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;
}