Animations

Animations — Animated images.

Synopsis

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


            GdkPixbufAnimation;
            GdkPixbufAnimationIter;
GdkPixbufAnimation* gdk_pixbuf_animation_new_from_file
                                            (const char *filename,
                                             GError **error);
GdkPixbufAnimation* gdk_pixbuf_animation_ref
                                            (GdkPixbufAnimation *animation);
void        gdk_pixbuf_animation_unref      (GdkPixbufAnimation *animation);
int         gdk_pixbuf_animation_get_width  (GdkPixbufAnimation *animation);
int         gdk_pixbuf_animation_get_height (GdkPixbufAnimation *animation);
GdkPixbufAnimationIter* gdk_pixbuf_animation_get_iter
                                            (GdkPixbufAnimation *animation,
                                             const GTimeVal *start_time);
gboolean    gdk_pixbuf_animation_is_static_image
                                            (GdkPixbufAnimation *animation);
GdkPixbuf*  gdk_pixbuf_animation_get_static_image
                                            (GdkPixbufAnimation *animation);
gboolean    gdk_pixbuf_animation_iter_advance
                                            (GdkPixbufAnimationIter *iter,
                                             const GTimeVal *current_time);
int         gdk_pixbuf_animation_iter_get_delay_time
                                            (GdkPixbufAnimationIter *iter);
gboolean    gdk_pixbuf_animation_iter_on_currently_loading_frame
                                            (GdkPixbufAnimationIter *iter);
GdkPixbuf*  gdk_pixbuf_animation_iter_get_pixbuf
                                            (GdkPixbufAnimationIter *iter);


Object Hierarchy

  GObject
   +----GdkPixbufAnimation
  GObject
   +----GdkPixbufAnimationIter

Description

The gdk-pixbuf library provides a simple mechanism to load and represent animations. An animation is conceptually a series of frames to be displayed over time. Each frame is the same size. The animation may not be represented as a series of frames internally; for example, it may be stored as a sprite and instructions for moving the sprite around a background. To display an animation you don't need to understand its representation, however; you just ask gdk-pixbuf what should be displayed at a given point in time.

Details

GdkPixbufAnimation

typedef struct _GdkPixbufAnimation GdkPixbufAnimation;

This object describes an animation.


GdkPixbufAnimationIter

typedef struct _GdkPixbufAnimationIter GdkPixbufAnimationIter;

A GdkPixbufAnimationIter provides the necessary functionality to display an animation. See gdk_pixbuf_animation_get_iter().


gdk_pixbuf_animation_new_from_file ()

GdkPixbufAnimation* gdk_pixbuf_animation_new_from_file
                                            (const char *filename,
                                             GError **error);

Creates a new animation by loading it from a file. The file format is detected automatically. If the file's format does not support multi-frame images, then an animation with a single frame will be created. Possible errors are in the GDK_PIXBUF_ERROR and G_FILE_ERROR domains.

filename : Name of file to load, in the GLib file name encoding
error : return location for error
Returns : A newly-created animation with a reference count of 1, or NULL if any of several error conditions ocurred: the file could not be opened, there was no loader for the file's format, there was not enough memory to allocate the image buffer, or the image file contained invalid data.

gdk_pixbuf_animation_ref ()

GdkPixbufAnimation* gdk_pixbuf_animation_ref
                                            (GdkPixbufAnimation *animation);

Warning

gdk_pixbuf_animation_ref is deprecated and should not be used in newly-written code. Use g_object_ref().

Adds a reference to an animation.

animation : An animation.
Returns : The same as the animation argument.

gdk_pixbuf_animation_unref ()

void        gdk_pixbuf_animation_unref      (GdkPixbufAnimation *animation);

Warning

gdk_pixbuf_animation_unref is deprecated and should not be used in newly-written code. Use g_object_unref().

Removes a reference from an animation.

animation : An animation.

gdk_pixbuf_animation_get_width ()

int         gdk_pixbuf_animation_get_width  (GdkPixbufAnimation *animation);

Queries the width of the bounding box of a pixbuf animation.

animation : An animation.
Returns : Width of the bounding box of the animation.

gdk_pixbuf_animation_get_height ()

int         gdk_pixbuf_animation_get_height (GdkPixbufAnimation *animation);

Queries the height of the bounding box of a pixbuf animation.

animation : An animation.
Returns : Height of the bounding box of the animation.

gdk_pixbuf_animation_get_iter ()

GdkPixbufAnimationIter* gdk_pixbuf_animation_get_iter
                                            (GdkPixbufAnimation *animation,
                                             const GTimeVal *start_time);

Get an iterator for displaying an animation. The iterator provides the frames that should be displayed at a given time. It should be freed after use with g_object_unref().

start_time would normally come from g_get_current_time(), and marks the beginning of animation playback. After creating an iterator, you should immediately display the pixbuf returned by gdk_pixbuf_animation_iter_get_pixbuf(). Then, you should install a timeout (with g_timeout_add()) or by some other mechanism ensure that you'll update the image after gdk_pixbuf_animation_iter_get_delay_time() milliseconds. Each time the image is updated, you should reinstall the timeout with the new, possibly-changed delay time.

