def eventFilter(self, source, event):
modifier = QGuiApplication.queryKeyboardModifiers()
if event.type() == QEvent.MouseMove:
# emit mouse moved signal and the drag signal if the mouse
# button is clicked
position = event.pos()
self.mouse_moved.emit(position)
if self.is_clicked:
self.dragged.emit(position)
return False
if event.type() == QEvent.Wheel:
# emit the mouse moved signal when the mousewheel is used
position = event.pos()
self.mouse_moved.emit(position)
if event.type() == QEvent.MouseButtonPress \
or event.type() == QEvent.MouseButtonDblClick:
# set the mouse button clicked state and emit the clicked signal
# if neither control nor alt modifiers are pressed
if not modifier == Qt.ControlModifier\
and not modifier == Qt.AltModifier:
self.is_clicked = True
position = event.pos()
self.clicked.emit(position)
return False
if event.type() == QEvent.MouseButtonRelease:
# release the mouse button clicked state and emit the release
# signal if neither ctontrol nor alt modifiers are pressed.
self.is_clicked = False
if not modifier == Qt.ControlModifier\
and not modifier == Qt.AltModifier:
position = event.pos()
self.released.emit(position)
return False
if event.type() == QEvent.Leave:
# emit a leave signal
self.leave.emit()
return False
return False
def eventFilter(self, obj, event):
if obj == self.child_obj and event.type() == QEvent.Wheel:
self.do_wheel(event)
return True
elif obj == self.child_obj and event.type() == QEvent.MouseButtonPress:
self.start_mouse_pos = event.localPos()
self.start_scroll_pos = self.page().scrollPosition()
return QWebEngineView.eventFilter(self, obj, event) # Make scrollbar work normally
elif obj == self.child_obj and event.type() == QEvent.MouseMove:
# Only process mouse move with left button pressed
if event.buttons() != Qt.LeftButton:
return QWebEngineView.eventFilter(self, obj, event)
# If Ctrl is pressed, use the default event handler. This enable select text.
if QGuiApplication.queryKeyboardModifiers() == Qt.ControlModifier:
return QWebEngineView.eventFilter(self, obj, event)
'''
OK. This is a mouse drag without Ctrl pressed. We will change it's behavior
to something like ImageView.
'''
current_mouse_pos = event.localPos()
delta = current_mouse_pos - self.start_mouse_pos
'''
Note: if mouse moves down 5 pixels, it's y-pos increase 5 pixels.
The page should also move down 5 pixels which means the scrollbar should
move up 5 pixels and the scroll position should decrease.
'''
target_scroll_pos = self.start_scroll_pos - delta
'''
Verify value range. I don't know if this is a must or whether this has any
effects or not.
'''
target_scroll_x = target_scroll_pos.x()
target_scroll_y = target_scroll_pos.y()
if target_scroll_x < 0:
target_scroll_x = 0
if target_scroll_y < 0:
target_scroll_y = 0
if target_scroll_x > self.page().contentsSize().width():
target_scroll_x = self.page().contentsSize().width()
if target_scroll_y > self.page().contentsSize().height():
target_scroll_y = self.page().contentsSize().height()
'''
We notice that if the page is zoomed in, the scrollbar moves faster than
the mouse cursor. Besides, the scrollbar may jump a large distance towards
the end in a weird way if you place the mouse cursor at the right bottom
corner and try to drag the page towards the left upper corner several times.
I don't know why but I print the target_scroll_pos which seems indeed correct.
So I guess this may be caused by the scrollTo function in JavaScript. I think
this function doesn't do things as I thought it would. Now that the page scrolls
faster than mouse cursor dragging only after the page is zoomed in and it seems
they have multiples relation, I guess if I divide the target_scroll_pos by
zoomFactor, the page scrolling speed may be slow down and maybe scrollTo can
scroll the page to correct position. Finally, this way is indeed the solution.
However, I don't know why.
If the page is zoomed out, it would be the opposite. The page scrolling speed
should be sped up to match the mouse cursor.
'''
target_scroll_x /= self.zoomFactor()
target_scroll_y /= self.zoomFactor()
# https://forum.qt.io/topic/60091/scroll-a-qwebengineview/3
self.page().runJavaScript(f"window.scrollTo({target_scroll_x}, {target_scroll_y})")
return QWebEngineView.eventFilter(self, obj, event) # Make scrollbar work normally
elif obj == self.child_obj and event.type() == QEvent.MouseButtonDblClick and event.buttons() == Qt.RightButton:
self.setZoomFactor(1)
return True
return QWebEngineView.eventFilter(self, obj, event)
