手写板（请在下方区域手写内容）

获取绘图上下文 context var isButtonDown = false;//是否在绘制中 var arrx = [];//动作横坐标 var arry = [];//动作纵坐标 var arrz = [];//总做状态，标识按下到抬起的一个组合 var canvasw = 0;//画布宽度 var canvash = 0;//画布高度 // pages/shouxieban/shouxieban.js Page({ /** * 页面的初始数据 */ data: { //canvas宽高 canvasw: 0,canvash: 0,//canvas生成的图片路径 canvasimgsrc: "" },//画布初始化执行 startCanvas: function () { var that = this; //创建canvas this.initCanvas(); //获取系统信息 wx.getSystemInfo({ success: function (res) { canvasw = res.windowWidth - 0;//设备宽度 canvash = canvasw; that.setData({ 'canvasw': canvasw }); that.setData({ 'canvash': canvash }); } });

},//初始化函数
initCanvas: function () {
// 使用 wx.createContext 获取绘图上下文 context
context = wx.createCanvasContext('canvas');
context.beginPath()
context.setStrokeStyle('#000000');
context.setLineWidth(4);
context.setLineCap('round');
context.setLineJoin('round');
},//事件监听
canvasIdErrorCallback: function (e) {
console.error(e.detail.errMsg)
},canvasStart: function (event) {
isButtonDown = true;
arrz.push(0);
arrx.push(event.changedTouches[0].x);
arry.push(event.changedTouches[0].y);

},canvasMove: function (event) {
if (isButtonDown) {
arrz.push(1);
arrx.push(event.changedTouches[0].x);
arry.push(event.changedTouches[0].y);

};

for (var i = 0; i < arrx.length; i++) {
if (arrz[i] == 0) {
context.moveTo(arrx[i],arry[i])
} else {
context.lineTo(arrx[i],arry[i])
};

};
context.clearRect(0,canvasw,canvash);

context.setStrokeStyle('#000000');
context.setLineWidth(4);
context.setLineCap('round');
context.setLineJoin('round');
context.stroke();

context.draw(false);
},canvasEnd: function (event) {
isButtonDown = false;
},//清除画布
cleardraw: function () {
//清除画布
arrx = [];
arry = [];
arrz = [];
context.clearRect(0,canvash);
context.draw(true);
},//提交签名内容
setSign: function () {
var that = this;
if (arrx.length == 0) {
wx.showModal({
title: '提示',content: '签名内容不能为空！',showCancel: false
});
return false;
};
console.log("不是空的，canvas即将生成图片")
//生成图片
wx.canvasToTempFilePath({
canvasId: 'canvas',success: function (res) {
console.log("canvas可以生成图片")
console.log(res.tempFilePath,'canvas图片地址');
that.setData({ canvasimgsrc: res.tempFilePath })
//code 比如上传操作

},fail: function () {
console.log("canvas不可以生成图片")
wx.showModal({
title: '提示',content: '微信当前版本不支持，请更新到最新版本！',showCancel: false
});
},complete: function () {

}
})

},/**

• 生命周期函数--监听页面加载
  */
  onLoad: function (options) {
  //画布初始化执行
  this.startCanvas();

}
})