deskflow/src/lib/platform/MSWindowsDropTarget.cpp

/*
 * Deskflow -- mouse and keyboard sharing utility
 * SPDX-FileCopyrightText: (C) 2014 - 2016 Symless Ltd.
 * SPDX-License-Identifier: GPL-2.0-only WITH LicenseRef-OpenSSL-Exception
 */

#include "platform/MSWindowsDropTarget.h"

#include "base/Log.h"
#include "common/Common.h"

#include <Shlobj.h>
#include <stdio.h>

void getDropData(IDataObject *pDataObject);

MSWindowsDropTarget *MSWindowsDropTarget::s_instance = nullptr;

MSWindowsDropTarget::MSWindowsDropTarget() : m_refCount(1), m_allowDrop(false)
{
  s_instance = this;
}

MSWindowsDropTarget &MSWindowsDropTarget::instance()
{
  assert(s_instance != nullptr);
  return *s_instance;
}

HRESULT
MSWindowsDropTarget::DragEnter(IDataObject *dataObject, DWORD keyState, POINTL point, DWORD *effect)
{
  // check if data object contain drop
  m_allowDrop = queryDataObject(dataObject);
  if (m_allowDrop) {
    getDropData(dataObject);
  }

  *effect = DROPEFFECT_NONE;

  return S_OK;
}

HRESULT
MSWindowsDropTarget::DragOver(DWORD keyState, POINTL point, DWORD *effect)
{
  *effect = DROPEFFECT_NONE;

  return S_OK;
}

HRESULT
MSWindowsDropTarget::DragLeave(void)
{
  return S_OK;
}

HRESULT
MSWindowsDropTarget::Drop(IDataObject *dataObject, DWORD keyState, POINTL point, DWORD *effect)
{
  *effect = DROPEFFECT_NONE;

  return S_OK;
}

bool MSWindowsDropTarget::queryDataObject(IDataObject *dataObject)
{
  // check if it supports CF_HDROP using a HGLOBAL
  FORMATETC fmtetc = {CF_HDROP, 0, DVASPECT_CONTENT, -1, TYMED_HGLOBAL};

  return dataObject->QueryGetData(&fmtetc) == S_OK ? true : false;
}

void MSWindowsDropTarget::setDraggingFilename(char *const filename)
{
  m_dragFilename = filename;
}

std::string MSWindowsDropTarget::getDraggingFilename()
{
  return m_dragFilename;
}

void MSWindowsDropTarget::clearDraggingFilename()
{
  m_dragFilename.clear();
}

void getDropData(IDataObject *dataObject)
{
  // construct a FORMATETC object
  FORMATETC fmtEtc = {CF_HDROP, 0, DVASPECT_CONTENT, -1, TYMED_HGLOBAL};
  STGMEDIUM stgMed;

  // See if the dataobject contains any DROP stored as a HGLOBAL
  if (dataObject->QueryGetData(&fmtEtc) == S_OK) {
    if (dataObject->GetData(&fmtEtc, &stgMed) == S_OK) {
      // get data here
      PVOID data = GlobalLock(stgMed.hGlobal);

      // data object global handler contains:
      // DROPFILESfilename1 filename2 two spaces as the end
      // TODO: get multiple filenames
      wchar_t *wcData = (wchar_t *)((LPBYTE)data + sizeof(DROPFILES));

      // convert wchar to char
      char *filename = new char[wcslen(wcData) + 1];
      filename[wcslen(wcData)] = '\0';
      wcstombs(filename, wcData, wcslen(wcData));

      MSWindowsDropTarget::instance().setDraggingFilename(filename);

      GlobalUnlock(stgMed.hGlobal);

      // release the data using the COM API
      ReleaseStgMedium(&stgMed);

      delete[] filename;
    }
  }
}

HRESULT __stdcall MSWindowsDropTarget::QueryInterface(REFIID iid, void **object)
{
  if (iid == IID_IDropTarget || iid == IID_IUnknown) {
    AddRef();
    *object = this;
    return S_OK;
  } else {
    *object = 0;
    return E_NOINTERFACE;
  }
}

ULONG __stdcall MSWindowsDropTarget::AddRef(void)
{
  return InterlockedIncrement(&m_refCount);
}

ULONG __stdcall MSWindowsDropTarget::Release(void)
{
  LONG count = InterlockedDecrement(&m_refCount);

  if (count == 0) {
    delete this;
    return 0;
  } else {
    return count;
  }
}