REXPaint .xp read/parse class

glyph-image.js

/*
Outputs a GlyphImage instance with following structure:
GlyphImage {
	'layer' : [
		Map(
			integer: {
				'char'	: alt-code or glyph,
				'bg'	: background css hex-string,
				'fg'	: foreground css hex-string
			}
		)
	],
	'width'  : integer,
	'height' : integer,
}

Individual cell position can be calculated as follows:
	x = Math.floor(key / GlyphImage.height)
	y = (key % GlyphImage.height)
*/

const zlib = require('zlib')

// char-code array, slightly altered to mimic REXPaint's default charset
const cp437 = [
	0x0000,	0x263A,	0x263B,	0x2665,	0x2666,	0x2663,	0x2660,	0x2022,	0x25D8,	0x25CB,	0x25D9,	0x2642,	0x2640,	0x266A,	0x266B,	0x263C,
	0x25BA,	0x25C4,	0x2195,	0x203C,	0x00B6,	0x00A7,	0x25AC,	0x21A8,	0x2191,	0x2193,	0x2192,	0x2190,	0x221F,	0x2194,	0x25B2,	0x25BC,
	0x0020,	0x0021,	0x0022,	0x0023,	0x0024,	0x0025,	0x0026,	0x0027,	0x0028,	0x0029,	0x002A,	0x002B,	0x002C,	0x002D,	0x002E,	0x002F,
	0x0030,	0x0031,	0x0032,	0x0033,	0x0034,	0x0035,	0x0036,	0x0037,	0x0038,	0x0039,	0x003A,	0x003B,	0x003C,	0x003D,	0x003E,	0x003F,
	0x0040,	0x0041,	0x0042,	0x0043,	0x0044,	0x0045,	0x0046,	0x0047,	0x0048,	0x0049,	0x004A,	0x004B,	0x004C,	0x004D,	0x004E,	0x004F,
	0x0050,	0x0051,	0x0052,	0x0053,	0x0054,	0x0055,	0x0056,	0x0057,	0x0058,	0x0059,	0x005A,	0x005B,	0x005C,	0x005D,	0x005E,	0x005F,
	0x0060,	0x0061,	0x0062,	0x0063,	0x0064,	0x0065,	0x0066,	0x0067,	0x0068,	0x0069,	0x006A,	0x006B,	0x006C,	0x006D,	0x006E,	0x006F,
	0x0070,	0x0071,	0x0072,	0x0073,	0x0074,	0x0075,	0x0076,	0x0077,	0x0078,	0x0079,	0x007A,	0x007B,	0x00A6,	0x007D,	0x007E,	0x2302,
	0x00C7,	0x00FC,	0x00E9,	0x00E2,	0x00E4,	0x00E0,	0x00E5,	0x00E7,	0x00EA,	0x00EB,	0x00E8,	0x00EF,	0x00EE,	0x00EC,	0x00C4,	0x00C5,
	0x00C9,	0x00E6,	0x00C6,	0x00F4,	0x00F6,	0x00F2,	0x00FB,	0x00F9,	0x00FF,	0x00D6,	0x00DC,	0x00A2,	0x00A3,	0x00A5,	0x20A7,	0x0192,
	0x00E1,	0x00ED,	0x00F3,	0x00FA,	0x00F1,	0x00D1,	0x00AA,	0x00BA,	0x00BF,	0x2310,	0x00AC,	0x00BD,	0x00BC,	0x00A1,	0x00AB,	0x00BB,
	0x2591,	0x2592,	0x2593,	0x2502,	0x2524,	0x2561,	0x2562,	0x2556,	0x2555,	0x2563,	0x2551,	0x2557,	0x255D,	0x255C,	0x255B,	0x2510,
	0x2514,	0x2534,	0x252C,	0x251C,	0x2500,	0x253C,	0x255E,	0x255F,	0x255A,	0x2554,	0x2569,	0x2566,	0x2560,	0x2550,	0x256C,	0x2567,
	0x2568,	0x2564,	0x2565,	0x2559,	0x2558,	0x2552,	0x2553,	0x256B,	0x256A,	0x2518,	0x250C,	0x2588,	0x2584,	0x258C,	0x2590,	0x2580,
	0x03B1,	0x00DF,	0x0393,	0x03C0,	0x03A3,	0x03C3,	0x00B5,	0x03C4,	0x03A6,	0x0398,	0x03A9,	0x03B4,	0x221E,	0x03C6,	0x03B5,	0x2229,
	0x2261,	0x00B1,	0x2265,	0x2264,	0x2320,	0x2321,	0x00F7,	0x2248,	0x00B0,	0x2219,	0x00B7,	0x221A,	0x207F,	0x00B2,	0x25A0,	0x25A1
]

const whitespace = [0, 32]						// NUL and SP symbol alt-codes
const transparentBG = ['#000000', '#ff00ff']	// black and hot-pink

function rgb2hex (r, g, b) {
	return '#' + ((1 << 24) + (r << 16) + (g << 8) + b).toString(16).slice(1)
}

class GlyphImage {
	constructor (deflated, toGlyph = true, ignoreTransparent = true) {
		this.layer = []									//because I like layer[n] more than layers[n]

		let x = 0
		let y = 0
		let inflated = zlib.unzipSync(deflated)

		let offset		= 8
		let layerCount	= inflated.readInt32LE(4)
		this.width		= inflated.readInt32LE(8)		//we only need these once
		this.height		= inflated.readInt32LE(12)

		for (let i = 0; i < layerCount; i++) {
			let layerMap = new Map()					//this is gonna be a map for easier access and ability to skip over keys
			offset += 8									//skip over width/height, since they're pointless now

			for (let c = 0, length = this.width * this.height; c < length; c++) {
				let alt = inflated.readInt32LE(offset)
				offset += 4

				// get both color hex values
				// we don't want to calculate at render
				let fg = rgb2hex(
					inflated[offset + 0],
					inflated[offset + 1],
					inflated[offset + 2]
				)

				let bg = rgb2hex(
					inflated[offset + 3],
					inflated[offset + 4],
					inflated[offset + 5]
				)

				offset += 6

				// skip transparent cells (no glyph and black or hot-pink bg)
				if (ignoreTransparent)
					if (whitespace.includes(alt) && transparentBG.includes(bg))
						continue

				let glyphData = {}

				// write alt-code or char-string
				if (toGlyph)
					glyphData.char = String.fromCharCode(cp437[alt])
				else
					glyphData.char = alt

				glyphData.bg = bg
				glyphData.fg = fg

				layerMap.set(c, glyphData)
			}

			this.layer.push(layerMap)
		}
	}

	//returns a combination of layer maps, ready to be iterated over with for...of
	getComposite () {
		let composite = this.layer[0]

		for (var i = 1; i < this.layer.length; i++)
			for (let [key, value] of this.layer[i])
				composite.set(key, value)

		return composite
	}
}

module.exports = {GlyphImage}