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javascript - HTML canvas art，从草图生成坐标数据

转载 作者：塔克拉玛干 更新时间：2023-11-02 22:08:11 24 4
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我用 HTML5 canvas 画了一个心形:

<!DOCTYPE HTML>
<html>
  <head>
    <style>
      body {
        margin: 0px;
        padding: 0px;
      }
    </style>
  </head>
  <body>
    <canvas id="myCanvas" width="1366" height="600"></canvas>
    <script>
     var heart = [
        [707,359],[707,359],[707,359],[707,359],[708,358],[711,354],[713,352],[714,348],[716,345],[720,335],
        [721,334],[722,333],[724,332],[725,330],[727,327],[731,322],[734,320],[737,318],[740,314],[743,312],
        [745,311],[749,309],[753,308],[757,306],[761,303],[764,302],[767,302],[771,301],[774,301],[778,301],
        [783,301],[786,301],[790,300],[796,300],[801,300],[805,300],[809,300],[811,300],[815,302],[817,303],
        [820,305],[822,306],[824,307],[827,309],[830,311],[834,313],[836,314],[838,316],[841,318],[844,321],
        [845,324],[847,326],[849,328],[852,332],[853,334],[855,336],[857,337],[858,339],[860,341],[862,345],
        [863,349],[863,352],[864,356],[864,359],[865,362],[866,364],[868,368],[869,372],[870,377],[871,381],
        [872,384],[872,388],[872,392],[872,395],[872,399],[872,401],[872,405],[872,409],[871,412],[870,417],
        [869,419],[869,422],[867,427],[866,429],[865,434],[863,438],[862,442],[861,443],[860,445],[857,448],
        [854,451],[852,454],[849,456],[846,459],[843,460],[836,466],[835,466],[833,467],[821,475],[820,477],
        [819,478],[817,481],[815,483],[811,486],[808,487],[803,491],[802,491],[800,492],[795,493],[791,497],
        [789,498],[786,498],[780,502],[772,507],[770,510],[767,511],[762,516],[758,520],[756,524],[753,527],
        [750,529],[746,532],[741,534],[736,537],[732,538],[731,539],[735,537],[735,537],[735,537],[730,543],
        [729,546],[727,551],[726,553],[723,555],[721,558],[715,568],[714,570],[714,572],[713,575],[708,585],
        [708,586],[707,586],[704,583],[704,359],[704,359],[700,356],[698,352],[697,350],[696,345],[694,343],
        [693,340],[690,335],[688,335],[687,334],[683,332],[681,329],[677,326],[675,323],[672,319],[669,314],
        [668,312],[663,310],[660,310],[656,310],[653,309],[647,309],[644,308],[642,308],[637,307],[632,303],
        [628,301],[624,297],[621,297],[619,297],[616,297],[616,298],[616,299],[614,300],[620,302],[620,302],
        [620,302],[618,302],[612,302],[605,302],[598,302],[596,303],[594,305],[592,307],[590,309],[586,310],
        [583,313],[582,315],[579,319],[576,320],[573,323],[571,325],[569,327],[563,329],[560,333],[558,336],
        [557,338],[556,341],[555,343],[551,346],[549,349],[549,354],[549,357],[547,361],[546,367],[543,372],
        [542,375],[541,380],[540,381],[540,382],[540,382],[540,382],[540,382],[540,384],[540,386],[540,389],
        [539,391],[539,394],[539,398],[539,404],[539,408],[539,412],[539,416],[540,423],[542,428],[544,433],
        [549,436],[552,439],[555,442],[557,445],[560,448],[562,452],[564,459],[565,461],[560,449],[560,449],
        [561,450],[571,458],[580,466],[584,469],[587,473],[589,476],[591,477],[575,466],[575,466],[575,466],
        [576,466],[582,471],[587,475],[590,477],[594,481],[598,484],[601,489],[604,491],[607,495],[611,496],
        [617,498],[622,500],[626,501],[629,504],[633,508],[636,510],[642,515],[650,522],[651,525],[655,528],
        [657,529],[660,530],[663,530],[667,533],[671,534],[676,536],[679,537],[681,539],[683,540],[676,536],
        [676,536],[676,536],[679,539],[684,546],[687,548],[689,551],[692,554],[696,558],[698,563],[701,567],
        [702,571],[704,574],[705,577],[706,579],[707,580],[708,582],[709,586]
    ];
    var canvas = document.getElementById('myCanvas');
    var context = canvas.getContext('2d');

    context.beginPath();
    context.moveTo(707, 359);
    for(var i = 1; i < (heart.length - 1) ; i++){
        context.lineTo(heart[i][0], heart[i][1])

