gwyutils (HEAD)

gwyutils — Various utility functions

Functions

Types and Values

Includes

#include <libgwyddion/gwyddion.h>

Description

Various utility functions: creating GLib lists from hash tables gwy_hash_table_to_list_cb()), protably finding Gwyddion application directories (gwy_find_self_dir()), string functions (gwy_strreplace()), path manipulation (gwy_canonicalize_path()).

Functions

GwySetFractionFunc ()

gboolean
(*GwySetFractionFunc) (gdouble fraction);

Type of function for reporting progress of a long computation.

Usually you want to use gwy_app_wait_set_fraction().

Parameters

Returns

TRUE if the computation should continue; FALSE if it should be cancelled.

GwySetMessageFunc ()

gboolean
(*GwySetMessageFunc) (const gchar *message);

Type of function for reporting what a long computation is doing now.

Usually you want to use gwy_app_wait_set_message().

Parameters

Returns

TRUE if the computation should continue; FALSE if it should be cancelled.

gwy_parse_doubles_error_quark ()

GQuark
gwy_parse_doubles_error_quark (void);

Returns error domain for floating point value parsing and evaluation.

See and use GWY_PARSE_DOUBLES_ERROR.

Returns

The error domain.

Since: 2.64

gwy_hash_table_to_slist_cb ()

void
gwy_hash_table_to_slist_cb (gpointer unused_key,
                            gpointer value,
                            gpointer user_data);

GHashTable to GSList convertor.

Usble in g_hash_table_foreach(), pass a pointer to a GSList* as user data to it.

Parameters

gwy_hash_table_to_list_cb ()

void
gwy_hash_table_to_list_cb (gpointer unused_key,
                           gpointer value,
                           gpointer user_data);

GHashTable to GList convertor.

Usble in g_hash_table_foreach(), pass a pointer to a GList* as user data to it.

Parameters

gwy_strkill ()

gchar *
gwy_strkill (gchar *s,
             const gchar *killchars);

Removes characters in killchars from string s , modifying it in place.

Use gwy_strkill(g_strdup(s ), killchars ) to get a modified copy.

Parameters

Returns

s itself, the return value is to allow function call nesting.

gwy_strreplace ()

gchar *
gwy_strreplace (const gchar *haystack,
                const gchar *needle,
                const gchar *replacement,
                gsize maxrepl);

Replaces occurences of string needle in haystack with replacement .

See gwy_gstring_replace() for a function which does in-place replacement on a GString.

Parameters

Returns

A newly allocated string.

gwy_strdiffpos ()

gint
gwy_strdiffpos (const gchar *s1,
                const gchar *s2);

Finds position where two strings differ.

Parameters

Returns

The last position where the strings do not differ yet. Possibly -1 can be returned if either string is NULL, zero-length, or they differ in the very first character.

gwy_strisident ()

gboolean
gwy_strisident (const gchar *s,
                const gchar *more,
                const gchar *startmore);

Checks whether a string is valid identifier.

Valid identifier must start with an alphabetic character or a character from startmore , and it must continue with alphanumeric characters or characters from more .

Note underscore is not allowed by default, you have to pass it in more and/or startmore .

Parameters

Returns

TRUE if s is valid identifier, FALSE otherwise.

gwy_ascii_strcase_equal ()

gboolean
gwy_ascii_strcase_equal (gconstpointer v1,
                         gconstpointer v2);

Compares two strings for equality, ignoring case.

The case folding is performed only on ASCII characters.

This function is intended to be passed to g_hash_table_new() as key_equal_func , namely in conjuction with gwy_ascii_strcase_hash() hashing function.

Parameters

Returns

TRUE if the two string keys match, ignoring case.

Since: 2.26

gwy_ascii_strcase_hash ()

guint
gwy_ascii_strcase_hash (gconstpointer v);

Converts a string to a hash value, ignoring case.

The case folding is performed only on ASCII characters.

This function is intended to be passed to g_hash_table_new() as hash_func , namely in conjuction with gwy_ascii_strcase_equal() comparison function.

Parameters

Returns

The hash value corresponding to the key v .

Since: 2.26

gwy_stramong ()

guint
gwy_stramong (const gchar *str,
              ...);

Checks whether a string is equal to any from given list.

Parameters

Returns

Zero if str does not equal to any string from the list, nozero othwerise. More precisely, the position

• 1 of the first string str equals to is returned in the latter case.

Since: 2.11

gwy_memmem ()

gpointer
gwy_memmem (gconstpointer haystack,
            gsize haystack_len,
            gconstpointer needle,
            gsize needle_len);

Find a block of memory in another block of memory.

