assimp/code/Bitmap.cpp

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Open Asset Import Library (assimp)
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/** @file Bitmap.cpp
 *  @brief Defines bitmap format helper for textures
 *
 * Used for file formats which embed their textures into the model file.
 */


#include "Bitmap.h"
#include "../include/assimp/texture.h"
#include "../include/assimp/IOStream.hpp"
#include "ByteSwapper.h"

namespace Assimp {

	void Bitmap::Save(aiTexture* texture, IOStream* file) {
		if(file != NULL) {
			Header header;
			DIB dib;

			dib.size = DIB::dib_size;
			dib.width = texture->mWidth;
			dib.height = texture->mHeight;
			dib.planes = 1;
			dib.bits_per_pixel = 8 * mBytesPerPixel;
			dib.compression = 0;
			dib.image_size = (((dib.width * mBytesPerPixel) + 3) & 0x0000FFFC) * dib.height;
			dib.x_resolution = 0;
			dib.y_resolution = 0;
			dib.nb_colors = 0;
			dib.nb_important_colors = 0;

			header.type = 0x4D42; // 'BM'
			header.offset = Header::header_size + DIB::dib_size;
			header.size = header.offset + dib.image_size;
			header.reserved1 = 0;
			header.reserved2 = 0;

			WriteHeader(header, file);
			WriteDIB(dib, file);
			WriteData(texture, file);
		}
	}

	template<typename T>
	inline std::size_t Copy(uint8_t* data, T& field) {
		std::memcpy(data, &AI_BE(field), sizeof(field)); return sizeof(field);
	}

	void Bitmap::WriteHeader(Header& header, IOStream* file) {
		uint8_t data[Header::header_size];

		std::size_t offset = 0;

		offset += Copy(&data[offset], header.type);
		offset += Copy(&data[offset], header.size);
		offset += Copy(&data[offset], header.reserved1);
		offset += Copy(&data[offset], header.reserved2);
		offset += Copy(&data[offset], header.offset);

		file->Write(data, Header::header_size, 1);
	}

	void Bitmap::WriteDIB(DIB& dib, IOStream* file) {
		uint8_t data[DIB::dib_size];

		std::size_t offset = 0;

		offset += Copy(&data[offset], dib.size);
		offset += Copy(&data[offset], dib.width);
		offset += Copy(&data[offset], dib.height);
		offset += Copy(&data[offset], dib.planes);
		offset += Copy(&data[offset], dib.bits_per_pixel);
		offset += Copy(&data[offset], dib.compression);
		offset += Copy(&data[offset], dib.image_size);
		offset += Copy(&data[offset], dib.x_resolution);
		offset += Copy(&data[offset], dib.y_resolution);
		offset += Copy(&data[offset], dib.nb_colors);
		offset += Copy(&data[offset], dib.nb_important_colors);

		file->Write(data, DIB::dib_size, 1);
	}

	void Bitmap::WriteData(aiTexture* texture, IOStream* file) {
		static const std::size_t padding_offset = 4;
		static const uint8_t padding_data[padding_offset] = {0x0, 0x0, 0x0, 0x0};

		unsigned int padding = (padding_offset - ((mBytesPerPixel * texture->mWidth) % padding_offset)) % padding_offset;
		uint8_t pixel[mBytesPerPixel];

		for(std::size_t i = 0; i < texture->mHeight; ++i) {
			for(std::size_t j = 0; j < texture->mWidth; ++j) {
				const aiTexel& texel = texture->pcData[(texture->mHeight - i - 1) * texture->mWidth + j]; // Bitmap files are stored in bottom-up format

				pixel[0] = texel.r;
				pixel[1] = texel.g;
				pixel[2] = texel.b;
				pixel[3] = texel.a;

				file->Write(pixel, mBytesPerPixel, 1);
			}

			file->Write(padding_data, padding, 1);
		}
	}

}