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Accepted
Alexandr_TT
Asked:2022-05-14 23:48:00 +0800 CST2022-05-14 23:48:00 +0800 CST

使用 <canvas> 创建网格

  • 772

坐标网格对布局有很大帮助。允许您查看某些元素在创建和相对于边界定位时的外观。

对于 SVG，开发了这样一个自适应坐标网格：

function changeHeight() {
  itrX.addEventListener("input",()=>{svg.setAttribute("height",itrX.value)});
    var x = document.getElementById("itrX").value;
    document.getElementById("infoX").innerHTML = "SVG height: " + x +"px";
}
  function changeWidth() {
  itrY.addEventListener("input",()=>{svg.setAttribute("width",itrY.value)});
    var x = document.getElementById("itrY").value;
    document.getElementById("infoY").innerHTML = "SVG width: " + x +"px";
}
<style>
text {
font-size:20px;
fill:black;
}
p {
display:inline-block;
font-weight:bold;
margin: 1em ;
}
</style>
<p id="infoX" ></p>
<p id="infoY" ></p>
<div>
 <span><input id="itrX" type="range" min="10" max="1000" value="1000" oninput="changeHeight()"/></span>
  <span><input id="itrY" type="range" min="10" max="1000" value="1000" oninput="changeWidth()"/></span>
</div>

 
 <svg id="svg" width="1000" height="1000" viewBox="-20 -20 1050 1050" xmlns="http://www.w3.org/2000/svg" preserveAspectRatio="xMinYMin meet" style="border:2px solid purple">
   <defs> 
    
      <pattern id="p10" width="10" height="10" patternUnits="userSpaceOnUse">
        <path d="M 10 0 L 0 0 0 10" fill="none" stroke="gray" stroke-width="0.5"/>
      </pattern>
      <pattern id="p100" width="100" height="100" patternUnits="userSpaceOnUse">
        <rect width="100" height="100" fill="url(#p10)"/>
        <path d="M 100 0 L 0 0 0 100" fill="none" stroke="gray" stroke-width="1"/>
      </pattern>
    </defs>
    <rect width="1000" height="1000" fill="url(#p100)" />
    
      <circle cx="500" cy="500" r="5" fill="black" />
      
     <!-- Вертикальный блок цифр -->

      <text x="-15" y="0">0,0</text> 
       <text x="-20" y="100" >100</text> 
        <text x="-20" y="200">200</text> 
         <text x="-20" y="300">300</text> 
          <text x="-20" y="400">400</text> 
           <text x="-20" y="500">500</text> 
          <text x="-20" y="600">600</text> 
         <text x="-20" y="700">700</text> 
        <text x="-20" y="800">800</text>
       <text x="-20" y="900">900</text> 
      <text x="-20" y="1000">1000</text> 
          <!-- Горизонтальный блок --> 
     <text x="100" y="-5" >100</text> 
       <text x="200" y="-5" >200</text> 
        <text x="300" y="-5">300</text> 
         <text x="400" y="-5">400</text> 
          <text x="500" y="-5">500</text>    
         <text x="600" y="-5">600</text> 
         <text x="700" y="-5">700</text> 
        <text x="800" y="-5">800</text>
       <text x="900" y="-5">900</text>  
      <text x="990" y="-5">1000</text>   
      <!-- Ракета      -->
      <g transform="scale(1)" fill="purple">
      <path  d="m308.167 241.52c0-28.766-23.403-52.169-52.17-52.169s-52.17 23.403-52.17 52.169c0 28.767 23.403 52.17 52.17 52.17s52.17-23.404 52.17-52.17zm-52.169 22.169c-12.225 0-22.17-9.945-22.17-22.17 0-12.224 9.945-22.169 22.17-22.169s22.17 9.945 22.17 22.169c-.001 12.225-9.946 22.17-22.17 22.17z"/>
  <path   d="m425.684 424.352v-132.322l-51.65-32.948c.615-14.332.261-28.762-1.117-43.191-7.162-74.973-41.384-144.771-96.362-196.535l-20.557-19.356-20.558 19.356c-54.978 51.765-89.2 121.563-96.362 196.535-1.378 14.429-1.732 28.859-1.117 43.191l-51.65 32.948v132.321l90.003-28.282c3.744 6.784 7.752 13.436 12.017 19.945v62.315h30v-48.333h22.667v23.252h30v-23.252h22.667v48.333h30v-62.315c4.265-6.508 8.273-13.161 12.017-19.945zm-30-115.874v75.001l-46.66-14.662c10.468-24.35 17.778-49.975 21.762-76.222zm-139.694-267.28c27.301 25.706 48.392 55.971 63.081 88.684h-126.153c14.687-32.713 35.775-62.979 63.072-88.684zm-139.679 342.281v-75.001l24.898-15.883c3.983 26.247 11.293 51.872 21.762 76.222zm124.687-10.983v27.499h-27.316c-47.563-72.299-57.394-161.126-32.242-240.114h149.112c25.156 78.987 15.325 167.815-32.238 240.114h-27.316v-27.499z"/>
   <path  d="m240.998 483.495h30v28.5h-30z"/> 
   </g>
  </svg>

