fabric.js 同时选中多个元素时,将多选框内的元素坐标定位改成相对整个画布来进行坐标定位,并举例...
时间: 2024-05-11 21:19:09 浏览: 8
在 fabric.js 中同时选中多个元素时,我们可以通过获取多个元素的左上角坐标和右下角坐标,计算出多选框相对于整个画布的坐标定位。
具体实现步骤如下:
1. 获取多个元素的左上角和右下角坐标:
```javascript
let objects = canvas.getActiveObjects();
let minX = objects[0].left;
let minY = objects[0].top;
let maxX = objects[0].left + objects[0].width;
let maxY = objects[0].top + objects[0].height;
objects.forEach(obj => {
if (obj.left < minX) {
minX = obj.left;
}
if (obj.top < minY) {
minY = obj.top;
}
if (obj.left + obj.width > maxX) {
maxX = obj.left + obj.width;
}
if (obj.top + obj.height > maxY) {
maxY = obj.top + obj.height;
}
});
```
2. 计算多选框相对于整个画布的坐标定位:
```javascript
let canvasRect = canvas.getBoundingClientRect();
let canvasLeft = canvasRect.left;
let canvasTop = canvasRect.top;
let left = minX - canvasLeft;
let top = minY - canvasTop;
let width = maxX - minX;
let height = maxY - minY;
```
3. 更新多选框的位置和大小:
```javascript
let rect = canvas.getActiveObject();
rect.set({
left: left,
top: top,
width: width,
height: height
});
canvas.renderAll();
```
下面是一个完整的示例代码:
```javascript
let objects = canvas.getActiveObjects();
let minX = objects[0].left;
let minY = objects[0].top;
let maxX = objects[0].left + objects[0].width;
let maxY = objects[0].top + objects[0].height;
objects.forEach(obj => {
if (obj.left < minX) {
minX = obj.left;
}
if (obj.top < minY) {
minY = obj.top;
}
if (obj.left + obj.width > maxX) {
maxX = obj.left + obj.width;
}
if (obj.top + obj.height > maxY) {
maxY = obj.top + obj.height;
}
});
let canvasRect = canvas.getBoundingClientRect();
let canvasLeft = canvasRect.left;
let canvasTop = canvasRect.top;
let left = minX - canvasLeft;
let top = minY - canvasTop;
let width = maxX - minX;
let height = maxY - minY;
let rect = canvas.getActiveObject();
rect.set({
left: left,
top: top,
width: width,
height: height
});
canvas.renderAll();
```
举个例子,假设我们有两个矩形,它们的坐标和大小如下:
```javascript
let rect1 = new fabric.Rect({
left: 100,
top: 100,
width: 50,
height: 50,
fill: 'red'
});
let rect2 = new fabric.Rect({
left: 150,
top: 150,
width: 50,
height: 50,
fill: 'blue'
});
canvas.add(rect1, rect2);
```
当我们同时选中这两个矩形时,多选框的坐标和大小将会相应地改变。如果我们想要将多选框相对于整个画布来进行坐标定位,可以使用上面的代码。