转自https://segmentfault.com/q/1010000012507519
wxml写入
<view bindtap='uploadImg'>上传</view>
<image bindtap='uploadImg' data-number="0" src="{{ uploadPic[0] }}" alt="" mode="widthFix"></image>
<canvas style="width: {{cw}}px; height: {{ch}}px;" canvas-id="firstCanvas"></canvas>
JS参考
uploadImg(e) {
let that = this;
console.log(e);
let index = e.currentTarget.dataset.number;
let uploadFile = ''; //最后处理完,图片上传的图片地址
wx.chooseImage({
success(res) {
console.log(res)
const tempFilePaths = res.tempFilePaths; //获得原始图片大小
wx.getImageInfo({
src: res.tempFilePaths[0],
success(res) {
// console.log('获得原始图片大小',res.width)
//console.log(res.height)
var originWidth, originHeight;
originHeight = res.height;
originWidth = res.width;
console.log(originWidth);
//压缩比例
// 最大尺寸限制
var maxWidth = 1200,
maxHeight = 600;
// 目标尺寸
var targetWidth = originWidth,
targetHeight = originHeight;
//等比例压缩,如果宽度大于高度,则宽度优先,否则高度优先
if (originWidth > maxWidth || originHeight > maxHeight) {
if (originWidth / originHeight > maxWidth / maxHeight) {
// 要求宽度*(原生图片比例)=新图片尺寸
targetWidth = maxWidth;
targetHeight = Math.round(maxWidth * (originHeight / originWidth));
} else {
targetHeight = maxHeight;
targetWidth = Math.round(maxHeight * (originWidth / originHeight));
}
}
//尝试压缩文件,创建 canvas
var ctx = wx.createCanvasContext('firstCanvas');
ctx.clearRect(0, 0, targetWidth, targetHeight);
ctx.drawImage(tempFilePaths[0], 0, 0, targetWidth, targetHeight);
ctx.draw();
//更新canvas大小
that.setData({
cw: targetWidth,
ch: targetHeight
});
//保存图片
setTimeout(function() {
wx.canvasToTempFilePath({
canvasId: 'firstCanvas',
success: (res) => {
//写入图片数组
var uploadpic = "uploadPic[" + index + "]";
//
that.setData({
[uploadpic]: res.tempFilePath
});
uploadFile = res.tempFilePath;
//保存到相册
// wx.saveImageToPhotosAlbum({
// filePath: res.tempFilePath,
// success: (res) => {
// console.log(res)
// },
// fail: (err) => {
// console.error(err)
// }
// })
wx.uploadFile({
url: 'https://example.weixin.qq.com/upload', //仅为示例,非真实的接口地址
filePath: uploadFile,
name: 'file',
formData: {
'user': 'test'
},
success(res) {
const data = res.data
//do something
}
})
},
fail: (err) => {
console.error(err)
}
}, this)
}, 500); }
}) }
})
}