Source: loader/TGALoader.js

import { FileLoader } from './FileLoader.js';
import { DefaultLoadingManager } from './LoadingManager.js';

/**
 * A loader for loading a .tga Image.
 * @constructor
 * @memberof zen3d
 * @param {zen3d.LoadingManager} manager — The loadingManager for the loader to use. Default is zen3d.DefaultLoadingManager.
 */
function TGALoader(manager) {
	this.manager = (manager !== undefined) ? manager : DefaultLoadingManager;
}

Object.assign(TGALoader.prototype, /** @lends zen3d.TGALoader.prototype */{

	/**
     * Load the URL and pass the response to the onLoad function.
     * @param {string} url — the path or URL to the file. This can also be a Data URI.
     * @param {Function} [onLoad=] — Will be called when loading completes. The argument will be the loaded image ( draw to an canvas element ).
     * @param {Function} [onProgress=] — Will be called while load progresses. The argument will be the XMLHttpRequest instance, which contains .total and .loaded bytes.
     * @param {Function} [onError=] — Will be called if an error occurs.
     */
	load: function(url, onLoad, onProgress, onError) {
		var that = this;

		var loader = new FileLoader(this.manager);
		loader.setResponseType('arraybuffer');
		loader.load(url, function(buffer) {
			if (onLoad !== undefined) {
				onLoad(that.parse(buffer));
			}
		}, onProgress, onError);
	},

	// reference from vthibault, https://github.com/vthibault/roBrowser/blob/master/src/Loaders/Targa.js
	parse: function(buffer) {
		// TGA Constants
		var TGA_TYPE_NO_DATA = 0,
			TGA_TYPE_INDEXED = 1,
			TGA_TYPE_RGB = 2,
			TGA_TYPE_GREY = 3,
			TGA_TYPE_RLE_INDEXED = 9,
			TGA_TYPE_RLE_RGB = 10,
			TGA_TYPE_RLE_GREY = 11,

			TGA_ORIGIN_MASK = 0x30,
			TGA_ORIGIN_SHIFT = 0x04,
			TGA_ORIGIN_BL = 0x00,
			TGA_ORIGIN_BR = 0x01,
			TGA_ORIGIN_UL = 0x02,
			TGA_ORIGIN_UR = 0x03;


		if (buffer.length < 19) {
			console.error('TGALoader.parse: Not enough data to contain header.');
		}

		var content = new Uint8Array(buffer),
			offset = 0,
			header = {
				id_length: content[offset++],
				colormap_type: content[offset++],
				image_type: content[offset++],
				colormap_index: content[offset++] | content[offset++] << 8,
				colormap_length: content[offset++] | content[offset++] << 8,
				colormap_size: content[offset++],

				origin: [
					content[offset++] | content[offset++] << 8,
					content[offset++] | content[offset++] << 8
				],
				width: content[offset++] | content[offset++] << 8,
				height: content[offset++] | content[offset++] << 8,
				pixel_size: content[offset++],
				flags: content[offset++]
			};

		function tgaCheckHeader(header) {
			switch (header.image_type) {
			// Check indexed type
			case TGA_TYPE_INDEXED:
			case TGA_TYPE_RLE_INDEXED:
				if (header.colormap_length > 256 || header.colormap_size !== 24 || header.colormap_type !== 1) {
					console.error('TGALoader.parse.tgaCheckHeader: Invalid type colormap data for indexed type');
				}
				break;

				// Check colormap type
			case TGA_TYPE_RGB:
			case TGA_TYPE_GREY:
			case TGA_TYPE_RLE_RGB:
			case TGA_TYPE_RLE_GREY:
				if (header.colormap_type) {
					console.error('TGALoader.parse.tgaCheckHeader: Invalid type colormap data for colormap type');
				}
				break;

				// What the need of a file without data ?
			case TGA_TYPE_NO_DATA:
				console.error('TGALoader.parse.tgaCheckHeader: No data');

				// Invalid type ?
			default:
				console.error('TGALoader.parse.tgaCheckHeader: Invalid type " ' + header.image_type + '"');
			}

			// Check image width and height
			if (header.width <= 0 || header.height <= 0) {
				console.error('TGALoader.parse.tgaCheckHeader: Invalid image size');
			}

			// Check image pixel size
			if (header.pixel_size !== 8  &&
				header.pixel_size !== 16 &&
				header.pixel_size !== 24 &&
				header.pixel_size !== 32) {
				console.error('TGALoader.parse.tgaCheckHeader: Invalid pixel size "' + header.pixel_size + '"');
			}
		}

		// Check tga if it is valid format
		tgaCheckHeader(header);

		if (header.id_length + offset > buffer.length) {
			console.error('TGALoader.parse: No data');
		}

