libwebp/imageio/image_enc.c

// Copyright 2016 Google Inc. All Rights Reserved.
//
// Use of this source code is governed by a BSD-style license
// that can be found in the COPYING file in the root of the source
// tree. An additional intellectual property rights grant can be found
// in the file PATENTS. All contributing project authors may
// be found in the AUTHORS file in the root of the source tree.
// -----------------------------------------------------------------------------
//
// Save image

#include "./image_enc.h"

#include <assert.h>
#include <string.h>

#ifdef WEBP_HAVE_PNG
#include <png.h>
#include <setjmp.h>   // note: this must be included *after* png.h
#endif

#ifdef HAVE_WINCODEC_H
#ifdef __MINGW32__
#define INITGUID  // Without this GUIDs are declared extern and fail to link
#endif
#define CINTERFACE
#define COBJMACROS
#define _WIN32_IE 0x500  // Workaround bug in shlwapi.h when compiling C++
                         // code with COBJMACROS.
#include <ole2.h>  // CreateStreamOnHGlobal()
#include <shlwapi.h>
#include <tchar.h>
#include <windows.h>
#include <wincodec.h>
#endif

#include "./imageio_util.h"
#include "../examples/unicode.h"

//------------------------------------------------------------------------------
// PNG

#ifdef HAVE_WINCODEC_H

#define IFS(fn)                                                     \
  do {                                                              \
    if (SUCCEEDED(hr)) {                                            \
      hr = (fn);                                                    \
      if (FAILED(hr)) fprintf(stderr, #fn " failed %08lx\n", hr);   \
    }                                                               \
  } while (0)

#ifdef __cplusplus
#define MAKE_REFGUID(x) (x)
#else
#define MAKE_REFGUID(x) &(x)
#endif

static HRESULT CreateOutputStream(const char* out_file_name,
                                  int write_to_mem, IStream** stream) {
  HRESULT hr = S_OK;
  if (write_to_mem) {
    // Output to a memory buffer. This is freed when 'stream' is released.
    IFS(CreateStreamOnHGlobal(NULL, TRUE, stream));
  } else {
    IFS(SHCreateStreamOnFile((const LPTSTR)out_file_name,
                             STGM_WRITE | STGM_CREATE, stream));
  }
  if (FAILED(hr)) {
    _ftprintf(stderr, _T("Error opening output file %s (%08lx)\n"),
              (const LPTSTR)out_file_name, hr);
  }
  return hr;
}

static HRESULT WriteUsingWIC(const char* out_file_name, int use_stdout,
                             REFGUID container_guid,
                             uint8_t* rgb, int stride,
                             uint32_t width, uint32_t height, int has_alpha) {
  HRESULT hr = S_OK;
  IWICImagingFactory* factory = NULL;
  IWICBitmapFrameEncode* frame = NULL;
  IWICBitmapEncoder* encoder = NULL;
  IStream* stream = NULL;
  WICPixelFormatGUID pixel_format = has_alpha ? GUID_WICPixelFormat32bppBGRA
                                              : GUID_WICPixelFormat24bppBGR;

  if (out_file_name == NULL || rgb == NULL) return E_INVALIDARG;

  IFS(CoInitialize(NULL));
  IFS(CoCreateInstance(MAKE_REFGUID(CLSID_WICImagingFactory), NULL,
                       CLSCTX_INPROC_SERVER,
                       MAKE_REFGUID(IID_IWICImagingFactory),
                       (LPVOID*)&factory));
  if (hr == REGDB_E_CLASSNOTREG) {
    fprintf(stderr,
            "Couldn't access Windows Imaging Component (are you running "
            "Windows XP SP3 or newer?). PNG support not available. "
            "Use -ppm or -pgm for available PPM and PGM formats.\n");
  }
  IFS(CreateOutputStream(out_file_name, use_stdout, &stream));
  IFS(IWICImagingFactory_CreateEncoder(factory, container_guid, NULL,
                                       &encoder));
  IFS(IWICBitmapEncoder_Initialize(encoder, stream,
                                   WICBitmapEncoderNoCache));
  IFS(IWICBitmapEncoder_CreateNewFrame(encoder, &frame, NULL));
  IFS(IWICBitmapFrameEncode_Initialize(frame, NULL));
  IFS(IWICBitmapFrameEncode_SetSize(frame, width, height));
  IFS(IWICBitmapFrameEncode_SetPixelFormat(frame, &pixel_format));
  IFS(IWICBitmapFrameEncode_WritePixels(frame, height, stride,
                                        height * stride, rgb));
  IFS(IWICBitmapFrameEncode_Commit(frame));
  IFS(IWICBitmapEncoder_Commit(encoder));

