向canvas元素添加一个单击事件处理程序，返回单击的x和y坐标(相对于canvas元素)，最简单的方法是什么?
不需要传统浏览器兼容性，Safari、Opera和Firefox就可以了。
当前回答
这是一个非常好的教程-
http://www.html5canvastutorials.com/advanced/html5-canvas-mouse-coordinates/
<canvas id="myCanvas" width="578" height="200"></canvas>
<script>
function writeMessage(canvas, message) {
var context = canvas.getContext('2d');
context.clearRect(0, 0, canvas.width, canvas.height);
context.font = '18pt Calibri';
context.fillStyle = 'black';
context.fillText(message, 10, 25);
}
function getMousePos(canvas, evt) {
var rect = canvas.getBoundingClientRect();
return {
x: evt.clientX - rect.left,
y: evt.clientY - rect.top
};
}
var canvas = document.getElementById('myCanvas');
var context = canvas.getContext('2d');
canvas.addEventListener('mousemove', function(evt) {
var mousePos = getMousePos(canvas, evt);
var message = 'Mouse position: ' + mousePos.x + ',' + mousePos.y;
writeMessage(canvas, message);
}, false);
希望这能有所帮助!
其他回答
这是一个非常好的教程-
http://www.html5canvastutorials.com/advanced/html5-canvas-mouse-coordinates/
<canvas id="myCanvas" width="578" height="200"></canvas>
<script>
function writeMessage(canvas, message) {
var context = canvas.getContext('2d');
context.clearRect(0, 0, canvas.width, canvas.height);
context.font = '18pt Calibri';
context.fillStyle = 'black';
context.fillText(message, 10, 25);
}
function getMousePos(canvas, evt) {
var rect = canvas.getBoundingClientRect();
return {
x: evt.clientX - rect.left,
y: evt.clientY - rect.top
};
}
var canvas = document.getElementById('myCanvas');
var context = canvas.getContext('2d');
canvas.addEventListener('mousemove', function(evt) {
var mousePos = getMousePos(canvas, evt);
var message = 'Mouse position: ' + mousePos.x + ',' + mousePos.y;
writeMessage(canvas, message);
}, false);
希望这能有所帮助!
你可以这样做:
var canvas = yourCanvasElement;
var mouseX = (event.clientX - (canvas.offsetLeft - canvas.scrollLeft)) - 2;
var mouseY = (event.clientY - (canvas.offsetTop - canvas.scrollTop)) - 2;
这将为您提供鼠标指针的确切位置。
如果你喜欢简单，但仍然需要跨浏览器功能，我发现这个解决方案最适合我。这是一个简化的@Aldekein的解决方案，但没有jQuery。
function getCursorPosition(canvas, event) {
const rect = canvas.getBoundingClientRect()
const x = event.clientX - rect.left
const y = event.clientY - rect.top
console.log("x: " + x + " y: " + y)
}
const canvas = document.querySelector('canvas')
canvas.addEventListener('mousedown', function(e) {
getCursorPosition(canvas, e)
})
在Prototype中，使用cumulativeOffset()执行上面Ryan Artecona提到的递归求和。
http://www.prototypejs.org/api/element/cumulativeoffset
我推荐这个链接 http://miloq.blogspot.in/2011/05/coordinates-mouse-click-canvas.html
<style type="text/css">
#canvas{background-color: #000;}
</style>
<script type="text/javascript">
document.addEventListener("DOMContentLoaded", init, false);
function init()
{
var canvas = document.getElementById("canvas");
canvas.addEventListener("mousedown", getPosition, false);
}
function getPosition(event)
{
var x = new Number();
var y = new Number();
var canvas = document.getElementById("canvas");
if (event.x != undefined && event.y != undefined)
{
x = event.x;
y = event.y;
}
else // Firefox method to get the position
{
x = event.clientX + document.body.scrollLeft +
document.documentElement.scrollLeft;
y = event.clientY + document.body.scrollTop +
document.documentElement.scrollTop;
}
x -= canvas.offsetLeft;
y -= canvas.offsetTop;
alert("x: " + x + " y: " + y);
}
</script>
