Vue and Canvas: How to achieve gorgeous animation effects

Vue and Canvas: How to achieve gorgeous animation effects

Introduction:
In Web development, animation effects are one of the important factors that are pleasing to the eye. Vue is a popular JavaScript framework, while Canvas is an HTML element used for drawing graphics and animations. This article will introduce how to combine Vue and Canvas to achieve gorgeous animation effects, and provide code examples for readers' reference.

1. New Vue project
   First, we need to create a Vue project. Run the following command in the command line:

   vue create vue-canvas-animation

   Then, select the default configuration to complete the project creation process. Enter the project directory and start the development server:

   cd vue-canvas-animation
   npm run serve

   By accessing http://localhost:8080 in the browser, you will see the initial interface of the Vue project.

2. Add Canvas element
   In the src directory of the Vue project, create a new component file CanvasAnimation.vue. In this file, we will use the Canvas element to achieve animation effects. In the template tag, add the following code:

   <template>
     <div>
    <canvas ref="canvas"></canvas>
     </div>
   </template>

   This code will create an empty Canvas element. Through the ref attribute, we can reference the element in the Vue component.

3. Using Vue's life cycle hooks and Canvas API
   In the Vue component, we can use the life cycle hook function to control the rendering and destruction of the page. Here, we will use the created hook function to initialize the Canvas and draw the animation in the mounted hook function.

First, we import the CanvasAnimation.vue file in the <script> tag and add the following code: </script>

<script>
import { onMounted, reactive } from 'vue';

export default {
  name: 'CanvasAnimation',
  setup() {
    const canvasRef = reactive(null); // 用于引用Canvas元素的响应式数据

    onMounted(() => {
      const canvas = canvasRef.value;
      const ctx = canvas.getContext('2d'); // 获取Canvas的2D绘图上下文

      // 编写绘制动画的代码
      // ...
    });

    return {
      canvasRef,
    };
  },
};
</script>

In this example, we use the Composition API of Vue 3 , the reactive function declares canvasRef as responsive data. Then, in the onMounted hook function, we obtain the context object ctx of the Canvas for subsequent drawing animation.

4. Drawing animation
   In the previous step, we have obtained the context object ctx of Canvas. Next, we can use the Canvas API to draw animations.

In the onMounted hook function, add the following code:

const drawAnimation = () => {
  requestAnimationFrame(drawAnimation); // 循环调用绘制函数，实现动画效果

  // 在这里编写绘制动画的代码
};

drawAnimation(); // 调用绘制函数，启动动画

Through the requestAnimationFrame function, we can loop the drawing function to achieve animation effects. In the drawing function, we can use the methods of the ctx object to draw graphics, change styles and handle animation logic.

Here is a simple sample code for drawing a moving ball:

const drawAnimation = () => {
  requestAnimationFrame(drawAnimation);

  ctx.clearRect(0, 0, canvas.width, canvas.height); // 清除画布

  ctx.beginPath();
  ctx.arc(ball.x, ball.y, ball.radius, 0, Math.PI * 2); // 绘制小球
  ctx.fillStyle = ball.color;
  ctx.fill();

  // 移动小球
  ball.x += ball.speedX;
  ball.y += ball.speedY;

  // 碰撞检测
  if (ball.x + ball.radius > canvas.width || ball.x - ball.radius < 0) {
    ball.speedX *= -1;
  }
  if (ball.y + ball.radius > canvas.height || ball.y - ball.radius < 0) {
    ball.speedY *= -1;
  }
};

const ball = {
  x: 100,
  y: 100,
  radius: 20,
  speedX: 2,
  speedY: 1,
  color: '#ff0000',
};

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