		// Skip the needn't data
		offset += header.id_length;

		// Get targa information about RLE compression and palette
		var use_rle = false,
			use_pal = false,
			use_grey = false;

		switch (header.image_type) {
		case TGA_TYPE_RLE_INDEXED:
			use_rle = true;
			use_pal = true;
			break;

		case TGA_TYPE_INDEXED:
			use_pal = true;
			break;

		case TGA_TYPE_RLE_RGB:
			use_rle = true;
			break;

		case TGA_TYPE_RGB:
			break;

		case TGA_TYPE_RLE_GREY:
			use_rle = true;
			use_grey = true;
			break;

		case TGA_TYPE_GREY:
			use_grey = true;
			break;
		}

		// Parse tga image buffer
		function tgaParse(use_rle, use_pal, header, offset, data) {
			var pixel_data,
				pixel_size,
				pixel_total,
				palettes;

			pixel_size = header.pixel_size >> 3;
			pixel_total = header.width * header.height * pixel_size;

			// Read palettes
			if (use_pal) {
				palettes = data.subarray(offset, offset += header.colormap_length * (header.colormap_size >> 3));
			}

			// Read RLE
			if (use_rle) {
				pixel_data = new Uint8Array(pixel_total);

				var c, count, i;
				var shift = 0;
				var pixels = new Uint8Array(pixel_size);

				while (shift < pixel_total) {
					c     = data[offset++];
					count = (c & 0x7f) + 1;

					// RLE pixels.
					if (c & 0x80) {
						// Bind pixel tmp array
						for (i = 0; i < pixel_size; ++i) {
							pixels[i] = data[offset++];
						}

						// Copy pixel array
						for (i = 0; i < count; ++i) {
							pixel_data.set(pixels, shift + i * pixel_size);
						}

						shift += pixel_size * count;
					} else {
						// Raw pixels.
						count *= pixel_size;
						for (i = 0; i < count; ++i) {
							pixel_data[shift + i] = data[offset++];
						}
						shift += count;
					}
				}
			} else {
				// RAW Pixels
				pixel_data = data.subarray(
					offset, offset += (use_pal ? header.width * header.height : pixel_total)
				);
			}

			return {
				pixel_data: pixel_data,
				palettes: palettes
			};
		}

		function tgaGetImageData8bits(imageData, y_start, y_step, y_end, x_start, x_step, x_end, image, palettes) {
			var colormap = palettes;
			var color, i = 0, x, y;
			var width = header.width;

			for (y = y_start; y !== y_end; y += y_step) {
				for (x = x_start; x !== x_end; x += x_step, i++) {
					color = image[i];
					imageData[(x + width * y) * 4 + 3] = 255;
					imageData[(x + width * y) * 4 + 2] = colormap[(color * 3) + 0];
					imageData[(x + width * y) * 4 + 1] = colormap[(color * 3) + 1];
					imageData[(x + width * y) * 4 + 0] = colormap[(color * 3) + 2];
				}
			}

			return imageData;
		}

		function tgaGetImageData16bits(imageData, y_start, y_step, y_end, x_start, x_step, x_end, image) {
			var color, i = 0, x, y;
			var width = header.width;

			for (y = y_start; y !== y_end; y += y_step) {
				for (x = x_start; x !== x_end; x += x_step, i += 2) {
					color = image[i + 0] + (image[i + 1] << 8); // Inversed ?
					imageData[(x + width * y) * 4 + 0] = (color & 0x7C00) >> 7;
					imageData[(x + width * y) * 4 + 1] = (color & 0x03E0) >> 2;
					imageData[(x + width * y) * 4 + 2] = (color & 0x001F) >> 3;
					imageData[(x + width * y) * 4 + 3] = (color & 0x8000) ? 0 : 255;
				}
			}

			return imageData;
		}

		function tgaGetImageData24bits(imageData, y_start, y_step, y_end, x_start, x_step, x_end, image) {
			var i = 0, x, y;
			var width = header.width;

			for (y = y_start; y !== y_end; y += y_step) {
				for (x = x_start; x !== x_end; x += x_step, i += 3) {
					imageData[(x + width * y) * 4 + 3] = 255;
					imageData[(x + width * y) * 4 + 2] = image[i + 0];
					imageData[(x + width * y) * 4 + 1] = image[i + 1];
					imageData[(x + width * y) * 4 + 0] = image[i + 2];
				}
			}

			return imageData;
		}

		function tgaGetImageData32bits(imageData, y_start, y_step, y_end, x_start, x_step, x_end, image) {
			var i = 0, x, y;
			var width = header.width;

