static GUID IIDFromString(String lpsz) {
   int length = lpsz.length();
   char[] buffer = new char[length + 1];
   lpsz.getChars(0, length, buffer, 0);
   GUID lpiid = new GUID();
   if (COM.IIDFromString(buffer, lpiid) == COM.S_OK) return lpiid;
   return null;
 }
 private int SetData(long /*int*/ pFormatetc, long /*int*/ pmedium, int fRelease) {
   if (pFormatetc == 0 || pmedium == 0) return COM.E_INVALIDARG;
   FORMATETC formatetc = new FORMATETC();
   COM.MoveMemory(formatetc, pFormatetc, FORMATETC.sizeof);
   if (formatetc.cfFormat == CFSTR_PERFORMEDDROPEFFECT && formatetc.tymed == COM.TYMED_HGLOBAL) {
     STGMEDIUM stgmedium = new STGMEDIUM();
     COM.MoveMemory(stgmedium, pmedium, STGMEDIUM.sizeof);
     // TODO - this should be GlobalLock()
     long /*int*/[] ptrEffect = new long /*int*/[1];
     OS.MoveMemory(ptrEffect, stgmedium.unionField, OS.PTR_SIZEOF);
     int[] effect = new int[1];
     OS.MoveMemory(effect, ptrEffect[0], 4);
     dataEffect = osToOp(effect[0]);
   }
   if (fRelease == 1) {
     COM.ReleaseStgMedium(pmedium);
   }
   return COM.S_OK;
 }
 private int Release() {
   refCount--;
   if (refCount == 0) {
     disposeCOMInterfaces();
     if (COM.FreeUnusedLibraries) {
       COM.CoFreeUnusedLibraries();
     }
   }
   return refCount;
 }
  /* QueryInterface([in] riid, [out] ppvObject)
   * Ownership of ppvObject transfers from callee to caller so reference count on ppvObject
   * must be incremented before returning.  Caller is responsible for releasing ppvObject.
   */
  private int QueryInterface(long /*int*/ riid, long /*int*/ ppvObject) {
    if (riid == 0 || ppvObject == 0) return COM.E_INVALIDARG;
    GUID guid = new GUID();
    COM.MoveMemory(guid, riid, GUID.sizeof);

    if (COM.IsEqualGUID(guid, COM.IIDIUnknown) || COM.IsEqualGUID(guid, COM.IIDIDropSource)) {
      OS.MoveMemory(ppvObject, new long /*int*/[] {iDropSource.getAddress()}, OS.PTR_SIZEOF);
      AddRef();
      return COM.S_OK;
    }

    if (COM.IsEqualGUID(guid, COM.IIDIDataObject)) {
      OS.MoveMemory(ppvObject, new long /*int*/[] {iDataObject.getAddress()}, OS.PTR_SIZEOF);
      AddRef();
      return COM.S_OK;
    }

    OS.MoveMemory(ppvObject, new long /*int*/[] {0}, OS.PTR_SIZEOF);
    return COM.E_NOINTERFACE;
  }
  private int GetData(long /*int*/ pFormatetc, long /*int*/ pmedium) {
    /* Called by a data consumer to obtain data from a source data object.
       The GetData method renders the data described in the specified FORMATETC
       structure and transfers it through the specified STGMEDIUM structure.
       The caller then assumes responsibility for releasing the STGMEDIUM structure.
    */
    if (pFormatetc == 0 || pmedium == 0) return COM.E_INVALIDARG;

    if (QueryGetData(pFormatetc) != COM.S_OK) return COM.DV_E_FORMATETC;

    TransferData transferData = new TransferData();
    transferData.formatetc = new FORMATETC();
    COM.MoveMemory(transferData.formatetc, pFormatetc, FORMATETC.sizeof);
    transferData.type = transferData.formatetc.cfFormat;
    transferData.stgmedium = new STGMEDIUM();
    transferData.result = COM.E_FAIL;

    DNDEvent event = new DNDEvent();
    event.widget = this;
    event.time = OS.GetMessageTime();
    event.dataType = transferData;
    notifyListeners(DND.DragSetData, event);

    if (!event.doit) return COM.E_FAIL;

    // get matching transfer agent to perform conversion
    Transfer transfer = null;
    for (int i = 0; i < transferAgents.length; i++) {
      Transfer transferAgent = transferAgents[i];
      if (transferAgent != null && transferAgent.isSupportedType(transferData)) {
        transfer = transferAgent;
        break;
      }
    }

    if (transfer == null) return COM.DV_E_FORMATETC;
    transfer.javaToNative(event.data, transferData);
    if (transferData.result != COM.S_OK) return transferData.result;
    COM.MoveMemory(pmedium, transferData.stgmedium, STGMEDIUM.sizeof);
    return transferData.result;
  }
  private int QueryGetData(long /*int*/ pFormatetc) {
    if (transferAgents == null) return COM.E_FAIL;
    TransferData transferData = new TransferData();
    transferData.formatetc = new FORMATETC();
    COM.MoveMemory(transferData.formatetc, pFormatetc, FORMATETC.sizeof);
    transferData.type = transferData.formatetc.cfFormat;

