在按住键的同时让画布元素移动然后在放开时停止-Java 学习之路

Problem with code: 如果按住箭头键并查看控制台 - 键盘在每次击键后都会触发 . 此外，按住箭头键后对象停止移动 .

Why this is a problem in this context: 我希望每次触发箭头keydown时移动方块，然后在触发keyup时停止 .

Desired effect ：我想按住一个键来移动盒子，然后当我松开键时它停止移动 .

这可以实现吗？如果是这样，大概怎么样？如果没有，是否有另一种注册方向的方法？

为了记录，我不想使用Jquery . 感谢您的任何提示或建议 .

使用Javascript

keyLeft = 0;
keyRight = 0;
keyNorth = 0;
keyBot = 0;
var interval;
var c = 0;

window.onload=function(){
    addButton.addEventListener
        ('click',function(){addRowCell("table1")},false);
    removeButton.addEventListener
        ('click',function(){deleteRowCell("table1")},false);
    stopButton.addEventListener('click',stop,false);
    startButton.addEventListener('click',initiate,false);
}
//38 up
//37 left
//40 down
//39 right
document.onkeydown = function (e) {

    console.debug(e.keyCode, "down");
    console.debug(e.keyCode, "up");

    switch (e.keyCode){
        case 37:
            initiateLeft();
            break;
        case 38:
            initiateNorth();
            break;
        case 40:
            initiateBot();
            break;
        case 39:
            initiateRight();
            break;
        case 32:
            stop();
            break;
    }
}

function stop(){
    clearInterval(interval);
}
function initiateRight(){
    clearInterval(interval);
    interval = setInterval(right,100);
}
function initiateLeft(){
    clearInterval(interval);
    interval = setInterval(left,100);
}
function initiateNorth(){
    clearInterval(interval);
    c=0;
    interval = setInterval(north,100);
}
function initiateBot(){
    clearInterval(interval);
    interval = setInterval(bot,100);
}

function right(){
    var x = document.getElementById("counter");
    x.value = keyRight;
    var d = document.getElementById("canv1");
    var ctx = d.getContext("2d");
    var ctx1 = document.querySelector('#canv1').getContext('2d');
    ctx1.clearRect(0,0,100,100);    
    ctx.strokeRect(20+keyRight-keyLeft,20-keyNorth+keyBot,40,40);
    keyRight++;
}
function left(){
    var x = document.getElementById("counter");
    x.value = keyLeft;
    var d = document.getElementById("canv1");
    var ctx = d.getContext("2d");
    var ctx1 = document.querySelector('#canv1').getContext('2d');
    ctx1.clearRect(0,0,100,100);
    ctx.strokeRect(20+keyRight-keyLeft,20-keyNorth+keyBot,40,40);
    keyLeft++;
}
function north(){
    var x = document.getElementById("counter");
    x.value = keyNorth;
    var d = document.getElementById("canv1");
    var ctx = d.getContext("2d");
    var ctx1 = document.querySelector('#canv1').getContext('2d');
    ctx1.clearRect(0,0,100,100);
    keyNorth+=(10-c);
    c+=2;
    ctx.strokeRect(20+keyRight-keyLeft,20-keyNorth+keyBot,40,40);
    if(20-keyNorth == 20)
    clearInterval(interval);
}
function bot(){
    var x = document.getElementById("counter");
    x.value = keyBot;
    var d = document.getElementById("canv1");
    var ctx = d.getContext("2d");
    var ctx1 = document.querySelector('#canv1').getContext('2d');
    ctx1.clearRect(0,0,100,100);
    ctx.strokeRect(20+keyRight-keyLeft,20-keyNorth+keyBot,40,40);
    keyBot++;
}

HTML

<canvas id="canv1" width="300px" height="100px"></canvas>
<input id="counter" style="width:40px;"></input>
<div style="clear:left;">
Press spacebar to pause.<br>

1 回答

我希望我不做你的功课 . 如果是这样你应该感到内疚 .

keyLeft = 0;
keyRight = 0;
keyNorth = 0;
keyBot = 0;
var interval;
var c = 0;



//38 up
//37 left
//40 down
//39 right
document.onkeydown = function (e) {

    console.debug(e.keyCode, "down");
    console.debug(e.keyCode, "up");

    switch (e.keyCode){
        case 37:
            initiateLeft();
            break;
        case 38:
            initiateNorth();
            break;
        case 40:
            initiateBot();
            break;
        case 39:
            initiateRight();
            break;
        case 32:
            stop();
            break;
    }
}

function stop(){

}
function initiateRight(){

    interval = setTimeout(right,100);
}
function initiateLeft(){

    interval = setTimeout(left,100);
}
function initiateNorth(){

    c=0;
    interval = setTimeout(north,100);
}
function initiateBot(){

    interval = setTimeout(bot,100);
}

function right(){

    var x = document.getElementById("counter");
    x.value = keyRight;
    var d = document.getElementById("canv1");
    var ctx = d.getContext("2d");
    var ctx1 = document.querySelector('#canv1').getContext('2d');
    ctx1.clearRect(0,0,100,100);    
    ctx.strokeRect(20+keyRight-keyLeft,20-keyNorth+keyBot,40,40);
    keyRight++;
}
function left(){
    var x = document.getElementById("counter");
    x.value = keyLeft;
    var d = document.getElementById("canv1");
    var ctx = d.getContext("2d");
    var ctx1 = document.querySelector('#canv1').getContext('2d');
    ctx1.clearRect(0,0,100,100);
    ctx.strokeRect(20+keyRight-keyLeft,20-keyNorth+keyBot,40,40);
    keyLeft++;
}
function north(){
    var x = document.getElementById("counter");
    x.value = keyNorth;
    var d = document.getElementById("canv1");
    var ctx = d.getContext("2d");
    var ctx1 = document.querySelector('#canv1').getContext('2d');
    ctx1.clearRect(0,0,100,100);
    keyNorth+=(10-c);
    c+=2;
    ctx.strokeRect(20+keyRight-keyLeft,20-keyNorth+keyBot,40,40);
}
function bot(){
    var x = document.getElementById("counter");
    x.value = keyBot;
    var d = document.getElementById("canv1");
    var ctx = d.getContext("2d");
    var ctx1 = document.querySelector('#canv1').getContext('2d');
    ctx1.clearRect(0,0,100,100);
    ctx.strokeRect(20+keyRight-keyLeft,20-keyNorth+keyBot,40,40);
    keyBot++;
}

回复于 2024-05-04T09:25:21+08:00

在按住键的同时让画布元素移动然后在放开时停止

1 回答

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