This function is very similar to strstr(), except that it works with arbitrary memory blocks instead of NUL-terminated strings.

If needle_len is zero, haystack is always returned.

On GNU systems with glibc at least 2.1 this is a just a trivial memmem() wrapper. On other systems it emulates memmem() behaviour but may be a bit slower.

Parameters

Returns

Pointer to the first byte of memory block in haystack that matches needle ; NULL if no such block exists.

Since: 2.12

gwy_file_get_contents ()

gboolean
gwy_file_get_contents (const gchar *filename,
                       guchar **buffer,
                       gsize *size,
                       GError **error);

Reads or mmaps file filename into memory.

The buffer must be treated as read-only and must be freed with gwy_file_abandon_contents(). It is NOT guaranteed to be NUL-terminated, use size to find its end.

Parameters

Returns

Whether it succeeded. In case of failure buffer and size are reset too.

gwy_file_abandon_contents ()

gboolean
gwy_file_abandon_contents (guchar *buffer,
                           gsize size,
                           GError **error);

Frees or unmmaps memory allocated by gwy_file_get_contents().

Parameters

Returns

Whether it succeeded. Since 2.22 it always return TRUE.

gwy_find_self_dir ()

gchar *
gwy_find_self_dir (const gchar *dirname);

Finds a system Gwyddion directory.

On Unix, a compiled-in path is returned, unless it's overriden with environment variables (see gwyddion manual page).

On Win32, the directory where the libgwyddion DLL from which this function was called resides is taken as the base and the location of other Gwyddion directories is calculated from it.

The returned value is not actually tested for existence, it's up to caller.

To obtain the Gwyddion user directory see gwy_get_user_dir().

Parameters

Returns

The path as a newly allocated string.

gwy_get_user_dir ()

const gchar *
gwy_get_user_dir (void);

Returns the directory where Gwyddion user settings and data should be stored.

On Unix this is usually a dot-directory in user's home directory. On modern Win32 the returned directory resides in user's Documents and Settings. On silly platforms or silly occasions, silly locations (namely a temporary directory) can be returned as fallback.

To obtain a Gwyddion system directory see gwy_find_self_dir().

Returns

The directory as a constant string that should not be freed.

gwy_get_home_dir ()

const gchar *
gwy_get_home_dir (void);

Returns home directory, or temporary directory as a fallback.

Under normal circumstances the same string as g_get_home_dir() would return is returned. But on MS Windows, something like "C:\Windows\Temp" can be returned too, as it is as good as anything else (we can write there).

Returns

Something usable as user home directory. It may be silly, but never NULL or empty.

gwy_canonicalize_path ()

gchar *
gwy_canonicalize_path (const gchar *path);

Canonicalizes a filesystem path.

Particularly it makes the path absolute, resolves ..' and .', and fixes slash sequences to single slashes. On Win32 it also converts all backslashes to slashes along the way.

Note this function does NOT resolve symlinks, use g_file_read_link() for that.

Parameters

Returns

The canonical path, as a newly created string.

gwy_filename_ignore ()

gboolean
gwy_filename_ignore (const gchar *filename_sys);

Checks whether file should be ignored.

This function checks for common file names indicating files that should be normally ignored. Currently it means backup files (ending with ~ or .bak) and Unix hidden files (starting with a dot).

Parameters

Returns

TRUE to ignore this file, FALSE otherwise.

gwy_sgettext ()

gchar *
gwy_sgettext (const gchar *msgid);

Translate a message id containing disambiguating prefix ending with `|'.

Parameters

Returns

Translated message, or msgid itself with all text up to the last `|' removed if there is no translation.

gwy_str_next_line ()

gchar *
gwy_str_next_line (gchar **buffer);

Extracts a next line from a character buffer, modifying it in place.

buffer is updated to point after the end of the line and the "\n" (or "\r" or "\r\n") is replaced with "\0", if present.

The final line may or may not be terminated with an EOL marker, its contents is returned in either case. Note, however, that the empty string "" is not interpreted as an empty unterminated line. Instead, NULL is immediately returned.

The typical usage of gwy_str_next_line() is:

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gchar *p = text;
for (gchar *line = gwy_str_next_line(&p);
     line;
     line = gwy_str_next_line(&p)) {
    g_strstrip(line);
    // Do something more with line
}

Parameters

Returns

The start of the line. NULL if the buffer is empty or NULL. The return value is not a new string; the normal return value is the previous value of buffer .

gwy_str_fixed_font_width ()

guint
gwy_str_fixed_font_width (const gchar *str);

Measures the width of UTF-8 encoded string in fixed-width font.

