File saving

## File saving File saving — Saving a pixbuf to a file. |

## Synopsis

    #include <gdk-pixbuf/gdk-pixbuf.h>

    gboolean    gdk_pixbuf_savev                (GdkPixbuf *pixbuf,
                                                 const char *filename,
                                                 const char *type,
                                                 char **option_keys,
                                                 char **option_values,
                                                 GError **error);
    gboolean    gdk_pixbuf_save                 (GdkPixbuf *pixbuf,
                                                 const char *filename,
                                                 const char *type,
                                                 GError **error,
                                                 ...);
    gboolean    (*GdkPixbufSaveFunc)            (const gchar *buf,
                                                 gsize count,
                                                 GError **error,
                                                 gpointer data);
    gboolean    gdk_pixbuf_save_to_callback     (GdkPixbuf *pixbuf,
                                                 GdkPixbufSaveFunc save_func,
                                                 gpointer user_data,
                                                 const char *type,
                                                 GError **error,
                                                 ...);
    gboolean    gdk_pixbuf_save_to_callbackv    (GdkPixbuf *pixbuf,
                                                 GdkPixbufSaveFunc save_func,
                                                 gpointer user_data,
                                                 const char *type,
                                                 char **option_keys,
                                                 char **option_values,
                                                 GError **error);
    gboolean    gdk_pixbuf_save_to_buffer       (GdkPixbuf *pixbuf,
                                                 gchar **buffer,
                                                 gsize *buffer_size,
                                                 const char *type,
                                                 GError **error,
                                                 ...);
    gboolean    gdk_pixbuf_save_to_bufferv      (GdkPixbuf *pixbuf,
                                                 gchar **buffer,
                                                 gsize *buffer_size,
                                                 const char *type,
                                                 char **option_keys,
                                                 char **option_values,
                                                 GError **error);

## Description

These functions allow to save a GdkPixbuf in a number of file formats. The formatted data can be written to a file or to a memory buffer. gdk-pixbuf can also call a user-defined callback on the data, which allows to e.g. write the image to a socket or store it in a database.

## Details

### gdk_pixbuf_savev ()

    gboolean    gdk_pixbuf_savev                (GdkPixbuf *pixbuf,
                                                 const char *filename,
                                                 const char *type,
                                                 char **option_keys,
                                                 char **option_values,
                                                 GError **error);

Saves pixbuf to a file in `type`, which is currently "jpeg", "png", "ico" or "bmp". If `error` is set, `FALSE` will be returned. See `gdk_pixbuf_save()` for more details.

`pixbuf` : | a GdkPixbuf.
`filename` : | name of file to save.
`type` : | name of file format.
`option_keys` : | name of options to set, `NULL`-terminated
`option_values` : | values for named options
`error` : | return location for error, or `NULL`
Returns : | whether an error was set

### gdk_pixbuf_save ()

    gboolean    gdk_pixbuf_save                 (GdkPixbuf *pixbuf,
                                                 const char *filename,
                                                 const char *type,
                                                 GError **error,
                                                 ...);

Saves pixbuf to a file in format `type`. By default, "jpeg", "png", "ico" and "bmp" are possible file formats to save in, but more formats may be installed. The list of all writable formats can be determined in the following way:

    void add_if_writable (GdkPixbufFormat *data, GSList **list)
    {
      if (gdk_pixbuf_format_is_writable (data))
        *list = g_slist_prepend (*list, data);
    }

    GSList *formats = gdk_pixbuf_get_formats ();
    GSList *writable_formats = NULL;
    g_slist_foreach (formats, add_if_writable, &writable_formats);
    g_slist_free (formats);

If `error` is set, `FALSE` will be returned. Possible errors include those in the GDK_PIXBUF_ERROR domain and those in the G_FILE_ERROR domain.

The variable argument list should be `NULL`-terminated; if not empty, it should contain pairs of strings that modify the save parameters. For example:

    gdk_pixbuf_save (pixbuf, handle, "jpeg", &error,
                     "quality", "100", NULL);

Currently only few parameters exist. JPEG images can be saved with a "quality" parameter; its value should be in the range [0,100].

Text chunks can be attached to PNG images by specifying parameters of the form "tEXt::key", where key is an ASCII string of length 1-79. The values are UTF-8 encoded strings. The PNG compression level can be specified using the "compression" parameter; it's value is in an integer in the range of [0,9].

ICO images can be saved in depth 16, 24, or 32, by using the "depth" parameter. When the ICO saver is given "x_hot" and "y_hot" parameters, it produces a CUR instead of an ICO.

`pixbuf` : | a GdkPixbuf.
`filename` : | name of file to save.
`type` : | name of file format.
`error` : | return location for error, or `NULL`
`...` : | list of key-value save options
Returns : | whether an error was set

### GdkPixbufSaveFunc ()

    gboolean    (*GdkPixbufSaveFunc)            (const gchar *buf,
                                                 gsize count,
                                                 GError **error,
                                                 gpointer data);

Specifies the type of the function passed to `gdk_pixbuf_save_to_callback()`. It is called once for each block of bytes that is "written" by `gdk_pixbuf_save_to_callback()`. If successful it should return `TRUE`. If an error occurs it should set `error` and return `FALSE`, in which case `gdk_pixbuf_save_to_callback()` will fail with the same error.

`buf` : | bytes to be written.
`count` : | number of bytes in `buf`.
`error` : | A location to return an error.
`data` : | user data passed to `gdk_pixbuf_save_to_callback()`.
Returns : | `TRUE` if successful, `FALSE` (with `error` set) if failed.

Since 2.4

### gdk_pixbuf_save_to_callback ()

    gboolean    gdk_pixbuf_save_to_callback     (GdkPixbuf *pixbuf,
                                                 GdkPixbufSaveFunc save_func,
                                                 gpointer user_data,
                                                 const char *type,
                                                 GError **error,
                                                 ...);

Saves pixbuf in format `type` by feeding the produced data to a callback. Can be used when you want to store the image to something other than a file, such as an in-memory buffer or a socket. If `error` is set, `FALSE` will be returned. Possible errors include those in the GDK_PIXBUF_ERROR domain and whatever the save function generates.

See `gdk_pixbuf_save()` for more details.

`pixbuf` : | a GdkPixbuf.
`save_func` : | a function that is called to save each block of data that the save routine generates.
`user_data` : | user data to pass to the save function.
`type` : | name of file format.
`error` : | return location for error, or `NULL`
`...` : | list of key-value save options
Returns : | whether an error was set

Since 2.4

### gdk_pixbuf_save_to_callbackv ()

    gboolean    gdk_pixbuf_save_to_callbackv    (GdkPixbuf *pixbuf,
                                                 GdkPixbufSaveFunc save_func,
                                                 gpointer user_data,
                                                 const char *type,
                                                 char **option_keys,
                                                 char **option_values,
                                                 GError **error);

Saves pixbuf to a callback in format `type`, which is currently "jpeg", "png", "ico" or "bmp". If `error` is set, `FALSE` will be returned. See `gdk_pixbuf_save_to_callback()` for more details.

`pixbuf` : | a GdkPixbuf.
`save_func` : | a function that is called to save each block of data that the save routine generates.
`user_data` : | user data to pass to the save function.
`type` : | name of file format.
`option_keys` : | name of options to set, `NULL`-terminated
`option_values` : | values for named options
`error` : | return location for error, or `NULL`
Returns : | whether an error was set

Since 2.4

### gdk_pixbuf_save_to_buffer ()

    gboolean    gdk_pixbuf_save_to_buffer       (GdkPixbuf *pixbuf,
                                                 gchar **buffer,
                                                 gsize *buffer_size,
                                                 const char *type,
                                                 GError **error,
                                                 ...);

Saves pixbuf to a new buffer in format `type`, which is currently "jpeg", "png", "ico" or "bmp". This is a convenience function that uses `gdk_pixbuf_save_to_callback()` to do the real work. Note that the buffer is not nul-terminated and may contain embedded nuls. If `error` is set, `FALSE` will be returned and `string` will be set to `NULL`. Possible errors include those in the GDK_PIXBUF_ERROR domain.

See `gdk_pixbuf_save()` for more details.

`pixbuf` : | a GdkPixbuf.
`buffer` : | location to receive a pointer to the new buffer.
`buffer_size` : | location to receive the size of the new buffer.
`type` : | name of file format.
`error` : | return location for error, or `NULL`
`...` : | list of key-value save options
Returns : | whether an error was set

Since 2.4

### gdk_pixbuf_save_to_bufferv ()

    gboolean    gdk_pixbuf_save_to_bufferv      (GdkPixbuf *pixbuf,
                                                 gchar **buffer,
                                                 gsize *buffer_size,
                                                 const char *type,
                                                 char **option_keys,
                                                 char **option_values,
                                                 GError **error);

Saves pixbuf to a new buffer in format `type`, which is currently "jpeg", "png", "ico" or "bmp". See `gdk_pixbuf_save_to_buffer()` for more details.

`pixbuf` : | a GdkPixbuf.
`buffer` : | location to receive a pointer to the new buffer.
`buffer_size` : | location to receive the size of the new buffer.
`type` : | name of file format.
`option_keys` : | name of options to set, `NULL`-terminated
`option_values` : | values for named options
`error` : | return location for error, or `NULL`
Returns : | whether an error was set

Since 2.4