    }
    // line 1


    context.lineWidth = 2;
    context.strokeStyle = 'blue';
    context.stroke();
    </script>
  </body>
</html>

看起来像这样:

enter image description here

有没有更简单的方法来生成其他形状的坐标数据？我希望有一些工具可以让我绘制形状草图并为我生成坐标数据。

最佳答案

录音机

Fiddle demo

您需要一种方法来记录您的点，以便您可以将它们重现为字符串、数组等。

这将记录您在 Canvas 上绘制的任何内容:

var points = [],    /// holds strokes and points
    isDown = false, /// for draw mode
    prevX, prevY;   /// for draw mode

第一次点击时，记录第一个点:

canvas.onmousedown = function(e) {

    /// adjust mouse position (see below)
    var pos = getXY(e);

    /// this is used to draw a line
    prevX = pos.x;
    prevY = pos.y;

    /// add new stroke
    points.push([]);

    /// record point in this stroke
    points[points.length - 1].push([pos.x, pos.y]);

    /// we are in draw mode   
    isDown = true;
}

然后只需将所有绘制的点推到当前笔划即可:

canvas.onmousemove = function(e) {

    if (!isDown) return;

    var pos = getXY(e);

    /// draw a line from previous point to this        
    ctx.beginPath();
    ctx.moveTo(prevX, prevY);
    ctx.lineTo(pos.x, pos.y);
    ctx.stroke();

    /// set previous to this point
    prevX = pos.x;
    prevY = pos.y;

    /// record to current stroke
    points[points.length - 1].push([pos.x, pos.y]);
}

在鼠标松开时；在演示中，它将点生成为字符串，可以将其直接复制到您的 JS 代码中:

canvas.onmouseup = function() {
    isDown = false;
    coords.innerHTML = JSON.stringify(points);
}

我们调整鼠标位置，使其相对于 Canvas :

function getXY(e) {
    var r = canvas.getBoundingClientRect();
    return {x: e.clientX - r.left, y: e.clientY - r.top}
}

渲染

现在我们已经记录了点，我们需要一种方法来重现它们。

此代码段能够渲染我们刚刚记录的笔划和点 - 对于演示，我设置红色以区分渲染的笔划和绘制的笔划:

function renderPoints(points) {

    ctx.clearRect(0, 0, canvas.width, canvas.height);
    ctx.strokeStyle = '#f00';

    /// get a stroke
    for(var i = 0, t, p, pts; pts = points[i]; i++) {

        /// render stroke
        ctx.beginPath();
        ctx.moveTo(pts[0][0], pts[0][2]);
        for(t = 1; p =pts[t]; t++) {
            ctx.lineTo(p[0], p[1]);
        }
        ctx.stroke();
    }
    ctx.strokeStyle = '#000';
}

结论

这颗心(？!):

snapshot

为您生成这些点:

[[[103,99],[103,100],[103,98],[105,93],[115,79],[129,61],[139,52],[145,49],[149,49],[152,51],[154,54],[155,57],[156,65],[154,79],[152,89],[149,99],[145,110],[139,124],[131,142],[118,163],[108,176],[101,184],[97,185],[94,187],[87,187],[76,180],[65,166],[60,156],[54,145],[46,119],[41,98],[39,84],[39,81],[39,79],[39,77],[39,76],[40,75],[42,74],[43,72],[46,69],[47,67],[48,67],[49,67],[50,67],[51,68],[52,69],[54,70],[61,75],[71,87],[82,101],[84,105],[87,108],[89,111],[89,112],[89,113],[89,114],[89,115],[89,116],[90,118]]]

它们可以直接提供给 render 方法，或者通过在它前面加上一些代码以允许您直接复制和粘贴生成的字符串，可以使笔划/点数组更加复杂，例如:

var code = '    var points = ' + JSON.stringify(points) + ';';

Fiddle demo

关于javascript - HTML canvas art，从草图生成坐标数据，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/21050014/

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塔克拉玛干
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