Package dev.matrixlab.webp4j.animation

Class FrameNormalizer

java.lang.Object

dev.matrixlab.webp4j.animation.FrameNormalizer

public final class FrameNormalizer
extends Object

Utility class for normalizing animation frames to a common canvas size.

When creating animated WebP from images of different sizes, all frames must have identical dimensions. This class provides methods to resize and position frames onto a common canvas with configurable fit strategies.

Author:

MrNanko

Method Summary

Modifier and Type	Method	Description
static List<BufferedImage>	normalize(List<BufferedImage> frames)	Normalizes a list of frames for animation using default strategy.
static List<BufferedImage>	normalize(List<BufferedImage> frames, Integer targetWidth, Integer targetHeight, FitMode fitMode, boolean allowUpscale, Color background)	Normalizes frames to a common canvas with configurable strategy.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

normalize

public static List<BufferedImage> normalize(List<BufferedImage> frames)

Normalizes a list of frames for animation using default strategy.

• Target size: min width/height among frames (avoids upscaling)
• Fit: CONTAIN (preserve aspect, letterbox center)
• Background: transparent

Parameters:

frames - Source frames (must be non-empty)

Returns:

New list of TYPE_INT_ARGB frames of identical size

Throws:

IllegalArgumentException - if frames is null/empty or contains invalid images

normalize

public static List<BufferedImage> normalize(List<BufferedImage> frames,
 Integer targetWidth,
 Integer targetHeight,
 FitMode fitMode,
 boolean allowUpscale,
 Color background)

Normalizes frames to a common canvas with configurable strategy. Returns new TYPE_INT_ARGB frames with identical dimensions.

Parameters:

frames - Source frames (must be non-empty)

targetWidth - Target canvas width (nullable: use min width across frames)

targetHeight - Target canvas height (nullable: use min height across frames)

fitMode - How to fit frames onto canvas (CONTAIN/COVER/STRETCH)

allowUpscale - Whether to allow upscaling smaller images

background - Background color to fill (use transparent for alpha)

Returns:

List of normalized frames (new BufferedImage instances)