如何旋转形状？

Question

到目前为止我所拥有的：

我可以使用一些简单的语法将形状绘制到画布中：

let shape = "10n10" // example shapeSyntax (*)



shapeSyntax:  "1" == "colored area"
              "0" == "blank area"
              "n" == "new line"


* So creating a simple line (width = 4, height = 1) is possible using the syntax "1111"
* Creating a square (width = 2, height = 2) is possible using the syntax "11n11" (n stands for new line)
* Creating a stair -shape would be possible using the syntax "001n011n111"

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到目前为止，这确实非常有效。 所以我添加了代码，以便您可以自己看看：

我想要得到的东西：

我想开发一个功能rotate(degree)，它可以旋转语法（不仅是canvas元素或其他东西！）大约[90, 180, 270]度的任何形状。

因此，围绕90deg旋转语法为“ 1111”的行应得到“ 1n1n1n1”：

rotate("1111", 90) // == "1n1n1n1"

请看一下这张图片，我很确定它将有助于您理解：

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我注意到的是，将任何形状旋转180度都可以通过向后阅读"1011" gets "1101"来更改语法。但是如何从0->90deg获取语法？我不知道如何解决该问题，将不胜感激。预先感谢。

// This is what I've got

// The 4 shapes where
// "1" == "colored area"
// "0" == "blank area"
// "n" == "new line"
let shapeA = "1111"
let shapeB = "10n11"
let shapeC = "111n011"
let shapeD = "00111n11100"


// This is the function to draw the shapes using *canvas*
let drawShape = function(shape, offset) {
  shape = shape.split("n");
  let shapeHeight = shape.length,
      shapeWidth = shape[0].length;
      
  let canvas = document.createElement("canvas");
  let ctx = canvas.getContext("2d");
  canvas.width = canvas.height = 300;
  ctx.fillStyle=["red", "green", "blue", "gray", "magenta", "orange", "yellow"][Math.round(Math.random()*6)];
  
  for (let y=0; y<shapeHeight; y++) {
    for (let x=0; x<shapeWidth; x++) {
      if (shape[y][x] === "1") 
        ctx.fillRect(x*20, y*20, 20, 20);
    }
  }
  canvas.style.position = "absolute";
  canvas.style.left = offset + "%";
  document.getElementById("element").append(canvas)
}


// This is how I'm able to call the function (the second parameter is for the offset of the position)
drawShape(shapeA, 0);
drawShape(shapeB, 20);
drawShape(shapeC, 40);
drawShape(shapeD, 60);

input {
position: absolute;
  top: 50%;
  z-index: 4
} 

<input type="text" oninput="document.getElementById('element').innerHTML = ''; drawShape(this.value, 10)" placeholder="input shape syntax"/>
<div id="element"></div>

Answer 1

转换为2D数组，旋转（转置）并转换回。

编辑：谢谢meowgoesthedog，转置不代表我的意思。

var rotate = array => array[0].map( (col, i) => array.map(row => row[i]).reverse() );
var decode = str => str.split('n').map( s => s.split('') )
var encode = arr => arr.map( a => a.join('') ).join('n')

encode( rotate( decode( '01n00' ) ) )