class DetachableTabBar(QTabBar):
'''
The TabBar class re-implements some of the functionality of the QTabBar widget
'''
detach_tab_signal = Signal(int, QPoint, bool) # tab at pos, mouse cursor position, by double click
move_tab_signal = Signal(int, int)
empty_signal = Signal()
def __init__(self, parent=None):
QTabBar.__init__(self, parent)
self.setAcceptDrops(True)
self.setElideMode(Qt.ElideRight)
self.setSelectionBehaviorOnRemove(QTabBar.SelectLeftTab)
self.drag_start_pos = QPoint()
self.drag_droped_pos = QPoint()
self.mouse_cursor = QCursor()
self.drag_initiated = False
def mouseDoubleClickEvent(self, event):
'''
Send the detach_tab_signal when a tab is double clicked
'''
event.accept()
self.detach_tab_signal.emit(self.tabAt(event.pos()), self.mouse_cursor.pos(), True)
def mousePressEvent(self, event):
'''
Set the starting position for a drag event when the mouse button is pressed
'''
self.drag_droped_pos = QPoint(0, 0)
self.drag_initiated = False
if event.button() == Qt.LeftButton:
self.drag_start_pos = event.pos()
QTabBar.mousePressEvent(self, event)
def mouseMoveEvent(self, event):
'''
Determine if the current movement is a drag. If it is, convert it into a QDrag. If the
drag ends inside the tab bar, emit an move_tab_signal. If the drag ends outside the tab
bar, emit an detach_tab_signal.
'''
# Determine if the current movement is detected as a drag
if not self.drag_start_pos.isNull() and ((event.pos() - self.drag_start_pos).manhattanLength() > QApplication.startDragDistance()):
self.drag_initiated = True
# If the current movement is a drag initiated by the left button
if ((event.buttons() & Qt.LeftButton)) and self.drag_initiated:
# Stop the move event
finishMoveEvent = QMouseEvent(QEvent.MouseMove, event.pos(), Qt.NoButton, Qt.NoButton, Qt.NoModifier)
QTabBar.mouseMoveEvent(self, finishMoveEvent)
# Convert the move event into a drag
drag = QDrag(self)
mime_data = QMimeData()
mime_data.setData('action', b'application/tab-detach')
drag.setMimeData(mime_data)
# Create the appearance of dragging the tab content
# tab_index = self.tabAt(self.drag_start_pos)
pixmap = self.parentWidget().grab()
targetPixmap = QPixmap(pixmap.size())
targetPixmap.fill(Qt.transparent)
painter = QPainter(targetPixmap)
painter.setOpacity(0.85)
painter.drawPixmap(0, 0, pixmap)
painter.end()
drag.setPixmap(targetPixmap)
# Initiate the drag
dropAction = drag.exec_(Qt.MoveAction | Qt.CopyAction)
# If the drag completed outside of the tab bar, detach the tab and move
# the content to the current cursor position
if dropAction == Qt.IgnoreAction:
event.accept()
self.detach_tab_signal.emit(self.tabAt(self.drag_start_pos), self.mouse_cursor.pos(), False)
elif dropAction == Qt.MoveAction:
# else if the drag completed inside the tab bar, move the selected tab to the new position
if not self.drag_droped_pos.isNull():
self.move_tab_signal.emit(self.tabAt(self.drag_start_pos), self.tabAt(self.drag_droped_pos))
else:
# else if the drag completed inside the tab bar new TabBar, move the selected tab to the new TabBar
self.detach_tab_signal.emit(self.tabAt(self.drag_start_pos), self.mouse_cursor.pos(), False)
event.accept()
else:
QTabBar.mouseMoveEvent(self, event)
def dragEnterEvent(self, event):
'''
Determine if the drag has entered a tab position from another tab position
'''
self.drag_droped_pos = QPoint(0, 0)
mime_data = event.mimeData()
formats = mime_data.formats()
if 'action' in formats and mime_data.data('action') == 'application/tab-detach':
event.acceptProposedAction()
QTabBar.dragMoveEvent(self, event)
def dropEvent(self, event):
'''
Get the position of the end of the drag
'''
self.drag_droped_pos = event.pos()
mime_data = event.mimeData()
formats = mime_data.formats()
if 'action' in formats and mime_data.data('action') == 'application/tab-detach':
event.acceptProposedAction()
QTabBar.dropEvent(self, event)
def prepared_for_drop(self):
return not self.drag_droped_pos.isNull()
def tabRemoved(self, index):
QTabBar.tabRemoved(self, index)
if self.count() == 0:
self.empty_signal.emit()