This corresponds to width of the string displayed on a text terminal, for instance. Zero and double width characters are taken into account. It is not guaranteed all terminals display the string with the calculated width.

Parameters

Returns

String width in fixed font, in character cells.

Since: 2.52

gwy_gstring_replace ()

guint
gwy_gstring_replace (GString *str,
                     const gchar *old,
                     const gchar *replacement,
                     gint count);

Replaces non-overlapping occurrences of one string with another in a GString.

Passing NULL or the empty string for replacement will cause the occurrences of old to be removed.

Passing NULL or the empty string for old means a match occurs at every position in the string, including after the last character. So replacement will be inserted at every position in this case.

See gwy_strreplace() for a function which creates a new plain C string with substring replacement.

Parameters

Returns

The number of replacements made. A non-zero value means the string has been modified, no-op replacements do not count.

Since: 2.36

gwy_gstring_to_native_eol ()

void
gwy_gstring_to_native_eol (GString *str);

Converts "\n" in a string to operating system native line terminators.

Text files are most easily written by opening them in the text mode. This function can be useful for writing text files using functions such as g_file_set_contents() that do not permit the conversion to happen automatically.

It is a no-op on all POSIX systems, including OS X. So at present, it actually performs any conversion at all only on MS Windows.

Parameters

Since: 2.36

gwy_get_decimal_separator ()

const gchar *
gwy_get_decimal_separator (void);

Find the decimal separator for the current locale.

This is a localeconv() wrapper.

Returns

The decimal separator for the current locale as a static string.

Since: 2.63

gwy_append_doubles_to_gstring ()

void
gwy_append_doubles_to_gstring (GString *str,
                               const gdouble *values,
                               guint n,
                               gint precision,
                               const gchar *field_separator,
                               gboolean force_decimal_dot);

Formats a sequence of double values to a GString.

Parameters

Since: 2.63

gwy_parse_doubles ()

gdouble *
gwy_parse_doubles (const gchar *s,
                   gdouble *values,
                   GwyParseDoublesFlags flags,
                   gint *nlines,
                   gint *ncols,
                   gchar **endptr,
                   GError **error);

Parse a block of text floating point values.

Any combinations of a priori known and unknown dimensions is possible. For an unknown number of columns the number of columns must still be the same on each line, unless the flag GWY_PARSE_DOUBLES_FREE_FORM is passed. If any dimension is unknown, values cannot be preallocated as must be NULL.

Currently the values must be whitespace separated and in the POSIX format.

Parameters

Returns

On success, either values (if non-NULL values was passed) or a newly allocated array with the data. On failure, NULL is returned.

Since: 2.64

gwy_memcpy_byte_swap ()

void
gwy_memcpy_byte_swap (const guint8 *source,
                      guint8 *dest,
                      gsize item_size,
                      gsize nitems,
                      gsize byteswap);

Copies a block of memory swapping bytes along the way.

The bits in byteswap correspond to groups of bytes to swap: if j-th bit is set, adjacent groups of 2j bits are swapped. For example, value 3 means items will be divided into couples (bit 1) of bytes and adjacent couples of bytes swapped, and then divided into single bytes (bit 0) and adjacent bytes swapped. The net effect is reversal of byte order in groups of four bytes. More generally, if you want to reverse byte order in groups of size 2^j, use byte swap pattern j-1.

When byteswap is zero, this function reduces to plain memcpy().

Parameters

Since: 2.1

gwy_convert_raw_data ()

void
gwy_convert_raw_data (gconstpointer data,
                      gsize nitems,
                      gssize stride,
                      GwyRawDataType datatype,
                      GwyByteOrder byteorder,
                      gdouble *target,
                      gdouble scale,
                      gdouble offset);

Converts a block of raw data items to doubles.

Note that conversion from 64bit integral types may lose information as they have more bits than the mantissa of doubles. All other conversions should be exact.

For backward reading, pass -1 (or other negative value) as stride and point data to the last raw item instead of the first. More precisely, data must point to the first byte of the last raw value, not to the very last byte (for most data sizes this is intuitive, but 12bit data may involve some head scracthing). Zero stride is also allowed and results in target being filled with a constant value.

If the raw data size is not a whole number of bytes, parameter byteorder gives the order in which the pieces are packed into bytes. However, the usual order is to start from the high bits regardless of the machine endianness, so you normally always pass GWY_BYTE_ORDER_BIG_ENDIAN for fractional sized data.

