unit.c

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/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * Contributor(s): Campbell Barton
 *
 * ***** END GPL LICENSE BLOCK *****
 */

#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <assert.h>
#include "BKE_unit.h"

#include "BLI_math.h"
#include "BLI_string.h"
#include "BLI_winstuff.h"


#define TEMP_STR_SIZE 256

#define SEP_CHR     '#'
#define SEP_STR     "#"

#define EPS 0.00001

#define UN_SC_KM    1000.0f
#define UN_SC_HM    100.0f
#define UN_SC_DAM   10.0f
#define UN_SC_M     1.0f
#define UN_SC_DM    0.1f
#define UN_SC_CM    0.01f
#define UN_SC_MM    0.001f
#define UN_SC_UM    0.000001f

#define UN_SC_MI    1609.344f
#define UN_SC_FUR   201.168f
#define UN_SC_CH    20.1168f
#define UN_SC_YD    0.9144f
#define UN_SC_FT    0.3048f
#define UN_SC_IN    0.0254f
#define UN_SC_MIL   0.0000254f

#define UN_SC_MTON  1000.0f /* metric ton */
#define UN_SC_QL    100.0f
#define UN_SC_KG    1.0f
#define UN_SC_HG    0.1f
#define UN_SC_DAG   0.01f
#define UN_SC_G     0.001f

#define UN_SC_ITON  907.18474f /* imperial ton */
#define UN_SC_CWT   45.359237f
#define UN_SC_ST    6.35029318f
#define UN_SC_LB    0.45359237f
#define UN_SC_OZ    0.028349523125f

/* define a single unit */
typedef struct bUnitDef {
    const char *name;
    const char *name_plural;    /* abused a bit for the display name */
    const char *name_short; /* this is used for display*/
    const char *name_alt;       /* keyboard-friendly ASCII-only version of name_short, can be NULL */
                        /* if name_short has non-ASCII chars, name_alt should be present */
    
    const char *name_display;       /* can be NULL */

    double scalar;
    double bias;        /* not used yet, needed for converting temperature */
    int flag;
} bUnitDef;

#define B_UNIT_DEF_NONE 0
#define B_UNIT_DEF_SUPPRESS 1 /* Use for units that are not used enough to be translated into for common use */

/* define a single unit */
typedef struct bUnitCollection {
    struct bUnitDef *units;
    int base_unit;              /* basic unit index (when user doesn't specify unit explicitly) */
    int flag;                   /* options for this system */
    int length;                 /* to quickly find the last item */
} bUnitCollection;

/* Dummy */
static struct bUnitDef buDummyDef[] = {
    {"",    NULL, "",   NULL, NULL, 1.0, 0.0},
    {NULL,  NULL, NULL, NULL, NULL, 0.0, 0.0}
};
static struct bUnitCollection buDummyCollecton = {buDummyDef, 0, 0, sizeof(buDummyDef)};


/* Lengths */
static struct bUnitDef buMetricLenDef[] = {
    {"kilometer", "kilometers",     "km", NULL, "Kilometers", UN_SC_KM, 0.0,    B_UNIT_DEF_NONE},
    {"hectometer", "hectometers",   "hm", NULL, "100 Meters", UN_SC_HM, 0.0,    B_UNIT_DEF_SUPPRESS},
    {"dekameter", "dekameters",     "dam",NULL, "10 Meters",  UN_SC_DAM, 0.0,   B_UNIT_DEF_SUPPRESS},
    {"meter", "meters",             "m",  NULL, "Meters",     UN_SC_M, 0.0,     B_UNIT_DEF_NONE}, /* base unit */
    {"decimetre", "decimetres",     "dm", NULL, "10 Centimeters", UN_SC_DM, 0.0,    B_UNIT_DEF_SUPPRESS},
    {"centimeter", "centimeters",   "cm", NULL, "Centimeters", UN_SC_CM, 0.0,   B_UNIT_DEF_NONE},
    {"millimeter", "millimeters",   "mm", NULL, "Millimeters", UN_SC_MM, 0.0,   B_UNIT_DEF_NONE},
    {"micrometer", "micrometers",   "µm", "um",    "Micrometers", UN_SC_UM, 0.0,   B_UNIT_DEF_NONE}, // micron too?

