DEV Community

loading...
Cover image for Getting started with the HTML canvas

Getting started with the HTML canvas

dailydevtips1 profile image Chris Bongers Originally published at daily-dev-tips.com ・2 min read

My confession: I've never used canvas before this article.
I just have a cool idea in my head, which needs Canvas, so why not document my explorations using the HTML canvas element.

<canvas> is an HTML element which can be used to draw graphics via JavaScript.

It can do quite a lot of cool things, including;

  • Draw shapes
  • Animations
  • Combine photos
  • User drawings

Today, we'll get started by exploring some of it's basic options.

It will look like this:

HTML Canvas

Creating our first HTML Canvas

To create our first canvas, we don't need to do much:

<canvas id="canvas">
Enter fullscreen mode Exit fullscreen mode

This will create a default canvas element, which is 300x150 pixels. We can set the width and height on a canvas element, or style it via CSS.

It doesn't look like much, since we haven't rendered anything on it.

Creating our first shape on the HTML Canvas

To add our first shape we need to use JavaScript to first get our canvas element.

const canvas = document.getElementById('canvas');
Enter fullscreen mode Exit fullscreen mode

Now we have our actual canvas element, we need to specify it's context:

const ctx = canvas.getContext('2d');
Enter fullscreen mode Exit fullscreen mode

We can also get the 3D Engine, but that's for a later article.

Ok, let's add a square, maybe?

ctx.fillRect(50, 50, 100, 100);
Enter fullscreen mode Exit fullscreen mode

The parameters we are sending are as follows (x, y, width, height).

Cool, so now we see our first rectangle!

Other shapes

There are quite a lot of shapes we can make with the Canvas;

  • Rectangles
  • Paths
  • Arcs
  • Curves (Quadratic & Bezier)

With that, we can create any shape. Here are some examples:

Canvas Circle

// Cirlce
ctx.beginPath();
ctx.arc(100, 100, 50, 0, 2 * Math.PI);
ctx.stroke();
Enter fullscreen mode Exit fullscreen mode

The parameters for arc are (x, y, Radius, startingAngle, endAngle)

Canvas Triangle

// Triangle
ctx.beginPath();
ctx.moveTo(200, 75);
ctx.lineTo(100, 75);
ctx.lineTo(100, 25);
ctx.fill();
Enter fullscreen mode Exit fullscreen mode

As for the move argument is accepts the (x, y) coordinates.
And the lineTo (x, y) from where ever the moveTo is set.

Canvas Heart

// Hearth
ctx.beginPath();
ctx.moveTo(75, 40);
ctx.bezierCurveTo(75, 37, 70, 25, 50, 25);
ctx.bezierCurveTo(20, 25, 20, 62.5, 20, 62.5);
ctx.bezierCurveTo(20, 80, 40, 102, 75, 120);
ctx.bezierCurveTo(110, 102, 130, 80, 130, 62.5);
ctx.bezierCurveTo(130, 62.5, 130, 25, 100, 25);
ctx.bezierCurveTo(85, 25, 75, 37, 75, 40);
ctx.stroke();
Enter fullscreen mode Exit fullscreen mode

The bezierCurveTo accepts (x of control point 1, y of control point 1, x of control point 2, y of control point 2, x ending, y ending)

Find these on the following Codepen.

Note: We will continue exploring in other articles!

Browser Support

The canvas element is well supported these days and is defiantly a good option if you want to draw vectors on screen.

HTML Canvas support

Thank you for reading, and let's connect!

Thank you for reading my blog. Feel free to subscribe to my email newsletter and connect on Facebook or Twitter

Discussion (0)

pic
Editor guide