For 12bit data only the big endian variant is defined at present. It means always storing the highest remaining bits of the 12bit value to the highest available bits of the byte, as TIFF and various cameras normally do.

For fractional sized data parameter stride specifies both the stride (always measured in raw values) and starting position within the first byte:

• For 1bit data stride is equal to 8S + R, where S is the actual stride. R = 0 means start conversion from the first bit and R = 1 from the second bit, …, up to R = 7 meaning starting from the last bit (which one is first depends on byteorder).
• For 4bit data stride is equal to 2S + R, where S is the actual stride. R = 0 means start conversion from the first nibble and R = 1 from the second nibble (which one is first depends on byteorder).
• For 12bit data stride is equal to 2S + R, where S is the actual stride. R = 0 means the conversion starts from a value split 8+4 (in forward direction), whereas R = 1 means the conversion starts from the value split 4+8.
• R is always positive and its meaning does not change for negative S.

For example, consider conversion of 3 nibbles of 4bit data (in the usual big endian order). This is how they will be read to the output:

• [0 1] [2 .] [. .] for R = 0, S = 1 (stride = 2), starting from the first byte.
• [. 0] [1 2] [. .] for R = 1, S = 1 (stride = 3), starting from the first byte.
• [0 .] [1 .] [2 .] for R = 0, S = 2 (stride = 4), starting from the first byte.
• [. .] [. 2] [1 0] for R = 1, S = -1 (stride = -1), starting from the last byte.
• [. .] [2 1] [0 .] for R = 0, S = -1 (stride = -2), starting from the last byte.

Parameters

Since: 2.25

gwy_raw_data_size ()

guint
gwy_raw_data_size (GwyRawDataType datatype);

Reports the size of a single raw data item in bytes.

For raw data types which are not whole bytes (whether smaller or larger, like 12bit), zero is returned. Use gwy_raw_data_size_bits() to get the size in bits.

Parameters

Returns

The size (in bytes) of a single raw data item of type datatype .

Since: 2.25

gwy_raw_data_size_bits ()

guint
gwy_raw_data_size_bits (GwyRawDataType datatype);

Reports the size of a single raw data item in bits.

If the data type is known to be whole bytes, gwy_raw_data_size() is usually simpler to use.

Parameters

Returns

The size (in bits) of a single raw data item of type datatype .

Since: 2.67

gwy_convert_to_utf8 ()

gchar *
gwy_convert_to_utf8 (const guchar *str,
                     glong len,
                     const gchar *codeset);

Converts a string to UTF-8.

This is a g_convert() wrapper for the typical SPM file reading use case. Conversion failure is indicated just by a NULL return value. Conversion is either completely successful or fails. Use g_convert() or g_iconv() if you need to handle partial conversions and failure details.

Parameters

Returns

A newly allocated string on success; NULL on failure.

Since: 2.64

gwy_utf16_to_utf8 ()

gchar *
gwy_utf16_to_utf8 (const gunichar2 *str,
                   glong len,
                   GwyByteOrder byteorder);

Convert a string from UTF-16 to UTF-8. The result will be terminated with a 0 byte.

This functions differs from g_utf16_to_utf8() mainly by the handling of byte order. In particular, the caller specifies the byte order explicitly and it can differ from the native byte order.

It is possible to pass GWY_BYTE_ORDER_IMPLICIT as byteorder . In such case str is checked for a byte-order mark. When one is present it is used for the byte order. Otherwise the behaviour is the same as for GWY_BYTE_ORDER_NATIVE. The output string never begins with a byte-order mark.

Conversion failure is indicated just by a NULL return value. Conversion is either completely successful or fails. Use g_utf16_to_utf8() if you need to handle partial conversions and failure details.

Parameters

Returns

A newly allocated string on success; NULL on failure.

Since: 2.60

gwy_utf8_strescape ()

gchar *
gwy_utf8_strescape (const gchar *source,
                    const gchar *exceptions);

Escapes special characters in a string.

Escapes the special characters '\b', '\f', '\n', '\r', '\t', '\v', '\' and '"' in the string source by inserting a '\' before them. Additionally all characters in the range 0x01-0x1F (everything below SPACE), the character 0x7F, characters 0xC0 and 0xC1, and all characters in the range 0xF5-0xFF are replaced with a '\' followed by their octal representation. Characters supplied in exceptions are not escaped.

In essence, this functions differs from g_strescape() by preserving valid UTF-8 strings, unless they contain ‘odd’ characters. Passing strings which are not valid UTF-8 is possible, but generally not advised.

Function g_strcompress() does the reverse conversion.

