极客笔记如何在使用FabricJS分组多个折线后取消分组
我们可以通过创建实例 fabric.Polyline 来创建折线对象。折线对象可以由一组相连的直线段组成。由于它是FabricJS的基本元素之一，我们也可以通过应用属性如角度、不透明度等轻松自定义它。要取消分组多个折线对象，我们可以使用 toActiveSelection() 方法。
语法
toActiveSelection(): fabric.ActiveSelection
示例1：使用一次点击将所有折线分组
在看如何取消分组之前，让我们先看看如何分组对象。在这个示例中，我们将有一个按钮，点击该按钮，所有的折线将被分组成一个对象。因此，移动该对象将同时移动所有的折线，并且在调整大小或倾斜时，它将作为一个单一的对象来表现。
我们将创建一个函数，该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2：一键取消所有已分组的折线组
在这个示例中，我们将有一个按钮，点击该按钮将取消已分组的折线组。因此，这些对象将作为单独的对象进行操作。首先，我们将把所有对象分组成一个单独的对象。进一步，在点击取消分组按钮时，我们将使用 toActiveSelection() 来取消分组对象。
<!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 all the 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 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: 100 },
{ x: 150, y: 60 },
{ x: 250, y: 10 },
], {
stroke: "green",
fill: "white",
strokeWidth: 5,
});
// Initiate another Polyline object
var polyLine3 = new fabric.Polyline([
{ x: 400, y: 200 },
{ x: 250, y: 160 },
{ x: 150, y: 200 },
], {
stroke: "green",
fill: "white",
strokeWidth: 5,
});
// Add them to the canvas instance
canvas.add(polyLine1);
canvas.add(polyLine2);
canvas.add(polyLine3);
// 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();
// Function to ungroup the grouped polyline objects
function ungroup() {
canvas.getActiveObject().toActiveSelection();
}
</script>
</body>
</html>