As a shortcut, if start_time is NULL, the result of g_get_current_time() will be used automatically.

To update the image (i.e. possibly change the result of gdk_pixbuf_animation_iter_get_pixbuf() to a new frame of the animation), call gdk_pixbuf_animation_iter_advance().

If you're using GdkPixbufLoader, in addition to updating the image after the delay time, you should also update it whenever you receive the area_updated signal and gdk_pixbuf_animation_iter_on_currently_loading_frame() returns TRUE. In this case, the frame currently being fed into the loader has received new data, so needs to be refreshed. The delay time for a frame may also be modified after an area_updated signal, for example if the delay time for a frame is encoded in the data after the frame itself. So your timeout should be reinstalled after any area_updated signal.

A delay time of -1 is possible, indicating "infinite."

animation : a GdkPixbufAnimation
start_time : time when the animation starts playing
Returns : an iterator to move over the animation

gdk_pixbuf_animation_is_static_image ()

gboolean    gdk_pixbuf_animation_is_static_image
                                            (GdkPixbufAnimation *animation);

If you load a file with gdk_pixbuf_animation_new_from_file() and it turns out to be a plain, unanimated image, then this function will return TRUE. Use gdk_pixbuf_animation_get_static_image() to retrieve the image.

animation : a GdkPixbufAnimation
Returns : TRUE if the "animation" was really just an image

gdk_pixbuf_animation_get_static_image ()

GdkPixbuf*  gdk_pixbuf_animation_get_static_image
                                            (GdkPixbufAnimation *animation);

If an animation is really just a plain image (has only one frame), this function returns that image. If the animation is an animation, this function returns a reasonable thing to display as a static unanimated image, which might be the first frame, or something more sophisticated. If an animation hasn't loaded any frames yet, this function will return NULL.

animation : a GdkPixbufAnimation
Returns : unanimated image representing the animation

gdk_pixbuf_animation_iter_advance ()

gboolean    gdk_pixbuf_animation_iter_advance
                                            (GdkPixbufAnimationIter *iter,
                                             const GTimeVal *current_time);

Possibly advances an animation to a new frame. Chooses the frame based on the start time passed to gdk_pixbuf_animation_get_iter().

current_time would normally come from g_get_current_time(), and must be greater than or equal to the time passed to gdk_pixbuf_animation_get_iter(), and must increase or remain unchanged each time gdk_pixbuf_animation_iter_get_pixbuf() is called. That is, you can't go backward in time; animations only play forward.

As a shortcut, pass NULL for the current time and g_get_current_time() will be invoked on your behalf. So you only need to explicitly pass current_time if you're doing something odd like playing the animation at double speed.

If this function returns FALSE, there's no need to update the animation display, assuming the display had been rendered prior to advancing; if TRUE, you need to call gdk_animation_iter_get_pixbuf() and update the display with the new pixbuf.

iter : a GdkPixbufAnimationIter
current_time : current time
Returns : TRUE if the image may need updating

gdk_pixbuf_animation_iter_get_delay_time ()

int         gdk_pixbuf_animation_iter_get_delay_time
                                            (GdkPixbufAnimationIter *iter);

Gets the number of milliseconds the current pixbuf should be displayed, or -1 if the current pixbuf should be displayed forever. g_timeout_add() conveniently takes a timeout in milliseconds, so you can use a timeout to schedule the next update.

iter : an animation iterator
Returns : delay time in milliseconds (thousandths of a second)

gdk_pixbuf_animation_iter_on_currently_loading_frame ()

gboolean    gdk_pixbuf_animation_iter_on_currently_loading_frame
                                            (GdkPixbufAnimationIter *iter);

Used to determine how to respond to the area_updated signal on GdkPixbufLoader when loading an animation. area_updated is emitted for an area of the frame currently streaming in to the loader. So if you're on the currently loading frame, you need to redraw the screen for the updated area.

iter : a GdkPixbufAnimationIter
Returns : TRUE if the frame we're on is partially loaded, or the last frame

gdk_pixbuf_animation_iter_get_pixbuf ()

GdkPixbuf*  gdk_pixbuf_animation_iter_get_pixbuf
                                            (GdkPixbufAnimationIter *iter);

Gets the current pixbuf which should be displayed; the pixbuf will be the same size as the animation itself (gdk_pixbuf_animation_get_width(), gdk_pixbuf_animation_get_height()). This pixbuf should be displayed for gdk_pixbuf_animation_iter_get_delay_time() milliseconds. The caller of this function does not own a reference to the returned pixbuf; the returned pixbuf will become invalid when the iterator advances to the next frame, which may happen anytime you call gdk_pixbuf_animation_iter_advance(). Copy the pixbuf to keep it (don't just add a reference), as it may get recycled as you advance the iterator.

iter : an animation iterator
Returns : the pixbuf to be displayed

See Also

GdkPixbufLoader