go-libwebp

Experimental translation from libwebp to Go source.
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README.md (1988B)

      1 # WebP JavaScript decoder
      2 
      3 ```
      4  __   __ ____ ____ ____     __  ____
      5 /  \\/  \  _ \  _ \  _ \   (__)/  __\
      6 \       /  __/ _  \  __/   _)  \_   \
      7  \__\__/_____/____/_/     /____/____/
      8 ```
      9 
     10 This file describes the compilation of libwebp into a JavaScript decoder using
     11 Emscripten and CMake.
     12 
     13 -   install the Emscripten SDK following the procedure described at:
     14     https://emscripten.org/docs/getting_started/downloads.html#installation-instructions-using-the-emsdk-recommended
     15     After installation, you should have some global variable positioned to the
     16     location of the SDK. In particular, `$EMSDK` should point to the top-level
     17     directory containing Emscripten tools.
     18 
     19 -   configure the project 'WEBP_JS' with CMake using:
     20 
     21     ```shell
     22     cd webp_js && \
     23     emcmake cmake -DWEBP_BUILD_WEBP_JS=ON ../
     24     ```
     25 
     26 -   compile webp.js using `emmake make`.
     27 
     28 -   that's it! Upon completion, you should have the 'webp.js', 'webp.js.mem',
     29     'webp_wasm.js' and 'webp_wasm.wasm' files generated.
     30 
     31 The callable JavaScript function is `WebPToSDL()`, which decodes a raw WebP
     32 bitstream into a canvas. See webp_js/index.html for a simple usage sample (see
     33 below for instructions).
     34 
     35 ## Demo HTML page
     36 
     37 The HTML page webp_js/index.html requires the built files 'webp.js' and
     38 'webp.js.mem' to be copied to webp_js/. An HTTP server to serve the WebP image
     39 example is also needed. With Python, just run:
     40 
     41 ```shell
     42 cd webp_js && python3 -m http.server 8080
     43 ```
     44 
     45 and then navigate to http://localhost:8080 in your favorite browser.
     46 
     47 ## Web-Assembly (WASM) version:
     48 
     49 CMakeLists.txt is configured to build the WASM version when using the option
     50 WEBP_BUILD_WEBP_JS=ON. The compilation step will assemble the files
     51 'webp_wasm.js' and 'webp_wasm.wasm' that you then need to copy to the webp_js/
     52 directory.
     53 
     54 See webp_js/index_wasm.html for a simple demo page using the WASM version of the
     55 library.
     56 
     57 ## Caveats
     58 
     59 -   First decoding using the library is usually slower, due to just-in-time
     60     compilation.