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
下面是对Ryan Artecona关于画布宽度可变(%)的答案的一个小修改:
HTMLCanvasElement.prototype.relMouseCoords = function (event) {
var totalOffsetX = 0;
var totalOffsetY = 0;
var canvasX = 0;
var canvasY = 0;
var currentElement = this;
do {
totalOffsetX += currentElement.offsetLeft;
totalOffsetY += currentElement.offsetTop;
}
while (currentElement = currentElement.offsetParent)
canvasX = event.pageX - totalOffsetX;
canvasY = event.pageY - totalOffsetY;
// Fix for variable canvas width
canvasX = Math.round( canvasX * (this.width / this.offsetWidth) );
canvasY = Math.round( canvasY * (this.height / this.offsetHeight) );
return {x:canvasX, y:canvasY}
}
其他回答
下面是对Ryan Artecona关于画布宽度可变(%)的答案的一个小修改:
HTMLCanvasElement.prototype.relMouseCoords = function (event) {
var totalOffsetX = 0;
var totalOffsetY = 0;
var canvasX = 0;
var canvasY = 0;
var currentElement = this;
do {
totalOffsetX += currentElement.offsetLeft;
totalOffsetY += currentElement.offsetTop;
}
while (currentElement = currentElement.offsetParent)
canvasX = event.pageX - totalOffsetX;
canvasY = event.pageY - totalOffsetY;
// Fix for variable canvas width
canvasX = Math.round( canvasX * (this.width / this.offsetWidth) );
canvasY = Math.round( canvasY * (this.height / this.offsetHeight) );
return {x:canvasX, y:canvasY}
}
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)
})
这里是一个简化的解决方案(这并不适用于边框/滚动):
function click(event) {
const bound = event.target.getBoundingClientRect();
const xMult = bound.width / can.width;
const yMult = bound.height / can.height;
return {
x: Math.floor(event.offsetX / xMult),
y: Math.floor(event.offsetY / yMult),
};
}
三JS r77
var x = event.offsetX == undefined ? event.layerX : event.offsetX;
var y = event.offsetY == undefined ? event.layerY : event.offsetY;
mouse2D.x = ( x / renderer.domElement.width ) * 2 - 1;
mouse2D.y = - ( y / renderer.domElement.height ) * 2 + 1;
在尝试了许多解决方案后。这对我很管用。可能会帮助其他人，因此发帖。从这里开始
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。
