Explanation of lineTo()

The lineTo() method is part of the Canvas 2D API. It is used to create a line from the current drawing position to a specified position (x, y). It does not actually draw the line; instead, it specifies the path for the line, which can later be drawn with stroke() or fill().

Getting Started

To get a canvas rendering interface you must first have an HTML <canvas> element. You can access the canvas element using various JavaScript methods such as getElementById() . Once you have the canvas element, you can use the getContext() method to get a 2D rendering context.

<canvas id="canvas" width="300" height="300">
// Get element by Id
const canvas = document.getElementById("canvas");
// Get 2d rendering context
const ctx = canvas.getContext("2d");

Drawing Shapes

Now that we've our canvas interface, we can move to drawing shapes with the lineTo() method

ctx.beginPath();
ctx.moveTo(220, 10);
ctx.lineTo(220, 100);
ctx.lineTo(300, 100);
ctx.stroke();

1.ctx.beginPath();

• This method starts a new path by emptying the list of sub-paths. When you call beginPath(), you start a new set of instructions for drawing shapes or lines on the canvas.

• It essentially resets the current path, so any previous paths or lines will not affect the new drawing.

2.ctx.moveTo(220, 10);

• This command moves the drawing cursor (or pen) to the coordinates (220, 10) without drawing anything. The starting position for the next drawing command is set at (220, 10).

  • x-coordinate: 220 (positioned 220 pixels to the right of the origin)

  • y-coordinate: 10 (positioned 10 pixels down from the top of the canvas)

3.ctx.lineTo(220, 100);

• This command adds a line to the current path. The line is drawn from the current position (220, 10) to the new position (220, 100).

  • x-coordinate: 220 (same x-coordinate, so the line will be vertical)

  • y-coordinate: 100 (new y-coordinate, which is 90 pixels further down the canvas from the previous y-coordinate of 10)

Since the x-coordinate remains the same (220) and the y-coordinate changes from 10 to 100, this creates a vertical line.

4.ctx.lineTo(300, 100);

• This command adds another line to the current path. The line is drawn from the current position (220, 100) to the new position (300, 100).

  • x-coordinate: 300 (new x-coordinate, which is 80 pixels to the right of the previous x-coordinate of 220)

  • y-coordinate: 100 (same y-coordinate, so the line will be horizontal)

Since the y-coordinate remains the same (100) and the x-coordinate changes from 220 to 300, this creates a horizontal line.

5.ctx.stroke();

• This method draws the lines that the path methods have defined (moveTo(), lineTo()).

• It outlines the path with the current stroke style, which is a 1-pixel-wide black line by default.

Visual Representation

Imagine a blank canvas:

1. moveTo(220, 10) moves the drawing cursor to point (220, 10).

2. lineTo(220, 100) draws a vertical line down to point (220, 100).

3. lineTo(300, 100) draws a horizontal line to the right to point (300, 100).

After calling ctx.stroke(), these lines are rendered on the canvas, resulting in a path that looks like an "L" shape:

(220,10)
   |
   |
   |
   |
   |
   |
   |
   |
(220,100) --- (300,100)

Conclusion

The ctx.lineTo() method is used to create lines as part of a path. The path is defined by a sequence of moveTo() and lineTo() commands, and stroke() renders the path onto the canvas. The provided code snippet draws an "L" shaped line starting at (220, 10), going vertically down to (220, 100), and then horizontally right to (300, 100).