clip_win_wic.h

// Clip Library
// Copyright (c) 2020 David Capello
//
// This file is released under the terms of the MIT license.
// Read LICENSE.txt for more information.

#include "clip.h"

#include <algorithm>
#include <vector>

#include <shlwapi.h>
#include <wincodec.h>

namespace clip {
namespace win {

// Successful calls to CoInitialize() (S_OK or S_FALSE) must match
// the calls to CoUninitialize().
// From: https://docs.microsoft.com/en-us/windows/win32/api/combaseapi/nf-combaseapi-couninitialize#remarks
struct coinit {
  HRESULT hr;
  coinit() {
    hr = CoInitialize(nullptr);
  }
  ~coinit() {
    if (hr == S_OK || hr == S_FALSE)
      CoUninitialize();
  }
};

template<class T>
class comptr {
public:
  comptr() : m_ptr(nullptr) { }
  explicit comptr(T* ptr) : m_ptr(ptr) { }
  comptr(const comptr&) = delete;
  comptr& operator=(const comptr&) = delete;
  ~comptr() { reset(); }

  T** operator&() { return &m_ptr; }
  T* operator->() { return m_ptr; }
  bool operator!() const { return !m_ptr; }

  T* get() { return m_ptr; }
  void reset() {
    if (m_ptr) {
      m_ptr->Release();
      m_ptr = nullptr;
    }
  }
private:
  T* m_ptr;
};

//////////////////////////////////////////////////////////////////////
// Encode the image as PNG format

bool write_png_on_stream(const image& image,
                         IStream* stream) {
  const image_spec& spec = image.spec();

  comptr<IWICBitmapEncoder> encoder;
  HRESULT hr = CoCreateInstance(CLSID_WICPngEncoder,
                                nullptr, CLSCTX_INPROC_SERVER,
                                IID_PPV_ARGS(&encoder));
  if (FAILED(hr))
    return nullptr;

  hr = encoder->Initialize(stream, WICBitmapEncoderNoCache);
  if (FAILED(hr))
    return false;

  comptr<IWICBitmapFrameEncode> frame;
  comptr<IPropertyBag2> options;
  hr = encoder->CreateNewFrame(&frame, &options);
  if (FAILED(hr))
    return false;

  hr = frame->Initialize(options.get());
  if (FAILED(hr))
    return false;

  // PNG encoder (and decoder) only supports GUID_WICPixelFormat32bppBGRA for 32bpp.
  // See: https://docs.microsoft.com/en-us/windows/win32/wic/-wic-codec-native-pixel-formats#png-native-codec
  WICPixelFormatGUID pixelFormat = GUID_WICPixelFormat32bppBGRA;
  hr = frame->SetPixelFormat(&pixelFormat);
  if (FAILED(hr))
    return false;

  hr = frame->SetSize(spec.width, spec.height);
  if (FAILED(hr))
    return false;

  std::vector<uint32_t> buf;
  uint8_t* ptr = (uint8_t*)image.data();
  int bytes_per_row = spec.bytes_per_row;

  // Convert to GUID_WICPixelFormat32bppBGRA if needed
  if (spec.red_mask != 0xff0000 ||
      spec.green_mask != 0xff00 ||
      spec.blue_mask != 0xff ||
      spec.alpha_mask != 0xff000000) {
    buf.resize(spec.width * spec.height);
    uint32_t* dst = (uint32_t*)&buf[0];
    uint32_t* src = (uint32_t*)image.data();
    for (int y=0; y<spec.height; ++y) {
      auto src_line_start = src;
      for (int x=0; x<spec.width; ++x) {
        uint32_t c = *src;
        *dst = ((((c & spec.red_mask  ) >> spec.red_shift  ) << 16) |
                (((c & spec.green_mask) >> spec.green_shift) <<  8) |
                (((c & spec.blue_mask ) >> spec.blue_shift )      ) |
                (((c & spec.alpha_mask) >> spec.alpha_shift) << 24));
        ++dst;
        ++src;
      }
      src = (uint32_t*)(((uint8_t*)src_line_start) + spec.bytes_per_row);
    }
    ptr = (uint8_t*)&buf[0];
    bytes_per_row = 4 * spec.width;
  }

  hr = frame->WritePixels(spec.height,
                          bytes_per_row,
                          bytes_per_row * spec.height,
                          (BYTE*)ptr);
  if (FAILED(hr))
    return false;

  hr = frame->Commit();
  if (FAILED(hr))
    return false;

  hr = encoder->Commit();
  if (FAILED(hr))
    return false;

  return true;
}

HGLOBAL write_png(const image& image) {
  coinit com;

  comptr<IStream> stream;
  HRESULT hr = CreateStreamOnHGlobal(nullptr, false, &stream);
  if (FAILED(hr))
    return nullptr;

  bool result = write_png_on_stream(image, stream.get());

  HGLOBAL handle;
  hr = GetHGlobalFromStream(stream.get(), &handle);
  if (result)
    return handle;

  GlobalFree(handle);
  return nullptr;
}

//////////////////////////////////////////////////////////////////////
// Decode the clipboard data from PNG format

bool read_png(const uint8_t* buf,
              const UINT len,
              image* output_image,
              image_spec* output_spec) {
  coinit com;

  comptr<IStream> stream(SHCreateMemStream(buf, len));
  if (!stream)
    return false;

  comptr<IWICBitmapDecoder> decoder;
  HRESULT hr = CoCreateInstance(CLSID_WICPngDecoder2,
                                nullptr, CLSCTX_INPROC_SERVER,
                                IID_PPV_ARGS(&decoder));
  if (FAILED(hr)) {
    hr = CoCreateInstance(CLSID_WICPngDecoder1,
                          nullptr, CLSCTX_INPROC_SERVER,
                          IID_PPV_ARGS(&decoder));
    if (FAILED(hr))
      return false;
  }

  hr = decoder->Initialize(stream.get(), WICDecodeMetadataCacheOnDemand);
  if (FAILED(hr))
    return false;

  comptr<IWICBitmapFrameDecode> frame;
  hr = decoder->GetFrame(0, &frame);
  if (FAILED(hr))
    return false;

  WICPixelFormatGUID pixelFormat;
  hr = frame->GetPixelFormat(&pixelFormat);
  if (FAILED(hr))
    return false;

  // Only support this pixel format
  // TODO add support for more pixel formats
  if (pixelFormat != GUID_WICPixelFormat32bppBGRA)
    return false;

  UINT width = 0, height = 0;
  hr = frame->GetSize(&width, &height);
  if (FAILED(hr))
    return false;

  image_spec spec;
  spec.width = width;
  spec.height = height;
  spec.bits_per_pixel = 32;
  spec.bytes_per_row = 4 * width;
  spec.red_mask    = 0xff0000;
  spec.green_mask  = 0xff00;
  spec.blue_mask   = 0xff;
  spec.alpha_mask  = 0xff000000;
  spec.red_shift   = 16;
  spec.green_shift = 8;
  spec.blue_shift  = 0;
  spec.alpha_shift = 24;

  if (output_spec)
    *output_spec = spec;

  if (output_image) {
    image img(spec);

    hr = frame->CopyPixels(
      nullptr, // Entire bitmap
      spec.bytes_per_row,
      spec.bytes_per_row * spec.height,
      (BYTE*)img.data());
    if (FAILED(hr)) {
      return false;
    }

    std::swap(*output_image, img);
  }

  return true;
}

} // namespace win
} // namespace clip