let canvas2 = wx.createCanvas()
        canvas2.width = 500
        canvas2.heigth = 400
        let context = canvas2.getContext('2d')

        //资源图片
        let img = new Image();  
        img.onload = function(){  
            //背景图片
            context.drawImage(img,0,432,500,400,0,0,500,400);   
            //底图图片
            context.drawImage(img,0,65,473,306,13,47,473,306);   
            //标题
            context.drawImage(img,0,372,100,45,186,50+10,100,45);  
            canvas2.toTempFilePath({
                x: 0, 
                y: 0, 
                width: 500,
                height: 400,
                destWidth: 500,
                destHeight: 400,
                success(res) {
                    //可以保存该截屏图片
                    console.log('截屏成功：' + res.tempFilePath)
                    console.log(res)
                    //微信分享
                    wx.shareAppMessage({
                        title: '标题' ),
                        imageUrl: res.tempFilePath
                    })
                }
            }) 
        }  
        img.src = "http://XXX.png";