如何使用 FabricJS 將多個 Polyline 物件組合成單個物件?
我們可以透過建立fabric.Polyline的例項來建立一個 Polyline 物件。Polyline 物件可以由一組連線的直線段來表徵。由於它是 FabricJS 的基本元素之一,我們也可以透過應用角度、不透明度等屬性來輕鬆自定義它。為了組合多個 Polyline 物件,我們可以使用toGroup()方法。
語法
toGroup(): Fabric.Group
示例 1:建立 fabric.Polyline() 的例項並將其新增到畫布
在瞭解如何將多個物件組合成一個物件之前,讓我們先看一個程式碼示例,說明如何將 polyline 物件新增到畫布中。唯一需要的引數是points陣列,第二個引數是可選的options物件。
<!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> Creating an instance of fabric.Polyline() and adding it to our canvas </h2>
<p>You can see that the polyline object has been added</p>
<canvas id="canvas"></canvas>
<script>
// Initiate a canvas instance
var canvas = new fabric.Canvas("canvas");
canvas.setWidth(document.body.scrollWidth);
canvas.setHeight(250);
// Initiating a points array
var points = [
{ x: 30, y: 50 },
{ x: 0, y: 0 },
{ x: 60, y: 0 },
];
// Initiating a polyline object
var polyline = new fabric.Polyline(points, {
left: 100,
top: 40,
fill: "white",
strokeWidth: 4,
stroke: "green",
});
// Adding it to the canvas
canvas.add(polyline);
</script>
</body>
</html>
示例 2:一鍵組合所有 Polyline
在這個例子中,我們將有一個按鈕,單擊該按鈕將所有 Polyline 組合成一個物件。因此,移動該物件將移動所有 Polyline,並且在調整大小或傾斜時,它也將表現為單個物件。我們將建立一個函式,該函式獲取畫布中的所有物件並將它們組合成一個物件。
<!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>
<p> Click on the `Group` Button to group all the Polyline objects in the canvas </p>
<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>
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