(e) {
        log("handleDragStart");                
        this.style.opacity = '0.4';  // this ==> e.target is the source node.
    };
    
    var registercb = function () {
       
        $("#cvs > rect").mousedown(function (e) {
            // save the original values when the user clicks on the element
            currentX = e.clientX;
            currentY = e.clientY;
            selectedElement = e.target;
        }).mousemove(function (e) {    
            // if there is an active element, move it around by updating its coordinates           
            if (selectedElement) {
                var dx = parseInt(selectedElement.getAttribute("x")) + e.clientX - currentX;
                var dy = parseInt(selectedElement.getAttribute("y")) + e.clientY - currentY;
                currentX = e.clientX;
                currentY = e.clientY;
                selectedElement.setAttribute("x", dx);
                selectedElement.setAttribute("y", dy);
            }
        }).mouseup(function (e) {
            // deactivate element when the mouse is up
            selectedElement = null;  
        });
    };
    
    function log() {
        if (window.console && window.console.log)
            window.console.log('[XXX] ' + Array.prototype.join.call(arguments, ' '));
    };
    
    registercb();
}); 
rect { cursor: move; }
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<h1>SVG/HTML 5 Example</h1>
<svg id="cvs">
    <rect x="0" y="10" width="100" height="80" fill="#69c" />
    <rect x="50" y="50" width="90" height="50" fill="#c66" />        
</svg>

You can also see it on this JSFiddle: http://jsfiddle.net/YNReB/61/

If you want to add drop functionality, you can modify the mouseup function to read the element on the cursor position (with document.elementFromPoint(e.clientX, e.clientY)) and then you can perform actions on the original element and the one where it was dropped.

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傲
3楼-- · 2019-01-18 12:14

This behavior may be caused by several reasons:

  • HTML 5 drag and drop is a mess, according to this article. I know it's a bit older, but the issue still seems not to be solved
  • jQuery does not support the SVG DOM-model. Therefore some parts of it may work, others don't (like offset() or width()).

I'd definitely not rely on HTML5 drag & drop support right now, but rather use a library to handle this issue. If you want to work with SVG, you could try Raphaël. If you need jQuery too, maybe the SVG plugin is the way to go. Note that both projects are not actively developed at the moment. I know this is not really a satisfactory answer, but I had to learn too, that jQuery and SVG do not go that well together. Hopefully someone proves me wrong ;).

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