webpdec.h: single-file WebP decoder

libwebp 1.6.0's decode + demux path (lossy VP8, lossless VP8L, VP8X container, ALPH alpha, and the WebPDemux/WebPAnimDecoder animation API) amalgamated into one stb-style header, built as portable C99 with all SIMD, threads and host file I/O disabled. amalgamate.py regenerates webpdec.h from a pinned, auto-cloned libwebp checkout; tests/run.sh checks decode output bit-exactly against reference libwebp. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
2026-06-14 03:28:11 +00:00
commit 4da9a48d7c
10 changed files with 22045 additions and 0 deletions
@@ -0,0 +1,59 @@
+#!/bin/sh
+# Build and run the webpdec.h tests.  If Pillow is available, samples are
+# generated and decode output is checked bit-exactly against reference libwebp;
+# otherwise the tests just decode whatever .webp files are passed/present.
+#
+#   sh tests/run.sh
+set -e
+
+cd "$(dirname "$0")/.."          # repo root
+CC=${CC:-cc}
+CFLAGS="-O2 -std=c99 -Wall -I."
+TMP=$(mktemp -d)
+trap 'rm -rf "$TMP"' EXIT
+
+# Generate samples with Pillow if present (covers lossy, lossless, alpha,
+# odd dimensions, and a multi-frame animation).
+HAVE_PIL=0
+if python3 - "$TMP" >/dev/null 2>&1 <<'PY'
+import sys
+from PIL import Image
+d = sys.argv[1]
+w, h = 137, 83
+img = Image.new("RGBA", (w, h))
+px = img.load()
+for y in range(h):
+    for x in range(w):
+        px[x, y] = ((x*255)//w, (y*255)//h, (x*y) % 256, (x+y) % 256)
+img.save(d+"/lossless.webp", lossless=True)
+img.save(d+"/lossy.webp", quality=90)
+frames = [Image.new("RGBA", (48, 32), (i*50 % 256, 80, 200, 255)) for i in range(5)]
+frames[0].save(d+"/anim.webp", save_all=True, append_images=frames[1:],
+               duration=[100, 120, 140, 160, 180], loop=0, lossless=True)
+PY
+then HAVE_PIL=1; fi
+
+echo "== build =="
+$CC $CFLAGS -o "$TMP/test_decode" tests/test_decode.c -lm
+$CC $CFLAGS -o "$TMP/test_demux"  tests/test_demux.c  -lm
+
+if [ "$HAVE_PIL" = 1 ]; then
+  echo "== decode (still) =="
+  for k in lossless lossy; do
+    "$TMP/test_decode" "$TMP/$k.webp" "$TMP/$k.raw"
+    python3 - "$TMP/$k.webp" "$TMP/$k.raw" <<'PY'
+import sys
+from PIL import Image
+ref = Image.open(sys.argv[1]).convert("RGBA").tobytes()
+mine = open(sys.argv[2], "rb").read()
+assert ref == mine, "%s: pixels differ from reference libwebp!" % sys.argv[1]
+print("  %s: bit-exact vs reference libwebp" % sys.argv[1].split('/')[-1])
+PY
+  done
+  echo "== demux + animation =="
+  "$TMP/test_demux" "$TMP/anim.webp"
+else
+  echo "(Pillow not found -- decoding any .webp passed as args)"
+  for f in "$@"; do "$TMP/test_decode" "$f"; done
+fi
+echo "ALL TESTS PASSED"