使用vue + canvas画出四条依次相连的直线 在相连的夹角使用圆弧在内部连接并展示当前角度
时间: 2024-03-09 14:50:32 浏览: 19
好的,让我们来实现这个需求。首先,我们需要在Vue组件中使用canvas,并绘制四条依次相连的直线。代码如下:
```html
<template>
<canvas ref="canvas" width="400" height="400"></canvas>
</template>
<script>
export default {
mounted() {
const canvas = this.$refs.canvas
const ctx = canvas.getContext('2d')
ctx.beginPath()
ctx.moveTo(50, 50)
ctx.lineTo(100, 50)
ctx.lineTo(100, 100)
ctx.lineTo(150, 100)
ctx.stroke()
}
}
</script>
```
在这段代码中,我们使用`this.$refs.canvas`获取到canvas元素,并使用`getContext('2d')`获取到CanvasRenderingContext2D对象。接着,我们使用`moveTo()`和`lineTo()`方法绘制四条依次相连的直线,并使用`stroke()`方法使其显示在canvas上。
接下来,我们需要在相连的夹角使用圆弧在内部连接,并展示当前角度。代码如下:
```html
<template>
<canvas ref="canvas" width="400" height="400"></canvas>
</template>
<script>
export default {
mounted() {
const canvas = this.$refs.canvas
const ctx = canvas.getContext('2d')
ctx.beginPath()
ctx.moveTo(50, 50)
ctx.lineTo(100, 50)
ctx.lineTo(100, 100)
ctx.lineTo(150, 100)
ctx.stroke()
const x1 = 100
const y1 = 50
const x2 = 100
const y2 = 100
const x3 = 150
const y3 = 100
const angle = getAngle(x1, y1, x2, y2, x3, y3)
const radius = 20
const startAngle = Math.PI
const endAngle = Math.PI + angle * Math.PI / 180
const centerX = x2
const centerY = y2
ctx.beginPath()
ctx.arc(centerX, centerY, radius, startAngle, endAngle)
ctx.stroke()
ctx.font = '20px Arial'
ctx.fillStyle = 'black'
ctx.fillText(`${angle}°`, centerX - 10, centerY - radius - 5)
}
}
function getAngle(x1, y1, x2, y2, x3, y3) {
const dx1 = x1 - x2
const dy1 = y1 - y2
const dx2 = x3 - x2
const dy2 = y3 - y2
const angle1 = Math.atan2(dy1, dx1)
const angle2 = Math.atan2(dy2, dx2)
let angle = angle2 - angle1
if (angle < 0) {
angle += 2 * Math.PI
}
return angle * 180 / Math.PI
}
</script>
```
在这段代码中,我们使用`getAngle()`函数计算夹角的角度,并使用`arc()`方法绘制圆弧。需要注意的是,在计算夹角的角度时,我们使用了`Math.atan2()`方法,该方法返回从x轴正方向到指定点(x, y)之间的角度。接着,我们使用`fillText()`方法在圆弧上方展示当前角度。
完整代码如下:
```html
<template>
<canvas ref="canvas" width="400" height="400"></canvas>
</template>
<script>
export default {
mounted() {
const canvas = this.$refs.canvas
const ctx = canvas.getContext('2d')
ctx.beginPath()
ctx.moveTo(50, 50)
ctx.lineTo(100, 50)
ctx.lineTo(100, 100)
ctx.lineTo(150, 100)
ctx.stroke()
const x1 = 100
const y1 = 50
const x2 = 100
const y2 = 100
const x3 = 150
const y3 = 100
const angle = getAngle(x1, y1, x2, y2, x3, y3)
const radius = 20
const startAngle = Math.PI
const endAngle = Math.PI + angle * Math.PI / 180
const centerX = x2
const centerY = y2
ctx.beginPath()
ctx.arc(centerX, centerY, radius, startAngle, endAngle)
ctx.stroke()
ctx.font = '20px Arial'
ctx.fillStyle = 'black'
ctx.fillText(`${angle}°`, centerX - 10, centerY - radius - 5)
}
}
function getAngle(x1, y1, x2, y2, x3, y3) {
const dx1 = x1 - x2
const dy1 = y1 - y2
const dx2 = x3 - x2
const dy2 = y3 - y2
const angle1 = Math.atan2(dy1, dx1)
const angle2 = Math.atan2(dy2, dx2)
let angle = angle2 - angle1
if (angle < 0) {
angle += 2 * Math.PI
}
return angle * 180 / Math.PI
}
</script>
```