Demo : https://www.lenlop123.com/2020/09/153-control-by-keyboard_24.html
<!DOCTYPE html>
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<style>
canvas {
border: 1px solid #d3d3d3;
background-color: #f1f1f1;
}
</style>
<div>
<canvas id="canvas" class="canvas"></canvas>
</div>
<script>
var myGamePiece;
// hàm onload sẽ chạy sau cùng, sau khi load đủ dữ liệu
window.onload = function () {
startGame()
};
function startGame() {
myGamePiece = new component(30, 30, "red", 10, 120); // vẽ 1 component
myGameArea.start(); // khởi tạo canvas
}
var myGameArea = {
canvas: document.getElementById('canvas'),
start: function () {
this.canvas.width = 480; // Lấy thẻ HTML Canvas
this.canvas.height = 270;
this.context = this.canvas.getContext("2d"); // Vẽ ở mô hình 2D
this.interval = setInterval(updateGameArea, 20); // Vẽ lại hình mỗi 20ms
window.addEventListener('keydown', function (e) { // khai báo ghi nhận bàn phím cho canvas
myGameArea.key = e.keyCode;
})
window.addEventListener('keyup', function (e) {
myGameArea.key = false;
})
},
clear: function () {
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
}
}
// khai báo cấu trúc 1 component và gán cho 1 biến nào đó
function component(width, height, color, x, y) {
this.gamearea = myGameArea;
this.width = width;
this.height = height;
this.speedX = 0;
this.speedY = 0;
this.x = x;
this.y = y;
this.update = function () {
ctx = myGameArea.context;
ctx.fillStyle = color;
ctx.fillRect(this.x, this.y, this.width, this.height);
}
this.newPos = function () {
this.x += this.speedX;
this.y += this.speedY;
}
}
function updateGameArea() {
myGameArea.clear();
myGamePiece.speedX = 0;
myGamePiece.speedY = 0;
if (myGameArea.key && myGameArea.key == 37) { myGamePiece.speedX = -1; }
if (myGameArea.key && myGameArea.key == 39) { myGamePiece.speedX = 1; }
if (myGameArea.key && myGameArea.key == 38) { myGamePiece.speedY = -1; }
if (myGameArea.key && myGameArea.key == 40) { myGamePiece.speedY = 1; }
myGamePiece.newPos();
myGamePiece.update();
}
</script>
<p>Make sure this window has focus, then you can use the arrow keys on you keyboard to move the red square.</p>
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