			for (y = y_start; y !== y_end; y += y_step) {
				for (x = x_start; x !== x_end; x += x_step, i += 4) {
					imageData[(x + width * y) * 4 + 2] = image[i + 0];
					imageData[(x + width * y) * 4 + 1] = image[i + 1];
					imageData[(x + width * y) * 4 + 0] = image[i + 2];
					imageData[(x + width * y) * 4 + 3] = image[i + 3];
				}
			}

			return imageData;
		}

		function tgaGetImageDataGrey8bits(imageData, y_start, y_step, y_end, x_start, x_step, x_end, image) {
			var color, i = 0, x, y;
			var width = header.width;

			for (y = y_start; y !== y_end; y += y_step) {
				for (x = x_start; x !== x_end; x += x_step, i++) {
					color = image[i];
					imageData[(x + width * y) * 4 + 0] = color;
					imageData[(x + width * y) * 4 + 1] = color;
					imageData[(x + width * y) * 4 + 2] = color;
					imageData[(x + width * y) * 4 + 3] = 255;
				}
			}

			return imageData;
		}

		function tgaGetImageDataGrey16bits(imageData, y_start, y_step, y_end, x_start, x_step, x_end, image) {
			var i = 0, x, y;
			var width = header.width;

			for (y = y_start; y !== y_end; y += y_step) {
				for (x = x_start; x !== x_end; x += x_step, i += 2) {
					imageData[(x + width * y) * 4 + 0] = image[i + 0];
					imageData[(x + width * y) * 4 + 1] = image[i + 0];
					imageData[(x + width * y) * 4 + 2] = image[i + 0];
					imageData[(x + width * y) * 4 + 3] = image[i + 1];
				}
			}

			return imageData;
		}

		function getTgaRGBA(data, width, height, image, palette) {
			var x_start,
				y_start,
				x_step,
				y_step,
				x_end,
				y_end;

			switch ((header.flags & TGA_ORIGIN_MASK) >> TGA_ORIGIN_SHIFT) {
			default:
			case TGA_ORIGIN_UL:
				x_start = 0;
				x_step = 1;
				x_end = width;
				y_start = 0;
				y_step = 1;
				y_end = height;
				break;

			case TGA_ORIGIN_BL:
				x_start = 0;
				x_step = 1;
				x_end = width;
				y_start = height - 1;
				y_step = -1;
				y_end = -1;
				break;

			case TGA_ORIGIN_UR:
				x_start = width - 1;
				x_step = -1;
				x_end = -1;
				y_start = 0;
				y_step = 1;
				y_end = height;
				break;

			case TGA_ORIGIN_BR:
				x_start = width - 1;
				x_step = -1;
				x_end = -1;
				y_start = height - 1;
				y_step = -1;
				y_end = -1;
				break;
			}

			if (use_grey) {
				switch (header.pixel_size) {
				case 8:
					tgaGetImageDataGrey8bits(data, y_start, y_step, y_end, x_start, x_step, x_end, image);
					break;
				case 16:
					tgaGetImageDataGrey16bits(data, y_start, y_step, y_end, x_start, x_step, x_end, image);
					break;
				default:
					console.error('TGALoader.parse.getTgaRGBA: not support this format');
					break;
				}
			} else {
				switch (header.pixel_size) {
				case 8:
					tgaGetImageData8bits(data, y_start, y_step, y_end, x_start, x_step, x_end, image, palette);
					break;

				case 16:
					tgaGetImageData16bits(data, y_start, y_step, y_end, x_start, x_step, x_end, image);
					break;

				case 24:
					tgaGetImageData24bits(data, y_start, y_step, y_end, x_start, x_step, x_end, image);
					break;

				case 32:
					tgaGetImageData32bits(data, y_start, y_step, y_end, x_start, x_step, x_end, image);
					break;

				default:
					console.error('TGALoader.parse.getTgaRGBA: not support this format');
					break;
				}
			}

			// Load image data according to specific method
			// var func = 'tgaGetImageData' + (use_grey ? 'Grey' : '') + (header.pixel_size) + 'bits';
			// func(data, y_start, y_step, y_end, x_start, x_step, x_end, width, image, palette );
			return data;
		}

		var canvas = document.createElement('canvas');
		canvas.width = header.width;
		canvas.height = header.height;

		var context = canvas.getContext('2d');
		var imageData = context.createImageData(header.width, header.height);

		var result = tgaParse(use_rle, use_pal, header, offset, content);
		getTgaRGBA(imageData.data, header.width, header.height, result.pixel_data, result.palettes);

		context.putImageData(imageData, 0, 0);

		return canvas;
	}

});

export { TGALoader };