通过画布在页面上画笔效果

问题描述 投票:0回答:2

我正在研究必须在网页上创建类似画笔的效果的功能。

要求是背景中有多种可用的图案/纹理。用户将拖动鼠标以在页面上创建该图案的效果。

下面是JSFiddle链接,我在其中创建了结构,我能够创建图案,但我不确定如何创建画笔状效果。

我已将画笔图像添加为我的

JSFiddle Link

中的数据源

我是画布初学者,不知道如何继续前进。请让我知道我的方向是否正确。

检查此功能正在运行和工作的

Reference Website

javascript jquery html canvas html5-canvas
2个回答
2
投票

对于基本的画笔效果,您可以绘制一堆较小的点,而不是绘制单个大点,每个点代表一个画笔描边。如果需要,您还可以为笔画添加可变宽度,但这取决于您。 这是一个基本的画笔示例,不要画圆,而是这样画: JS 小提琴

let canvas = document.getElementById("canvas");
let ctx = canvas.getContext("2d");
let drawCheck = false;
ctx.strokeStyle = "#808080";
let points = 40;
let offsets = [];
let radius = 50;
let prev = {
  x: -1,
  y: -1
};
let curr = {
  x: -1,
  y: -1
};

for (let i = 0; i < points; i++) {
  offsets.push([Math.random() * radius * (-1) ** i, Math.random() * radius * (-1) ** i, 1 + Math.random() * 4]);
}

function draw(x, y) {
  curr.x = x;
  curr.y = y;

  if (drawCheck) {
    if (prev.x == -1) {
      offsets.forEach(offset => {
        ctx.beginPath();
        ctx.arc(curr.x + offset[0], curr.y + offset[1], 1, 0, 2 * Math.PI);
        ctx.fill();
        prev.x = curr.x;
        prev.y = curr.y;
      });
    } else {
      offsets.forEach(offset => {
      ctx.lineWidth = offset[2];
        ctx.beginPath();
        ctx.moveTo(prev.x + offset[0], prev.y + offset[1]);
        ctx.lineTo(curr.x + offset[0], curr.y + offset[1]);
        ctx.stroke();
      })
      prev.x = curr.x;
      prev.y = curr.y;
    }

  }
}

document.addEventListener("mousedown", (e) => drawCheck = true);
document.addEventListener("mousemove", (e) =>
  draw(e.clientX, e.clientY));
document.addEventListener("mouseup", (e) => {
  drawCheck = false;
  prev = {
    "x": -1,
    "y": -1
  };
});
#canvas {
  border: 2px solid black;
}
<html>
<head>
</head>
<body>
<canvas id="canvas" height=320 width=600></canvas>
</body>
</html>


0
投票

let canvas = document.getElementById("canvas");
let ctx = canvas.getContext("2d");
let drawCheck = false;
ctx.strokeStyle = "#808080";
let points = 40;
let offsets = [];
let radius = 50;
let prev = {
  x: -1,
  y: -1
};
let curr = {
  x: -1,
  y: -1
};

for (let i = 0; i < points; i++) {
  offsets.push([Math.random() * radius * (-1) ** i, Math.random() * radius * (-1) ** i, 1 + Math.random() * 4]);
}

function draw(x, y) {
  curr.x = x;
  curr.y = y;

  if (drawCheck) {
    if (prev.x == -1) {
      offsets.forEach(offset => {
        ctx.beginPath();
        ctx.arc(curr.x + offset[0], curr.y + offset[1], 1, 0, 2 * Math.PI);
        ctx.fill();
        prev.x = curr.x;
        prev.y = curr.y;
      });
    } else {
      offsets.forEach(offset => {
      ctx.lineWidth = offset[2];
        ctx.beginPath();
        ctx.moveTo(prev.x + offset[0], prev.y + offset[1]);
        ctx.lineTo(curr.x + offset[0], curr.y + offset[1]);
        ctx.stroke();
      })
      prev.x = curr.x;
      prev.y = curr.y;
    }

  }
}

document.addEventListener("mousedown", (e) => drawCheck = true);
document.addEventListener("mousemove", (e) =>
  draw(e.clientX, e.clientY));
document.addEventListener("mouseup", (e) => {
  drawCheck = false;
  prev = {
    "x": -1,
    "y": -1
  };
});
#canvas {
  border: 2px solid black;
}
<html>
<head>
</head>
<body>
<canvas id="canvas" height=320 width=600></canvas>
</body>
</html>

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