Merge pull request #50 from GoogleChromeLabs/webp-dec

Decoder for webp
2018-06-14 13:25:49 +01:00
parent 60543dd0a5 91945da5ae
commit d75a3aca9b
8 changed files with 1300 additions and 1 deletions
--- a/codecs/example.webp
+++ b/codecs/example.webp
--- a/codecs/webp_dec/.gitignore
+++ b/codecs/webp_dec/.gitignore
@ -0,0 +1,2 @@
+/*.wasm
+/*.js
--- a/codecs/webp_dec/README.md
+++ b/codecs/webp_dec/README.md
@ -0,0 +1,42 @@
+# WebP decoder
+
+- Source: <https://github.com/webmproject/libwebp>
+- Version: v0.6.1
+
+## Example
+
+See `example.html`
+
+## API
+
+### `int version()`
+
+Returns the version of libwebp as a number. va.b.c is encoded as 0x0a0b0c
+
+### `uint8_t* create_buffer(int size)`
+
+Allocates an buffer for the file data.
+
+### `void destroy_buffer(uint8_t* p)`
+
+Frees a buffer created with `create_buffer`.
+
+### `void decode(uint8_t* img_in, int size)`
+
+Decodes the given webp file into raw RGBA. The result is implicitly stored and can be accessed using the `get_result_*()` functions.
+
+### `void free_result()`
+
+Frees the result created by `decode()`.
+
+### `int get_result_pointer()`
+
+Returns the pointer to the start of the buffer holding the encoded data. Length is width x height x 4 bytes.
+
+### `int get_result_width()`
+
+Returns the width of the image.
+
+### `int get_result_height()`
+
+Returns the height of the image.
--- a/codecs/webp_dec/example.html
+++ b/codecs/webp_dec/example.html
@ -0,0 +1,44 @@
+<!doctype html>
+<script src='webp_dec.js'></script>
+<script>
+  const Module = webp_dec();
+
+  async function loadFile(src) {
+    const resp = await fetch(src);
+    return await resp.arrayBuffer();
+  }
+
+  Module.onRuntimeInitialized = async _ => {
+    const api = {
+      version: Module.cwrap('version', 'number', []),
+      create_buffer: Module.cwrap('create_buffer', 'number', ['number', 'number']),
+      destroy_buffer: Module.cwrap('destroy_buffer', '', ['number']),
+      decode: Module.cwrap('decode', '', ['number', 'number']),
+      free_result: Module.cwrap('free_result', '', ['number']),
+      get_result_pointer: Module.cwrap('get_result_pointer', 'number', []),
+      get_result_width: Module.cwrap('get_result_width', 'number', []),
+      get_result_height: Module.cwrap('get_result_height', 'number', []),
+    };
+    const image = await loadFile('../example.webp');
+    const p = api.create_buffer(image.byteLength);
+    Module.HEAP8.set(new Uint8Array(image), p);
+    api.decode(p, image.byteLength);
+    const resultPointer = api.get_result_pointer();
+    if(resultPointer === 0) {
+      throw new Error("Could not decode image");
+    }
+    const resultWidth = api.get_result_width();
+    const resultHeight = api.get_result_height();
+    const resultView = new Uint8Array(Module.HEAP8.buffer, resultPointer, resultWidth * resultHeight * 4);
+    const result = new Uint8ClampedArray(resultView);
+    const imageData = new ImageData(result, resultWidth, resultHeight);
+    api.free_result(resultPointer);
+    api.destroy_buffer(p);
+    const canvas = document.createElement('canvas');
+    canvas.width = resultWidth;
+    canvas.height = resultHeight;
+    document.body.appendChild(canvas);
+    const ctx = canvas.getContext('2d');
+    ctx.putImageData(imageData, 0, 0);
+  };
+</script>
--- a/codecs/webp_dec/package-lock.json
+++ b/codecs/webp_dec/package-lock.json
--- a/codecs/webp_dec/package.json
+++ b/codecs/webp_dec/package.json
@ -0,0 +1,13 @@
+{
+  "name": "webp_dec",
+  "scripts": {
+    "install": "napa",
+    "build": "docker run --rm -v $(pwd):/src trzeci/emscripten emcc -O3 -s WASM=1 -s EXTRA_EXPORTED_RUNTIME_METHODS='[\"cwrap\"]' -s ALLOW_MEMORY_GROWTH=1 -s MODULARIZE=1 -s 'EXPORT_NAME=\"webp_dec\"' -I node_modules/libwebp -o ./webp_dec.js webp_dec.c node_modules/libwebp/src/{dec,dsp,demux,enc,mux,utils}/*.c"
+  },
+  "napa": {
+    "libwebp": "webmproject/libwebp#v0.6.1"
+  },
+  "devDependencies": {
+    "napa": "^3.0.0"
+  }
+}
--- a/codecs/webp_dec/webp_dec.c
+++ b/codecs/webp_dec/webp_dec.c
@ -0,0 +1,51 @@
+#include "emscripten.h"
+#include "src/webp/decode.h"
+#include "src/webp/demux.h"
+#include <stdlib.h>
+
+EMSCRIPTEN_KEEPALIVE
+int version() {
+  return WebPGetDecoderVersion();
+}
+
+EMSCRIPTEN_KEEPALIVE
+uint8_t* create_buffer(int size) {
+  return malloc(size);
+}
+
+EMSCRIPTEN_KEEPALIVE
+void destroy_buffer(uint8_t* p) {
+  free(p);
+}
+
+int result[3];
+EMSCRIPTEN_KEEPALIVE
+void decode(uint8_t* img_in, int size) {
+  int width, height;
+  uint8_t* img_out = WebPDecodeRGBA(img_in, size, &width, &height);
+  result[0] = (int)img_out;
+  result[1] = width;
+  result[2] = height;
+
+}
+
+EMSCRIPTEN_KEEPALIVE
+void free_result() {
+  WebPFree(result[0]);
+}
+
+EMSCRIPTEN_KEEPALIVE
+int get_result_pointer() {
+  return result[0];
+}
+
+EMSCRIPTEN_KEEPALIVE
+int get_result_width() {
+  return result[1];
+}
+
+EMSCRIPTEN_KEEPALIVE
+int get_result_height() {
+  return result[2];
+}
+
--- a/codecs/webp_enc/example.html
+++ b/codecs/webp_enc/example.html
@ -38,7 +38,7 @@
    api.free_result(resultPointer);
    api.destroy_buffer(p);

-    const blob = new Blob([result], {type: 'image/jpeg'});
+    const blob = new Blob([result], {type: 'image/webp'});
    const blobURL = URL.createObjectURL(blob);
    const img = document.createElement('img');
    img.src = blobURL;