Image for Node.js

This is a part of Node3D project.

npm install @node-3d/image

Using FreeImage, this addon loads images from:

• Local file.
• Data URI.
• Http(s) URL.
• Node.js Blob URL.
• Raw RGBA pixel data.

The Image class is similar to HTMLImageElement, and can be used as a replacement in non-DOM environments.

Additional features:

• save - saves the image to a local file.
• drawImage - is similar to drawImage.

Note: this addon uses N-API, and therefore is ABI-compatible across different Node.js versions. Addon binaries are precompiled and there is no compilation step during the npm install command.

Image

import { Image } from '@node-3d/image';
const image = new Image('images/test.png'); // relative to CWD
image.on('load', () => { console.log('data', image.width, image.height, image.data); });

For loaded images, image.data will contain a Buffer of 4 * width * height bytes. You can directly interact with that buffer - read or write, and then save the image to a file or use it any other way.

With Image.fromPixels() it is possible to generate new images from scratch by providing your own data buffer.

Set window icon

Compatible with @node-3d/glfw window.icon property.

const icon = new Image();
icon.src = 'icons/logo.png';
icon.on('load', () => { window.icon = icon; });

Load an OpenGL texture

Here Image is used to load a texture. The constructed object receives src property, then the file is read and 'load' event is emitted. After that, image.data is available as a Buffer, containing the whole pixel data, and image.width/image.height contain the dimensions.

import { Image } from '@node-3d/image';
const image = new Image();
// Web-style onload
image.onload = () => {
	gl.bindTexture(gl.TEXTURE_2D, texture);
	gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, image);
	gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
	gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_NEAREST);
	gl.generateMipmap(gl.TEXTURE_2D);
	gl.bindTexture(gl.TEXTURE_2D, null);
};

image.src = 'textures/grass.jpg';

Make an OpenGL snapshot

Image can save its current content to the filesystem. It can also load from raw pixel values using static fromPixels() method.

const memSize = screen.w * screen.h * 4; // estimated number of bytes
const storage = { data: Buffer.allocUnsafeSlow(memSize) };

gl.readPixels(
	0, 0,
	screen.w, screen.h,
	gl.RGBA,
	gl.UNSIGNED_BYTE,
	storage
);

const img = Image.fromPixels(screen.w, screen.h, 32, storage.data);

img.save(`${Date.now()}.jpg`);