I want to make canvas drawing but this code not working on Mobile browser
const canvas = document.getElementById("draw");
canvas.width = window.innerWidth - 60;
canvas.height = 400;
let context = canvas.getContext("2d");
context.fillStyle = "white";
context.fillRect(0, 0, canvas.width, canvas.height);
let draw_color = "black";
let draw_width = "2";
let is_drawing = false;
canvas.addEventListener("touchstart", start, false);
canvas.addEventListener("touchmove", draw, false);
canvas.addEventListener("mousedown", start, false);
canvas.addEventListener("mousemove", draw, false);
canvas.addEventListener("touchend", stop, false);
canvas.addEventListener("mouseup", stop, false);
canvas.addEventListener("mouseout", stop, false);
function start(event) {
is_drawing = true;
context.beginPath();
context.moveTo(event.clientX - canvas.offsetLeft,
event.clientY - canvas.offsetTop);
event.preventDefault();
}
function draw(event) {
if (is_drawing) {
context.lineTo(event.clientX - canvas.offsetLeft,
event.clientY - canvas.offsetTop);
context.strokeStyle = draw_color;
context.lineWidth = draw_width;
context.lineCap = "round";
context.lineJoin = "round";
context.stroke();
}
event.preventDefault();
}
function stop(event) {
if (is_drawing) {
context.stroke();
context.closePath();
is_drawing = false;
}
event.preventDefault();
}
try this
function draw(event) {
e.preventDefault();
e.stopPropagation();
if (is_drawing) {
context.lineTo(event.clientX - canvas.offsetLeft,
event.clientY - canvas.offsetTop);
context.strokeStyle = draw_color;
context.lineWidth = draw_width;
context.lineCap = "round";
context.lineJoin = "round";
context.stroke();
}
}
Related
const canvas = document.getElementById("canvas");
canvas.width = window.innerWidth = 750;
canvas.height = 600;
var context = canvas.getContext("2d");
context.fillStyle = "white";
context.fillReact(0, 0, canvas.width, canvas.height);
let draw_color = "black";
let draw_width = "2";
let is_drawing = false;
canvas.addEventListener("touchstart", start, false);
canvas.addEventListener("touchmove", draw, false);
canvas.addEventListener("mousedown", start, false);
canvas.addEventListener("mousemove", draw, false);
function start(event) {
is_drawing = true;
context.beginPath();
context.moveTo(event.clientX = canvas.offsetLeft, event.clientY = canvas.offsetTop);
event.preventDefault();
}
function draw(event) {
if (is_drawing) {
context.beginPath();
context.moveTo(event.clientX = canvas.offsetLeft, event.clientY = canvas.offsetTop);
context.strokeStyle = draw_color;
context.lineWidth = draw_width;
context.lineCap = "round";
context.lineJoin = "round";
context.stroke();
}
}
I did everything right yet it is showing context.fillReact is not a function, it should have draw a line on moving the cursor but it is not doing anything just showing the error.
As far as I know, canvas element's context object does not have any fillReact method in it. Maybe you mean fillRect?
I'm looking for a solution to freehand draw a line with a gradient in canvas like this:
I already found this, but the gradient seems to be 'locked' on the background and is not following the line.
window.addEventListener('load', ()=>{
resize(); // Resizes the canvas once the window loads
document.addEventListener('mousedown', startPainting);
document.addEventListener('mouseup', stopPainting);
document.addEventListener('mousemove', sketch);
window.addEventListener('resize', resize);
});
const canvas = document.querySelector('#canvas');
const ctx = canvas.getContext('2d');
function resize(){
ctx.canvas.width = window.innerWidth;
ctx.canvas.height = window.innerHeight;
}
let coord = {x:0 , y:0};
let paint = false;
function getPosition(event){
coord.x = event.clientX - canvas.offsetLeft;
coord.y = event.clientY - canvas.offsetTop;
}
function startPainting(event){
paint = true;
getPosition(event);
}
function stopPainting(){
paint = false;
}
function sketch(event){
if (!paint) return;
ctx.beginPath();
ctx.lineWidth = 5;
ctx.lineCap = 'round';
var gradient = ctx.createLinearGradient(0, 0, 200, 0);
gradient.addColorStop(0.00, 'grey');
gradient.addColorStop(1 / 2, 'white');
gradient.addColorStop(1.00, 'grey');
ctx.strokeStyle = gradient;
ctx.moveTo(coord.x, coord.y);
getPosition(event);
ctx.lineTo(coord.x , coord.y);
ctx.stroke();
}
Can somebody help me please?