    /* These get displayed because of float precision problems in the transform header,
     * could work around, but for now probably people wont use these */
    /*
    {"nanometer", "Nanometers",     "nm", NULL, 0.000000001, 0.0,   B_UNIT_DEF_NONE},
    {"picometer", "Picometers",     "pm", NULL, 0.000000000001, 0.0,B_UNIT_DEF_NONE},
    */
    {NULL, NULL, NULL,  NULL, NULL, 0.0, 0.0}
};
static struct bUnitCollection buMetricLenCollecton = {buMetricLenDef, 3, 0, sizeof(buMetricLenDef)/sizeof(bUnitDef)};

static struct bUnitDef buImperialLenDef[] = {
    {"mile", "miles",       "mi", "m", "Miles",     UN_SC_MI, 0.0,  B_UNIT_DEF_NONE},
    {"furlong", "furlongs", "fur", NULL, "Furlongs",UN_SC_FUR, 0.0, B_UNIT_DEF_SUPPRESS},
    {"chain", "chains",     "ch", NULL, "Chains",   UN_SC_CH, 0.0,  B_UNIT_DEF_SUPPRESS},
    {"yard", "yards",       "yd", NULL, "Yards",    UN_SC_YD, 0.0,  B_UNIT_DEF_NONE},
    {"foot", "feet",        "'", "ft", "Feet",      UN_SC_FT, 0.0,  B_UNIT_DEF_NONE}, /* base unit */
    {"inch", "inches",      "\"", "in", "Inches",   UN_SC_IN, 0.0,  B_UNIT_DEF_NONE},
    {"thou", "thou",        "thou", "mil", "Thou",  UN_SC_MIL, 0.0, B_UNIT_DEF_NONE}, /* plural for thou has no 's' */
    {NULL, NULL, NULL, NULL, NULL, 0.0, 0.0}
};
static struct bUnitCollection buImperialLenCollecton = {buImperialLenDef, 4, 0, sizeof(buImperialLenDef)/sizeof(bUnitDef)};

/* Areas */
static struct bUnitDef buMetricAreaDef[] = {
    {"square kilometer", "square kilometers",   "km²", "km2",  "Square Kilometers", UN_SC_KM*UN_SC_KM, 0.0,    B_UNIT_DEF_NONE},
    {"square hectometer","square hectometers",  "hm²", "hm2",  "Square Hectometers", UN_SC_HM*UN_SC_HM, 0.0,   B_UNIT_DEF_NONE}, /* hectare */
    {"square dekameter", "square dekameters",   "dam²","dam2", "Square Dekameters", UN_SC_DAM*UN_SC_DAM, 0.0,  B_UNIT_DEF_SUPPRESS}, /* are */
    {"square meter", "square meters",           "m²",  "m2",   "Square Meters", UN_SC_M*UN_SC_M, 0.0,          B_UNIT_DEF_NONE}, /* base unit */
    {"square decimetre", "square decimetres",   "dm²", "dm2",  "Square Decimetres", UN_SC_DM*UN_SC_DM, 0.0,    B_UNIT_DEF_SUPPRESS},
    {"square centimeter", "square centimeters", "cm²", "cm2",  "Square Centimeters", UN_SC_CM*UN_SC_CM, 0.0,   B_UNIT_DEF_NONE},
    {"square millimeter", "square millimeters", "mm²", "mm2",  "Square Millimeters", UN_SC_MM*UN_SC_MM, 0.0,   B_UNIT_DEF_NONE},
    {"square micrometer", "square micrometers", "µm²", "um2", "Square Micrometers", UN_SC_UM*UN_SC_UM, 0.0,   B_UNIT_DEF_NONE},
    {NULL, NULL, NULL,  NULL, NULL, 0.0, 0.0}
};
static struct bUnitCollection buMetricAreaCollecton = {buMetricAreaDef, 3, 0, sizeof(buMetricAreaDef)/sizeof(bUnitDef)};

static struct bUnitDef buImperialAreaDef[] = {
    {"square mile", "square miles",         "sq mi", "sq m","Square Miles", UN_SC_MI*UN_SC_MI, 0.0,     B_UNIT_DEF_NONE},
    {"square furlong", "square furlongs",   "sq fur",NULL,  "Square Furlongs", UN_SC_FUR*UN_SC_FUR, 0.0,B_UNIT_DEF_SUPPRESS},
    {"square chain", "square chains",       "sq ch", NULL,  "Square Chains", UN_SC_CH*UN_SC_CH, 0.0,    B_UNIT_DEF_SUPPRESS},
    {"square yard", "square yards",         "sq yd", NULL,  "Square Yards", UN_SC_YD*UN_SC_YD, 0.0,     B_UNIT_DEF_NONE},
    {"square foot", "square feet",          "sq ft", NULL,  "Square Feet", UN_SC_FT*UN_SC_FT, 0.0,      B_UNIT_DEF_NONE}, /* base unit */
    {"square inch", "square inches",        "sq in", NULL,  "Square Inches", UN_SC_IN*UN_SC_IN, 0.0,    B_UNIT_DEF_NONE},
    {"square thou", "square thous",         "sq mil",NULL,  "Square Thous", UN_SC_MIL*UN_SC_MIL, 0.0,   B_UNIT_DEF_NONE},
    {NULL, NULL, NULL, NULL, NULL, 0.0, 0.0}
};
static struct bUnitCollection buImperialAreaCollecton = {buImperialAreaDef, 4, 0, sizeof(buImperialAreaDef)/sizeof(bUnitDef)};

