Animated GIFs

Limitations

• Each frame of an animated GIF can only have at most 256 different colors, including the transparent color.
• These colors cannot be partially transparent. Their alpha must be either 0 or 255.
• The duration of each frame must be a multiple of 10 milliseconds.

Setting the duration of a frame

Use the menu item Frames | Frame properties or double-click the frame thumbnail in the frame list below the editor.

The duration should be a multiple of 10 milliseconds.

Disposal method

In an animated GIF we can specify a disposal method for each frame, which determines what will happen when the frame's time slice is over. The available disposal methods are:

• Restore background (default): the next frame will be rendered over a transparent background.
• Restore previous: the current frame will be "undone" and the next frame will be drawn over whatever image was visible before the current frame was shown.
• Leave in place: current frame is not disposed of, i.e. the next one will be drawn on top of it.
• Unspecified: same meaning as "Leave in place", but not recommended as not all renderers may support it.

You can set the disposal method in the Frames | Frame properties dialog.

With Frames | Convert GIF frames to keyframes you can convert a GIF to an equivalent animation where each frame has the Restore background disposal method. This is useful if you want to extract the "effective" frames from a GIF.

Playing the animation

Use the test window: choose Icon | Test (Ctrl+Shift+T) or press on the toolbar above the image editor panel, just like when testing an icon.

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