极客笔记如何在使用FabricJS分组后，仅取消选定的分组多段线的分组
我们可以通过创建 fabric.Polyline 的实例来创建多段线对象。多段线对象可以由一组连接的直线段组成。由于它是FabricJS的基本元素之一，我们还可以通过应用诸如角度、不透明度等属性来轻松自定义它。为了取消分组多段线对象，我们可以使用 toActiveSelection() 方法。
语法
toActiveSelection(): fabric.ActiveSelection
示例1：一键将所有折线分组
在看如何取消分组之前，让我们看一下如何对对象进行分组。在这个示例中，我们会有一个按钮，点击该按钮将所有的折线分组成一个单一的对象。因此，移动该对象将移动所有的折线，并且在调整大小或倾斜时它将作为一个单一的对象行为。
我们将创建一个函数，获取画布中的所有对象并将它们分组成一个单一的对象。
<!DOCTYPE html>
<html>
<head>
<!-- Adding the Fabric JS Library-->
<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/510/fabric.min.js"></script>
</head>
<body>
<h2>Grouping all the Polyline objects using one click</h2>
Click on the `Group` Button to group all the Polyline objects in the canvas
<canvas id="canvas"></canvas>
<button type="button" onclick="group()">Group</button>
<script>
// Initiate a canvas instance
var canvas = new fabric.Canvas("canvas");
canvas.setWidth(document.body.scrollWidth);
canvas.setHeight(250);
// Initiate a Polyline object
var polyLine1 = new fabric.Polyline([
{ x: 500, y: 200 },
{ x: 550, y: 60 },
{ x: 350, y: 100 },
], {
stroke: "green",
fill: "white",
strokeWidth: 5,
});
// Initiate another Polyline object
var polyLine2 = new fabric.Polyline([
{ x: 300, y: 200 },
{ x: 150, y: 60 },
{ x: 250, y: 100 },
], {
stroke: "green",
fill: "white",
strokeWidth: 5,
});
// Add them to the canvas instance
canvas.add(polyLine1);
canvas.add(polyLine2);
// Function to group all the polyline objects into single object
function group() {
// Get all the objects as selection
var sel = new fabric.ActiveSelection(canvas.getObjects(), {
canvas: canvas,
});
// Make the objects active
canvas.setActiveObject(sel);
// Group the objects
canvas.getActiveObject().toGroup();
}
</script>
</body>
</html>
示例2：使用一键解组选定的分组折线
在这个示例中，我们将有一个按钮，点击这个按钮将解组选定的分组折线。因此，对象将会作为独立的对象进行操作。首先，我们将创建两个组的折线，每个组都有两个折线对象。
此外，当选择一个组并按下解组按钮时，我们将使用 toActiveSelection() 来解组这些对象。
<!DOCTYPE html>
<html>
<head>
<!-- Adding the Fabric JS Library-->
<script src="https://cdnjs.cloudflare.com/ajax/libs/fabric.js/510/fabric.min.js"></script>
</head>
<body>
<h2>Ungrouping the selected grouped Polylines using one click</h2>
Click on the grouped object and click on `Ungroup` button to ungroup the objects, further click in empty space to discard the selection
<canvas id="canvas"></canvas>
<button type="button" onclick="ungroup()">Ungroup</button>
<script>
// Initiate a canvas instance
var canvas = new fabric.Canvas("canvas");
canvas.setWidth(document.body.scrollWidth);
canvas.setHeight(250);
// Initiate another Polyline object
var polyLine1 = new fabric.Polyline([
{ x: 300, y: 100 },
{ x: 150, y: 60 },
{ x: 250, y: 10 },
], {
stroke: "green",
fill: "white",
strokeWidth: 5,
});
// Initiate another Polyline object
var polyLine2 = new fabric.Polyline([
{ x: 400, y: 200 },
{ x: 250, y: 160 },
{ x: 150, y: 200 },
], {
stroke: "blue",
fill: "white",
strokeWidth: 5,
});
// Group two objects and add to canvas
var group1 = new fabric.Group([polyLine1, polyLine2]);
canvas.add(group1);
// Initiate another Polyline object
var polyLine4 = new fabric.Polyline([
{ x: 400, y: 10 },
{ x: 350, y: 60 },
{ x: 450, y: 10 },
], {
stroke: "pink",
fill: "white",
strokeWidth: 5,
});
// Initiate a Polyline object
var polyLine3 = new fabric.Polyline([
{ x: 500, y: 200 },
{ x: 550, y: 60 },
{ x: 350, y: 100 },
], {
stroke: "red",
fill: "white",
strokeWidth: 5,
});
// Group two objects and add to canvas
var group2 = new fabric.Group([polyLine3, polyLine4]);
canvas.add(group2);
// Function to ungroup the selected grouped polyline objects
function ungroup() {
canvas.getActiveObject().toActiveSelection();
}
</script>
</body>
</html>