libfprint/libfprint/assembling.c

/*
 * Image assembling routines
 * Copyright (C) 2007-2008 Daniel Drake <dsd@gentoo.org>
 * Copyright (C) 2015 Vasily Khoruzhick <anarsoul@gmail.com>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#define FP_COMPONENT "assembling"

#include <errno.h>
#include <string.h>

#include <libusb.h>
#include <glib.h>

#include "fp_internal.h"
#include "assembling.h"

static unsigned int calc_error(struct fpi_frame_asmbl_ctx *ctx,
			       struct fpi_frame *first_frame,
			       struct fpi_frame *second_frame,
			       int dx,
			       int dy)
{
	unsigned int width, height;
	unsigned int x1, y1, x2, y2, err, i, j;

	width = ctx->frame_width - (dx > 0 ? dx : -dx);
	height = ctx->frame_height - dy;

	y1 = 0;
	y2 = dy;
	i = 0;
	err = 0;
	do {
		x1 = dx < 0 ? 0 : dx;
		x2 = dx < 0 ? -dx : 0;
		j = 0;

		do {
			unsigned char v1, v2;


			v1 = ctx->get_pixel(ctx, first_frame, x1, y1);
			v2 = ctx->get_pixel(ctx, second_frame, x2, y2);
			err += v1 > v2 ? v1 - v2 : v2 - v1;
			j++;
			x1++;
			x2++;

		} while (j < width);
		i++;
		y1++;
		y2++;
	} while (i < height);

	/* Normalize error */
	err *= (ctx->frame_height * ctx->frame_width);
	err /= (height * width);

	if (err == 0)
		return INT_MAX;

	return err;
}

/* This function is rather CPU-intensive. It's better to use hardware
 * to detect movement direction when possible.
 */
static void find_overlap(struct fpi_frame_asmbl_ctx *ctx,
			 struct fpi_frame *first_frame,
			 struct fpi_frame *second_frame,
			 unsigned int *min_error)
{
	int dx, dy;
	unsigned int err;
	*min_error = INT_MAX;

	/* Seeking in horizontal and vertical dimensions,
	 * for horizontal dimension we'll check only 8 pixels
	 * in both directions. For vertical direction diff is
	 * rarely less than 2, so start with it.
	 */
	for (dy = 2; dy < ctx->frame_height; dy++) {
		for (dx = -8; dx < 8; dx++) {
			err = calc_error(ctx, first_frame, second_frame,
				dx, dy);
			if (err < *min_error) {
				*min_error = err;
				second_frame->delta_x = -dx;
				second_frame->delta_y = dy;
			}
		}
	}
}

unsigned int fpi_do_movement_estimation(struct fpi_frame_asmbl_ctx *ctx,
			    GSList *stripes, size_t num_stripes,
			    gboolean reverse)
{
	GSList *list_entry = stripes;
	GTimer *timer;
	int frame = 1;
	int height = 0;
	struct fpi_frame *prev_stripe = list_entry->data;
	unsigned int min_error;

	list_entry = g_slist_next(list_entry);

	timer = g_timer_new();
	do {
		struct fpi_frame *cur_stripe = list_entry->data;

		if (reverse) {
			find_overlap(ctx, prev_stripe, cur_stripe, &min_error);
			prev_stripe->delta_y = -prev_stripe->delta_y;
			prev_stripe->delta_x = -prev_stripe->delta_x;
		}
		else
			find_overlap(ctx, cur_stripe, prev_stripe, &min_error);

		frame++;
		height += prev_stripe->delta_y;
		prev_stripe = cur_stripe;
		list_entry = g_slist_next(list_entry);

	} while (frame < num_stripes);

	if (height < 0)
		height = -height;
	height += ctx->frame_height;
	g_timer_stop(timer);
	fp_dbg("calc delta completed in %f secs", g_timer_elapsed(timer, NULL));
	g_timer_destroy(timer);

	return height;
}

static inline void aes_blit_stripe(struct fpi_frame_asmbl_ctx *ctx,
				   struct fp_img *img,
				   struct fpi_frame *stripe,
				   int x, int y)
{
	unsigned int ix, iy;
	unsigned int fx, fy;
	unsigned int width, height;

	/* Find intersection */
	if (x < 0) {
		width = ctx->frame_width + x;
		ix = 0;
		fx = -x;
	} else {
		ix = x;
		fx = 0;
		width = ctx->frame_width;
	}
	if ((ix + width) > img->width)
		width = img->width - ix;

	if (y < 0) {
		iy = 0;
		fy = -y;
		height = ctx->frame_height + y;
	} else {
		iy = y;
		fy = 0;
		height = ctx->frame_height;
	}

	if (fx > ctx->frame_width)
		return;

	if (fy > ctx->frame_height)
		return;

	if (ix > img->width)
		return;

	if (iy > img->height)
		return;

	if ((iy + height) > img->height)
		height = img->height - iy;

	for (; fy < height; fy++, iy++) {
		if (x < 0) {
			ix = 0;
			fx = -x;
		} else {
			ix = x;
			fx = 0;
		}
		for (; fx < width; fx++, ix++) {
			img->data[ix + (iy * img->width)] = ctx->get_pixel(ctx, stripe, fx, fy);
		}
	}
}

struct fp_img *fpi_assemble_frames(struct fpi_frame_asmbl_ctx *ctx,
			    GSList *stripes, size_t stripes_len)
{
	GSList *stripe;
	struct fp_img *img;
	int height = 0;
	int i, y, x;
	gboolean reverse = FALSE;
	struct fpi_frame *fpi_frame;

	BUG_ON(stripes_len == 0);
	BUG_ON(ctx->image_width < ctx->frame_width);

	/* Calculate height */
	i = 0;
	stripe = stripes;

	/* No offset for 1st image */
	fpi_frame = stripe->data;
	fpi_frame->delta_x = 0;
	fpi_frame->delta_y = 0;
	do {
		fpi_frame = stripe->data;

		height += fpi_frame->delta_y;
		i++;
		stripe = g_slist_next(stripe);
	} while (i < stripes_len);

	fp_dbg("height is %d", height);

	if (height < 0) {
		reverse = TRUE;
		height = -height;
	}

	/* For last frame */
	height += ctx->frame_height;

	/* Create buffer big enough for max image */
	img = fpi_img_new(ctx->image_width * height);
	img->flags = FP_IMG_COLORS_INVERTED;
	img->width = ctx->image_width;
	img->height = height;

	/* Assemble stripes */
	i = 0;
	stripe = stripes;
	y = reverse ? (height - ctx->frame_height) : 0;
	x = (ctx->image_width - ctx->frame_width) / 2;

	do {
		fpi_frame = stripe->data;

		y += fpi_frame->delta_y;
		x += fpi_frame->delta_x;

		aes_blit_stripe(ctx, img, fpi_frame, x, y);

		stripe = g_slist_next(stripe);
		i++;
	} while (i < stripes_len);

	return img;
}