我是大学三年级，在网页设计课上我们手动绘制画布元素。这对我来说非常无聊，所以我尝试制作一些2D绘画，我可以用鼠标做它，另一端用它自己编写代码。
我设法做了这么多，即使这不是很多＆＃34;但现在我想知道有没有办法撤消一些脚本从代码中删除它？一种方法是添加新的画布并减少一个移动但是有什么东西可以删除现有的但不能一遍又一遍地重新创建新的画布吗？
在下面的这个例子中（尝试全屏），当我添加新行时，我向数组添加新的移动，当我在起点完成时，我可以绘制新元素。但是每次我添加新线时，我都会在现有线和新线上创建或绘制线条，因此它显示为一个可以填充样式的元素，依此类推。 通过这样做，您将看到现有的添加线创建一个更粗的粗线，并且因此我想知道是否有某种方法来删除或撤消这些线并添加全新的线而不将其放在现有线上的。
$(document).ready(function(){
var mainCanvas = $('#mainCanvas')[0].getContext('2d');
var coordsCanvas = $('#coordsCanvas')[0].getContext('2d');
var moves = [];
$('#newCoords').click(function(){
var mainCanvasWidth = $('#mainCanvas').width();
$(this).parent().prepend('<input class="input-class" id="x-n0" placeholder="X number of blocks"><input class="input-class" id="y-n0" placeholder="Y number of blocks"> <span class="notes">Note: canvas full width is: '+Math.floor(mainCanvasWidth)+'px. </span><button id="saveCoords">Save</button>')
$(this).remove();
});
$(document).on('click','#saveCoords',function(){
var x = $(this).siblings('input#x-n0').val(),
y = $(this).siblings('input#y-n0').val(),
mainCanvasWidth = $('#mainCanvas').width(),
mainCanvasHeight = $('#mainCanvas').height(),
xWidthPx = Math.floor(mainCanvasWidth/x),
yHeightPx = Math.floor(mainCanvasHeight/y);
$('#coordsCanvas, #mainCanvas').attr('width', Math.floor(xWidthPx*x));
$('#coordsCanvas, #mainCanvas').attr('height', Math.floor(yHeightPx*y));
var marginLeftRight = 'calc(50% - '+Math.floor(xWidthPx*x)/2+'px)';
$('#coordsCanvas, #mainCanvas').css({'width':Math.floor(xWidthPx*x)+'px','height':Math.floor(yHeightPx*y)+'px','left': marginLeftRight, 'top':'10vh'});
for(var i=0; i<x-1; i++){
coordsCanvas.beginPath();
coordsCanvas.moveTo(Math.floor(xWidthPx+(xWidthPx*i)), 0);
coordsCanvas.lineTo(Math.floor(xWidthPx+(xWidthPx*i)), Math.floor(yHeightPx*y));
coordsCanvas.stroke();
coordsCanvas.closePath();
}
for(var i=0; i<y-1; i++){
coordsCanvas.beginPath();
coordsCanvas.moveTo(0 ,Math.floor(yHeightPx+(yHeightPx*i))+1);
coordsCanvas.lineTo(Math.floor(xWidthPx*x), Math.floor(yHeightPx+(yHeightPx*i))+1);
coordsCanvas.stroke();
coordsCanvas.closePath();
}
$(this).parent().html('<label for="#mouse-position"><input type="checkbox" id="mouse-position">Show mouse position</label><span class="notes">X = '+Math.floor(xWidthPx)+'px; Y = '+Math.floor(yHeightPx)+'px;</span><div class="tools"><button id="line">Lines</button></div>');
});
$(document).on( "change", "#mouse-position", function() {
if($('input[id="mouse-position"]:checked').length === 1){
$('#mouse-coords').css('display','block');
}else{
$('#mouse-coords').css('display','none');
}
});
$(document).on( "click", "#line", function() {
$(this).css('background','silver');
$('#mainCanvas').css({'cursor':'url(./pen.png) 0 24, auto'});
});
$(document).on( "click", "#mainCanvas", function(e) {
var cursor = $('#mainCanvas').css('cursor');
var strokeStyle = $('#strokestyle').val();
if(~cursor.indexOf('pen.png')){
var posX = $(this).position().left,
posY = $(this).position().top;
if(moves[0]==='beginPath'){
if(Object.keys(moves[1])[0]==='moveTo'){
var len = moves.length-1,
nowpos = Math.floor((e.pageX - posX)) + ',' + Math.floor((e.pageY - posY)),
renderDrawing = [];
renderDrawing.push({'func': 'beginPath', init: function(){ mainCanvas.beginPath(); }});
if(moves[len]!=="stroke" || moves[len]!=="closePath"){
for(var ee=1; ee<moves.length; ee++){
if(Object.keys(moves[ee])[0]==="moveTo"){