CSS，JS中坐标网格的其他选项：here和here

需要一个<canvas>具有缩放可能性的变体width和height

沿着网格的边缘有数字也是非常可取的，如下图所示：

在此处输入图像描述

我将不胜感激想法和解决方案。

javascript

1 个回答

  1. Best Answer

    canvas细线的缩放不是很好。这是在较大的画布上合成网格图像的尝试，并转移到较小的画布上。

    相反input[type="range"]，我添加了一个红色控制器来更改容器的宽度和高度。没有火箭。

    const grid = document.querySelector('.grid');
const control = document.querySelector('.grid__controls');
const canvas = document.querySelector('.grid__canvas');

drawGrid(canvas, 1000, 1000, 2200,2200,100,10,10,100);

function drawGrid(canvas, w, h, ...options){
    const ctx = canvas.getContext('2d');
    canvas.width = w;
    canvas.height = h;
    
    ctx.drawImage(getGrid(...options), 0, 0, options[0], options[1], 0,0,w,h);
}

function getGrid(img_w,img_h,cell_num,cell_weight,text_freq,side_w){
    const canvas = document.createElement('canvas');
    const ctx = canvas.getContext('2d');
    const w = canvas.width = img_w;
    const h = canvas.height = img_h;
    
    const cell_size = (img_w-side_w*2)/cell_num;
    const x_num = cell_num;
    const y_num = (img_h-side_w*2)/cell_size;
    
    ctx.font = `${side_w*1.4/(y_num.toString().length+1)}px monospace`;
    
    let basic_grid_path = '';
    let text_grid_path = '';
    
    ctx.save();
    ctx.textBaseline = 'bottom';
    ctx.textAlign = 'center';
    
    for(let i = 0; i < x_num + 1; i++){
        let line = `M ${cell_size*i + side_w} ${side_w} V ${h-side_w}`;
        basic_grid_path += line;
        
        if(i%text_freq == 0){
            text_grid_path += line;
            ctx.fillText(i*cell_weight, cell_size*i + side_w, side_w);
        }
    }   
    ctx.restore();
    
    ctx.save();
    ctx.textBaseline = 'middle';
    ctx.textAlign = 'right';
    
    for(let i = 0; i < y_num + 1; i++){
        let line = `M ${side_w} ${cell_size*i + side_w} H ${w-side_w}`;
        basic_grid_path += line;
        
        if(i%text_freq == 0){
            text_grid_path += line;
            ctx.fillText(i*cell_weight + ' ', side_w, cell_size*i + side_w);
        }
    }
    ctx.restore();
    
    ctx.save();
    ctx.strokeStyle = 'rgb(100,100,100)';
    ctx.stroke(new Path2D(basic_grid_path));
    ctx.restore();
    
    ctx.save();
    ctx.strokeStyle = 'rgb(50,50,50)';
    ctx.lineWidth = 2;
    ctx.stroke(new Path2D(text_grid_path));
    ctx.restore();
    
    return canvas;
}

let start_point = [0,0];
let is_dragging = false;

control.addEventListener('mousedown', event => {
    is_dragging = true;
    start_point = [event.pageX, event.pageY];
})

document.addEventListener('mouseup', () => {
    is_dragging = false;
})

document.addEventListener('mousemove', event => {
    if(is_dragging) resizeGrid(event);
})

function resizeGrid(event){
    const x = event.pageX;
    const y = event.pageY;
    const width = parseFloat(window.getComputedStyle(grid).width);
    const height = parseFloat(window.getComputedStyle(grid).height);
    
    grid.style.width = (width - start_point[0] + x) + 'px';
    grid.style.height = (height - start_point[1] + y) + 'px';
    
    start_point[0] = x;
    start_point[1] = y;
}
    .grid {
    box-sizing: border-box;
    border: 1px solid black;
    position: relative;
    width: 600px;
    height: 600px;
}

.grid__canvas {
    max-width: 100%;
    max-height: 100%;
}

.grid__controls {
    width: 10px;
    height: 10px;
    background: red;
    position: absolute;
    bottom: -5px;
    right: -5px;
    cursor: nw-resize;
}
    <div class="grid">
    <canvas class="grid__canvas"></canvas>
    <div class="grid__controls"></div>
</div>

    • 2

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