I found a way to do it:
var context = canvas.getContext("2d");
context.strokeStyle = '#000000';
context.fillStyle = '#000000';
context.beginPath();
context.moveTo(10, 10);
context.lineTo(50, 10);
context.lineWidth = 2;
context.stroke();
context.beginPath();
context.lineWidth = 15;
context.moveTo(10, 30);
context.lineTo(50, 30);
context.stroke();
context.beginPath();
context.moveTo(10, 50);
context.lineTo(50, 50);
context.lineWidth = 2;
context.stroke();
Where I reconstructed the gradient with multiple lines and a blur on those lines.
I have tried a few solutions on SO but they didn't work for my setup. For some reason the mouse position is off on my canvas. I have pasted my HTML and JS below for reference.
The mouse works fine when the canvas size matches the window size, but I need it to work well when it is smaller or bigger too. How can I do this?
HTML
<canvas id="canvas"></canvas>
JS
window.addEventListener('load', () => {
const canvas = document.querySelector('#canvas');
const ctx = canvas.getContext('2d');
// canvas.height = window.innerHeight;
// canvas.width = window.innerWidth;
canvas.height = 540;
canvas.width = 960;
// canvas.height = canvas.offsetHeight;
// canvas.width = canvas.offsetWidth;
let painting = false;
var gradient = ctx.createLinearGradient(0, 0, 170, 0);
gradient.addColorStop("0", "magenta");
gradient.addColorStop("0.5", "blue");
gradient.addColorStop("1.0", "red");
function windowSize() {
// canvas.height = window.innerHeight;
// canvas.width = window.innerWidth;
// canvas.height = 540;
// canvas.width = 960;
// canvas.height = canvas.offsetHeight;
// canvas.width = canvas.offsetWidth;
}
function startPosition(e) {
painting = true;
draw(e);
}
function finishedPosition() {
painting = false;
ctx.beginPath();
}
function draw(e) {
if(!painting) return;
ctx.lineWidth = lineSize;
ctx.lineCap = "round";
ctx.strokeStyle = color;
ctx.lineTo(e.clientX, e.clientY);
ctx.stroke();
ctx.beginPath();
ctx.moveTo(e.clientX, e.clientY);
}
var lineSize = 5;
var color = "Black";
// Event Listeners
canvas.addEventListener('mousedown', startPosition);
canvas.addEventListener('mouseup', finishedPosition);
canvas.addEventListener('mousemove', draw);
canvas.addEventListener('touchstart', startPosition);
canvas.addEventListener('touchend', finishedPosition);
canvas.addEventListener('touchmove', draw);
// window.addEventListener('resize', windowSize);
});
The accepted solution here solved my problem. I hope this helps someone else in the future, as it did not appear high in search results.
Real mouse position in canvas
When I load the page, the canvas loads and fills the background as white. But, when I click and drag in the canvas, it wont draw for me.
window.addEventListener("load", () => {
const canvas = document.querySelector('#canvas');
const ctx = canvas.getContext('2d');
canvas.height = 200;
canvas.width = window.innerWidth;
ctx.fillStyle = 'white';
ctx.fillRect(0, 0, canvas.width, canvas.height);
let painting = false;
function startPosition(e) {
painting = true;
draw(e);
}
function endPosition() {
painting = false;
ctx.beginPath();
}
function draw(e) {
if (!painting) return;
ctx.lineWidth = 7;
ctx.lineCap = "round";
ctx.strokeStyle = "black";
ctx.lineTo(e.clientX, e.clientY);
ctx.stroke();
ctx.beginPath();
ctx.moveTo(e.clientX, e.clientY);
}
//Event Listeners
canvas.addEventListener("mousedown", startPosition);
canvas.addEventListener("mouseup", endPosition);
canvas.addEventListener("mousemove", draw);
})
<canvas id='canvas'></canvas>
I have a drawing interface which the drawings need to be saved at 1280x720px. However, I want the canvas to be able to be scalable in relation to that aspect ratio. A problem is that when I draw, the start of the path is not on the cursor.
