//变量定义
letmyCanvas=document.querySelector('#myCanvas');
letctx=myCanvas.getContext('2d');
letcanvasWidth=200;
letcanvasHeight=200;
letcanvasHistory=[];
letstep=-1;
//绘制方法
canvasDraw(){
step++;
if(step=0){
step--;
ctx.clearRect(0,0,canvasWidth,canvasHeight);
letcanvasPic=newImage();
canvasPic.src=canvasHistory[step];
canvasPic.addEventListener('load',()=>{
ctx.drawImage(canvasPic,0,0);
});
}else{
console.log('不能再继续撤销了');
}
}
//反撤销方法
canvasRedo(){
if(step{
ctx.clearRect(0,0,canvasWidth,canvasHeight);
ctx.drawImage(canvasPic,0,0);
});
}else{
console.log('已经是最新的记录了');
}
} |