    // is this type supported by the transfer agent?
    for (int i = 0; i < transferAgents.length; i++) {
      Transfer transfer = transferAgents[i];
      if (transfer != null && transfer.isSupportedType(transferData)) return COM.S_OK;
    }

    return COM.DV_E_FORMATETC;
  }
 public int Show(boolean fShow) {
   return COM.VtblCall(7, address, fShow);
 }
 public int Drop(long /*int*/ pDataObject, POINT ppt, int dwEffect) {
   return COM.VtblCall(6, address, pDataObject, ppt, dwEffect);
 }
 public int DragOver(POINT ppt, int dwEffect) {
   return COM.VtblCall(5, address, ppt, dwEffect);
 }
 public int DragLeave() {
   return COM.VtblCall(4, address);
 }
 public int DragEnter(long /*int*/ hwndTarget, long /*int*/ pDataObject, POINT ppt, int dwEffect) {
   return COM.VtblCall(3, address, hwndTarget, pDataObject, ppt, dwEffect);
 }
  private void drag(Event dragEvent) {
    DNDEvent event = new DNDEvent();
    event.widget = this;
    event.x = dragEvent.x;
    event.y = dragEvent.y;
    event.time = OS.GetMessageTime();
    event.doit = true;
    notifyListeners(DND.DragStart, event);
    if (!event.doit || transferAgents == null || transferAgents.length == 0) return;

    int[] pdwEffect = new int[1];
    int operations = opToOs(getStyle());
    Display display = control.getDisplay();
    String key = "org.eclipse.swt.internal.win32.runMessagesInIdle"; // $NON-NLS-1$
    Object oldValue = display.getData(key);
    display.setData(key, Boolean.TRUE);
    ImageList imagelist = null;
    Image image = event.image;
    hwndDrag = 0;
    topControl = null;
    if (image != null) {
      imagelist = new ImageList(SWT.NONE);
      imagelist.add(image);
      topControl = control.getShell();
      /*
       * Bug in Windows. The image is inverted if the shell is RIGHT_TO_LEFT.
       * The fix is to create a transparent window that covers the shell client
       * area and use it during the drag to prevent the image from being inverted.
       * On XP if the shell is RTL, the image is not displayed.
       */
      int offsetX = event.offsetX;
      hwndDrag = topControl.handle;
      if ((topControl.getStyle() & SWT.RIGHT_TO_LEFT) != 0) {
        offsetX = image.getBounds().width - offsetX;
        RECT rect = new RECT();
        OS.GetClientRect(topControl.handle, rect);
        hwndDrag =
            OS.CreateWindowEx(
                OS.WS_EX_TRANSPARENT | OS.WS_EX_NOINHERITLAYOUT,
                WindowClass,
                null,
                OS.WS_CHILD | OS.WS_CLIPSIBLINGS,
                0,
                0,
                rect.right - rect.left,
                rect.bottom - rect.top,
                topControl.handle,
                0,
                OS.GetModuleHandle(null),
                null);
        OS.ShowWindow(hwndDrag, OS.SW_SHOW);
      }
      OS.ImageList_BeginDrag(imagelist.getHandle(), 0, offsetX, event.offsetY);
      /*
       * Feature in Windows. When ImageList_DragEnter() is called,
       * it takes a snapshot of the screen  If a drag is started
       * when another window is in front, then the snapshot will
       * contain part of the other window, causing pixel corruption.
       * The fix is to force all paints to be delivered before
       * calling ImageList_DragEnter().
       */
      if (OS.IsWinCE) {
        OS.UpdateWindow(topControl.handle);
      } else {
        int flags = OS.RDW_UPDATENOW | OS.RDW_ALLCHILDREN;
        OS.RedrawWindow(topControl.handle, null, 0, flags);
      }
      POINT pt = new POINT();
      pt.x = dragEvent.x;
      pt.y = dragEvent.y;
      OS.MapWindowPoints(control.handle, 0, pt, 1);
      RECT rect = new RECT();
      OS.GetWindowRect(hwndDrag, rect);
      OS.ImageList_DragEnter(hwndDrag, pt.x - rect.left, pt.y - rect.top);
    }
    int result = COM.DRAGDROP_S_CANCEL;
    try {
      result =
          COM.DoDragDrop(iDataObject.getAddress(), iDropSource.getAddress(), operations, pdwEffect);
    } finally {
      // ensure that we don't leave transparent window around
      if (hwndDrag != 0) {
        OS.ImageList_DragLeave(hwndDrag);
        OS.ImageList_EndDrag();
        imagelist.dispose();
        if (hwndDrag != topControl.handle) OS.DestroyWindow(hwndDrag);
        hwndDrag = 0;
        topControl = null;
      }
      display.setData(key, oldValue);
    }
    int operation = osToOp(pdwEffect[0]);
    if (dataEffect == DND.DROP_MOVE) {
      operation =
          (operation == DND.DROP_NONE || operation == DND.DROP_COPY)
              ? DND.DROP_TARGET_MOVE
              : DND.DROP_MOVE;
    } else {
      if (dataEffect != DND.DROP_NONE) {
        operation = dataEffect;
      }
    }
    event = new DNDEvent();
    event.widget = this;
    event.time = OS.GetMessageTime();
    event.doit = (result == COM.DRAGDROP_S_DROP);
    event.detail = operation;
    notifyListeners(DND.DragEnd, event);
    dataEffect = DND.DROP_NONE;
  }