path: root/gerber/utils.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

# Copyright 2014 Hamilton Kibbe <ham@hamiltonkib.be>

# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at

#     http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
"""
gerber.utils
============
**Gerber and Excellon file handling utilities**

This module provides utility functions for working with Gerber and Excellon
files.
"""

import os
from math import radians, sin, cos, sqrt, atan2, pi

MILLIMETERS_PER_INCH = 25.4


def parse_gerber_value(value, format=(2, 5), zero_suppression='trailing'):
    """ Convert gerber/excellon formatted string to floating-point number

    .. note::
        Format and zero suppression are configurable. Note that the Excellon
        and Gerber formats use opposite terminology with respect to leading
        and trailing zeros. The Gerber format specifies which zeros are
        suppressed, while the Excellon format specifies which zeros are
        included. This function uses the Gerber-file convention, so an
        Excellon file in LZ (leading zeros) mode would use
        `zero_suppression='trailing'`


    Parameters
    ----------
    value : string
        A Gerber/Excellon-formatted string representing a numerical value.

    format :  tuple (int,int)
        Gerber/Excellon precision format expressed as a tuple containing:
        (number of integer-part digits, number of decimal-part digits)

    zero_suppression : string
        Zero-suppression mode. May be 'leading', 'trailing' or 'none'

    Returns
    -------
    value : float
        The specified value as a floating-point number.

    """
    # Handle excellon edge case with explicit decimal. "That was easy!"
    if '.' in value:
        return float(value)

    # Format precision
    integer_digits, decimal_digits = format
    MAX_DIGITS = integer_digits + decimal_digits

    # Absolute maximum number of digits supported. This will handle up to
    # 6:7 format, which is somewhat supported, even though the gerber spec
    # only allows up to 6:6
    if MAX_DIGITS > 13 or integer_digits > 6 or decimal_digits > 7:
        raise ValueError('Parser only supports precision up to 6:7 format')

    # Remove extraneous information
    value = value.lstrip('+')
    negative = '-' in value
    if negative:
        value = value.lstrip('-')

    missing_digits = MAX_DIGITS - len(value)

    if zero_suppression == 'trailing':
        digits = list(value + ('0' * missing_digits))
    elif zero_suppression == 'leading':
        digits = list(('0' * missing_digits) + value)
    else:
        digits = list(value)

    result = float(
        ''.join(digits[:integer_digits] + ['.'] + digits[integer_digits:]))
    return -result if negative else result


def write_gerber_value(value, format=(2, 5), zero_suppression='trailing'):
    """ Convert a floating point number to a Gerber/Excellon-formatted string.

    .. note::
        Format and zero suppression are configurable. Note that the Excellon
        and Gerber formats use opposite terminology with respect to leading
        and trailing zeros. The Gerber format specifies which zeros are
        suppressed, while the Excellon format specifies which zeros are
        included. This function uses the Gerber-file convention, so an
        Excellon file in LZ (leading zeros) mode would use
        `zero_suppression='trailing'`

    Parameters
    ----------
    value : float
        A floating point value.

    format :  tuple (n=2)
        Gerber/Excellon precision format expressed as a tuple containing:
        (number of integer-part digits, number of decimal-part digits)

    zero_suppression : string
        Zero-suppression mode. May be 'leading', 'trailing' or 'none'

    Returns
    -------
    value : string
        The specified value as a Gerber/Excellon-formatted string.
    """
    # Format precision
    integer_digits, decimal_digits = format
    MAX_DIGITS = integer_digits + decimal_digits

    if MAX_DIGITS > 13 or integer_digits > 6 or decimal_digits > 7:
        raise ValueError('Parser only supports precision up to 6:7 format')

    # Edge case... (per Gerber spec we should return 0 in all cases, see page
    # 77)
    if value == 0:
        return '0'

    # negative sign affects padding, so deal with it at the end...
    negative = value < 0.0
    if negative:
        value = -1.0 * value

    # Format string for padding out in both directions
    fmtstring = '%%0%d.0%df' % (MAX_DIGITS + 1, decimal_digits)
    digits = [val for val in fmtstring % value if val != '.']

