How to create cool clock and countdown applications using Vue and Canvas

How to use Vue and Canvas to create cool clock and countdown applications

Introduction:
In modern Web development, with the popularity of the Vue framework and the widespread application of Canvas technology, we can Combine Vue and Canvas to create a variety of breathtaking animation effects. This article will focus on how to use Vue and Canvas to create cool clock and countdown applications, and provide corresponding code examples for readers to follow and learn.

1. Clock Application

1. Create Vue instance and Canvas element
   First, we need to create a Vue instance and a Canvas element. In Vue's data, we will create a variable currentTime that represents the current time, and use the mounted hook function to obtain the current time after the page is loaded and assign it to currentTime. In the HTML template, we will insert the Canvas element into the page.

<template>
  <div>
    <canvas id="clockCanvas"></canvas>
  </div>
</template>

<script>
export default {
  data() {
    return {
      currentTime: null
    };
  },
  mounted() {
    this.currentTime = new Date();
    this.drawClock();
  },
  methods: {
    drawClock() {
      // 在这里实现绘制时钟的逻辑
    }
  }
};
</script>

2. Draw the clock
   In the drawClock method, we will use the Canvas API to draw the various parts of the clock. First, we need to get the Canvas object and set its width and height, as well as the drawing environment.

const canvas = document.getElementById('clockCanvas');
const ctx = canvas.getContext('2d');
const width = canvas.width;
const height = canvas.height;

Next, we will set the style for drawing the clock, such as the color, thickness, font and color of the hands, etc. We then need to figure out the angles for hours, minutes, and seconds in order to draw the hands accurately.

const hour = this.currentTime.getHours();
const minute = this.currentTime.getMinutes();
const second = this.currentTime.getSeconds();

const hourAngle = ((hour % 12) + minute / 60 + second / 3600) * 30 * Math.PI / 180;
const minuteAngle = (minute + second / 60) * 6 * Math.PI / 180;
const secondAngle = second * 6 * Math.PI / 180;

Next, we will use the Canvas drawing method to draw various parts of the clock. For example, we can use the ctx.arc() method to draw the outer circle of the clock, and the ctx.moveTo() and ctx.lineTo() methods to draw the pointer . After drawing, we need to call the ctx.stroke() method to stroke.

// 绘制时钟的外圆
ctx.beginPath();
ctx.arc(width / 2, height / 2, width / 2 - 10, 0, 2 * Math.PI);
ctx.lineWidth = 10;
ctx.strokeStyle = 'black';
ctx.stroke();

// 绘制时钟的时针
ctx.beginPath();
ctx.moveTo(width / 2, height / 2);
ctx.lineTo(width / 2 + Math.sin(hourAngle) * (width / 2 - 50), height / 2 - Math.cos(hourAngle) * (width / 2 - 50));
ctx.lineWidth = 6;
ctx.strokeStyle = 'black';
ctx.stroke();

// 绘制时钟的分针
ctx.beginPath();
ctx.moveTo(width / 2, height / 2);
ctx.lineTo(width / 2 + Math.sin(minuteAngle) * (width / 2 - 30), height / 2 - Math.cos(minuteAngle) * (width / 2 - 30));
ctx.lineWidth = 4;
ctx.strokeStyle = 'black';
ctx.stroke();

// 绘制时钟的秒针
ctx.beginPath();
ctx.moveTo(width / 2, height / 2);
ctx.lineTo(width / 2 + Math.sin(secondAngle) * (width / 2 - 20), height / 2 - Math.cos(secondAngle) * (width / 2 - 20));
ctx.lineWidth = 2;
ctx.strokeStyle = 'red';
ctx.stroke();

Finally, we need to use the requestAnimationFrame() method to achieve the real-time update effect of the clock.

requestAnimationFrame(this.drawClock);

At this point, we have completed the creation and drawing logic of the clock application.

2. Countdown application

1. Create a Vue instance and Canvas element
   Similar to the clock application, we also need to create a Vue instance and a Canvas element. In Vue's data, we will create a variable remainingTime to represent the remaining time of the countdown, and through the mounted hook function, set the end time of the countdown to 7 days later, and start the countdown logic.

<template>
  <div>
    <canvas id="countdownCanvas"></canvas>
  </div>
</template>

<script>
export default {
  data() {
    return {
      remainingTime: null
    };
  },
  mounted() {
    const endTime = new Date();
    endTime.setDate(endTime.getDate() + 7);
    this.startCountdown(endTime);
    this.drawCountdown();
  },
  methods: {
    startCountdown(endTime) {
      // 在这里实现倒计时的逻辑
    },
    drawCountdown() {
      // 在这里实现绘制倒计时的逻辑
    }
  }
};
</script>

2. Countdown logic
   In the startCountdown method, we need to calculate the remaining time of the countdown and save it in remainingTime in variables.

const now = new Date();
const remainingTime = Math.floor((endTime - now) / 1000);
this.remainingTime = remainingTime;

In order to achieve the countdown effect, we can use the setInterval() method to regularly update the remaining time and clear the timer when the remaining time is zero.

this.timer = setInterval(() => {
  if (this.remainingTime > 0) {
    this.remainingTime--;
  } else {
    clearInterval(this.timer);
  }
}, 1000);

3. Draw Countdown
   In the drawCountdown method, we will use the Canvas API to draw the countdown effect. First, we need to get the Canvas object and set its width and height, as well as the drawing environment.

const canvas = document.getElementById('countdownCanvas');
const ctx = canvas.getContext('2d');
const width = canvas.width;
const height = canvas.height;

Next, we will set the style of drawing the countdown, such as the size, color and alignment of the font, etc. We can then use the ctx.fillText() method to plot the remaining time.

ctx.font = '30px Arial';
ctx.fillStyle = 'black';
ctx.textAlign = 'center';
ctx.fillText(this.remainingTime, width / 2, height / 2);

Finally, we need to use the requestAnimationFrame() method to achieve the real-time update effect of the countdown.

requestAnimationFrame(this.drawCountdown);

At this point, we have completed the creation and drawing logic of the countdown application.

Conclusion:
Through the introduction of this article, we have learned how to use Vue and Canvas to create cool clock and countdown applications. By using Canvas's drawing method and Vue's data-driven capabilities, we can easily achieve various animation effects. I hope this article will be helpful to readers in practice and inspire their creativity and imagination in front-end development.

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