单击画布时获取鼠标坐标

Question

一个常见问题,但我仍然需要帮助.当有人在画布中点击时,我正试图获取并存储鼠标坐标.

我的HTML

<canvas id="puppyCanvas" width="500" height="500" style="border:2px solid black" onclick = "storeGuess(event)"></canvas>

和我的javascript

//setup canvas
var canvasSetup = document.getElementById("puppyCanvas");
var ctx = canvasSetup.getContext("2d");

guessX = 0;//stores user's click on canvas
 guessY = 0;//stores user's click on canvas

function storeGuess(event){
    var x = event.clientX - ctx.canvas.offsetLeft;
    var y = event.clientY - ctx.canvas.offsetTop;
    /*guessX = x;
    guessY = y;*/


    console.log("x coords:" + x + ", y coords" + y);

我已经阅读了很多论坛,w3schools和视频.我已经接近搞清楚,但我错过了一些东西.如果删除ctx.canvas.offsetLeft和ctx.canvas.offsetTop,我可以获取页面的坐标.但我需要以某种方式合并这些以获取画布的坐标,然后存储到变量guessX和guessY中.

Answer 1

你可以通过使用offsetX和的offsetY属性来实现MouseEvent

//setup canvas
var canvasSetup = document.getElementById("puppyCanvas");
var ctx = canvasSetup.getContext("2d");
guessX = 0; //stores user's click on canvas
guessY = 0; //stores user's click on canvas
function storeGuess(event) {
    var x = event.offsetX;
    var y = event.offsetY;
    guessX = x;
    guessY = y;
    console.log("x coords: " + guessX + ", y coords: " + guessY);
}

<canvas id="puppyCanvas" width="500" height="500" style="border:2px solid black" onclick="storeGuess(event)"></canvas>