  if (SUCCEEDED(hr) && use_stdout) {
    HGLOBAL image;
    IFS(GetHGlobalFromStream(stream, &image));
    if (SUCCEEDED(hr)) {
      HANDLE std_output = GetStdHandle(STD_OUTPUT_HANDLE);
      DWORD mode;
      const BOOL update_mode = GetConsoleMode(std_output, &mode);
      const void* const image_mem = GlobalLock(image);
      DWORD bytes_written = 0;

      // Clear output processing if necessary, then output the image.
      if (update_mode) SetConsoleMode(std_output, 0);
      if (!WriteFile(std_output, image_mem, (DWORD)GlobalSize(image),
                     &bytes_written, NULL) ||
          bytes_written != GlobalSize(image)) {
        hr = E_FAIL;
      }
      if (update_mode) SetConsoleMode(std_output, mode);
      GlobalUnlock(image);
    }
  }

  if (frame != NULL) IUnknown_Release(frame);
  if (encoder != NULL) IUnknown_Release(encoder);
  if (factory != NULL) IUnknown_Release(factory);
  if (stream != NULL) IUnknown_Release(stream);
  return hr;
}

int WebPWritePNG(const char* out_file_name, int use_stdout,
                 const WebPDecBuffer* const buffer) {
  const uint32_t width = buffer->width;
  const uint32_t height = buffer->height;
  uint8_t* const rgb = buffer->u.RGBA.rgba;
  const int stride = buffer->u.RGBA.stride;
  const int has_alpha = WebPIsAlphaMode(buffer->colorspace);

  return SUCCEEDED(WriteUsingWIC(out_file_name, use_stdout,
                                 MAKE_REFGUID(GUID_ContainerFormatPng),
                                 rgb, stride, width, height, has_alpha));
}

#elif defined(WEBP_HAVE_PNG)    // !HAVE_WINCODEC_H
static void PNGAPI PNGErrorFunction(png_structp png, png_const_charp unused) {
  (void)unused;  // remove variable-unused warning
  longjmp(png_jmpbuf(png), 1);
}

int WebPWritePNG(FILE* out_file, const WebPDecBuffer* const buffer) {
  volatile png_structp png;
  volatile png_infop info;

  if (out_file == NULL || buffer == NULL) return 0;

  png = png_create_write_struct(PNG_LIBPNG_VER_STRING,
                                NULL, PNGErrorFunction, NULL);
  if (png == NULL) {
    return 0;
  }
  info = png_create_info_struct(png);
  if (info == NULL) {
    png_destroy_write_struct((png_structpp)&png, NULL);
    return 0;
  }
  if (setjmp(png_jmpbuf(png))) {
    png_destroy_write_struct((png_structpp)&png, (png_infopp)&info);
    return 0;
  }
  png_init_io(png, out_file);
  {
    const uint32_t width = buffer->width;
    const uint32_t height = buffer->height;
    png_bytep row = buffer->u.RGBA.rgba;
    const int stride = buffer->u.RGBA.stride;
    const int has_alpha = WebPIsAlphaMode(buffer->colorspace);
    uint32_t y;

    png_set_IHDR(png, info, width, height, 8,
                 has_alpha ? PNG_COLOR_TYPE_RGBA : PNG_COLOR_TYPE_RGB,
                 PNG_INTERLACE_NONE, PNG_COMPRESSION_TYPE_DEFAULT,
                 PNG_FILTER_TYPE_DEFAULT);
    png_write_info(png, info);
    for (y = 0; y < height; ++y) {
      png_write_rows(png, &row, 1);
      row += stride;
    }
  }
  png_write_end(png, info);
  png_destroy_write_struct((png_structpp)&png, (png_infopp)&info);
  return 1;
}
#else    // !HAVE_WINCODEC_H && !WEBP_HAVE_PNG
int WebPWritePNG(FILE* fout, const WebPDecBuffer* const buffer) {
  if (fout == NULL || buffer == NULL) return 0;

  fprintf(stderr, "PNG support not compiled. Please install the libpng "
          "development package before building.\n");
  fprintf(stderr, "You can run with -ppm flag to decode in PPM format.\n");
  return 0;
}
#endif

