我们可以通过创建fabric.Polygon的实例来创建一个Polygon对象。多边形对象的特征可以是由一组连接的直线段组成的任何闭合形状。由于它是 FabricJS 的基本元素之一，我们还可以通过应用角度、不透明度等属性轻松自定义它。为了找到表示当前变换的变换矩阵，我们使用 calcOwnMatrix 方法。
calcOwnMatrix(): Array
让我们看一个代码示例，了解如何使用 calcOwnMatrix 方法找到表示多边形当前变换的变换矩阵。您可以从开发工具打开控制台来查看正在显示的数组值。
<!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 the calcOwnMatrix method</h2>
<p>
You can open console from dev tools and see that the logged output contains the transform matrix of the polygon instance
</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 polygon object
var polygon = new fabric.Polygon(
[
{ x: 200, y: 10 },
{ x: 250, y: 50 },
{ x: 250, y: 180 },
{ x: 150, y: 180 },
{ x: 150, y: 50 },
{ x: 200, y: 10 },
],
{
fill: "green",
stroke: "blue",
strokeWidth: 20,
skewX: 15,
}
);
// Adding it to the canvas
canvas.add(polygon);
// Using calcOwnMatrix method
console.log(
"The transform matrix which represents current transformation of the polygon instance is: ",
polygon.calcOwnMatrix()
);
</script>
</body>
</html>
让我们看一个代码示例，以了解当我们对多边形对象应用水平缩放时，返回数组的值是如何受到影响的。在这里，我们向scaleX属性传递了值2。这确保了我们的多边形对象在水平方向上缩放2倍。我们还可以在控制台中看到返回数组的第0个索引值发生了变化。这是因为第 0 个索引表示scaleX 值。
<!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 the calcOwnMatrix method along with scaleX property</h2>
<p>
You can open console from dev tools and see that the logged output has changed
</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 polygon object
var polygon = new fabric.Polygon(
[
{ x: 200, y: 10 },
{ x: 250, y: 50 },
{ x: 250, y: 180 },
{ x: 150, y: 180 },
{ x: 150, y: 50 },
{ x: 200, y: 10 },
],
{
fill: "green",
stroke: "blue",
strokeWidth: 20,
skewX: 15,
scaleX: 2,
}
);
// Adding it to the canvas
canvas.add(polygon);
// Using calcOwnMatrix method
console.log(
"The transform matrix which represents current transformation of the polygon instance is: ",
polygon.calcOwnMatrix()
);
</script>
</body>
</html>
在本教程中，我们使用两个简单的示例来演示如何使用 FabricJS 找到表示 Polygon 对象当前变换的变换矩阵。
以上是FabricJS – 找到表示多边形对象当前变换的变换矩阵？的详细内容。更多信息请关注PHP中文网其他相关文章！