/* Volumes */
static struct bUnitDef buMetricVolDef[] = {
    {"cubic kilometer", "cubic kilometers",     "km³", "km3",  "Cubic Kilometers", UN_SC_KM*UN_SC_KM*UN_SC_KM, 0.0,    B_UNIT_DEF_NONE},
    {"cubic hectometer","cubic hectometers",    "hm³", "hm3",  "Cubic Hectometers", UN_SC_HM*UN_SC_HM*UN_SC_HM, 0.0,   B_UNIT_DEF_NONE},
    {"cubic dekameter", "cubic dekameters",     "dam³","dam3", "Cubic Dekameters", UN_SC_DAM*UN_SC_DAM*UN_SC_DAM, 0.0, B_UNIT_DEF_SUPPRESS},
    {"cubic meter", "cubic meters",             "m³",  "m3",   "Cubic Meters", UN_SC_M*UN_SC_M*UN_SC_M, 0.0,           B_UNIT_DEF_NONE}, /* base unit */
    {"cubic decimetre", "cubic decimetres",     "dm³", "dm3",  "Cubic Decimetres", UN_SC_DM*UN_SC_DM*UN_SC_DM, 0.0,    B_UNIT_DEF_SUPPRESS},
    {"cubic centimeter", "cubic centimeters",   "cm³", "cm3",  "Cubic Centimeters", UN_SC_CM*UN_SC_CM*UN_SC_CM, 0.0,   B_UNIT_DEF_NONE},
    {"cubic millimeter", "cubic millimeters",   "mm³", "mm3",  "Cubic Millimeters", UN_SC_MM*UN_SC_MM*UN_SC_MM, 0.0,   B_UNIT_DEF_NONE},
    {"cubic micrometer", "cubic micrometers",   "µm³", "um3", "Cubic Micrometers", UN_SC_UM*UN_SC_UM*UN_SC_UM, 0.0,   B_UNIT_DEF_NONE},
    {NULL, NULL, NULL,  NULL, NULL, 0.0, 0.0}
};
static struct bUnitCollection buMetricVolCollecton = {buMetricVolDef, 3, 0, sizeof(buMetricVolDef)/sizeof(bUnitDef)};

static struct bUnitDef buImperialVolDef[] = {
    {"cubic mile", "cubic miles",       "cu mi", "cu m","Cubic Miles", UN_SC_MI*UN_SC_MI*UN_SC_MI, 0.0,     B_UNIT_DEF_NONE},
    {"cubic furlong", "cubic furlongs", "cu fur",NULL,  "Cubic Furlongs", UN_SC_FUR*UN_SC_FUR*UN_SC_FUR, 0.0,B_UNIT_DEF_SUPPRESS},
    {"cubic chain", "cubic chains",     "cu ch", NULL,  "Cubic Chains", UN_SC_CH*UN_SC_CH*UN_SC_CH, 0.0,    B_UNIT_DEF_SUPPRESS},
    {"cubic yard", "cubic yards",       "cu yd", NULL,  "Cubic Yards", UN_SC_YD*UN_SC_YD*UN_SC_YD, 0.0,     B_UNIT_DEF_NONE},
    {"cubic foot", "cubic feet",        "cu ft", NULL,  "Cubic Feet", UN_SC_FT*UN_SC_FT*UN_SC_FT, 0.0,      B_UNIT_DEF_NONE}, /* base unit */
    {"cubic inch", "cubic inches",      "cu in", NULL,  "Cubic Inches", UN_SC_IN*UN_SC_IN*UN_SC_IN, 0.0,    B_UNIT_DEF_NONE},
    {"cubic thou", "cubic thous",       "cu mil",NULL,  "Cubic Thous", UN_SC_MIL*UN_SC_MIL*UN_SC_MIL, 0.0,  B_UNIT_DEF_NONE},
    {NULL, NULL, NULL, NULL, NULL, 0.0, 0.0}
};
static struct bUnitCollection buImperialVolCollecton = {buImperialVolDef, 4, 0, sizeof(buImperialVolDef)/sizeof(bUnitDef)};

