How to set the border color of a selection area on the canvas using FabricJS?-JS Tutorial-php.cn

How to set the border color of a selection area on the canvas using FabricJS?

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Release： 2023-09-07 14:41:08

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如何使用 FabricJS 设置画布上选择区域的边框颜色？

In this article, we will learn how to set the border color of a selection area on the canvas using FabricJS. A selection indicating whether group selection should be enabled. FabricJS allows us to adjust the border color accordingly using the SelectionBorderColor property.

Syntax

new fabric.Canvas(element: HTMLElement|String, { selectionBorderColor: String }: Object)

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Parameters

Element - This parameter is The element itself can be derived using document.getElementById() or The id of the element itself. The FabricJS canvas will be initialized on this element.
Options (optional) - This parameter is an object that provides additional customization of our canvas. Using this parameter, you can change the properties related to the canvas such as color, cursor, border width, and many other properties, among which selectionBorderColor is the property we can use to indicate the color of the selection border. The default value of the SelectionBorderColor property is rgba(255,255,255,0.3).

Example 1

Use the color name to set the selection area color

selectionBorderColor property accepts a string that determines The color of the selection border. The color is usually darker than the selection itself. Let's look at a code example to see how to set the border color of a selection area in a canvas using FabricJS.

<!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>Setting the border color of a selection area on a canvas</h2>
   <p>Select an area around the object. You will notice that the border color of the selection would be red in color. </p>
   <canvas id="canvas"></canvas>
   <script>
      // Initiate a canvas instance
      var canvas = new fabric.Canvas("canvas", {
         selectionBorderColor: "green",
      });
      // Creating an instance of the fabric.Rect class
      var rect = new fabric.Rect({
         left: 170,
         top: 90,
         width: 60,
         height: 80,
         fill: "#006400",
         angle: 90,
      });
      // Adding it to the canvas
      canvas.add(rect);
      canvas.setWidth(document.body.scrollWidth);
      canvas.setHeight(250);
   </script>
</body>
</html>

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Example 2

Use rgba value as selection area color

We can also use "rgba" value, where "a" represents "alpha" ” means opacity. In this example, we used maroon with an "rgba" value of (112,0,0) and 0.9 for opacity.

<!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>Setting border colour of selection area using FabricJs</h2>
   <p>Select an area around the object to see the border color of the selection area. Here we have used "rgba" value to set the border color of the selection area.</p>
   <canvas id="canvas"></canvas>
   <script>
      // Initiate a canvas instance
      var canvas = new fabric.Canvas("canvas", {
         selectionBorderColor: "rgba(112,0,0,0.9)",
      });
      // Creating an instance of the fabric.Rect class
      var rect = new fabric.Rect({
         left: 170,
         top: 90,
         width: 60,
         height: 80,
         fill: "#006400",
         angle: 90,
      });
      // Adding it to the canvas
      canvas.add(rect);
      canvas.setWidth(document.body.scrollWidth);
      canvas.setHeight(250);
   </script>
</body>
</html>

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