wxWidgets TaskBarIcon as drop target - wxwidgets

Question

How can I define the tray icon as a drop target using wxWidgets?
SetDropTarget is neither available in the TaskBarIcon nor in the Icon class.
I would like to have something like:
class TextDropTarget(wx.TextDropTarget):
def __init__(self, obj):
wx.TextDropTarget.__init__(self)
self.obj = obj
def OnDropText(self, x, y, data):
self.obj.action(data)
class TaskBarIcon(wx.adv.TaskBarIcon):
def __init__(self):
super().__init__()
self.SetIcon(wx.Icon(wx.Bitmap(TRAY_ICON)), TRAY_TOOLTIP)
self.SetDropTarget(TextDropTarget(self))
def action(self, data):
# Do something

Answer 1

After some research I can answer the question myself:
On Mac this is possible, because it's a common feature on this OS.
On Windows and Linux this is possible through an ugly workaround. I'm wondering why this is not supported on these OS, because there are indeed some use cases for this feature.
Here is the workaround (which is also mentioned here) for Windows:
Get the system tray area:
def FindSysPagerWindow():
hWnd = win32gui.FindWindowEx(win32gui.GetDesktopWindow(), 0, "Shell_TrayWnd", None)
if hWnd:
hWnd = win32gui.FindWindowEx(hWnd, None, "TrayNotifyWnd", None)
if hWnd:
hWnd = win32gui.FindWindowEx(hWnd, None, "SysPager", None)
return hWnd
class TaskBarIcon(wx.adv.TaskBarIcon):
def __init__(self, r):
super().__init__()
hSysPager = FindSysPagerWindow()
# Get rectangle of system area
self.region = win32gui.GetWindowRect(hSysPager)
self.frm = None
self.source = None
Create a thread which detects drag start events and creates a transparent frame above the system tray:
def callback(self, hWinEventHook, event, hwnd, idObject, idChild, dwEventThread, dwmsEventTime):
length = user32.GetWindowTextLengthW(hwnd)
title = ctypes.create_unicode_buffer(length + 1)
user32.GetWindowTextW(hwnd, title, length + 1)
if self.frm is None and (title.value == "Drag"):
self.source = GetProcessFilename(GetProcessId(dwEventThread, hwnd))
self.frm = SystemTrayFrame(self.region, self.onDrop)
def DragDetectThread(self):
ole32.CoInitialize(0)
WinEventProc = WinEventProcType(self.callback)
user32.SetWinEventHook.restype = ctypes.wintypes.HANDLE
hookId = user32.SetWinEventHook(win32con.EVENT_OBJECT_SHOW, win32con.EVENT_OBJECT_SHOW,
0, WinEventProc, 0, 0, win32con.WINEVENT_OUTOFCONTEXT)
msg = ctypes.wintypes.MSG()
while user32.GetMessageW(ctypes.byref(msg), 0, 0, 0) != 0:
user32.TranslateMessageW(msg)
user32.DispatchMessageW(msg)
user32.UnhookWinEvent(hookId)
ole32.CoUninitialize()
A still unresolved problem here is that the detection of the correct drag source is not working reliable. If the mouse is moved too fast at the drag start, then the detected source may be wrong. But this is only a problem if this information is important.
Create a listener for mouse button events, using pynput, to detect left mouse button up event, which is interpreted as a drag end event. The listener and also the onDrop method destroy the transparent frame:
from pynput.mouse import Listener, Button
...
self.listener = Listener(on_click=self.onMouseButtonEvent)
self.listener.start()
def onMouseButtonEvent(self, x, y, button, pressed):
if self.frm is not None and (button == Button.left) and not pressed:
self.frm.Destroy()
self.frm = None
def onDrop(self, x, y, data):
# Do something with the dropped data
if self.frm is not None:
self.frm.Destroy()
self.frm = None
The class for the transparent frame looks something like this:
class SystemTrayFrame(wx.Frame):
def __init__(self, r, cbDrop):
super().__init__(None, wx.ID_ANY, "TransparentFrame", pos=(r[0], r[1]), size=(r[2] - r[0], r[3] - r[1]),
style=wx.STAY_ON_TOP)
dropTarget = DropTarget(cbDrop)
self.SetDropTarget(dropTarget)
self.SetTransparent(0)
self.Show()
Up to here this is all fine if it is ok that the whole system tray area is the drop target for your application. But if you want to limit the drop area to your system tray icon you need now the ugly workaround:
a) Replace your fancy system tray icon with a uniquely colored icon with a shape which you can easily detect.
b) Make a screenshot of the system tray area, replace the system tray icon back to your fancy application icon, then search for the position of your uniquely colored icon:
im = ImageGrab.grab(bbox=self.region)
# Search for icon position and size (because of optional scaling by OS)
The search operation can be a bit more complicated when scaling was enabled by the OS.
c) Use this result for positioning the transparent frame.
Hope this helps other people who are running into the same problem.