ゴールデンウイークの振り返り(2024)

/ Setup the input data
WebPPicture pic;
if (!WebPPictureInit(&pic)) {
  return 0;  // version error
}
pic.width = width;
pic.height = height;
// allocated picture of dimension width x height
if (!WebPPictureAlloc(&pic)) {
  return 0;   // memory error
}
// at this point, 'pic' has been initialized as a container,
// and can receive the Y/U/V samples.
// Alternatively, one could use ready-made import functions like
// WebPPictureImportRGB(), which will take care of memory allocation.
// In any case, past this point, one will have to call
// WebPPictureFree(&pic) to reclaim memory.

// Set up a byte-output write method. WebPMemoryWriter, for instance.
WebPMemoryWriter wrt;
WebPMemoryWriterInit(&wrt);     // initialize 'wrt'

pic.writer = MyFileWriter;
pic.custom_ptr = my_opaque_structure_to_make_MyFileWriter_work;

// Compress!
int ok = WebPEncode(&config, &pic);   // ok = 0 => error occurred!
WebPPictureFree(&pic);  // must be called independently of the 'ok' result.

WebPMemoryWriterClear(&wrt);

struct ManagedWebpPicture {
    config: WebPConfig,
    picture: WebPPicture,
}

// snip

impl Drop for ManagedWebpPicture {
    fn drop(&mut self) {
        unsafe { WebPPictureFree(&mut self.picture) }
    }
}