gtk.gdk.PixbufAnimationIter
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## gtk.gdk.PixbufAnimationIter

gtk.gdk.PixbufAnimationIter — an object providing access to the frames of a `gtk.gdk.PixbufAnimation`

## Synopsis

    class gtk.gdk.PixbufAnimationIter(gobject.GObject):
        def get_delay_time()
        def get_pixbuf()
        def on_currently_loading_frame()
        def advance(current_time=0.0)

## Ancestry

    +-- gobject.GObject
      +-- gtk.gdk.PixbufAnimationIter

## Description

A `gtk.gdk.PixbufAnimationIter` is used to access the frames of a `gtk.gdk.PixbufAnimation` at specified times. A `gtk.gdk.PixbufAnimationIter` object is created using the `gtk.gdk.PixbufAnimation.get_iter`() method. After creating an iterator, you should immediately display the pixbuf returned by the `get_pixbuf`() method. Then, you should install a timeout (with the `gobject.timeout_add`()() function) or by some other mechanism ensure that you'll update the image after the number of milliseconds specified by the `get_delay_time`() method. Each time the image is updated, you should reinstall the timeout with the new, possibly-changed delay time.

To update the image (i.e. possibly change the result of the `get_pixbuf`() method to a new frame of the animation), call the `advance`() method.

If you're using a `gtk.gdk.PixbufLoader`, in addition to updating the image after the delay time, you should also update it whenever you receive the "area_updated" signal and the `on_currently_loading_frame`() method 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."

## Methods

### gtk.gdk.PixbufAnimationIter.get_delay_time

        def get_delay_time()

Returns : | the delay time in milliseconds (thousandths of a second)

The `get_delay_time`() method returns the number of milliseconds the current pixbuf should be displayed, or -1 if the current pixbuf should be displayed forever. The `gobject.timeout_add`()() function conveniently takes a timeout in milliseconds, so you can use a timeout to schedule the next update.

### gtk.gdk.PixbufAnimationIter.get_pixbuf

        def get_pixbuf()

Returns : | the current `gtk.gdk.Pixbuf` to be displayed

The `get_pixbuf`() method returns the current `gtk.gdk.Pixbuf` that should be displayed. The pixbuf will be the same size as the animation itself (see the `gtk.gdk.PixbufAnimation.get_width`() and `gtk.gdk.PixbufAnimation.get_height`() methods). The `gtk.gdk.Pixbuf` should be displayed for the number of milliseconds specified by the `get_delay_time`() method.

### gtk.gdk.PixbufAnimationIter.on_currently_loading_frame

        def on_currently_loading_frame()

Returns : | `True` if the frame we're on is partially loaded, or the last frame

The `on_currently_loading_frame`() method returns `True` if the frame currently pointed to by the iterator is partially loaded or the last frame. This method is used to determine how to respond to the "area_updated" signal on `gtk.gdk.PixbufLoader` when loading an animation. The "area_updated" signal 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.

### gtk.gdk.PixbufAnimationIter.advance

        def advance(current_time=0.0)

`current_time` : | the current time as a float or 0.0 to automatically determine the current time
Returns : | `True` if the image may need updating

The `advance`() method attempts to advance an animation to a new frame. The frame is chosen based on the start time passed to the `gtk.gdk.PixbufAnimation.get_iter`() method. `current_time` is normally the current time (as specified by the Python time.time() function) and must be greater than or equal to the time passed to the `gtk.gdk.PixbufAnimation.get_iter`() method, and must increase or remain unchanged each time the `get_pixbuf`() method is called. That is, you can't go backward in time; animations only play forward. As a shortcut, pass 0.0 (the default) for the current time and the current time will automatically be determined an used. So you only need to explicitly pass `current_time` if you're doing something odd like playing the animation at double speed.

If this method 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 the `get_pixbuf`() method and update the display with the new pixbuf.

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