/* Mass */
static struct bUnitDef buMetricMassDef[] = {
    {"ton", "tonnes",           "ton", "t", "1000 Kilograms", UN_SC_MTON, 0.0,  B_UNIT_DEF_NONE},
    {"quintal", "quintals",     "ql", "q",  "100 Kilograms", UN_SC_QL, 0.0,     B_UNIT_DEF_NONE},
    {"kilogram", "kilograms",   "kg", NULL, "Kilograms", UN_SC_KG, 0.0,         B_UNIT_DEF_NONE}, /* base unit */
    {"hectogram", "hectograms", "hg", NULL, "Hectograms", UN_SC_HG, 0.0,        B_UNIT_DEF_NONE},
    {"dekagram", "dekagrams",   "dag",NULL, "10 Grams", UN_SC_DAG, 0.0,         B_UNIT_DEF_SUPPRESS},
    {"gram", "grams",           "g",  NULL, "Grams", UN_SC_G, 0.0,              B_UNIT_DEF_NONE},
    {NULL, NULL, NULL,  NULL, NULL, 0.0, 0.0}
};
static struct bUnitCollection buMetricMassCollecton = {buMetricMassDef, 2, 0, sizeof(buMetricMassDef)/sizeof(bUnitDef)};

static struct bUnitDef buImperialMassDef[] = {
    {"ton", "tonnes",   "ton", "t", "Tonnes", UN_SC_ITON, 0.0,      B_UNIT_DEF_NONE},
    {"centum weight", "centum weights", "cwt", NULL, "Centum weights", UN_SC_CWT, 0.0, B_UNIT_DEF_NONE},
    {"stone", "stones", "st", NULL,     "Stones", UN_SC_ST, 0.0,    B_UNIT_DEF_NONE},
    {"pound", "pounds", "lb", NULL,     "Pounds", UN_SC_LB, 0.0,    B_UNIT_DEF_NONE}, /* base unit */
    {"ounce", "ounces", "oz", NULL,     "Ounces", UN_SC_OZ, 0.0,    B_UNIT_DEF_NONE},
    {NULL, NULL, NULL, NULL, NULL, 0.0, 0.0}
};
static struct bUnitCollection buImperialMassCollecton = {buImperialMassDef, 3, 0, sizeof(buImperialMassDef)/sizeof(bUnitDef)};

/* Even if user scales the system to a point where km^3 is used, velocity and
 * acceleration aren't scaled: that's why we have so few units for them */

/* Velocity */
static struct bUnitDef buMetricVelDef[] = {
    {"meter per second", "meters per second",       "m/s",  NULL,   "Meters per second", UN_SC_M, 0.0,            B_UNIT_DEF_NONE}, /* base unit */
    {"kilometer per hour", "kilometers per hour",   "km/h", NULL,   "Kilometers per hour", UN_SC_KM/3600.0f, 0.0, B_UNIT_DEF_SUPPRESS},
    {NULL, NULL, NULL,  NULL, NULL, 0.0, 0.0}
};
static struct bUnitCollection buMetricVelCollecton = {buMetricVelDef, 0, 0, sizeof(buMetricVelDef)/sizeof(bUnitDef)};

static struct bUnitDef buImperialVelDef[] = {
    {"foot per second", "feet per second",  "ft/s", "fps",  "Feet per second", UN_SC_FT, 0.0,       B_UNIT_DEF_NONE}, /* base unit */
    {"mile per hour", "miles per hour",     "mph", NULL,    "Miles per hour", UN_SC_MI/3600.0f, 0.0,B_UNIT_DEF_SUPPRESS},
    {NULL, NULL, NULL, NULL, NULL, 0.0, 0.0}
};
static struct bUnitCollection buImperialVelCollecton = {buImperialVelDef, 0, 0, sizeof(buImperialVelDef)/sizeof(bUnitDef)};

/* Acceleration */
static struct bUnitDef buMetricAclDef[] = {
    {"meter per second squared", "meters per second squared", "m/s²", "m/s2", "Meters per second squared", UN_SC_M, 0.0, B_UNIT_DEF_NONE}, /* base unit */
    {NULL, NULL, NULL,  NULL, NULL, 0.0, 0.0}
};
static struct bUnitCollection buMetricAclCollecton = {buMetricAclDef, 0, 0, sizeof(buMetricAclDef)/sizeof(bUnitDef)};

static struct bUnitDef buImperialAclDef[] = {
    {"foot per second squared", "feet per second squared", "ft/s²", "ft/s2", "Feet per second squared", UN_SC_FT, 0.0, B_UNIT_DEF_NONE}, /* base unit */
    {NULL, NULL, NULL, NULL, NULL, 0.0, 0.0}
};
static struct bUnitCollection buImperialAclCollecton = {buImperialAclDef, 0, 0, sizeof(buImperialAclDef)/sizeof(bUnitDef)};

/* Time */
static struct bUnitDef buNaturalTimeDef[] = {
    /* weeks? - probably not needed for blender */
    {"day", "days",                 "d", NULL,  "Days",         90000.0, 0.0,   B_UNIT_DEF_NONE},
    {"hour", "hours",               "hr", "h",  "Hours",        3600.0, 0.0,    B_UNIT_DEF_NONE},
    {"minute", "minutes",           "min", "m", "Minutes",      60.0, 0.0,      B_UNIT_DEF_NONE},
    {"second", "seconds",           "sec", "s", "Seconds",      1.0, 0.0,       B_UNIT_DEF_NONE}, /* base unit */
    {"millisecond", "milliseconds", "ms", NULL, "Milliseconds", 0.001, 0.0  ,   B_UNIT_DEF_NONE},
    {"microsecond", "microseconds", "µs", "us",    "Microseconds", 0.000001, 0.0,  B_UNIT_DEF_NONE},
    {NULL, NULL, NULL, NULL, NULL, 0.0, 0.0}
};
static struct bUnitCollection buNaturalTimeCollecton = {buNaturalTimeDef, 3, 0, sizeof(buNaturalTimeDef)/sizeof(bUnitDef)};


static struct bUnitDef buNaturalRotDef[] = {
    {"degree", "degrees",           "°", NULL, "Degrees",      M_PI/180.0, 0.0,    B_UNIT_DEF_NONE},
//  {"radian", "radians",           "r", NULL, "Radians",       1.0, 0.0,           B_UNIT_DEF_NONE},
//  {"turn", "turns",               "t", NULL, "Turns",         1.0/(M_PI*2.0), 0.0,B_UNIT_DEF_NONE},
    {NULL, NULL, NULL, NULL, NULL, 0.0, 0.0}
};
static struct bUnitCollection buNaturalRotCollection = {buNaturalRotDef, 0, 0, sizeof(buNaturalRotDef)/sizeof(bUnitDef)};

#define UNIT_SYSTEM_TOT (((sizeof(bUnitSystems) / 9) / sizeof(void *)) - 1)
static struct bUnitCollection *bUnitSystems[][9] = {
    {NULL, NULL, NULL, NULL, NULL, &buNaturalRotCollection, &buNaturalTimeCollecton, NULL, NULL},
    {NULL, &buMetricLenCollecton, &buMetricAreaCollecton, &buMetricVolCollecton, &buMetricMassCollecton, &buNaturalRotCollection, &buNaturalTimeCollecton, &buMetricVelCollecton, &buMetricAclCollecton}, /* metric */
    {NULL, &buImperialLenCollecton, &buImperialAreaCollecton, &buImperialVolCollecton, &buImperialMassCollecton, &buNaturalRotCollection, &buNaturalTimeCollecton, &buImperialVelCollecton, &buImperialAclCollecton}, /* imperial */
    {NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL}
};



/* internal, has some option not exposed */
static bUnitCollection *unit_get_system(int system, int type)
{
    assert((system > -1) && (system < UNIT_SYSTEM_TOT) && (type > -1) && (type < B_UNIT_TYPE_TOT));
    return bUnitSystems[system][type]; /* select system to use, metric/imperial/other? */
}

static bUnitDef *unit_default(bUnitCollection *usys)
{
    return &usys->units[usys->base_unit];
}

static bUnitDef *unit_best_fit(double value, bUnitCollection *usys, bUnitDef *unit_start, int suppress)
{
    bUnitDef *unit;
    double value_abs= value>0.0?value:-value;

    for(unit= unit_start ? unit_start:usys->units; unit->name; unit++) {

        if(suppress && (unit->flag & B_UNIT_DEF_SUPPRESS))
            continue;

        /* scale down scalar so 1cm doesnt convert to 10mm because of float error */
        if (value_abs >= unit->scalar*(1.0-EPS))
            return unit;
    }

    return unit_default(usys);
}



/* convert into 2 units and 2 values for "2ft, 3inch" syntax */
static void unit_dual_convert(double value, bUnitCollection *usys,
        bUnitDef **unit_a, bUnitDef **unit_b, double *value_a, double *value_b)
{
    bUnitDef *unit= unit_best_fit(value, usys, NULL, 1);

