graphics 在线编辑器 | graphics代码测试

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0"/>
<style>canvas {
    border:1px solid #d3d3d3;
    background-color: #f1f1f1;
}
</style>
</head>
<body onload="startGame()">
<script>

var redGamePiece, blueGamePiece, yellowGamePiece;

function startGame() {
    redGamePiece = new component(75, 75, "red", 10, 10);
    yellowGamePiece = new component(75, 75, "yellow", 50, 60);    
    blueGamePiece = new component(75, 75, "blue", 10, 220);
    myGameArea.start();
}

function component(width, height, color, x, y) {
    this.width = width;
    this.height = height;
    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);
    }
}

function updateGameArea() {
    myGameArea.clear();
    redGamePiece.x += 1;
    yellowGamePiece.x += 1;    
    yellowGamePiece.y += 1;        
    blueGamePiece.x += 1;        
    blueGamePiece.y -= 1;            
    redGamePiece.update();
    yellowGamePiece.update();        
    blueGamePiece.update();
}
</script>
<p>这三个组件通过在每次更新时更改 x 和 y 坐标来移动。</p>
</body>
</html>

报个问题: