The gdk-pixbuf Library | ||||
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#include <gdk-pixbuf/gdk-pixbuf.h> gboolean gdk_pixbuf_set_option (GdkPixbuf *pixbuf, const gchar *key, const gchar *value); GSList* gdk_pixbuf_get_formats (void); gchar* gdk_pixbuf_format_get_name (GdkPixbufFormat *format); gchar* gdk_pixbuf_format_get_description (GdkPixbufFormat *format); gchar** gdk_pixbuf_format_get_mime_types (GdkPixbufFormat *format); gchar** gdk_pixbuf_format_get_extensions (GdkPixbufFormat *format); gboolean gdk_pixbuf_format_is_writable (GdkPixbufFormat *format); gboolean gdk_pixbuf_format_is_scalable (GdkPixbufFormat *format); gboolean gdk_pixbuf_format_is_disabled (GdkPixbufFormat *format); void gdk_pixbuf_format_set_disabled (GdkPixbufFormat *format, gboolean disabled); gchar* gdk_pixbuf_format_get_license (GdkPixbufFormat *format); GdkPixbufFormat; enum GdkPixbufFormatFlags; GdkPixbufModulePattern; void (*GdkPixbufModuleFillVtableFunc) (GdkPixbufModule *module); void (*GdkPixbufModuleFillInfoFunc) (GdkPixbufFormat *info); void (*GdkPixbufModuleSizeFunc) (gint *width, gint *height, gpointer user_data); void (*GdkPixbufModulePreparedFunc) (GdkPixbuf *pixbuf, GdkPixbufAnimation *anim, gpointer user_data); void (*GdkPixbufModuleUpdatedFunc) (GdkPixbuf *pixbuf, int x, int y, int width, int height, gpointer user_data); GdkPixbufModule; GdkPixbufAnimationClass; GdkPixbufAnimationIterClass;
If gdk-pixbuf has been compiled with GModule support, it can be extended by
modules which can load (and perhaps also save) new image and animation
formats. Each loadable module must export a
GdkPixbufModuleFillInfoFunc function named fill_info
and
a GdkPixbufModuleFillVtableFunc function named
fill_vtable
.
In order to make format-checking work before actually loading the modules
(which may require dlopening image libraries), modules export their
signatures (and other information) via the fill_info
function. An external utility, gdk-pixbuf-query-loaders,
uses this to create a text file containing a list of all available loaders and
their signatures. This file is then read at runtime by gdk-pixbuf to obtain
the list of available loaders and their signatures.
Modules may only implement a subset of the functionality available via
GdkPixbufModule. If a particular functionality is not implemented, the
fill_vtable
function will simply not set the corresponding
function pointers of the GdkPixbufModule structure. If a module supports
incremental loading (i.e. provides begin_load, stop_load and
load_increment), it doesn't have to implement load, since gdk-pixbuf can
supply a generic load implementation wrapping the incremental loading.
Installing a module is a two-step process:
copy the module file(s) to the loader directory (normally
,
unless overridden by the environment variable
libdir
/gtk-2.0/version
/loadersGDK_PIXBUF_MODULEDIR
)
call gdk-pixbuf-query-loaders to update the
module file (normally
,
unless overridden by the environment variable
sysconfdir
/gtk-2.0/gdk-pixbuf.loadersGDK_PIXBUF_MODULE_FILE
)
The gdk-pixbuf interfaces needed for implementing modules are contained in
gdk-pixbuf-io.h
(and
gdk-pixbuf-animation.h
if the module supports animations).
They are not covered by the same stability guarantees as the regular
gdk-pixbuf API. To underline this fact, they are protected by
#ifdef GDK_PIXBUF_ENABLE_BACKEND
.
gboolean gdk_pixbuf_set_option (GdkPixbuf *pixbuf, const gchar *key, const gchar *value);
Attaches a key/value pair as an option to a GdkPixbuf. If key
already
exists in the list of options attached to pixbuf
, the new value is
ignored and FALSE
is returned.
pixbuf : |
a GdkPixbuf |
key : |
a nul-terminated string. |
value : |
a nul-terminated string. |
Returns : | TRUE on success.
|
Since 2.2
GSList* gdk_pixbuf_get_formats (void);
Obtains the available information about the image formats supported by GdkPixbuf.
Returns : | A list of GdkPixbufFormats describing the supported image formats. The list should be freed when it is no longer needed, but the structures themselves are owned by GdkPixbuf and should not be freed. |
Since 2.2
gchar* gdk_pixbuf_format_get_name (GdkPixbufFormat *format);
Returns the name of the format.
format : |
a GdkPixbufFormat |
Returns : | the name of the format. |
Since 2.2
gchar* gdk_pixbuf_format_get_description (GdkPixbufFormat *format);
Returns a description of the format.
format : |
a GdkPixbufFormat |
Returns : | a description of the format. |
Since 2.2
gchar** gdk_pixbuf_format_get_mime_types (GdkPixbufFormat *format);
Returns the mime types supported by the format.
format : |
a GdkPixbufFormat |
Returns : | a NULL -terminated array of mime types which must be freed with
g_strfreev() when it is no longer needed.
|
Since 2.2
gchar** gdk_pixbuf_format_get_extensions (GdkPixbufFormat *format);
Returns the filename extensions typically used for files in the given format.
format : |
a GdkPixbufFormat |
Returns : | a NULL -terminated array of filename extensions which must be
freed with g_strfreev() when it is no longer needed.
|
Since 2.2
gboolean gdk_pixbuf_format_is_writable (GdkPixbufFormat *format);
Returns whether pixbufs can be saved in the given format.
format : |
a GdkPixbufFormat |
Returns : | whether pixbufs can be saved in the given format. |
Since 2.2
gboolean gdk_pixbuf_format_is_scalable (GdkPixbufFormat *format);
Returns whether this image format is scalable. If a file is in a scalable format, it is preferable to load it at the desired size, rather than loading it at the default size and scaling the resulting pixbuf to the desired size.
format : |
a GdkPixbufFormat |
Returns : | whether this image format is scalable. |
Since 2.6
gboolean gdk_pixbuf_format_is_disabled (GdkPixbufFormat *format);
Returns whether this image format is disabled. See
gdk_pixbuf_format_set_disabled()
.
format : |
a GdkPixbufFormat |
Returns : | whether this image format is disabled. |
Since 2.6
void gdk_pixbuf_format_set_disabled (GdkPixbufFormat *format, gboolean disabled);
Disables or enables an image format. If a format is disabled,
gdk-pixbuf won't use the image loader for this format to load
images. Applications can use this to avoid using image loaders
with an inappropriate license, see gdk_pixbuf_format_get_license()
.
format : |
a GdkPixbufFormat |
disabled : |
TRUE to disable the format format
|
Since 2.6
gchar* gdk_pixbuf_format_get_license (GdkPixbufFormat *format);
Returns information about the license of the image loader for the format. The
returned string should be a shorthand for a wellknown license, e.g. "LGPL",
"GPL", "QPL", "GPL/QPL", or "other" to indicate some other license. This
string should be freed with g_free()
when it's no longer needed.
format : |
a GdkPixbufFormat |
Returns : | a string describing the license of format .
|
Since 2.6
typedef struct { gchar *name; GdkPixbufModulePattern *signature; gchar *domain; gchar *description; gchar **mime_types; gchar **extensions; guint32 flags; gboolean disabled; gchar *license; } GdkPixbufFormat;
A GdkPixbufFormat contains information about the image format accepted by a
module. Only modules should access the fields directly, applications should
use the gdk_pixbuf_format_*
functions.
gchar *name ; |
the name of the image format. |
GdkPixbufModulePattern *signature ; |
the signature of the module. |
gchar *domain ; |
the message domain for the description .
|
gchar *description ; |
a description of the image format. |
gchar **mime_types ; |
a NULL -terminated array of MIME types for the image format.
|
gchar **extensions ; |
a NULL -terminated array of typical filename extensions for the
image format.
|
guint32 flags ; |
a combination of GdkPixbufFormatFlags. |
gboolean disabled ; |
a boolean determining whether the loader is disabled. |
gchar *license ; |
a string containing license information, typically set to shorthands like "GPL", "LGPL", etc. |
Since 2.2
typedef enum /*< skip >*/ { GDK_PIXBUF_FORMAT_WRITABLE = 1 << 0, GDK_PIXBUF_FORMAT_SCALABLE = 1 << 1, GDK_PIXBUF_FORMAT_THREADSAFE = 1 << 2 } GdkPixbufFormatFlags;
Flags which allow a module to specify further details about the supported operations.
Since 2.2
typedef struct { char *prefix; char *mask; int relevance; } GdkPixbufModulePattern;
The signature of a module is a set of prefixes. Prefixes are encoded as
pairs of ordinary strings, where the second string, called the mask, if
not NULL
, must be of the same length as the first one and may contain
' ', '!', 'x', 'z', and 'n' to indicate bytes that must be matched,
not matched, "don't-care"-bytes, zeros and non-zeros.
Each prefix has an associated integer that describes the relevance of
the prefix, with 0 meaning a mismatch and 100 a "perfect match".
Starting with gdk-pixbuf 2.8, the first byte of the mask may be '*', indicating an unanchored pattern that matches not only at the beginning, but also in the middle. Versions prior to 2.8 will interpret the '*' like an 'x'.
The signature of a module is stored as an array of
GdkPixbufModulePatterns. The array is terminated by a pattern
where the prefix
is NULL
.
GdkPixbufModulePattern *signature[] = { { "abcdx", " !x z", 100 }, { "bla", NULL, 90 }, { NULL, NULL, 0 } };The example matches e.g. "auud\0" with relevance 100, and "blau" with relevance 90.
char *prefix ; |
the prefix for this pattern |
char *mask ; |
mask containing bytes which modify how the prefix is matched against test data |
int relevance ; |
relevance of this pattern |
Since 2.2
void (*GdkPixbufModuleFillVtableFunc) (GdkPixbufModule *module);
Defines the type of the function used to set the vtable of a GdkPixbufModule when it is loaded.
module : |
a GdkPixbufModule. |
Since 2.2
void (*GdkPixbufModuleFillInfoFunc) (GdkPixbufFormat *info);
Defines the type of the function used to fill a GdkPixbufFormat structure with information about a module.
info : |
a GdkPixbufFormat. |
Since 2.2
void (*GdkPixbufModuleSizeFunc) (gint *width, gint *height, gpointer user_data);
Defines the type of the function that gets called once the size of the loaded image is known.
The function is expected to set width
and height
to the desired
size to which the image should be scaled. If a module has no efficient
way to achieve the desired scaling during the loading of the image, it may
either ignore the size request, or only approximate it -- gdk-pixbuf will
then perform the required scaling on the completely loaded image.
If the function sets width
or height
to zero, the module should interpret
this as a hint that it will be closed soon and shouldn't allocate further
resources. This convention is used to implement gdk_pixbuf_get_file_info()
efficiently.
width : |
pointer to a location containing the current image width |
height : |
pointer to a location containing the current image height |
user_data : |
the loader. |
Since 2.2
void (*GdkPixbufModulePreparedFunc) (GdkPixbuf *pixbuf, GdkPixbufAnimation *anim, gpointer user_data);
Defines the type of the function that gets called once the initial
setup of pixbuf
is done.
GdkPixbufLoader uses a function of this type to emit the "area_prepared" signal.
pixbuf : |
the GdkPixbuf that is currently being loaded. |
anim : |
if an animation is being loaded, the GdkPixbufAnimation, else NULL .
|
user_data : |
the loader. |
Since 2.2
void (*GdkPixbufModuleUpdatedFunc) (GdkPixbuf *pixbuf, int x, int y, int width, int height, gpointer user_data);
Defines the type of the function that gets called every time a region
of pixbuf
is updated.
GdkPixbufLoader uses a function of this type to emit the "area_updated" signal.
pixbuf : |
the GdkPixbuf that is currently being loaded. |
x : |
the X origin of the updated area. |
y : |
the Y origin of the updated area. |
width : |
the width of the updated area. |
height : |
the height of the updated area. |
user_data : |
the loader. |
Since 2.2
typedef struct { char *module_name; char *module_path; GModule *module; GdkPixbufFormat *info; GdkPixbuf *(* load) (FILE *f, GError **error); GdkPixbuf *(* load_xpm_data) (const char **data); /* Incremental loading */ gpointer (* begin_load) (GdkPixbufModuleSizeFunc size_func, GdkPixbufModulePreparedFunc prepare_func, GdkPixbufModuleUpdatedFunc update_func, gpointer user_data, GError **error); gboolean (* stop_load) (gpointer context, GError **error); gboolean (* load_increment) (gpointer context, const guchar *buf, guint size, GError **error); /* Animation loading */ GdkPixbufAnimation *(* load_animation) (FILE *f, GError **error); /* Saving */ gboolean (* save) (FILE *f, GdkPixbuf *pixbuf, gchar **param_keys, gchar **param_values, GError **error); gboolean (*save_to_callback) (GdkPixbufSaveFunc save_func, gpointer user_data, GdkPixbuf *pixbuf, gchar **option_keys, gchar **option_values, GError **error); } GdkPixbufModule;
A GdkPixbufModule contains the necessary functions to load and save images in a certain file format.
A GdkPixbufModule can be loaded dynamically from a GModule.
Each loadable module must contain a GdkPixbufModuleFillVtableFunc function
named fill_vtable
, which will get called when the module
is loaded and must set the function pointers of the GdkPixbufModule.
char *module_name ; |
the name of the module, usually the same as the usual file extension for images of this type, eg. "xpm", "jpeg" or "png". |
char *module_path ; |
the path from which the module is loaded. |
GModule *module ; |
the loaded GModule. |
GdkPixbufFormat *info ; |
a GdkPixbufFormat holding information about the module. |
load () |
loads an image from a file. |
load_xpm_data () |
loads an image from data in memory. |
begin_load () |
begins an incremental load. |
stop_load () |
stops an incremental load. |
load_increment () |
continues an incremental load. |
load_animation () |
loads an animation from a file. |
save () |
saves a GdkPixbuf to a file. |
save_to_callback () |
saves a GdkPixbuf by calling the given GdkPixbufSaveFunc. |
typedef struct { GObjectClass parent_class; gboolean (*is_static_image) (GdkPixbufAnimation *anim); GdkPixbuf* (*get_static_image) (GdkPixbufAnimation *anim); void (*get_size) (GdkPixbufAnimation *anim, int *width, int *height); GdkPixbufAnimationIter* (*get_iter) (GdkPixbufAnimation *anim, const GTimeVal *start_time); } GdkPixbufAnimationClass;
Modules supporting animations must derive a type from GdkPixbufAnimation, providing suitable implementations of the virtual functions.
GObjectClass parent_class ; |
the parent class |
is_static_image () |
returns whether the given animation is just a static image. |
get_static_image () |
returns a static image representing the given animation. |
get_size () |
fills width and height with the frame size of the animation.
|
get_iter () |
returns an iterator for the given animation. |
typedef struct { GObjectClass parent_class; int (*get_delay_time) (GdkPixbufAnimationIter *iter); GdkPixbuf* (*get_pixbuf) (GdkPixbufAnimationIter *iter); gboolean (*on_currently_loading_frame) (GdkPixbufAnimationIter *iter); gboolean (*advance) (GdkPixbufAnimationIter *iter, const GTimeVal *current_time); } GdkPixbufAnimationIterClass;
Modules supporting animations must derive a type from GdkPixbufAnimationIter, providing suitable implementations of the virtual functions.
GObjectClass parent_class ; |
the parent class |
get_delay_time () |
returns the time in milliseconds that the current frame should be shown. |
get_pixbuf () |
returns the current frame. |
on_currently_loading_frame () |
returns whether the current frame of iter is
being loaded.
|
advance () |
advances the iterator to current_time , possibly changing the
current frame.
|