Parameters

Returns

A newly allocated string with special characters escaped.

Since: 2.62

gwy_assign_string ()

gboolean
gwy_assign_string (gchar **target,
                   const gchar *newvalue);

Assigns a string, checking for equality and handling NULLs.

This function simplifies handling of string value setters.

The new value is duplicated and the old string is freed in a safe manner (it is possible to pass a pointer somewhere within the old value as the new value, for instance). Any of the old and new value can be NULL. If both values are equal (including both unset), the function returns FALSE.

Parameters

Returns

TRUE if the target string has changed.

Since: 2.59

gwy_object_set_or_reset ()

void
gwy_object_set_or_reset (gpointer object,
                         GType type,
                         ...);

Sets object properties, resetting other properties to defaults.

All explicitly specified properties are set. In addition, all unspecified settable properties of type type (or all unspecified properties if type is 0) are reset to defaults. Settable means the property is writable and not construction-only.

The order in which properties are set is undefined beside keeping the relative order of explicitly specified properties, therefore this function is not generally usable for objects with interdependent properties.

Unlike g_object_set(), it does not set properties that already have the requested value, as a consequences notifications are emitted only for properties which actually change.

Parameters

gwy_set_member_object ()

gboolean
gwy_set_member_object (gpointer instance,
                       gpointer member_object,
                       GType expected_type,
                       gpointer member_field,
                       ...);

Replaces a member object of another object, handling signal connection and disconnection.

If member_object is not NULL a reference is taken, sinking any floating objects (and conversely, the reference to the previous member object is released).

The purpose is to simplify bookkeeping in classes that have settable member objects and (usually but not necessarily) need to connect to some signals of these member objects. Since this function both connects and disconnects signals it must be always called with the same set of signals, including callbacks and flags, for a specific member object.

Example for a GwyFoo class owning a GwyGradient member object, assuming the usual conventions:

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typedef struct _GwyFooPrivate GwyFooPrivate;

struct _GwyFooPrivate {
    GwyGradient *gradient;
    gulong gradient_data_changed_id;
};

static gboolean
set_gradient(GwyFoo *foo)
{
    GwyFooPrivate *priv = G_TYPE_INSTANCE_GET_PRIVATE(foo, GWY_TYPE_FOO,
                                                      GwyFooPrivate);
    if (!gwy_set_member_object(foo, gradient, GWY_TYPE_GRADIENT,
                               &priv->gradient,
                               "data-changed", &foo_gradient_data_changed,
                               &priv->gradient_data_changed_id,
                               G_CONNECT_SWAPPED,
                               NULL))
        return FALSE;

    // Do whatever else needs to be done if the gradient changes.
    return TRUE;
}

The gradient setter then usually only calls set_gradient() and disposing of the member object again only calls set_gradient() but with NULL gradient.

Parameters

Returns

TRUE if member_field was changed. FALSE means the new member is identical to the current one and the function reduced to no-op (or that an assertion faled).

Since: 2.49

gwy_fopen ()

FILE *
gwy_fopen (const gchar *filename,
           const gchar *mode);

A wrapper for the stdio fopen() function. The fopen() function opens a file and associates a new stream with it.

Because file descriptors are specific to the C library on Windows, and a file descriptor is part of the FILE struct, the FILE* returned by this function makes sense only to functions in the same C library. Thus if the GLib-using code uses a different C library than GLib does, the FILE* returned by this function cannot be passed to C library functions like fprintf() or fread().

See your C library manual for more details about fopen().

Parameters

Returns

A FILE* if the file was successfully opened, or NULL if an error occurred.

Since: 2.43

gwy_fprintf ()

gint
gwy_fprintf (FILE *file,
             gchar const *format,
             ...);

An implementation of the standard fprintf() function which supports positional parameters, as specified in the Single Unix Specification.

Parameters

Returns

the number of bytes printed.

Since: 2.43

Types and Values

enum GwyRawDataType

Types of raw data.

They are used with gwy_convert_raw_data(). Multibyte types usually need to be complemented with GwyByteOrder to get a full type specification.

Members

Since: 2.25

enum GwyByteOrder

Type of byte order.

Note all types are valid for all functions.

Members

Since: 2.25

enum GwyParseDoublesFlags

Type of flags passed to gwy_parse_doubles().

Members

Since: 2.64

enum GwyParseDoublesError

Type of error which can occur in gwy_parse_doubles().

Members

Since: 2.64

GWY_PARSE_DOUBLES_ERROR

#define GWY_PARSE_DOUBLES_ERROR gwy_parse_doubles_error_quark()

See Also