Html 选择坐标点时,在画布中显示选定的空间
当单击坐标画布时,显示一个点,当再次单击时,显示一个点,但我想在选择“下一步”(单击)时删除上一个点, 请帮助我解决这个问题,我也在尝试用jquery来解决这个问题,但这也不合适,我也在尝试使用“clearRec”方法,但是它 同时删除坐标图Html 选择坐标点时,在画布中显示选定的空间,html,canvas,coordinate,Html,Canvas,Coordinate,当单击坐标画布时,显示一个点,当再次单击时,显示一个点,但我想在选择“下一步”(单击)时删除上一个点, 请帮助我解决这个问题,我也在尝试用jquery来解决这个问题,但这也不合适,我也在尝试使用“clearRec”方法,但是它 同时删除坐标图 <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
<style>
#cordCanvas {
border: 1px solid black;
}
</style>
</head>
<body>
<div id=container>
<canvas id="cordCanvas" width="150" height="150" onclick="draw(event); showCoords(event);"></canvas>
</div>
<p id='showCoords'></p>
<script>
var cordCanvas = document.getElementById("cordCanvas");
var context = cordCanvas.getContext("2d");
function draw(e) {
var pos = getMousePos(cordCanvas, e);
posx = pos.x;
posy = pos.y;
// context.clearRect(0, 0, cordCanvas.width, cordCanvas.height);
context.fillStyle = "#000000";
context.beginPath();
context.arc(posx, posy, 2, 0, 2 * Math.PI);
context.fill();
}
function getMousePos(cordCanvas, evt) {
var rect = cordCanvas.getBoundingClientRect();
return {
x: evt.clientX - rect.left,
y: evt.clientY - rect.top
};
}
window.onload = drawCord;
function drawCord() {
var cordCanvas = document.getElementById('cordCanvas');
if (cordCanvas.getContext) {
var context = cordCanvas.getContext('2d');
for (var x = 0.5; x < 150; x += 15) {
context.moveTo(x, 0);
context.lineTo(x, 150);
}
for (var y = 0.5; y < 150; y += 15) {
context.moveTo(0, y);
context.lineTo(150, y);
}
context.strokeStyle = '#00abff';
context.stroke();
}
}
function showCoords(event) {
var x = event.clientX - 10;
var y = event.clientY - 10;
var coords = "X coordinates: " + x + ", Y coordinates: " + y;
document.getElementById('showCoords').innerHTML = coords;
}
</script>
</body>
</html>
文件
#绳索帆布{
边框:1px纯黑;
}
var cordCanvas=document.getElementById(“cordCanvas”);
var context=cordCanvas.getContext(“2d”);
功能图(e){
var pos=getMousePos(cordCanvas,e);
posx=pos.x;
posy=pos.y;
//clearRect(0,0,cordCanvas.width,cordCanvas.height);
context.fillStyle=“#000000”;
context.beginPath();
arc(posx,posy,2,0,2*Math.PI);
context.fill();
}
函数getMousePos(cordCanvas,evt){
var rect=cordCanvas.getBoundingClientRect();
返回{
x:evt.clientX-rect.left,
y:evt.clientY-rect.top
};
}
window.onload=抽绳;
函数drawCord(){
var cordCanvas=document.getElementById('cordCanvas');
if(cordCanvas.getContext){
var context=cordCanvas.getContext('2d');
对于(var x=0.5;x<150;x+=15){
moveTo(x,0);
lineTo(x,150);
}
对于(变量y=0.5;y<150;y+=15){
上下文。移动到(0,y);
lineTo(150,y);
}
context.strokeStyle='#00abff';
stroke();
}
}
函数showCoords(事件){
var x=event.clientX-10;
var y=event.clientY-10;
var coords=“X坐标:”+X+”,Y坐标:“+Y;
document.getElementById('showCoords')。innerHTML=coords;
}