//------------------------------------------------------------------------------
// PPM / PAM

static int WritePPMPAM(FILE* fout, const WebPDecBuffer* const buffer,
                       int alpha) {
  if (fout == NULL || buffer == NULL) {
    return 0;
  } else {
    const uint32_t width = buffer->width;
    const uint32_t height = buffer->height;
    const uint8_t* row = buffer->u.RGBA.rgba;
    const int stride = buffer->u.RGBA.stride;
    const size_t bytes_per_px = alpha ? 4 : 3;
    uint32_t y;

    if (row == NULL) return 0;

    if (alpha) {
      fprintf(fout, "P7\nWIDTH %u\nHEIGHT %u\nDEPTH 4\nMAXVAL 255\n"
                    "TUPLTYPE RGB_ALPHA\nENDHDR\n", width, height);
    } else {
      fprintf(fout, "P6\n%u %u\n255\n", width, height);
    }
    for (y = 0; y < height; ++y) {
      if (fwrite(row, width, bytes_per_px, fout) != bytes_per_px) {
        return 0;
      }
      row += stride;
    }
  }
  return 1;
}

int WebPWritePPM(FILE* fout, const WebPDecBuffer* const buffer) {
  return WritePPMPAM(fout, buffer, 0);
}

int WebPWritePAM(FILE* fout, const WebPDecBuffer* const buffer) {
  return WritePPMPAM(fout, buffer, 1);
}

//------------------------------------------------------------------------------
// Raw PGM

// Save 16b mode (RGBA4444, RGB565, ...) for debugging purpose.
int WebPWrite16bAsPGM(FILE* fout, const WebPDecBuffer* const buffer) {
  const uint32_t width = buffer->width;
  const uint32_t height = buffer->height;
  const uint8_t* rgba = buffer->u.RGBA.rgba;
  const int stride = buffer->u.RGBA.stride;
  const uint32_t bytes_per_px = 2;
  uint32_t y;

  if (fout == NULL || buffer == NULL || rgba == NULL) return 0;

  fprintf(fout, "P5\n%u %u\n255\n", width * bytes_per_px, height);
  for (y = 0; y < height; ++y) {
    if (fwrite(rgba, width, bytes_per_px, fout) != bytes_per_px) {
      return 0;
    }
    rgba += stride;
  }
  return 1;
}

//------------------------------------------------------------------------------
// BMP

static void PutLE16(uint8_t* const dst, uint32_t value) {
  dst[0] = (value >> 0) & 0xff;
  dst[1] = (value >> 8) & 0xff;
}

static void PutLE32(uint8_t* const dst, uint32_t value) {
  PutLE16(dst + 0, (value >>  0) & 0xffff);
  PutLE16(dst + 2, (value >> 16) & 0xffff);
}

#define BMP_HEADER_SIZE 54
int WebPWriteBMP(FILE* fout, const WebPDecBuffer* const buffer) {
  const int has_alpha = WebPIsAlphaMode(buffer->colorspace);
  const uint32_t width = buffer->width;
  const uint32_t height = buffer->height;
  const uint8_t* rgba = buffer->u.RGBA.rgba;
  const int stride = buffer->u.RGBA.stride;
  const uint32_t bytes_per_px = has_alpha ? 4 : 3;
  uint32_t y;
  const uint32_t line_size = bytes_per_px * width;
  const uint32_t bmp_stride = (line_size + 3) & ~3;   // pad to 4
  const uint32_t total_size = bmp_stride * height + BMP_HEADER_SIZE;
  uint8_t bmp_header[BMP_HEADER_SIZE] = { 0 };

  if (fout == NULL || buffer == NULL || rgba == NULL) return 0;