    # If all the digits are 0, return '0'.
    digit_sum = sum([int(digit) for digit in digits])
    if digit_sum == 0:
        return '0'

    # Suppression...
    if zero_suppression == 'trailing':
        while digits and digits[-1] == '0':
            digits.pop()
    elif zero_suppression == 'leading':
        while digits and digits[0] == '0':
            digits.pop(0)

    if not digits:
        return '0'

    return ''.join(digits) if not negative else ''.join(['-'] + digits)


def decimal_string(value, precision=6, padding=False):
    """ Convert float to string with limited precision

    Parameters
    ----------
    value : float
        A floating point value.

    precision :
        Maximum number of decimal places to print

    Returns
    -------
    value : string
        The specified value as a  string.

    """
    floatstr = '%0.10g' % value
    integer = None
    decimal = None
    if '.' in floatstr:
        integer, decimal = floatstr.split('.')
    elif ',' in floatstr:
        integer, decimal = floatstr.split(',')
    else:
        integer, decimal = floatstr, "0"

    if len(decimal) > precision:
        decimal = decimal[:precision]
    elif padding:
        decimal = decimal + (precision - len(decimal)) * '0'

    if integer or decimal:
        return ''.join([integer, '.', decimal])
    else:
        return int(floatstr)


def detect_file_format(data):
    """ Determine format of a file

    Parameters
    ----------
    data : string
        string containing file data.

    Returns
    -------
    format : string
        File format. 'excellon' or 'rs274x' or 'unknown'
    """
    lines = data.split('\n')
    for line in lines:
        if 'M48' in line:
            return 'excellon'
        elif '%FS' in line:
            return 'rs274x'
        elif ((len(line.split()) >= 2) and
              (line.split()[0] == 'P') and (line.split()[1] == 'JOB')):
            return 'ipc_d_356'
    return 'unknown'


def validate_coordinates(position):
    if position is not None:
        if len(position) != 2:
            raise TypeError('Position must be a tuple (n=2) of coordinates')
        else:
            for coord in position:
                if not (isinstance(coord, int) or isinstance(coord, float)):
                    raise TypeError('Coordinates must be integers or floats')


def metric(value):
    """ Convert inch value to millimeters

    Parameters
    ----------
    value : float
        A value in inches.

    Returns
    -------
    value : float
        The equivalent value expressed in millimeters.
    """
    return value * MILLIMETERS_PER_INCH


def inch(value):
    """ Convert millimeter value to inches

    Parameters
    ----------
    value : float
        A value in millimeters.

    Returns
    -------
    value : float
        The equivalent value expressed in inches.
    """
    return value / MILLIMETERS_PER_INCH


def rotate_point(point, angle, center=(0.0, 0.0)):
    """ Rotate a point about another point.

    Parameters
    -----------
    point : tuple(<float>, <float>)
        Point to rotate about origin or center point

    angle : float
        Angle to rotate the point [degrees]

    center : tuple(<float>, <float>)
        Coordinates about which the point is rotated. Defaults to the origin.

    Returns
    -------
    rotated_point : tuple(<float>, <float>)
        `point` rotated about `center` by `angle` degrees.
    """
    angle = radians(angle)

    cos_angle = cos(angle)
    sin_angle = sin(angle)

    return (
            cos_angle * (point[0] - center[0]) - sin_angle * (point[1] - center[1]) + center[0],
            sin_angle * (point[0] - center[0]) + cos_angle * (point[1] - center[1]) + center[1])

def nearly_equal(point1, point2, ndigits = 6):
    '''Are the points nearly equal'''

    return round(point1[0] - point2[0], ndigits) == 0 and round(point1[1] - point2[1], ndigits) == 0


def sq_distance(point1, point2):

    diff1 = point1[0] - point2[0]
    diff2 = point1[1] - point2[1]
    return diff1 * diff1 + diff2 * diff2


def listdir(directory, ignore_hidden=True, ignore_os=True):
    """ List files in given directory.
    Differs from os.listdir() in that hidden and OS-generated files are ignored
    by default.

    Parameters
    ----------
    directory : str
        path to the directory for which to list files.

    ignore_hidden : bool
        If True, ignore files beginning with a leading '.'

