如何使用 FabricJS 在分组后取消对多个折线的组合?


我们可以通过创建fabric.Polyline的实例来创建一个折线对象。折线对象可以由一组连接的直线段来表示。由于它是 FabricJS 的基本元素之一,因此我们也可以通过应用角度、不透明度等属性轻松地自定义它。对于取消组合多个折线对象,我们可以使用toActiveSelection()方法。

语法

toActiveSelection(): fabric.ActiveSelection

示例 1:一键组合所有折线

在了解如何取消组合之前,让我们先看看如何组合对象。在本例中,我们将有一个按钮,点击它所有折线将被组合成一个对象。因此,移动该对象将移动所有折线,并且在调整大小或倾斜时,它也将表现为一个对象。

我们将创建一个函数,该函数获取画布中的所有对象并将它们组合成一个对象。

<!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>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>

示例 2:一键取消组合所有已组合的折线

在本例中,我们将有一个按钮,点击它已组合的折线将被取消组合。因此,该对象将表现为单独的对象。首先,我们将所有对象组合成一个对象。此外,当按下取消组合按钮时,我们将使用toActiveSelection()来取消组合对象。

<!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>Ungrouping all the grouped Polylines using one click</h2>
   <p> Click on the grouped object and click on `Ungroup` button to ungroup the objects, further click in empty space to discard the selection </p>
   <canvas id="canvas"></canvas>
   <button type="button" onclick="ungroup()">Ungroup</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: 100 },
         { x: 150, y: 60 },
         { x: 250, y: 10 },
      ], {
         stroke: "green",
         fill: "white",
         strokeWidth: 5,
      });

      // Initiate another Polyline object
      var polyLine3 = new fabric.Polyline([
         { x: 400, y: 200 },
         { x: 250, y: 160 },
         { x: 150, y: 200 },
      ], {
         stroke: "green",
         fill: "white",
         strokeWidth: 5,
      });

      // Add them to the canvas instance
      canvas.add(polyLine1);
      canvas.add(polyLine2);
      canvas.add(polyLine3);

      // 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();
      
      // Function to ungroup the grouped polyline objects
      function ungroup() { 
         canvas.getActiveObject().toActiveSelection();
      }
   </script>
</body>
</html>

更新于: 2023年2月16日

327 次浏览

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