  // bitmap file header
  PutLE16(bmp_header + 0, 0x4d42);                // signature 'BM'
  PutLE32(bmp_header + 2, total_size);            // size including header
  PutLE32(bmp_header + 6, 0);                     // reserved
  PutLE32(bmp_header + 10, BMP_HEADER_SIZE);      // offset to pixel array
  // bitmap info header
  PutLE32(bmp_header + 14, 40);                   // DIB header size
  PutLE32(bmp_header + 18, width);                // dimensions
  PutLE32(bmp_header + 22, -(int)height);         // vertical flip!
  PutLE16(bmp_header + 26, 1);                    // number of planes
  PutLE16(bmp_header + 28, bytes_per_px * 8);     // bits per pixel
  PutLE32(bmp_header + 30, 0);                    // no compression (BI_RGB)
  PutLE32(bmp_header + 34, 0);                    // image size (placeholder)
  PutLE32(bmp_header + 38, 2400);                 // x pixels/meter
  PutLE32(bmp_header + 42, 2400);                 // y pixels/meter
  PutLE32(bmp_header + 46, 0);                    // number of palette colors
  PutLE32(bmp_header + 50, 0);                    // important color count

  // TODO(skal): color profile

  // write header
  if (fwrite(bmp_header, sizeof(bmp_header), 1, fout) != 1) {
    return 0;
  }

  // write pixel array
  for (y = 0; y < height; ++y) {
    if (fwrite(rgba, line_size, 1, fout) != 1) {
      return 0;
    }
    // write padding zeroes
    if (bmp_stride != line_size) {
      const uint8_t zeroes[3] = { 0 };
      if (fwrite(zeroes, bmp_stride - line_size, 1, fout) != 1) {
        return 0;
      }
    }
    rgba += stride;
  }
  return 1;
}
#undef BMP_HEADER_SIZE

//------------------------------------------------------------------------------
// TIFF

#define NUM_IFD_ENTRIES 15
#define EXTRA_DATA_SIZE 16
// 10b for signature/header + n * 12b entries + 4b for IFD terminator:
#define EXTRA_DATA_OFFSET (10 + 12 * NUM_IFD_ENTRIES + 4)
#define TIFF_HEADER_SIZE (EXTRA_DATA_OFFSET + EXTRA_DATA_SIZE)

int WebPWriteTIFF(FILE* fout, const WebPDecBuffer* const buffer) {
  const int has_alpha = WebPIsAlphaMode(buffer->colorspace);
  const uint32_t width = buffer->width;
  const uint32_t height = buffer->height;
  const uint8_t* rgba = buffer->u.RGBA.rgba;
  const int stride = buffer->u.RGBA.stride;
  const uint8_t bytes_per_px = has_alpha ? 4 : 3;
  const uint8_t assoc_alpha =
      WebPIsPremultipliedMode(buffer->colorspace) ? 1 : 2;
  // For non-alpha case, we omit tag 0x152 (ExtraSamples).
  const uint8_t num_ifd_entries = has_alpha ? NUM_IFD_ENTRIES
                                            : NUM_IFD_ENTRIES - 1;
  uint8_t tiff_header[TIFF_HEADER_SIZE] = {
    0x49, 0x49, 0x2a, 0x00,   // little endian signature
    8, 0, 0, 0,               // offset to the unique IFD that follows
    // IFD (offset = 8). Entries must be written in increasing tag order.
    num_ifd_entries, 0,       // Number of entries in the IFD (12 bytes each).
    0x00, 0x01, 3, 0, 1, 0, 0, 0, 0, 0, 0, 0,    //  10: Width  (TBD)
    0x01, 0x01, 3, 0, 1, 0, 0, 0, 0, 0, 0, 0,    //  22: Height (TBD)
    0x02, 0x01, 3, 0, bytes_per_px, 0, 0, 0,     //  34: BitsPerSample: 8888
        EXTRA_DATA_OFFSET + 0, 0, 0, 0,
    0x03, 0x01, 3, 0, 1, 0, 0, 0, 1, 0, 0, 0,    //  46: Compression: none
    0x06, 0x01, 3, 0, 1, 0, 0, 0, 2, 0, 0, 0,    //  58: Photometric: RGB
    0x11, 0x01, 4, 0, 1, 0, 0, 0,                //  70: Strips offset:
        TIFF_HEADER_SIZE, 0, 0, 0,               //      data follows header
    0x12, 0x01, 3, 0, 1, 0, 0, 0, 1, 0, 0, 0,    //  82: Orientation: topleft
    0x15, 0x01, 3, 0, 1, 0, 0, 0,                //  94: SamplesPerPixels
        bytes_per_px, 0, 0, 0,
    0x16, 0x01, 3, 0, 1, 0, 0, 0, 0, 0, 0, 0,    // 106: Rows per strip (TBD)
    0x17, 0x01, 4, 0, 1, 0, 0, 0, 0, 0, 0, 0,    // 118: StripByteCount (TBD)
    0x1a, 0x01, 5, 0, 1, 0, 0, 0,                // 130: X-resolution
        EXTRA_DATA_OFFSET + 8, 0, 0, 0,
    0x1b, 0x01, 5, 0, 1, 0, 0, 0,                // 142: Y-resolution
        EXTRA_DATA_OFFSET + 8, 0, 0, 0,
    0x1c, 0x01, 3, 0, 1, 0, 0, 0, 1, 0, 0, 0,    // 154: PlanarConfiguration
    0x28, 0x01, 3, 0, 1, 0, 0, 0, 2, 0, 0, 0,    // 166: ResolutionUnit (inch)
    0x52, 0x01, 3, 0, 1, 0, 0, 0,
        assoc_alpha, 0, 0, 0,                    // 178: ExtraSamples: rgbA/RGBA
    0, 0, 0, 0,                                  // 190: IFD terminator
    // EXTRA_DATA_OFFSET:
    8, 0, 8, 0, 8, 0, 8, 0,      // BitsPerSample
    72, 0, 0, 0, 1, 0, 0, 0      // 72 pixels/inch, for X/Y-resolution
  };
  uint32_t y;