    ignore_os : bool
        If True, ignore OS-generated files, e.g. Thumbs.db

    Returns
    -------
    files : list
        list of files in specified directory
    """
    os_files = ('.DS_Store', 'Thumbs.db', 'ethumbs.db')
    files = os.listdir(directory)
    if ignore_hidden:
        files = [f for f in files if not f.startswith('.')]
    if ignore_os:
        files = [f for f in files if not f in os_files]
    return files

def ConvexHull_qh(points):
    #a hull must be a planar shape with nonzero area, so there must be at least 3 points
    if(len(points)<3):
        raise Exception("not a planar shape")
    #find points with lowest and highest X coordinates
    minxp=0;
    maxxp=0;
    for i in range(len(points)):
        if(points[i][0]<points[minxp][0]):
            minxp=i;
        if(points[i][0]>points[maxxp][0]):
            maxxp=i;
    if minxp==maxxp:
        #all points are collinear
        raise Exception("not a planar shape")
    #separate points into those above and those below the minxp-maxxp line
    lpoints=[]
    rpoints=[]
    #to detemine if point X is on the left or right of dividing line A-B, compare slope of A-B to slope of A-X
    #slope is (By-Ay)/(Bx-Ax)
    a=points[minxp]
    b=points[maxxp]
    slopeab=atan2(b[1]-a[1],b[0]-a[0])
    for i in range(len(points)):
        p=points[i]
        if i == minxp or i == maxxp:
            continue
        slopep=atan2(p[1]-a[1],p[0]-a[0])
        sdiff=slopep-slopeab
        if(sdiff<pi):sdiff+=2*pi
        if(sdiff>pi):sdiff-=2*pi
        if(sdiff>0):
            lpoints+=[i]
        if(sdiff<0):
            rpoints+=[i]
    hull=[minxp]+_findhull(rpoints, maxxp, minxp, points)+[maxxp]+_findhull(lpoints, minxp, maxxp, points)
    hullo=_optimize(hull,points)
    return hullo

def _optimize(hull,points):
    #find triplets that are collinear and remove middle point
    toremove=[]
    newhull=hull[:]
    l=len(hull)
    for i in range(l):
        p1=hull[i]
        p2=hull[(i+1)%l]
        p3=hull[(i+2)%l]
        #(p1.y-p2.y)*(p1.x-p3.x)==(p1.y-p3.y)*(p1.x-p2.x)
        if (points[p1][1]-points[p2][1])*(points[p1][0]-points[p3][0])==(points[p1][1]-points[p3][1])*(points[p1][0]-points[p2][0]):
            toremove+=[p2]
    for i in toremove:
        newhull.remove(i)
    return newhull

def _distance(a, b, x):
    #find the distance between point x and line a-b
    return abs((b[1]-a[1])*x[0]-(b[0]-a[0])*x[1]+b[0]*a[1]-a[0]*b[1])/sqrt((b[1]-a[1])**2 + (b[0]-a[0])**2 );

def _findhull(idxp, a_i, b_i, points):
    #if no points in input, return no points in output
    if(len(idxp)==0):
        return [];
    #find point c furthest away from line a-b
    farpoint=-1
    fdist=-1.0;
    for i in idxp:
        d=_distance(points[a_i], points[b_i], points[i])
        if(d>fdist):
            fdist=d;
            farpoint=i
    if(fdist<=0):
        #none of the points have a positive distance from line, bad things have happened
        return []
    #separate points into those inside triangle, those outside triangle left of far point, and those outside triangle right of far point
    a=points[a_i]
    b=points[b_i]
    c=points[farpoint]
    slopeac=atan2(c[1]-a[1],c[0]-a[0])
    slopecb=atan2(b[1]-c[1],b[0]-c[0])
    lpoints=[]
    rpoints=[]
    for i in idxp:
        if i==farpoint:
            #ignore triangle vertex
            continue
        x=points[i]
        #if point x is left of line a-c it's in left set
        slopeax=atan2(x[1]-a[1],x[0]-a[0])
        if slopeac==slopeax:
            continue
        sdiff=slopeac-slopeax
        if(sdiff<-pi):sdiff+=2*pi
        if(sdiff>pi):sdiff-=2*pi
        if(sdiff<0):
            lpoints+=[i]
        else:
            #if point x is right of line b-c it's in right set, otherwise it's inside triangle and can be ignored
            slopecx=atan2(x[1]-c[1],x[0]-c[0])
            if slopecx==slopecb:
                continue
            sdiff=slopecx-slopecb
            if(sdiff<-pi):sdiff+=2*pi
            if(sdiff>pi):sdiff-=2*pi
            if(sdiff>0):
                rpoints+=[i]
    #the hull segment between points a and b consists of the hull segment between a and c, the point c, and the hull segment between c and b
    ret=_findhull(rpoints, farpoint, b_i, points)+[farpoint]+_findhull(lpoints, a_i, farpoint, points)
    return ret


def convex_hull(points):
    vertices = ConvexHull_qh(points)
    return [points[idx] for idx in vertices]