Canvas Transform

Posted in Canvas Tutorial

Updated on May 19, 2024

By Mari Selvan

👁️ 37 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

Canvas transformation is a powerful feature in HTML5 that allows developers to manipulate the drawing context of the <canvas> element. By applying transformations, such as scaling, rotation, translation, and skewing, developers can create complex and dynamic visual effects.

In this guide, we'll explore the syntax, methods, and examples of canvas transformations.

💡 Syntax

The canvas transformation functions are part of the 2D rendering context, accessed through the getContext('2d') method. Here's a basic syntax overview:

Syntax

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const canvas = document.getElementById('myCanvas');
const ctx = canvas.getContext('2d');

// Translate
ctx.translate(x, y);

// Scale
ctx.scale(scaleX, scaleY);

// Rotate
ctx.rotate(angle);

// Skew
ctx.transform(a, b, c, d, e, f);

// Reset transformations
ctx.setTransform(1, 0, 0, 1, 0, 0);

🧰 Methods and Parameters

translate(x, y): Moves the origin of the canvas to the specified (x, y) coordinates.
scale(scaleX, scaleY): Scales the canvas by the given factors along the x and y axes.
rotate(angle): Rotates the canvas around the origin by the specified angle (in radians).
transform(a, b, c, d, e, f): Applies a custom 2D transformation matrix to the canvas.
setTransform(a, b, c, d, e, f): Resets the current transformation matrix to the identity matrix.

📄 Example

Let's demonstrate a simple canvas transformation:

index.html

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<canvas id="myCanvas" width="200" height="200"></canvas>
<script>
  const canvas = document.getElementById('myCanvas');
  const ctx = canvas.getContext('2d');

  // Translate the origin to (100, 100)
  ctx.translate(100, 100);

  // Rotate by 45 degrees
  ctx.rotate(Math.PI / 4);

  // Draw a square
  ctx.fillRect(-50, -50, 100, 100);
</script>