用于在 Canvas 上按下按键的 addEventListener [英] addEventListener for keydown on Canvas
问题描述
我正在尝试制作一个响应键盘和鼠标输入的画布应用程序.我有这个代码:
I am trying to make a canvas app that responds to keyboard and mouse input. I have this code:
canvas = document.getElementById('canvas');
canvas.addEventListener('mousedown', function(event) {
alert('mousedown');
}, false);
canvas.addEventListener('keydown', function(event) {
alert('keydown');
}, false);
每当我点击鼠标时,'mousedown' 警报就会出现,但 'keydown' 警报永远不会出现.相同的代码在 JS Bin 上运行良好:http://jsbin.com/uteha3/66/
The 'mousedown' alert comes up whenever I click the mouse, but the 'keydown' alert never comes up. The same code works fine on JS Bin: http://jsbin.com/uteha3/66/
为什么它在我的页面上不起作用?画布无法识别键盘输入吗?
Why isn't it working on my page? Does canvas not recognize keyboard input?
推荐答案
Edit - 这个答案是一个解决方案,但更简单和正确的方法是设置画布元素上的 tabindex
属性(由 hobberwickey 建议).
Edit - This answer is a solution, but a much simpler and proper approach would be setting the tabindex
attribute on the canvas element (as suggested by hobberwickey).
您无法聚焦画布元素.解决此问题的一个简单方法是让您自己"专注.
var lastDownTarget, canvas;
window.onload = function() {
canvas = document.getElementById('canvas');
document.addEventListener('mousedown', function(event) {
lastDownTarget = event.target;
alert('mousedown');
}, false);
document.addEventListener('keydown', function(event) {
if(lastDownTarget == canvas) {
alert('keydown');
}
}, false);
}
这篇关于用于在 Canvas 上按下按键的 addEventListener的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!