    *value_a=  (value < 0.0 ? ceil:floor)(value/unit->scalar) * unit->scalar;
    *value_b= value - (*value_a);

    *unit_a=    unit;
    *unit_b=    unit_best_fit(*value_b, usys, *unit_a, 1);
}

static int unit_as_string(char *str, int len_max, double value, int prec, bUnitCollection *usys,
        /* non exposed options */
        bUnitDef *unit, char pad)
{
    double value_conv;
    int len, i;
    
    if(unit) {
        /* use unit without finding the best one */
    }
    else if(value == 0.0) {
        /* use the default units since there is no way to convert */
        unit= unit_default(usys);
    }
    else {
        unit= unit_best_fit(value, usys, NULL, 1);
    }

    value_conv= value/unit->scalar;

    /* Convert to a string */
    {
        len= BLI_snprintf(str, len_max, "%.*f", prec, value_conv);

        if(len >= len_max)
            len= len_max;
    }
    
    /* Add unit prefix and strip zeros */

    /* replace trailing zero's with spaces
     * so the number is less complicated but allignment in a button wont
     * jump about while dragging */
    i= len-1;

    while(i>0 && str[i]=='0') { /* 4.300 -> 4.3 */
        str[i--]= pad;
    }

    if(i>0 && str[i]=='.') { /* 10. -> 10 */
        str[i--]= pad;
    }
    
    /* Now add the suffix */
    if(i<len_max) {
        int j=0;
        i++;
        while(unit->name_short[j] && (i < len_max)) {
            str[i++]= unit->name_short[j++];
        }

        if(pad) {
            /* this loop only runs if so many zeros were removed that
             * the unit name only used padded chars,
             * In that case add padding for the name. */

            while(i<=len+j && (i < len_max)) {
                str[i++]= pad;
            }
        }
    }

    /* terminate no matter whats done with padding above */
    if(i >= len_max)
        i= len_max-1;

    str[i] = '\0';
    return i;
}


/* Used for drawing number buttons, try keep fast */
void bUnit_AsString(char *str, int len_max, double value, int prec, int system, int type, int split, int pad)
{
    bUnitCollection *usys = unit_get_system(system, type);

    if(usys==NULL || usys->units[0].name==NULL)
        usys= &buDummyCollecton;
   
    /* split output makes sense only for length, mass and time */
    if(split && (type==B_UNIT_LENGTH || type==B_UNIT_MASS || type==B_UNIT_TIME)) {
        bUnitDef *unit_a, *unit_b;
        double value_a, value_b;

        unit_dual_convert(value, usys,      &unit_a, &unit_b, &value_a, &value_b);

        /* check the 2 is a smaller unit */
        if(unit_b > unit_a) {
            int i= unit_as_string(str, len_max, value_a, prec, usys,  unit_a, '\0');

            /* is there enough space for at least 1 char of the next unit? */
            if(i+2 < len_max) {
                str[i++]= ' ';

                /* use low precision since this is a smaller unit */
                unit_as_string(str+i, len_max-i, value_b, prec?1:0, usys,  unit_b, '\0');
            }
            return;
        }
    }

    unit_as_string(str, len_max, value, prec, usys,    NULL, pad?' ':'\0');
}


static const char *unit_find_str(const char *str, const char *substr)
{
    const char *str_found;

    if(substr && substr[0] != '\0') {
        str_found= strstr(str, substr);
        if(str_found) {
            /* previous char cannot be a letter */
            if (str_found == str || isalpha(*(str_found-1))==0) {
                /* next char cannot be alphanum */
                int len_name = strlen(substr);

                if (!isalpha(*(str_found+len_name))) {
                    return str_found;
                }
            }
        }

    }
    return NULL;

}

/* Note that numbers are added within brackets
 * ") " - is used to detect numbers we added so we can detect if commas need to be added
 *
 * "1m1cm+2mm"              - Original value
 * "1*1#1*0.01#+2*0.001#"   - Replace numbers
 * "1*1,1*0.01 +2*0.001 "   - Add comma's if ( - + * / % ^ < > ) not found in between
 *
 */