  if (fout == NULL || buffer == NULL || rgba == NULL) return 0;

  // Fill placeholders in IFD:
  PutLE32(tiff_header + 10 + 8, width);
  PutLE32(tiff_header + 22 + 8, height);
  PutLE32(tiff_header + 106 + 8, height);
  PutLE32(tiff_header + 118 + 8, width * bytes_per_px * height);
  if (!has_alpha) PutLE32(tiff_header + 178, 0);  // IFD terminator

  // write header
  if (fwrite(tiff_header, sizeof(tiff_header), 1, fout) != 1) {
    return 0;
  }
  // write pixel values
  for (y = 0; y < height; ++y) {
    if (fwrite(rgba, bytes_per_px, width, fout) != width) {
      return 0;
    }
    rgba += stride;
  }

  return 1;
}

#undef TIFF_HEADER_SIZE
#undef EXTRA_DATA_OFFSET
#undef EXTRA_DATA_SIZE
#undef NUM_IFD_ENTRIES

//------------------------------------------------------------------------------
// Raw Alpha

int WebPWriteAlphaPlane(FILE* fout, const WebPDecBuffer* const buffer) {
  if (fout == NULL || buffer == NULL) {
    return 0;
  } else {
    const uint32_t width = buffer->width;
    const uint32_t height = buffer->height;
    const uint8_t* a = buffer->u.YUVA.a;
    const int a_stride = buffer->u.YUVA.a_stride;
    uint32_t y;

    if (a == NULL) return 0;

    fprintf(fout, "P5\n%u %u\n255\n", width, height);
    for (y = 0; y < height; ++y) {
      if (fwrite(a, width, 1, fout) != 1) return 0;
      a += a_stride;
    }
    return 1;
  }
}

//------------------------------------------------------------------------------
// PGM with IMC4 layout

int WebPWritePGM(FILE* fout, const WebPDecBuffer* const buffer) {
  if (fout == NULL || buffer == NULL) {
    return 0;
  } else {
    const int width = buffer->width;
    const int height = buffer->height;
    const WebPYUVABuffer* const yuv = &buffer->u.YUVA;
    const uint8_t* src_y = yuv->y;
    const uint8_t* src_u = yuv->u;
    const uint8_t* src_v = yuv->v;
    const uint8_t* src_a = yuv->a;
    const int uv_width = (width + 1) / 2;
    const int uv_height = (height + 1) / 2;
    const int a_height = (src_a != NULL) ? height : 0;
    int ok = 1;
    int y;

    if (src_y == NULL || src_u == NULL || src_v == NULL) return 0;

    fprintf(fout, "P5\n%d %d\n255\n",
            (width + 1) & ~1, height + uv_height + a_height);
    for (y = 0; ok && y < height; ++y) {
      ok &= (fwrite(src_y, width, 1, fout) == 1);
      if (width & 1) fputc(0, fout);    // padding byte
      src_y += yuv->y_stride;
    }
    for (y = 0; ok && y < uv_height; ++y) {
      ok &= (fwrite(src_u, uv_width, 1, fout) == 1);
      ok &= (fwrite(src_v, uv_width, 1, fout) == 1);
      src_u += yuv->u_stride;
      src_v += yuv->v_stride;
    }
    for (y = 0; ok && y < a_height; ++y) {
      ok &= (fwrite(src_a, width, 1, fout) == 1);
      if (width & 1) fputc(0, fout);    // padding byte
      src_a += yuv->a_stride;
    }
    return ok;
  }
}

