limitSize static method
Resize so the long side is at most maxDim (no-op when small enough).
Implementation
static RgbaImage limitSize(RgbaImage src, int maxDim) {
final long = src.width > src.height ? src.width : src.height;
if (long <= maxDim) return src;
final scale = maxDim / long;
final dw = (src.width * scale).round().clamp(1, maxDim);
final dh = (src.height * scale).round().clamp(1, maxDim);
return resize(src, dw, dh);
}