/* not too strict, (- = * /) are most common  */
static int ch_is_op(char op)
{
    switch(op) {
    case '+':
    case '-':
    case '*':
    case '/':
    case '|':
    case '&':
    case '~':
    case '<':
    case '>':
    case '^':
    case '!':
    case '=':
    case '%':
        return 1;
    default:
        return 0;
    }
}

static int unit_scale_str(char *str, int len_max, char *str_tmp,
                          double scale_pref, bUnitDef *unit, const char *replace_str)
{
    char *str_found;

    if((len_max>0) && (str_found= (char *)unit_find_str(str, replace_str))) {
        /* XXX - investigate, does not respect len_max properly  */

        int len, len_num, len_name, len_move, found_ofs;

        found_ofs = (int)(str_found-str);

        len= strlen(str);

        len_name = strlen(replace_str);
        len_move= (len - (found_ofs+len_name)) + 1; /* 1+ to copy the string terminator */
        len_num= BLI_snprintf(str_tmp, TEMP_STR_SIZE, "*%g"SEP_STR, unit->scalar/scale_pref); /* # removed later */

        if(len_num > len_max)
            len_num= len_max;

        if(found_ofs+len_num+len_move > len_max) {
            /* can't move the whole string, move just as much as will fit */
            len_move -= (found_ofs+len_num+len_move) - len_max;
        }

        if(len_move>0) {
            /* resize the last part of the string */
            memmove(str_found+len_num, str_found+len_name, len_move); /* may grow or shrink the string */
        }

        if(found_ofs+len_num > len_max) {
            /* not even the number will fit into the string, only copy part of it */
            len_num -= (found_ofs+len_num) - len_max;
        }

        if(len_num > 0) {
            /* its possible none of the number could be copied in */
            memcpy(str_found, str_tmp, len_num); /* without the string terminator */
        }

        /* since the null terminator wont be moved if the stringlen_max
         * was not long enough to fit everything in it */
        str[len_max-1]= '\0';
        return found_ofs + len_num;
    }
    return 0;
}

static int unit_replace(char *str, int len_max, char *str_tmp, double scale_pref, bUnitDef *unit)
{   
    int ofs= 0;
    ofs += unit_scale_str(str+ofs, len_max-ofs, str_tmp, scale_pref, unit, unit->name_short);
    ofs += unit_scale_str(str+ofs, len_max-ofs, str_tmp, scale_pref, unit, unit->name_plural);
    ofs += unit_scale_str(str+ofs, len_max-ofs, str_tmp, scale_pref, unit, unit->name_alt);
    ofs += unit_scale_str(str+ofs, len_max-ofs, str_tmp, scale_pref, unit, unit->name);
    return ofs;
}

static int unit_find(const char *str, bUnitDef *unit)
{
    if (unit_find_str(str, unit->name_short))   return 1;
    if (unit_find_str(str, unit->name_plural))  return 1;
    if (unit_find_str(str, unit->name_alt))     return 1;
    if (unit_find_str(str, unit->name))         return 1;

    return 0;
}

/* make a copy of the string that replaces the units with numbers
 * this is used before parsing
 * This is only used when evaluating user input and can afford to be a bit slower
 * 
 * This is to be used before python evaluation so..
 * 10.1km -> 10.1*1000.0
 * ...will be resolved by python.
 * 
 * values will be split by a comma's
 * 5'2" -> 5'0.0254, 2*0.3048
 *
 * str_prev is optional, when valid it is used to get a base unit when none is set.
 *
 * return true of a change was made.
 */
int bUnit_ReplaceString(char *str, int len_max, const char *str_prev, double scale_pref, int system, int type)
{
    bUnitCollection *usys = unit_get_system(system, type);

    bUnitDef *unit;
    char str_tmp[TEMP_STR_SIZE];
    int change= 0;

    if(usys==NULL || usys->units[0].name==NULL) {
        return 0;
    }
    

    {   /* make lowercase */
        int i;
        char *ch= str;

        for(i=0; (i>=len_max || *ch=='\0'); i++, ch++)
            if((*ch>='A') && (*ch<='Z'))
                *ch += ('a'-'A');
    }


    for(unit= usys->units; unit->name; unit++) {
        /* incase there are multiple instances */
        while(unit_replace(str, len_max, str_tmp, scale_pref, unit))
            change= 1;
    }
    unit= NULL;

    {
        /* try other unit systems now, so we can evaluate imperial when metric is set for eg. */
        bUnitCollection *usys_iter;
        int system_iter;

        for(system_iter= 0; system_iter<UNIT_SYSTEM_TOT; system_iter++) {
            if (system_iter != system) {
                usys_iter= unit_get_system(system_iter, type);
                if (usys_iter) {
                    for(unit= usys_iter->units; unit->name; unit++) {
                        int ofs = 0;
                        /* incase there are multiple instances */
                        while((ofs=unit_replace(str+ofs, len_max-ofs, str_tmp, scale_pref, unit)))
                            change= 1;
                    }
                }
            }
        }
    }
    unit= NULL;
    
    if(change==0) {
        /* no units given so infer a unit from the previous string or default */
        if(str_prev) {
            /* see which units the original value had */
            for(unit= usys->units; unit->name; unit++) {
                if (unit_find(str_prev, unit))
                    break;
            }
        }

        if(unit==NULL || unit->name == NULL)
            unit= unit_default(usys);


