我想使用折线连接两个矩形，并在矩形移动时保持连接到相应矩形上的相同点(具体来说，对于页面上的两个矩形，我希望折线连接底部一个矩形的中点到另一个矩形的顶部中间部分。我使用折线的原因是因为我最终也会在道路上添加弯头)。不过，我在响应移动矩形时更新折线坐标时遇到问题。
这演示了我遇到的一些问题:
var canvas = new fabric.Canvas('c');
rect = null;
line = null;
function addLine(x1, y1, x2, y2) {
var coords = [{x: x1, y: y1}, {x: x2, y: y2}];
this.line = new fabric.Polyline(coords, {
stroke: 'green',
strokeWidth: 5,
fill: 'rgba(0,0,0,0)',
selectable: true,
evented: false
});
this.canvas.add(this.line);
}
function addRect(left, top, width, height, line1, line2, line3, line4) {
this.rect = new fabric.Rect({
left: left,
top: top,
width: width,
height: height,
fill: '#9f9',
originX: 'left',
originY: 'top',
centeredRotation: true
});
this.rect.line1 = line1;
this.rect.line2 = line2;
this.rect.line3 = line3;
this.rect.line4 = line4;
this.canvas.add(this.rect);
}
var r1_left = 10;
var r1_top = 20;
var r1_width = 125;
var r1_height = 150;
var r2_left = 350;
var r2_top = 300;
var r2_width = 125;
var r2_height = 150;
addLine(r1_left + r1_width/2, r1_top + r1_height, r2_left + r2_width/2, r2_top);
addRect(r1_left, r1_top, r1_width, r1_height, null, null, this.line, null);
addRect(r2_left, r2_top, r2_width, r2_height, this.line, null, null, null);
this.canvas.renderAll();
this.canvas.on('object:moving', function(e) {
var p = e.target;
if (p.line1) {
let x_2_new = p.left + p.width/2;
let y_2_new = p.top;
p.line1.set('points', [p.line1.points[0], {'x': x_2_new, 'y': y_2_new}]);
p.line1.set('height', y_2_new - p.line1.points[0]['y']);
p.line1.set('width', x_2_new - p.line1.points[0]['x']);
p.set('oCoords', p.line1.calcCoords());
} else if (p.line2) {
p.line2.set({'points': [{'x': p.left + p.width, 'y': p.top + p.height/2}, p.line2.points[1]]});
} else if (p.line3) {
p.line3.set({'points': [{'x': p.left + p.width/2, 'y': p.top + p.height}, p.line3.points[1]]});
} else if (p.line4) {
p.line4.set({'points': [p.line4.points[0], {'x': p.left, 'y': p.top + p.height/2}]});
}
});<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<script src="https://rawgit.com/kangax/fabric.js/master/dist/fabric.js"></script>
</head>
<body>
<canvas id="c" width="700" height="700" style="border:1px solid #ccc"></canvas>
<script>
</script>
</body>
</html>对于上面的矩形，我尝试在对象移动时简单地设置 x 和 y 坐标。这样，我遇到了 x 和 y 似乎受直线的 oCoords 和 aCoords 约束的错误。
对于下方的矩形，我尝试直接设置坐标。这样，整行似乎在页面上移动。
任何关于我可以在这里改变什么的建议都会很棒。谢谢!
最佳答案
这是代码，您需要的，jsfiddle
(function() {
var canvas = this.__canvas = new fabric.Canvas('c', { selection: false });
fabric.Object.prototype.originX = fabric.Object.prototype.originY = 'center';
function makeCircle(left, top, line1, line2) {
var c = new fabric.Rect({
top: top,
left: left,
width: 30,
height: 30,
selection: false,
fill: '#ccc'
});
c.hasControls = c.hasBorders = false;
c.line1 = line1;
c.line2 = line2;
return c;
}
function makeLine(coords) {
return new fabric.Line(coords, {
fill: 'red',
stroke: 'red',
strokeWidth: 5,
selectable: false,
evented: false,
});
}
var line = makeLine([ 250, 125, 250, 375 ]),
line2 = makeLine([ 250, 375, 250, 350 ]);
canvas.add(line);
canvas.add(
makeCircle(line.get('x1'), line.get('y1'), null, line),
makeCircle(line.get('x2'), line.get('y2'), line, line2),
);
canvas.on('object:moving', function(e) {
var p = e.target;
p.line1 && p.line1.set({ 'x2': p.left, 'y2': p.top });
p.line2 && p.line2.set({ 'x1': p.left, 'y1': p.top });
canvas.renderAll();
});
})();<div>
<canvas id="c" width="700" height="575" style="border:1px solid #999"></canvas>
</div>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/fabric.js/2.7.0/fabric.min.js"></script>关于javascript - 使用 PolyLines 通过 FabricJS 连接拖放形状，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/55057419/