我在 Javascript 中使用 EaselJS,并使用 keydown
和 keyup
事件来捕获键盘输入(见下文):
/*Connecting keydown input to keyPressed handler*/
this.document.onkeydown = keyPressed;
/*Connecting key up event to keyUp handler*/
this.document.onkeyup = keyUp;
我有以下代码来捕获按下上下、左和/或右时的情况,并暂时对它们使用react。现在这个 Action 很简陋,我还在努力完善它。为了能够正确移动物体,我应该能够同时捕获 Angular 变化(左/右)和加速度(向前)。
这是我当前拥有的 keyDown 代码:
/*Keyboard input handlers - keydown and keyup*/
function keyPressed(event){
if(!event){ var event = window.event; }
switch(event.keyCode){
case KEYCODE_LEFT:
console.log("left held");
ellip.x -= 5;
break;
case KEYCODE_RIGHT:
console.log("right held");
ellip.x += 5;
break;
case KEYCODE_UP:
console.log("up held");
ellip.y -= 5;
break;
case KEYCODE_DOWN:
console.log("down held");
ellip.y += 5;
break;
}
}
现在请注意,在控制台中点击两个箭头按钮不会产生消息组合(例如向上保持
和向右保持
)
我如何处理(或监听)多个事件?
Here is a Fiddle!使用上、下、左、右箭头移动红色 Blob 。
最佳答案
处理这个问题的方法是在 keyDown 代码中捕获哪些键被按下,然后在 handleTick 函数中执行移动本身。您还需要查看 keyUp,以便知道按键何时不再按下:
/*Keyboard input handlers - keydown and keyup*/
var left,
right,
up,
down;
function keyPressed(event){
if(!event){ var event = window.event; }
switch(event.keyCode){
case KEYCODE_LEFT:
console.log("left held");
left = true;
break;
case KEYCODE_RIGHT:
console.log("right held");
right = true;
break;
case KEYCODE_UP:
console.log("up held");
up = true;
break;
case KEYCODE_DOWN:
console.log("down held");
down = true;
break;
}
}
function keyReleased(event){
if(!event){ var event = window.event; }
switch(event.keyCode){
case KEYCODE_LEFT:
console.log("left released");
left = false;
break;
case KEYCODE_RIGHT:
console.log("right released");
right = false;
break;
case KEYCODE_UP:
console.log("up released");
up = false;
break;
case KEYCODE_DOWN:
console.log("down released");
down = false;
break;
}
}
function handleTick(event){
/*Scaling down the image*/
ellip.scaleX = 0.10;
ellip.scaleY = 0.10;
if(left) {
ellip.x -= 5;
} else if(right) {
ellip.x += 5;
}
if(up) {
ellip.y -= 5;
} else if(down) {
ellip.y += 5;
}
if (ellip.x > stage.canvas.width) {
ellip.x = stage.canvas.width;
}
stage.update();
}
编辑: fork fiddle 在行动:http://jsfiddle.net/t2M82/
关于javascript - 移动物体时如何最好地结合方向运动(向上和向左、向上和向右......)?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/21095824/