如何让这些画布正确对齐？

Question

我试图将三个画布叠加显示，但它们只是并排显示。我对 css 的经验很少。我需要添加什么？

<body>
<div id="canvas_container">
<canvas id="Background" width="330" height="330"></canvas>
<canvas id="mycanvas" width="330" height="330"></canvas>
<canvas id="Overlay" width="330" height="330"></canvas>
</div>

<style>
.canvas_container {
  position: relative;
}

.container > canvas {
  position: absolute;
  top: 0;
  left: 0;
}
</style>

<div id="codeinput">
<br>
The "X" goes here:<input type="text" id="shapeX">

<br>
The "Y" goes here:<input type="text" id="shapeY">

<br>
Choose the color: <input type="text" id="shapeColor" value="green">


<script>
unrelated javascript
</script>

<br>
<button onclick=makeSquare();>Draw shape</button>
</div>
</body>

Answer 1

你的 css 不错，但你设置了错误的选择器。您有 id = canvas_container，但为 class canvas_container 和 class container

设置了样式

#canvas_container {
  position: relative;
  width: 330px;
  height: 330px;
}

#canvas_container > canvas {
  position: absolute;
  top: 0;
  left: 0;
  border: 1px solid red;
}

<div id="canvas_container">
  <canvas id="Background" width="330" height="330"></canvas>
  <canvas id="mycanvas" width="330" height="330"></canvas>
  <canvas id="Overlay" width="330" height="330"></canvas>
</div>

<div id="codeinput">
  <br>
  The "X" goes here:<input type="text" id="shapeX">
  <br>
  The "Y" goes here:<input type="text" id="shapeY">
  <br>
  Choose the color: <input type="text" id="shapeColor" value="green">
  <br>
  <button onclick=makeSquare();>Draw shape</button>
</div>

如何让这些画布正确对齐？

How do I get these canvases to align properly?

html

css

canvas

html5-canvas