//------------------------------------------------------------------------------
// Raw YUV(A) planes

int WebPWriteYUV(FILE* fout, const WebPDecBuffer* const buffer) {
  if (fout == NULL || buffer == NULL) {
    return 0;
  } else {
    const int width = buffer->width;
    const int height = buffer->height;
    const WebPYUVABuffer* const yuv = &buffer->u.YUVA;
    const uint8_t* src_y = yuv->y;
    const uint8_t* src_u = yuv->u;
    const uint8_t* src_v = yuv->v;
    const uint8_t* src_a = yuv->a;
    const int uv_width = (width + 1) / 2;
    const int uv_height = (height + 1) / 2;
    const int a_height = (src_a != NULL) ? height : 0;
    int ok = 1;
    int y;

    if (src_y == NULL || src_u == NULL || src_v == NULL) return 0;

    for (y = 0; ok && y < height; ++y) {
      ok &= (fwrite(src_y, width, 1, fout) == 1);
      src_y += yuv->y_stride;
    }
    for (y = 0; ok && y < uv_height; ++y) {
      ok &= (fwrite(src_u, uv_width, 1, fout) == 1);
      src_u += yuv->u_stride;
    }
    for (y = 0; ok && y < uv_height; ++y) {
      ok &= (fwrite(src_v, uv_width, 1, fout) == 1);
      src_v += yuv->v_stride;
    }
    for (y = 0; ok && y < a_height; ++y) {
      ok &= (fwrite(src_a, width, 1, fout) == 1);
      src_a += yuv->a_stride;
    }
    return ok;
  }
}

//------------------------------------------------------------------------------
// Generic top-level call

int WebPSaveImage(const WebPDecBuffer* const buffer,
                  WebPOutputFileFormat format,
                  const char* const out_file_name) {
  FILE* fout = NULL;
  int needs_open_file = 1;
  const int use_stdout =
      (out_file_name != NULL) && !WSTRCMP(out_file_name, "-");
  int ok = 1;

  if (buffer == NULL || out_file_name == NULL) return 0;

#ifdef HAVE_WINCODEC_H
  needs_open_file = (format != PNG);
#endif

  if (needs_open_file) {
    fout = use_stdout ? ImgIoUtilSetBinaryMode(stdout)
                      : WFOPEN(out_file_name, "wb");
    if (fout == NULL) {
      WFPRINTF(stderr, "Error opening output file %s\n",
               (const W_CHAR*)out_file_name);
      return 0;
    }
  }

  if (format == PNG ||
      format == RGBA || format == BGRA || format == ARGB ||
      format == rgbA || format == bgrA || format == Argb) {
#ifdef HAVE_WINCODEC_H
    ok &= WebPWritePNG(out_file_name, use_stdout, buffer);
#else
    ok &= WebPWritePNG(fout, buffer);
#endif
  } else if (format == PAM) {
    ok &= WebPWritePAM(fout, buffer);
  } else if (format == PPM || format == RGB || format == BGR) {
    ok &= WebPWritePPM(fout, buffer);
  } else if (format == RGBA_4444 || format == RGB_565 || format == rgbA_4444) {
    ok &= WebPWrite16bAsPGM(fout, buffer);
  } else if (format == BMP) {
    ok &= WebPWriteBMP(fout, buffer);
  } else if (format == TIFF) {
    ok &= WebPWriteTIFF(fout, buffer);
  } else if (format == RAW_YUV) {
    ok &= WebPWriteYUV(fout, buffer);
  } else if (format == PGM || format == YUV || format == YUVA) {
    ok &= WebPWritePGM(fout, buffer);
  } else if (format == ALPHA_PLANE_ONLY) {
    ok &= WebPWriteAlphaPlane(fout, buffer);
  }
  if (fout != NULL && fout != stdout) {
    fclose(fout);
  }
  return ok;
}