The HTML <canvas> element is used to draw graphics on a web page.
The HTML <canvas> element is used to draw graphics, on the fly, via JavaScript. The <canvas> element is only a container for graphics. You must use JavaScript to actually draw the graphics. Canvas has several methods for drawing paths, boxes, circles, text, and adding images.
The graphic to the left is created with <canvas>. It shows four elements: a red rectangle, a gradient rectangle, a multicolor rectangle, and a multicolor text.
What is HTML Canvas?
The HTML <canvas> element is used to draw graphics, on the fly, via JavaScript. The <canvas> element is only a container for graphics. You must use JavaScript to actually draw the graphics. Canvas has several methods for drawing paths, boxes, circles, text, and adding images.
How do I make a drawing canvas in HTML?
HTML Canvas Drawing
- Step 1: Find the Canvas Element. First of all, you must find the <canvas> element. This is done by using the HTML DOM method getElementById(): …
- Step 2: Create a Drawing Object. Secondly, you need a drawing object for the canvas. …
- Step 3: Draw on the Canvas. Finally, you can draw on the canvas.
Understanding Canvas Coordinates
The canvas is a two-dimensional rectangular area. The coordinates of the top-left corner of the canvas are (0, 0) which is known as origin, and the coordinates of the bottom-right corner are (canvas width, canvas height). Here’s a simple demonstration of canvas default coordinate system.
Drawing Path and Shapes on Canvas
In this section we’re going to take a closer look at how to draw basic paths and shapes using the newly introduced HTML5 canvas element and JavaScript. Here is the base template for drawing paths and shapes onto the 2D HTML5 canvas.
Example
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Drawing on Canvas</title>
<script>
window.onload = function() {
var canvas = document.getElementById("myCanvas");
var context = canvas.getContext("2d");
// draw stuff here
};
</script>
</head>
<body>
<canvas id="myCanvas" width="300" height="200"></canvas>
</body>
</html>Browser Support
The numbers in the table specify the first browser version that fully supports the <canvas> element.
Canvas Examples
A canvas is a rectangular area on an HTML page. By default, a canvas has no border and no content.
The markup looks like this:
<canvas id="myCanvas" width="200" height="100"></canvas>
Note: Always specify an id attribute (to be referred to in a script), and a width and height attribute to define the size of the canvas. To add a border, use the style attribute.
Example
<canvas id="myCanvas" width="200" height="100" style="border:1px solid #000000;"> </canvas>
Add a JavaScript
After creating the rectangular canvas area, you must add a JavaScript to do the drawing.
Here are some examples:
<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.moveTo(0, 0);
ctx.lineTo(200, 100);
ctx.stroke();
</script>Draw a Circle
Example
<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.arc(95, 50, 40, 0, 2 * Math.PI);
ctx.stroke();
</script>Draw a Text
Example
<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.font = "30px Arial";
ctx.fillText("Hello World", 10, 50);
</script>Stroke Text
Example
<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
ctx.font = "30px Arial";
ctx.strokeText("Hello World", 10, 50);
</script>Draw Linear Gradient
Example
<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
// Create gradient
var grd = ctx.createLinearGradient(0, 0, 200, 0);
grd.addColorStop(0, "red");
grd.addColorStop(1, "white");
// Fill with gradient
ctx.fillStyle = grd;
ctx.fillRect(10, 10, 150, 80);
</script>Draw Circular Gradient
Example
<script>
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
// Create gradient
var grd = ctx.createRadialGradient(75, 50, 5, 90, 60, 100);
grd.addColorStop(0, "red");
grd.addColorStop(1, "white");
// Fill with gradient
ctx.fillStyle = grd;
ctx.fillRect(10, 10, 150, 80);
</script>
