animation.md

Animated Images

Some image formats, such as GIF, PNG, or WebP, support multiple frames for animation or other purposes. An Image has a frames list. For non-animated images, the frames list will have a single element, the image itself. For animated images, the frames list will include the other frames of the animation.

bool hasAnim = image.hasAnimation; // True if the image has more than 1 frame.
int loopCount = image.loopCount; // The repeat count for the animated image, 0 means repeat forever.
FrameType type = image.frameType; // How frames can be interpreted, as animation, pages, or just a sequence of images.
for (final frame in image.frames) { // Iterate over the frames of the image.
  final frameIndex = frame.frameIndex; // The index of the frame in the frame list.
  final duration = frmae.frameDuration; // The duration of the frame, in milliseconds.
}

Frames are always stored as full images, meaning they don't support blend modes, clear states, or partial frames.

Filters and Transforms for Animated Images

Most filters and transforms will apply to all frames of an animated image.

// Decode an animated PNG file.
final anim = await decodePngFile('animated.png');
// Resize the animation to 128x*, maintaining the aspect ratio of the frames
final resizedAnim = copyResize(anim, width: 128);
// Apply smoothing to the resized animation
smooth(resizedAnim, weight: 0.8);
// Save the animation to an animated GIF
encodeGifFile('resized_animated.gif', resizedAnim);