compat.libwebp

// Behavioral test: encode a synthetic image and decode it back.
//
// Linking is not the interesting question for this package — the source list is
// five directory globs including every SIMD variant, and a variant that failed
// to self-gate would still LINK while producing wrong pixels. So the assertions
// are on the pixels: lossless must round-trip exactly, lossy must stay close,
// and the encoder must actually respond to its quality knob.
#include <webp/decode.h>
#include <webp/encode.h>

#include <cassert>
#include <cstdint>
#include <cstdlib>
#include <vector>

namespace {

constexpr int kW = 64;
constexpr int kH = 48;

// A gradient with a hard edge: smooth enough for the lossy path to do well,
// structured enough that a broken transform shows up as a large delta.
// …