<canvas class="edit-question-canvas" type="2d" id="canvasCuteImage"></canvas> /* .edit-question-canvas { position: absolute; left: -750rpx; width: 690rpx; height: 100rpx; } 样式随便自己写 */ // 使用方法 let path = await this.canvasCuteImageExecute(item.data.path, 690, item.data.rect, '#canvasCuteImage', this.pxRatio) /* path:本地图片的地址 w: 截取后图片的宽度 rect:[x,y,width,height] 解决的矩形范围 canvasId:canvas id pxRatio:rpx 转 px 的比例 onLoad() { let that = this uni.getSystemInfo({ success: function(res) { that.pxRatio = res.windowWidth / 750 } }) }, */ canvasCuteImageExecute(path, w, rect, canvasId, pxRatio) { return new Promise((resolve, reject) => { let canvasHeight = Math.floor(w * rect[3] / rect[2]) let x = rect[0] let y = rect[1] let width = rect[2] let height = rect[3] let destWidth = w * pxRatio let destHeight = canvasHeight * pxRatio const query = wx.createSelectorQuery() query.select(canvasId) .fields({ node: true, size: true }) .exec((res) => { const canvas = res[0].node const ctx = canvas.getContext('2d') canvas.width = destWidth canvas.height = destHeight let image = canvas.createImage(); //创建image实例 image.src = path image.onload = function() { ctx.drawImage(image, x, y, width, height, 0, 0, destWidth, destHeight); wx.canvasToTempFilePath({ canvas: canvas, success(res) { // console.log(res.tempFilePath); resolve(res.tempFilePath) }, fail(err) { console.log(err) resolve('') } }) } }) }) // 计算 canvas 的高度 },
标签:uniapp,canvas,裁切,res,image,let,pxRatio,rect From: https://www.cnblogs.com/nfan/p/18033877