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H5 Canvas 举牌小人

news 2025/6/17 18:01:30

之前看到这种的举牌小人的图片觉得很有意思，最近有时间所以就尝试写写看。

在线链接
https://linyisonger.github.io/H5.Examples/?name=./080.Canvas%20%E4%B8%BE%E7%89%8C%E5%B0%8F%E4%BA%BA.html
生成效果
请添加图片描述
实现代码

<!DOCTYPE html>
<html lang="en"><head><meta charset="UTF-8"><meta http-equiv="X-UA-Compatible" content="IE=edge"><meta name="viewport" content="width=device-width, initial-scale=1.0"><link rel="stylesheet" href="./assets/global.css"><style>.content {display: flex;}.content textarea {width: 300px;resize: none;border-radius: 0;outline: none;border-right-width: 0;}.content .save-btn {padding: 10px;background-color: #eefdfd;font-size: 15px;cursor: pointer;user-select: none;border-color: rgb(133, 133, 133);border-width: 1px; }.content .save-btn:disabled {background-color: #b3b3b3;}</style>
</head><body><div class="content"><textarea rows="2" placeholder="请输入需要生成的举牌文字"></textarea><button class="save-btn" disabled>保存图片</button></div><canvas id="preview"></canvas><script type="module">import { Randoms } from "https://gcore.jsdelivr.net/npm/@3r/tool/lib/randoms.js";/** @type {HTMLCanvasElement} */let canvas = document.querySelector("#preview")let ctx = canvas.getContext('2d')/*** 随机人物*/function randomPerson() {let length = 41;let width = 80;let height = 165let index = Randoms.int(0, length)return {sx: index * width,sy: 0,sw: width,sh: height,}}/*** 绘制字符*/function drawChar(char, x, y, w, h) {let charCenterX = x + 38let charCenterY = y + 28ctx.drawImage(image, ...Object.values(randomPerson()), x, y, w, h)ctx.font = '18px Helvetica'ctx.textAlign = "center"ctx.textBaseline = "middle"ctx.save();ctx.translate(charCenterX, charCenterY);ctx.rotate(Math.PI / 6);ctx.fillText(char, 0, 0)ctx.restore();}/*** 渲染文字* 1.分行决定渲染图片大小* 2.逐行偏移*/function drawText(text) {ctx.clearRect(0, 0, canvas.width, canvas.height)let rows = text.split('\n')// 预处理let drawCharParams = []let maxX = 0;let maxY = 0;let width = 80;let height = 165;for (let i = 0; i < rows.length; i++) {let cols = rows[i].split('')let offsetX = (rows.length - i - 1) * (width / 2)let offsetY = i * (width / 2);for (let j = 0; j < cols.length; j++) {const char = cols[j];if (char === ' ') continue // 空字符跳过 let x = j * 40 + offsetX;let y = j * 15 + offsetY;maxX = Math.max(maxX, x)maxY = Math.max(maxY, y)drawCharParams.push([char, x, y, width, height])}}// 更新画布大小canvas.setAttribute('style', `width:${maxX + width}px;height:${maxY + height}px`)canvas.width = canvas.clientWidth;canvas.height = canvas.clientHeight;// 处理for (let i = 0; i < drawCharParams.length; i++) {drawChar(...drawCharParams[i])}}let image = new Image()image.src = './assets/upup.png'let textareaDom = document.querySelector(".content textarea")textareaDom.addEventListener('change', (e) => {let text = e.target.valuedrawText(text)})let saveBtnDom = document.querySelector('.save-btn')saveBtnDom.addEventListener('click', (e) => {let a = document.createElement('a');a.href = window.URL.createObjectURL(base64ToBlob(canvas.toDataURL("image/png", 0.8)));a.setAttribute('download', '举牌小人.png');a.click();})image.onload = () => {saveBtnDom.disabled = false}// base64 转 Blobfunction base64ToBlob(base64) {let arr = base64.split(',');let mime = arr[0].match(/:(.*?);/)[1];let bstr = atob(arr[1]);let n = bstr.length;let u8arr = new Uint8Array(n);while (n--) {u8arr[n] = bstr.charCodeAt(n);}return new Blob([u8arr], { type: mime })}</script>
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