javascript - 如何在画布上设置鼠标滚轮缩小限制？

Question

我有一个画布，我正在向这个画布添加形状。我用鼠标滚轮缩放。但是，当我缩小时，我不想从画布的初始视图进一步缩小。缩小限制应达到第一个图像边框。我怎样才能做到这一点？我的代码如下。

否则，将出现不良图像，用户可以在缩小的图像中添加形状，这超出了其目的。

如何在画布上设置鼠标滚轮缩小限制？

var canvas = new fabric.Canvas('c');

var json ='{"version":"3.1.0","objects":[{"type":"group","version":"3.1.0","originX":"left","originY":"top","left":194,"top":157,"width":40,"height":80,"fill":"rgb(0,0,0)","stroke":null,"strokeWidth":0,"strokeDashArray":null,"strokeLineCap":"butt","strokeDashOffset":0,"strokeLineJoin":"miter","strokeMiterLimit":4,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","fillRule":"nonzero","paintFirst":"fill","globalCompositeOperation":"source-over","transformMatrix":null,"skewX":0,"skewY":0,"id":"1047","objects":[{"type":"rect","version":"3.1.0","originX":"left","originY":"top","left":-20,"top":-15,"width":35,"height":50,"fill":"blue","stroke":"blue","strokeWidth":5,"strokeDashArray":null,"strokeLineCap":"butt","strokeDashOffset":0,"strokeLineJoin":"miter","strokeMiterLimit":4,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","fillRule":"nonzero","paintFirst":"fill","globalCompositeOperation":"source-over","transformMatrix":null,"skewX":0,"skewY":0,"rx":0,"ry":0,"id":"1047"},{"type":"text","version":"3.1.0","originX":"center","originY":"top","left":0,"top":-40,"width":36,"height":20.34,"fill":"red","stroke":null,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeDashOffset":0,"strokeLineJoin":"miter","strokeMiterLimit":4,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"white","fillRule":"nonzero","paintFirst":"fill","globalCompositeOperation":"source-over","transformMatrix":null,"skewX":0,"skewY":0,"text":"1047","fontSize":18,"fontWeight":"normal","fontFamily":"Quicksand","fontStyle":"normal","lineHeight":1.16,"underline":false,"overline":false,"linethrough":false,"textAlign":"left","textBackgroundColor":"","charSpacing":0,"styles":{}}]},{"type":"group","version":"3.1.0","originX":"left","originY":"top","left":640,"top":473,"width":40,"height":80,"fill":"rgb(0,0,0)","stroke":null,"strokeWidth":0,"strokeDashArray":null,"strokeLineCap":"butt","strokeDashOffset":0,"strokeLineJoin":"miter","strokeMiterLimit":4,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","fillRule":"nonzero","paintFirst":"fill","globalCompositeOperation":"source-over","transformMatrix":null,"skewX":0,"skewY":0,"id":"1048","objects":[{"type":"rect","version":"3.1.0","originX":"left","originY":"top","left":-20,"top":-15,"width":35,"height":50,"fill":"blue","stroke":"blue","strokeWidth":5,"strokeDashArray":null,"strokeLineCap":"butt","strokeDashOffset":0,"strokeLineJoin":"miter","strokeMiterLimit":4,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","fillRule":"nonzero","paintFirst":"fill","globalCompositeOperation":"source-over","transformMatrix":null,"skewX":0,"skewY":0,"rx":0,"ry":0,"id":"1048"},{"type":"text","version":"3.1.0","originX":"center","originY":"top","left":0,"top":-40,"width":36,"height":20.34,"fill":"red","stroke":null,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeDashOffset":0,"strokeLineJoin":"miter","strokeMiterLimit":4,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"white","fillRule":"nonzero","paintFirst":"fill","globalCompositeOperation":"source-over","transformMatrix":null,"skewX":0,"skewY":0,"text":"1048","fontSize":18,"fontWeight":"normal","fontFamily":"Quicksand","fontStyle":"normal","lineHeight":1.16,"underline":false,"overline":false,"linethrough":false,"textAlign":"left","textBackgroundColor":"","charSpacing":0,"styles":{}}]}],"backgroundImage":{"type":"image","version":"3.1.0","originX":"left","originY":"top","left":0,"top":0,"width":780,"height":646,"fill":"rgb(0,0,0)","stroke":null,"strokeWidth":0,"strokeDashArray":null,"strokeLineCap":"butt","strokeDashOffset":0,"strokeLineJoin":"miter","strokeMiterLimit":4,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","fillRule":"nonzero","paintFirst":"fill","globalCompositeOperation":"source-over","transformMatrix":null,"skewX":0,"skewY":0,"crossOrigin":"","cropX":0,"cropY":0,"src":"https://i1.wp.com/onideal.com/wp-content/uploads/2020/03/Schlafzimmer-Grundriss-ideale-Position-Bett-Moebel-Kleiderschrank-dreieckchen-4-780x646.jpg?fit=780%2C646&ssl=1","filters":[]}}'
canvas.loadFromJSON(json, () => canvas.renderAll(), (o,object) => {
  object.on('selected', () => {
    console.log(object.id);
  });
});
//canvas.setBackgroundImage('https://i.hizliresim.com/iBHC0t.jpg', canvas.renderAll.bind(canvas));


//var uniqid = "0";
var uniqids = 0;
$("#door").on("click", function(e) {
  rect = new fabric.Rect({
        id:uniqid,
                left: 40,
                top: 40,
                width: 35,
                height: 50,      
                fill: 'blue',
                stroke: 'blue',
                strokeWidth: 5,
                strokeUniform: false,
                hasControls : true,
                 });  
  
                var uniqid = uniqids.toString(); 
  
               var text = new fabric.Text(uniqid, {
                  fontSize: 30,
                  originX: 'center',
                  originY: 'right'
                });
                
                var group = new fabric.Group([ rect, text ], {
                  left: 0,
                  top: 100,
                });
                                        
              canvas.add(group);
        uniqids++;
  
      canvas.on('selection:cleared', c => {
              console.log("empty");
          });
 
  
});
//*****************************
canvas.on('mouse:wheel', function(opt) {
  var delta = opt.e.deltaY;
  var zoom = canvas.getZoom();
  zoom *= 0.999 ** delta;
  if (zoom > 20) zoom = 20;
  if (zoom < 0.01) zoom = 0.01;
  canvas.setZoom(zoom);
  opt.e.preventDefault();
  opt.e.stopPropagation();
  
})

$('#getid').click(function() {
  var activeObject = canvas.getActiveObjects();
  alert(canvas.getActiveObject().id); 
});



//***************************************

$("#save").on("click", function(e) {
    $(".save").html(canvas.toSVG());
});

$('#delete').click(function() {
  var activeObject = canvas.getActiveObjects(); 
    canvas.discardActiveObject();
    canvas.remove(...activeObject); 
});

/*
canvas.on('mouse:over', function(e) {
    e.target.set('fill', 'red');
    canvas.renderAll();
  });
  canvas.on('mouse:out', function(e) {
    e.target.set('fill', 'green');
    canvas.renderAll();
  });
*/



 
 

#c {
  background-color: grey;
  margin-top: 10px;
}

button {
  padding: 10px 20px;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/3.1.0/fabric.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.min.js"></script>
<button id="door">Door</button>
<button id="delete">Delete Door</button>
<button id="save">Save</button>
<button id="getid">GET ID</button>
 

<p>Save bastıktan sonra altta SVG dosyası oluşur</p>
<br> 
<canvas id="c" width="800" height="800"></canvas>
<br>  
<p class="save">
</p>

标签： javascripthtmlcanvasfabricjs