bmp.c

在linux framebuffer上显示模拟的动态水波效果

/*
    fbv  --  simple image viewer for the linux framebuffer
    Copyright (C) 2002  Tomasz Sterna

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include "bmp.h"
int fh_bmp_id(char *name)
{
	int fd;
	char id[2];

	fd = open(name, O_RDONLY);
	if (fd == -1) {
		return (0);
	}

	read(fd, id, 2);
	close(fd);
	if (id[0] == 'B' && id[1] == 'M') {
		return (1);
	}
	return (0);
}

void fetch_pallete(int fd, struct color pallete[], int count)
{
	unsigned char buff[4];
	int i;

	lseek(fd, BMP_COLOR_OFFSET, SEEK_SET);
	for (i = 0; i < count; i++) {
		read(fd, buff, 4);
		pallete[i].red = buff[2];
		pallete[i].green = buff[1];
		pallete[i].blue = buff[0];
	}
	return;
}

int fh_bmp_load(char *name, unsigned char *buffer, int x, int y)
{
	int fd, bpp, raster, i, j, k, skip;
	unsigned char buff[4];
	unsigned char *wr_buffer = buffer + x * (y - 1) * 3;
	struct color pallete[256];

	fd = open(name, O_RDONLY);
	if (fd == -1) {
		return (FH_ERROR_FILE);
	}

	if (lseek(fd, BMP_TORASTER_OFFSET, SEEK_SET) == -1) {
		return (FH_ERROR_FORMAT);
	}
	read(fd, buff, 4);
	raster = buff[0] + (buff[1] << 8) + (buff[2] << 16) + (buff[3] << 24);

	if (lseek(fd, BMP_BPP_OFFSET, SEEK_SET) == -1) {
		return (FH_ERROR_FORMAT);
	}
	read(fd, buff, 2);
	bpp = buff[0] + (buff[1] << 8);

	switch (bpp) {
	case 1:					/* monochrome */
		skip = fill4B(x / 8 + (x % 8 ? 1 : 0));
		lseek(fd, raster, SEEK_SET);
		for (i = 0; i < y; i++) {
			for (j = 0; j < x / 8; j++) {
				read(fd, buff, 1);
				for (k = 0; k < 8; k++) {
					if (buff[0] & 0x80) {
						*wr_buffer++ = 0xff;
						*wr_buffer++ = 0xff;
						*wr_buffer++ = 0xff;
					} else {
						*wr_buffer++ = 0x00;
						*wr_buffer++ = 0x00;
						*wr_buffer++ = 0x00;
					}
					buff[0] = buff[0] << 1;
				}

			}
			if (x % 8) {
				read(fd, buff, 1);
				for (k = 0; k < x % 8; k++) {
					if (buff[0] & 0x80) {
						*wr_buffer++ = 0xff;
						*wr_buffer++ = 0xff;
						*wr_buffer++ = 0xff;
					} else {
						*wr_buffer++ = 0x00;
						*wr_buffer++ = 0x00;
						*wr_buffer++ = 0x00;
					}
					buff[0] = buff[0] << 1;
				}

			}
			if (skip) {
				read(fd, buff, skip);
			}
			wr_buffer -= x * 6;	/* backoff 2 lines - x*2 *3 */
		}
		break;
	case 4:					/* 4bit palletized */
		skip = fill4B(x / 2 + x % 2);
		fetch_pallete(fd, pallete, 16);
		lseek(fd, raster, SEEK_SET);
		for (i = 0; i < y; i++) {
			for (j = 0; j < x / 2; j++) {
				read(fd, buff, 1);
				buff[1] = buff[0] >> 4;
				buff[2] = buff[0] & 0x0f;
				*wr_buffer++ = pallete[buff[1]].red;
				*wr_buffer++ = pallete[buff[1]].green;
				*wr_buffer++ = pallete[buff[1]].blue;
				*wr_buffer++ = pallete[buff[2]].red;
				*wr_buffer++ = pallete[buff[2]].green;
				*wr_buffer++ = pallete[buff[2]].blue;
			}
			if (x % 2) {
				read(fd, buff, 1);
				buff[1] = buff[0] >> 4;
				*wr_buffer++ = pallete[buff[1]].red;
				*wr_buffer++ = pallete[buff[1]].green;
				*wr_buffer++ = pallete[buff[1]].blue;
			}
			if (skip) {
				read(fd, buff, skip);
			}
			wr_buffer -= x * 6;	/* backoff 2 lines - x*2 *3 */
		}
		break;
	case 8:					/* 8bit palletized */
		skip = fill4B(x);
		fetch_pallete(fd, pallete, 256);
		lseek(fd, raster, SEEK_SET);
		for (i = 0; i < y; i++) {
			for (j = 0; j < x; j++) {
				read(fd, buff, 1);
				*wr_buffer++ = pallete[buff[0]].red;
				*wr_buffer++ = pallete[buff[0]].green;
				*wr_buffer++ = pallete[buff[0]].blue;
			}
			if (skip) {
				read(fd, buff, skip);
			}
			wr_buffer -= x * 6;	/* backoff 2 lines - x*2 *3 */
		}
		break;
	case 16:					/* 16bit RGB */
		return (FH_ERROR_FORMAT);
		break;
	case 24:					/* 24bit RGB */
		skip = fill4B(x * 3);
		lseek(fd, raster, SEEK_SET);
		for (i = 0; i < y; i++) {
			for (j = 0; j < x; j++) {
				read(fd, buff, 3);
				*wr_buffer++ = buff[2];
				*wr_buffer++ = buff[1];
				*wr_buffer++ = buff[0];
			}
			if (skip) {
				read(fd, buff, skip);
			}
			wr_buffer -= x * 6;	/* backoff 2 lines - x*2 *3 */
		}
		break;
	default:
		return (FH_ERROR_FORMAT);
	}

	close(fd);
	return (FH_ERROR_OK);
}
int fh_bmp_getsize(char *name, int *x, int *y)
{
	int fd;
	unsigned char size[4];

	fd = open(name, O_RDONLY);
	if (fd == -1) {
		return (FH_ERROR_FILE);
	}
	if (lseek(fd, BMP_SIZE_OFFSET, SEEK_SET) == -1) {
		return (FH_ERROR_FORMAT);
	}

	read(fd, size, 4);
	*x = size[0] + (size[1] << 8) + (size[2] << 16) + (size[3] << 24);
//  *x-=1;
	read(fd, size, 4);
	*y = size[0] + (size[1] << 8) + (size[2] << 16) + (size[3] << 24);

	close(fd);
	return (FH_ERROR_OK);
}