libfprint/libfprint/fpi-assembling.h

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/*
* Copyright (C) 2007 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
*/
#pragma once
#include <fprint.h>
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/**
* fpi_frame:
* @delta_x: X offset of the frame
* @delta_y: Y offset of the frame
* @data: bitmap
*
* #fpi_frame is used to store frames for swipe sensors. Drivers should
* populate delta_x and delta_y if the device supports hardware movement
* estimation.
*/
struct fpi_frame
{
int delta_x;
int delta_y;
unsigned char data[0];
};
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/**
* fpi_frame_asmbl_ctx:
* @frame_width: width of the frame
* @frame_height: height of the frame
* @image_width: resulting image width
* @get_pixel: pixel accessor, returns pixel brightness at x,y of frame
*
* #fpi_frame_asmbl_ctx is a structure holding the context for frame
* assembling routines.
*
* Drivers should define their own #fpi_frame_asmbl_ctx depending on
* hardware parameters of scanner. @image_width is usually 25% wider than
* @frame_width to take horizontal movement into account.
*/
struct fpi_frame_asmbl_ctx
{
unsigned int frame_width;
unsigned int frame_height;
unsigned int image_width;
unsigned char (*get_pixel)(struct fpi_frame_asmbl_ctx *ctx,
struct fpi_frame *frame,
unsigned int x,
unsigned int y);
};
void fpi_do_movement_estimation (struct fpi_frame_asmbl_ctx *ctx,
GSList *stripes);
FpImage *fpi_assemble_frames (struct fpi_frame_asmbl_ctx *ctx,
GSList *stripes);
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/**
* fpi_line_asmbl_ctx:
* @line_width: width of line
* @max_height: maximal height of assembled image
* @resolution: scale factor used for line assembling routines.
* @median_filter_size: size of median filter for movement estimation
* @max_search_offset: the number of lines to search for the next line
* @get_deviation: pointer to a function that returns the numerical difference
* between two lines
* @get_pixel: pixel accessor, returns pixel brightness at x of line
*
* #fpi_line_asmbl_ctx is a structure holding the context for line assembling
* routines.
*
* Drivers should define their own #fpi_line_asmbl_ctx depending on
* the hardware parameters of the scanner. Swipe scanners of this type usually
* return two lines, the second line is often narrower than first and is used
* for movement estimation.
*
* The @max_search_offset value indicates how many lines forward the assembling
* routines should look while searching for next line. This value depends on
* how fast the hardware sends frames.
*
* The function pointed to by @get_deviation should return the numerical difference
* between two lines. Higher values means lines are more different. If the reader
* returns two lines at a time, this function should be used to estimate the
* difference between pairs of lines.
*/
struct fpi_line_asmbl_ctx
{
unsigned int line_width;
unsigned int max_height;
unsigned int resolution;
unsigned int median_filter_size;
unsigned int max_search_offset;
int (*get_deviation)(struct fpi_line_asmbl_ctx *ctx,
GSList *line1,
GSList *line2);
unsigned char (*get_pixel)(struct fpi_line_asmbl_ctx *ctx,
GSList *line,
unsigned int x);
};
FpImage *fpi_assemble_lines (struct fpi_line_asmbl_ctx *ctx,
GSList *lines,
size_t num_lines);