sketchboard Archives - Lena Design

Do you like sketching? Did you know that you can sketch on Java Script canvas too?

Demo:

What do you need to do?

To create the JavaScript sketch board you need to have the pencil image(cursor) in the .png/ SVG format and follow the steps below:

Add HTML
Add CSS
Add JavaScript/ jQuery

Step1.

Add HTML

<div id="canvas-wrap">
  <div class="sketch-board">
    <div class="paper"></div>
  </div>
  <div class="paperclip"></div>
<canvas id="canvas"></canvas>
<button class="button" id="clear">Clear</button>
<button class="button" id="undo">Undo</button>
<button class="button" id="brushBlack">Black</button>
<button class="button" id="brushYellow">Yellow</button>
<button class="button" id="brushRed">Red</button>
<button class="button" id="brushBlue">Blue</button>
<button class="button" id="brushGreen">Green</button>

</div>

Step2.

Add CSS

Set the colour and the position of the background and elements:

body {
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}
#canvas-wrap {
  position: relative;
  top:-200px;
}

And the canvas with mouse cursor:

canvas {  
  background-color: #fff;
  cursor: url(https://lenadesignorg.files.wordpress.com/2020/06/pencil.png?w=79) 10 60, auto;
  z-index:100;
}

Style the sketch board:

.sketch-board {
  position: absolute;
  width: 600px;
  height: 440px;
  background-color: #c19875;
  z-index:-5;
  border-radius: 30px;
  left: -80px;
  box-shadow:inset 5px -5px 0 #846c5b;
}

.sketch-board:before {
  background-color: #fff;
  position: absolute;
  width: 50px;
  height: 170px;
  border-radius: 30px;
  content:"";
  left: 30px;
  top: 140px;
  box-shadow:inset 5px -5px 0 #846c5b;
}

.paper {
  background-color: #e6e3dc;
  width: 400px;
  height: 320px;
  position: absolute;
  top: 50px;
  left: 140px;
}

.paperclip {
  position: absolute;
  width: 150px;
  height: 40px;
  border: 7px solid #c0c0c0;
  border-radius: 20px;
  left: 180px;
  top: 15px;
  z-index:999;
}

.paperclip:after {
  position: absolute;
  content:"";
  width: 200px;
  height: 30px;
  top: -10px;
  left:-25px;
  background-color: #8b786d;
  box-shadow:inset 5px -5px 0 rgba(0,0,0,0.07);
  border-radius: 20px;  
}

Style buttons:

.button {
  position: relative;
  background-color: #443742;
  border: none;
  border-radius:20px;
  color: #fff;
  padding: 7px 7px;
  text-align: center;
  text-decoration: none;
  display: inline-block;
  font-size: 14px;
  margin: 2px 2px;
  top: 385px;
  left:60px;
  transition-duration: 0.4s;
}

.button:hover {
  background-color: #cea07e;
}

Step3.

Add JavaScript/ jQuery

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>

Note: Remember to add jQuery (code above) in the <head> section in your code.

var canvas = document.querySelector('canvas');
  canvas.style.position = 'absolute';
  canvas.style.top = "80px";
  canvas.style.left = "50px";

var ctx = canvas.getContext('2d');
canvas.width = 500;
canvas.height = 350;

var lastX;
var lastY;
var mouseX;
var mouseY;
var canvasOffset = $("#canvas").offset();
var offsetX = canvasOffset.left;
var offsetY = canvasOffset.top;
var isMouseDown = false;
var brushSize = 3;
var brushColor = "#000";

ctx.lineJoin = ctx.lineCap = 'round';

var points = [];


function handleMouseDown(e) {
    mouseX = parseInt(e.clientX - offsetX);
    mouseY = parseInt(e.clientY - offsetY);

    ctx.beginPath();
    if (ctx.lineWidth != brushSize) {
        ctx.lineWidth = brushSize;
    }
    if (ctx.strokeStyle != brushColor) {
        ctx.strokeStyle = brushColor;
    }
    ctx.moveTo(mouseX, mouseY);
    points.push({
        x: mouseX,
        y: mouseY,
        size: brushSize,
        color: brushColor,
        mode: "begin"
    });
    lastX = mouseX;
    lastY = mouseY;
    isMouseDown = true;
}

function handleMouseUp(e) {
    mouseX = parseInt(e.clientX - offsetX);
    mouseY = parseInt(e.clientY - offsetY);

    isMouseDown = false;
    points.push({
        x: mouseX,
        y: mouseY,
        size: brushSize,
        color: brushColor,
        mode: "end"
    });
}


function handleMouseMove(e) {
    mouseX = parseInt(e.clientX - offsetX);
    mouseY = parseInt(e.clientY - offsetY);

    if (isMouseDown) {
        ctx.lineTo(mouseX, mouseY);
        ctx.stroke();
        lastX = mouseX;
        lastY = mouseY;
       
        points.push({
            x: mouseX,
            y: mouseY,
            size: brushSize,
            color: brushColor,
            mode: "draw"
        });
    }
}

$("#canvas").mousedown(function (e) {
    handleMouseDown(e);
});
$("#canvas").mousemove(function (e) {
    handleMouseMove(e);
});
$("#canvas").mouseup(function (e) {
    handleMouseUp(e);
});


function redrawAll() {

    if (points.length == 0) {
        return;
    }

    ctx.clearRect(0, 0, canvas.width, canvas.height);

    for (var i = 0; i < points.length; i++) {

        var pt = points[i];

        var begin = false;

        if (ctx.lineWidth != pt.size) {
            ctx.lineWidth = pt.size;
            begin = true;
        }
        if (ctx.strokeStyle != pt.color) {
            ctx.strokeStyle = pt.color;
            begin = true;
        }
        if (pt.mode == "begin" || begin) {
            ctx.beginPath();
            ctx.moveTo(pt.x, pt.y);
        }
        ctx.lineTo(pt.x, pt.y);
        if (pt.mode == "end" || (i == points.length - 1)) {
            ctx.stroke();
        }
    }
    ctx.stroke();
}

function undoLast() {
    points.pop();
    redrawAll();
}

$("#brushGreen").click(function () {
    brushColor = "#89bd9e";
});
$("#brushYellow").click(function () {
    brushColor = "#fde74c";
});
$("#brushRed").click(function () {
    brushColor = "#e55934";
});
$("#brushBlue").click(function () {
    brushColor = "#5bc0eb";
});

$("#brushBlack").click(function () {
    brushColor = "#000";
});

var interval;
$("#undo").mousedown(function () {
    interval = setInterval(undoLast, 20);
}).mouseup(function () {
    clearInterval(interval);
});

var clear = function(){
  ctx.clearRect(0,0,500,350);
};

$('#clear').on("click",clear);

Enjoy coding!