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codeonion/canvasDraw.html

Created January 21, 2022 14:06
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Canvas Draw Quick
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canvasDraw.html
<!-- html blank page -->
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
</head>
<body>
<!-- canvas -->
<canvas id="canvas" width="500" height="500"></canvas>
<!-- clear button -->
<button id="clear">Clear</button>
</body>
<!-- jquery -->
<script src="https://code.jquery.com/jquery-3.3.1.min.js"></script>
<script>
// Draw on canvas with mouse
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var lastX = -1;
var lastY = -1;
$("#canvas").mousedown(function () {
console.log("mousedown");
$(this).mousemove(function (e) {
var mouseX = e.pageX - this.offsetLeft;
var mouseY = e.pageY - this.offsetTop;
if (lastX > -1) {
// render a point
ctx.beginPath();
ctx.moveTo(lastX, lastY);
ctx.lineTo(mouseX, mouseY);
ctx.strokeStyle = "black";
ctx.lineWidth = 5;
ctx.stroke();
ctx.closePath();
}
lastX = mouseX;
lastY = mouseY;
});
}).mouseup(function () {
$(this).unbind('mousemove');
}).mouseout(function () {
$(this).unbind('mousemove');
});
// canvas.addEventListener("mousedown", function(e){
// this.addEventListener("mousemove", function (e) {
// var mouseX = e.pageX - this.offsetLeft;
// var mouseY = e.pageY - this.offsetTop;
// if (lastX > -1) {
// ctx.beginPath();
// ctx.moveTo(lastX, lastY);
// ctx.lineTo(mouseX, mouseY);
// ctx.strokeStyle = "black";
// ctx.lineWidth = 5;
// ctx.stroke();
// ctx.closePath();
// }
// lastX = mouseX;
// lastY = mouseY;
// });
// }).mouseup(function () {
// $(this).unbind('mousemove');
// }).mouseout(function () {
// $(this).unbind('mousemove');
// });
// Clear canvas
var clearCanvas = document.getElementById("clear");
clearCanvas.addEventListener("click", function () {
ctx.clearRect(0, 0, canvas.width, canvas.height);
lastX = -1;
lastY = -1;
});
</script>
</html>
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