        /* add the unit prefix and re-run, use brackets incase there was an expression given */
        if(BLI_snprintf(str_tmp, sizeof(str_tmp), "(%s)%s", str, unit->name) < sizeof(str_tmp)) {
            strncpy(str, str_tmp, len_max);
            return bUnit_ReplaceString(str, len_max, NULL, scale_pref, system, type);
        }
        else {
            /* BLI_snprintf would not fit into str_tmp, cant do much in this case
             * check for this because otherwise bUnit_ReplaceString could call its self forever */
            return 0;
        }

    }

    /* replace # with commas when there is no operator between it and the next number
     *
     * "1*1# 3*100# * 3"  ->  "1 *1, 3 *100  * 3"
     *
     * */
    {
        char *str_found= str;
        char *ch= str;

        while((str_found= strchr(str_found, SEP_CHR))) {

            int op_found= 0;
            /* any operators after this?*/
            for(ch= str_found+1; *ch!='\0'; ch++) {

                if(*ch==' ' || *ch=='\t') {
                    /* do nothing */
                }
                else if (ch_is_op(*ch) || *ch==',') { /* found an op, no need to insert a ,*/
                    op_found= 1;
                    break;
                }
                else { /* found a non-op character */
                    op_found= 0;
                    break;
                }
            }

            *str_found++ = op_found ? ' ':',';
        }
    }

    return change;
}

/* 45µm --> 45um */
void bUnit_ToUnitAltName(char *str, int len_max, const char *orig_str, int system, int type)
{
    bUnitCollection *usys = unit_get_system(system, type);

    bUnitDef *unit;
    bUnitDef *unit_def= unit_default(usys);

    /* find and substitute all units */
    for(unit= usys->units; unit->name; unit++) {
        if(len_max > 0 && (unit->name_alt || unit == unit_def))
        {
            const char *found= unit_find_str(orig_str, unit->name_short);
            if(found) {
                int offset= (int)(found - orig_str);
                int len_name= 0;

                /* copy everything before the unit */
                offset= (offset<len_max? offset: len_max);
                strncpy(str, orig_str, offset);

                str+= offset;
                orig_str+= offset + strlen(unit->name_short);
                len_max-= offset;

                /* print the alt_name */
                if(unit->name_alt)
                    len_name= BLI_snprintf(str, len_max, "%s", unit->name_alt);
                else
                    len_name= 0;

                len_name= (len_name<len_max? len_name: len_max);
                str+= len_name;
                len_max-= len_name;
            }
        }
    }

    /* finally copy the rest of the string */
    strncpy(str, orig_str, len_max);
}

double bUnit_ClosestScalar(double value, int system, int type)
{
    bUnitCollection *usys = unit_get_system(system, type);
    bUnitDef *unit;

    if(usys==NULL)
        return -1;

    unit= unit_best_fit(value, usys, NULL, 1);
    if(unit==NULL)
        return -1;

    return unit->scalar;
}

double bUnit_BaseScalar(int system, int type)
{
    bUnitCollection *usys = unit_get_system(system, type);
    return unit_default(usys)->scalar;
}

/* external access */
int bUnit_IsValid(int system, int type)
{
    return !(system < 0 || system > UNIT_SYSTEM_TOT || type < 0 || type > B_UNIT_TYPE_TOT);
}


void bUnit_GetSystem(void **usys_pt, int *len, int system, int type)
{
    bUnitCollection *usys = unit_get_system(system, type);
    *usys_pt= usys;

    if(usys==NULL) {
        *len= 0;
        return;
    }

    *len= usys->length;
}

int bUnit_GetBaseUnit(void *usys_pt)
{
    return ((bUnitCollection *)usys_pt)->base_unit;
}

const char *bUnit_GetName(void *usys_pt, int index)
{
    return ((bUnitCollection *)usys_pt)->units[index].name;
}
const char *bUnit_GetNameDisplay(void *usys_pt, int index)
{
    return ((bUnitCollection *)usys_pt)->units[index].name_display;
}

double bUnit_GetScaler(void *usys_pt, int index)
{
    return ((bUnitCollection *)usys_pt)->units[index].scalar;
}