在本教程中,我们将学习如何使用 FabricJS 将 Line 对象移动到绘制对象堆栈的顶部。 Line 元素是 FabricJS 中提供的基本元素之一。它用于创建直线。由于线元素在几何上是一维的并且不包含内部,因此它们永远不会被填充。我们可以通过创建 fabric.Line 实例来创建线条对象,指定线条的 x 和 y 坐标并将其添加到画布中。为了将 Line 对象移动到绘制对象堆栈的顶部,我们使用 bringToFront 方法。
bringToFront(): fabric.Object
让我们看一个代码示例,看看使用 bringToFront 方法时的输出。 bringToFront 方法将对象移动到绘制对象堆栈的顶部。在本例中,使用 bringToFront 方法将 line1 移动到 line2 之上。
<!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>Using bringToFront method</h2> <p>You can see that line1 (blue) lies above line2 (red)</p> <canvas id="canvas"></canvas> <script> // Initiate a canvas instance var canvas = new fabric.Canvas("canvas"); canvas.setWidth(document.body.scrollWidth); canvas.setHeight(250); // Initiate a Line object var line1 = new fabric.Line([200, 100, 100, 40], { stroke: "blue", strokeWidth: 20, }); // Initiate another Line object var line2 = new fabric.Line([200, 70, 70, 40], { stroke: "red", strokeWidth: 20, }); // Add both to the canvas canvas.add(line1); canvas.add(line2); // Using bringToFront method line1.bringToFront(); </script> </body> </html>
在此示例中,我们使用了三个线条对象,即 line1、line2 和 line3。尽管它们已根据数字顺序添加到画布中,但 line1 显然位于最顶部。这是因为我们使用了 bringToFront 方法,该方法将 line1 发送到绘制对象堆栈的顶部。
<!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>Using bringToFront method with three objects</h2> <p> You can see that line1 (blue) lies at the top of the stack of drawn objects </p> <canvas id="canvas"></canvas> <script> // Initiate a canvas instance var canvas = new fabric.Canvas("canvas"); canvas.setWidth(document.body.scrollWidth); canvas.setHeight(250); // Initiate a Line object var line1 = new fabric.Line([200, 100, 100, 40], { stroke: "blue", strokeWidth: 20, }); // Initiate another Line object var line2 = new fabric.Line([200, 70, 70, 40], { stroke: "red", strokeWidth: 20, }); // Initiate another Line object var line3 = new fabric.Line([200, 30, 30, 90], { stroke: "green", strokeWidth: 20, }); // Add them all to the canvas canvas.add(line1); canvas.add(line2); canvas.add(line3); // Using bringToFront method line1.bringToFront(); </script> </body> </html>
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