var mtp = moves[ee]['moveTo'],
pos = mtp.split(',');
renderDrawing.push({func: 'moveTo', val: pos, init: function(){
mainCanvas.moveTo(this.val[0], this.val[1]);
}});
}else if(Object.keys(moves[ee])[0]==="lineTo"){
var mtp = moves[ee]['lineTo'],
pos = mtp.split(',');
renderDrawing.push({func: 'lineTo', val: pos, init: function(){
mainCanvas.lineTo(this.val[0], this.val[1]);
}});
}
}
var nowX = Math.floor((e.pageX - posX));
var nowY = Math.floor((e.pageY - posY));
var nowXY = nowX + ',' + nowY;
moves.push({'lineTo':nowXY});
renderDrawing.push(
{func: 'lineTo', val: nowXY, init: function(){
mainCanvas.lineTo(this.val.split(',')[0], this.val.split(',')[1]);
}},
{func: 'stroke', init: function(){ mainCanvas.stroke(); }},
{func: 'closePath', init: function(){ mainCanvas.closePath(); }});
for(var q=0; q<renderDrawing.length; q++){
if(renderDrawing[q]['func']!=="beginPath" && renderDrawing[q]['func']!=="closePath" && renderDrawing[q]['func']!=="stroke"){
renderDrawing[q].init();
}else renderDrawing[q].init();
}
console.log(moves);
if(Object.keys(moves[len])[0]==="lineTo" && nowpos===moves[1]['moveTo']){
moves = [];
}
}
}
}else{
mainCanvas.beginPath();
mainCanvas.moveTo(Math.floor(e.pageX - posX) , Math.floor(e.pageY - posY));
moves.push('beginPath',{'moveTo':Math.floor((e.pageX - posX)) + ',' + Math.floor((e.pageY - posY))});
console.log(moves);
}
}
});
$(document).on('mousemove', "#mainCanvas", function(e){
var parentOffset = $('#mainCanvas').offset();
var relX = e.pageX - parentOffset.left;
var relY = e.pageY - parentOffset.top;
$('#mouse-coords').css({
left: e.pageX + 20,
top: e.pageY
}).text( "X: " + Math.floor(relX) + ", Y: " + Math.floor(relY) );
});
});* {
margin: 0;
padding: 0;
list-style: none;
text-decoration: none;
box-sizing: border-box;
}
body {
overflow: hidden;
font-size: 100%;
}
.container {
width: 100vw;
height: 100vh;
padding-right: 5vw;
padding-left: 5vw;
padding-top: 10vh;
padding-bottom: 5vh;
overflow: hidden;
position: relative;
}
canvas {
width: 90vw;
height: 85vh;
border: 1px solid #000;
float: left;
}
.toolsBar {
width: calc(100% - 10vw);
position: absolute;
top: 5px;
left: 5vw;
border: 1px solid #000;
height: calc(10vh - 10px);
overflow: hidden;
overflow-y: auto;
}
button {
color: #fff;
background: skyblue;
border: 0;
border-radius: 5px;
margin: 5px;
padding: 15px;
cursor: pointer;
float: left;
}
.input-class {
border-radius: 5px;
margin: 5px;
padding: 15px;
float: left;
border: 1px solid #e0e0e0;
outline: none;
}
.notes {
display: inline-block;
height: 60px;
text-align: center;
float: left;
color: red;
line-height: 60px;
}
#mouse-coords {
position: absolute;
display: none;
background: #000;
padding: 2px;
color: #fff;
}
label[for="#mouse-position"] {
display: inline-block;
height: 60px;
text-align: center;
line-height: 60px;
font-size: 1.2rem;
float: left;
padding: 5px;
}
label>input {
height: 1.2rem;
width: 1.2rem;
}
.coordsCanvas {
position: absolute;
z-index: 100;
}
#mainCanvas {
background: rgba(255,255,255,.5);
position: absolute;
z-index: 200;
}
.tools {
width: auto;
overflow: hidden;
overflow-y: auto;
height: 100%;
}<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="container">
<div class="toolsBar">
<button id="newCoords">X & Y</button>
</div>
<div id="mouse-coords"></div>
<canvas class="coordsCanvas" id="coordsCanvas"></canvas>
<canvas id="mainCanvas"></canvas>
</div>