如何使用 FabricJS 创建带有折线的画布?
我们可以通过创建fabric.Polyline的实例来创建一个Polyline对象。折线对象可以由一组连接的直线段来表征。因为它属于FabricJS的基本元素之一,所以我们也可以通过应用角度、不透明度等属性来轻松定制它。
语法
new fabric.Polyline(points: Array, options: Object)
参数
points − 此参数接受一个数组,表示构成折线对象的点的数组。
options (可选) − 此参数是一个对象,它为我们的对象提供额外的自定义功能。使用此参数可以更改与Polyline对象相关的原点、笔划宽度和许多其他属性。
Explore our latest online courses and learn new skills at your own pace. Enroll and become a certified expert to boost your career.
示例 1:创建 fabric.Polyline() 的实例并将其添加到我们的画布
让我们来看一个代码示例,说明如何将折线对象添加到我们的画布中。唯一必需的参数是points数组,而第二个参数是可选的options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>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:使用set方法操作Polyline对象
在这个例子中,我们使用set方法(一个值的setter)为Polyline对象分配了属性。任何与笔划、笔划宽度、角度、缩放、旋转等相关的属性都可以使用此方法进行修改。
<!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>Manipulating the Polyline object by using the set method</h2> <p>You can see the Polyline object in canvas now with set values</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); // Set the properties polyline.set("stroke", "blue"); polyline.set("strokeWidth", 5); polyline.set("top", 50); polyline.set("left", 100); polyline.set("scaleX", 2); polyline.set("scaleY", 2); // Adding it to the canvas canvas.add(polyline); </script> </body> </html>
广告