97 lines
2.6 KiB
Vue
97 lines
2.6 KiB
Vue
<template>
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<view class="canvas-con">
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<canvas :canvas-id="canvasId" :style="{width:canvasWidth + 'px', height: canvasHeight + 'px'}"></canvas>
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</view>
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</template>
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<script>
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import { showLoading, showToast, hideLoading, canvasGetImageData, getImageInfo, promiseTimeout } from "@/common/untool"
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import * as canvasUtil from "@/common/canvasUtil"
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export default {
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props:{
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},
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computed: {
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},
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data () {
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return {
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canvasId: uni.$u.guid(20),
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canvasWidth: 1,
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canvasHeight: 1,
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imgData: '',
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imageUrl: '',
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}
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},
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mounted () {
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this.initData()
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},
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unmounted() {
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},
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methods: {
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async initData() {
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this.imageUrl && await this.renderCanvasImg(this.imageUrl);
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},
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renderCanvasImg(filePath, paperWidth) {
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let that = this
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showLoading()
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console.log("===renderCanvasImg:filePath=====", filePath)
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return new Promise(async (resolve, reject)=> {
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try{
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let res = await getImageInfo(filePath)
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console.log("getImageInfo res====", res)
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const ctx = uni.createCanvasContext(that.canvasId, that);
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// 打印宽度须是8的整数倍，这里处理掉多余的，使得宽度合适，不然有可能乱码
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const remainder = paperWidth % 8;
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const w = remainder === 0 ? paperWidth : paperWidth - remainder;
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// 等比算出图片的高度
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const h = Math.floor((res.height * w) / res.width);
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that.canvasWidth = w
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that.canvasHeight = h
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// 在canvas 画一张图片
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let imgRect = canvasUtil.containImg(0, 0, w, h, res.width, res.height)
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let ctData = [imgRect.dx, imgRect.dy, imgRect.dWidth, imgRect.dHeight]
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ctx.fillStyle = 'rgba(255,255,255,1)';
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ctx.clearRect(...ctData);
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ctx.fillRect(...ctData);
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// 把原图缩放到 打印宽度的比例 绘制
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ctx.drawImage(filePath, ...ctData);
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ctx.draw(false, async() => {
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let imgData = await canvasGetImageData({ canvasId: that.canvasId, width: w, height: h, })
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hideLoading()
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that.imgData = imgData
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console.log("canvasGetImageData imgData.data.length =====", imgData.data.length)
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// 多次渲染，createCanvasContext，必须使用新的才可以
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that.canvasId = uni.$u.guid(20)
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resolve({
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imgData,
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width: w,
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height: h
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})
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});
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}catch(e){
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console.log("renderCanvasImg error==========", e)
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// 多次渲染，createCanvasContext，必须使用新的才可以
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that.canvasId = uni.$u.guid(20)
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hideLoading()
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reject(e)
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}
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})
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},
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}
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}
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</script>
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<style scoped lang="scss">
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.canvas-con{
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width: 100%;
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}
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/*图片隐藏到窗口外*/
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canvas {
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position: absolute;
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z-index: -999;
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top: -999px;
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}
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</style> |