I've looked everywhere and cannot find a solution. Here is the javascript:
var clearButton = document.getElementById('doodle-bin');
var canvascontainer = document.getElementById('doodle-canvas-container');
var canvas = document.getElementById('doodle-canvas');
var context = canvas.getContext('2d');
var radius = (document.getElementById('doodle-canvas-container').clientWidth + document.getElementById('doodle-canvas-container').clientHeight)/150;
var dragging = false;
context.mozImageSmoothingEnabled = false;
context.imageSmoothingEnabled = false;
canvas.width = 1280;
canvas.height = 720;
canvas.style.width = '100%';
canvas.style.height = '100%';
/* CLEAR CANVAS */
function clearCanvas() {
context.clearRect(0, 0, canvas.width, canvas.height);
}
clearButton.addEventListener('click', clearCanvas);
var putPoint = function (e) {
if (dragging) {
context.lineTo(e.offsetX, e.offsetY);
context.lineWidth = radius * 2;
context.stroke();
context.beginPath();
context.arc(e.offsetX, e.offsetY, radius, 0, Math.PI * 2);
context.fill();
context.beginPath();
context.moveTo(e.offsetX, e.offsetY);
}
};
var engage = function (e) {
dragging = true;
putPoint(e);
};
var disengage = function () {
dragging = false;
context.beginPath();
};
canvas.addEventListener('mousedown', engage);
canvas.addEventListener('mousemove', putPoint);
canvas.addEventListener('mouseup', disengage);
document.addEventListener('mouseup', disengage);
canvas.addEventListener('contextmenu', disengage);
Use the following function to get the proper mouse position even if the canvas is re-scaled. This will resolve the path start issue.
function getMouesPosition(e) {
var mouseX = e.offsetX * canvas.width / canvas.clientWidth | 0;
var mouseY = e.offsetY * canvas.height / canvas.clientHeight | 0;
return {x: mouseX, y: mouseY};
}
var clearButton = document.getElementById('doodle-bin');
var canvascontainer = document.getElementById('doodle-canvas-container');
var canvas = document.getElementById('doodle-canvas');
var context = canvas.getContext('2d');
var radius = (document.getElementById('doodle-canvas-container').clientWidth + document.getElementById('doodle-canvas-container').clientHeight) / 150;
var dragging = false;
context.mozImageSmoothingEnabled = false;
context.imageSmoothingEnabled = false;
canvas.width = 1280;
canvas.height = 720;
canvas.style.width = '100%';
canvas.style.height = '100%';
/* CLEAR CANVAS */
function clearCanvas() {
context.clearRect(0, 0, canvas.width, canvas.height);
}
clearButton.addEventListener('click', clearCanvas);
function getMouesPosition(e) {
var mouseX = e.offsetX * canvas.width / canvas.clientWidth | 0;
var mouseY = e.offsetY * canvas.height / canvas.clientHeight | 0;
return {x: mouseX, y: mouseY};
}
var putPoint = function (e) {
if (dragging) {
context.lineTo(getMouesPosition(e).x, getMouesPosition(e).y);
context.lineWidth = radius * 2;
context.stroke();
context.beginPath();
context.arc(getMouesPosition(e).x, getMouesPosition(e).y, radius, 0, Math.PI * 2);
context.fill();
context.beginPath();
context.moveTo(getMouesPosition(e).x, getMouesPosition(e).y);
}
};
var engage = function (e) {
dragging = true;
putPoint(e);
};
var disengage = function () {
dragging = false;
context.beginPath();
};
canvas.addEventListener('mousedown', engage);
canvas.addEventListener('mousemove', putPoint);
canvas.addEventListener('mouseup', disengage);
document.addEventListener('mouseup', disengage);
canvas.addEventListener('contextmenu', disengage);
body{margin:0;overflow:hidden}canvas{border:1px solid #ccc}
<button id="doodle-bin">Clear</button>
<div id="doodle-canvas-container">
<canvas id="doodle-canvas"></canvas>
</div>