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
It can do quite a lot of cool things, including;
- Draw shapes
- Combine photos
- User drawings
Today, we'll get started by exploring some of it's basic options.
It will look like this:
To create our first canvas, we don't need to do much:
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
It doesn't look like much, since we haven't rendered anything on it.
const canvas = document.getElementById('canvas');
Now we have our actual canvas element, we need to specify it's context:
const ctx = canvas.getContext('2d');
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);
The parameters we are sending are as follows (x, y, width, height).
Cool, so now we see our first rectangle!
There are quite a lot of shapes we can make with the Canvas;
- Curves (Quadratic & Bezier)
With that, we can create any shape. Here are some examples:
// Cirlce ctx.beginPath(); ctx.arc(100, 100, 50, 0, 2 * Math.PI); ctx.stroke();
The parameters for arc are (x, y, Radius, startingAngle, endAngle)
// Triangle ctx.beginPath(); ctx.moveTo(200, 75); ctx.lineTo(100, 75); ctx.lineTo(100, 25); ctx.fill();
As for the move argument is accepts the (x, y) coordinates.
And the lineTo (x, y) from where ever the moveTo is set.
// 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();
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!
The canvas element is well supported these days and is defiantly a good option if you want to draw vectors on screen.