利用electron框架结合canvas,调用类似于[{"pts":[{"X":0,"Y":8},{"X":1,"Y":4}]},{"pts":[{"X":0,"Y":9},{"X":1,"Y":9}]}) 的本地json,画波形图的全部过程以及代码
时间: 2023-09-02 13:14:12 浏览: 46
以下是利用Electron框架结合Canvas,调用本地JSON,画波形图的代码:
index.html:
```html
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Waveform Graph</title>
</head>
<body>
<canvas id="waveform" width="800" height="600"></canvas>
<script src="./renderer.js"></script>
</body>
</html>
```
renderer.js:
```javascript
const { app, BrowserWindow } = require('electron');
const path = require('path');
const url = require('url');
const fs = require('fs');
let mainWindow;
function createWindow() {
mainWindow = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
nodeIntegration: true
}
});
mainWindow.loadURL(url.format({
pathname: path.join(__dirname, 'index.html'),
protocol: 'file:',
slashes: true
}));
mainWindow.webContents.openDevTools();
mainWindow.on('closed', function () {
mainWindow = null;
});
}
app.on('ready', createWindow);
app.on('window-all-closed', function () {
if (process.platform !== 'darwin') {
app.quit();
}
});
app.on('activate', function () {
if (mainWindow === null) {
createWindow();
}
});
function drawWaveform(data) {
const canvas = document.getElementById('waveform');
const ctx = canvas.getContext('2d');
ctx.clearRect(0, 0, canvas.width, canvas.height);
const maxPoints = data.reduce((max, { pts }) => Math.max(max, pts.length), 0);
const scaleY = canvas.height / 10;
const scaleX = canvas.width / maxPoints;
for (let i = 0; i < data.length; i++) {
const { pts } = data[i];
ctx.beginPath();
ctx.moveTo(pts[0].X * scaleX, canvas.height - pts[0].Y * scaleY);
for (let j = 1; j < pts.length; j++) {
ctx.lineTo(pts[j].X * scaleX, canvas.height - pts[j].Y * scaleY);
}
ctx.stroke();
}
}
fs.readFile('data.json', 'utf-8', (err, data) => {
if (err) {
console.error(err);
return;
}
drawWaveform(JSON.parse(data));
});
```
data.json:
```json
[
{
"pts": [
{ "X": 0, "Y": 8 },
{ "X": 1, "Y": 4 }
]
},
{
"pts": [
{ "X": 0, "Y": 9 },
{ "X": 1, "Y": 9 }
]
}
]
```
在以上代码中,我们创建了一个Electron窗口,并加载了一个包含canvas元素和renderer.js脚本的HTML文件。然后,我们定义了一个drawWaveform函数,该函数接收一个包含波形数据的数组,并将其绘制在canvas上。最后,我们使用fs模块读取本地存储的JSON文件,并将其解析为JavaScript对象,然后调用drawWaveform函数将数据绘制到canvas上。