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304 lines
10 KiB
Python
304 lines
10 KiB
Python
"""
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This based on the flickcharm-python code from:
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https://code.google.com/archive/p/flickcharm-python/
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Which states:
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This is a Python (PyQt) port of Ariya Hidayat's elegant FlickCharm
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hack which adds kinetic scrolling to any scrollable Qt widget.
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Licensed under GNU GPL version 2 or later.
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It has been altered to fix edge cases where clicks and drags would not
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propagate correctly under some conditions. It also allows a small "dead zone"
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threshold in which it will still propagate the user pressed click if he or she
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travelled only very slightly with the cursor.
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"""
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import copy
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from qtpy import QtWidgets, QtCore, QtGui
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class FlickData(object):
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Steady = 0
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Pressed = 1
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ManualScroll = 2
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AutoScroll = 3
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Stop = 4
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def __init__(self):
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self.state = FlickData.Steady
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self.widget = None
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self.pressPos = QtCore.QPoint(0, 0)
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self.offset = QtCore.QPoint(0, 0)
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self.dragPos = QtCore.QPoint(0, 0)
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self.speed = QtCore.QPoint(0, 0)
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self.travelled = 0
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self.ignored = []
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class FlickCharm(QtCore.QObject):
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"""Make scrollable widgets flickable.
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For example:
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charm = FlickCharm()
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charm.activateOn(widget)
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It can `activateOn` multiple widgets with a single FlickCharm instance.
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Be aware that the FlickCharm object must be kept around for it not
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to get garbage collected and losing the flickable behavior.
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Flick away!
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"""
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def __init__(self, parent=None):
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super(FlickCharm, self).__init__(parent=parent)
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self.flickData = {}
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self.ticker = QtCore.QBasicTimer()
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# The flick button to use
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self.button = QtCore.Qt.LeftButton
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# The time taken per update tick of flicking behavior
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self.tick_time = 20
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# Allow a item click/press directly when AutoScroll is slower than
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# this threshold velocity
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self.click_in_autoscroll_threshold = 10
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# Allow an item click/press to propagate as opposed to scrolling
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# when the cursor travelled less than this amount of pixels
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# Note: back & forth motion increases the value too
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self.travel_threshold = 20
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self.max_speed = 64 # max scroll speed
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self.drag = 1 # higher drag will stop autoscroll faster
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def activateOn(self, widget):
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viewport = widget.viewport()
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viewport.installEventFilter(self)
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widget.installEventFilter(self)
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self.flickData[viewport] = FlickData()
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self.flickData[viewport].widget = widget
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self.flickData[viewport].state = FlickData.Steady
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def deactivateFrom(self, widget):
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viewport = widget.viewport()
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viewport.removeEventFilter(self)
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widget.removeEventFilter(self)
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self.flickData.pop(viewport)
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def eventFilter(self, obj, event):
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if not obj.isWidgetType():
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return False
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eventType = event.type()
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if eventType != QtCore.QEvent.MouseButtonPress and \
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eventType != QtCore.QEvent.MouseButtonRelease and \
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eventType != QtCore.QEvent.MouseMove:
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return False
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if event.modifiers() != QtCore.Qt.NoModifier:
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return False
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if obj not in self.flickData:
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return False
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data = self.flickData[obj]
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found, newIgnored = removeAll(data.ignored, event)
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if found:
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data.ignored = newIgnored
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return False
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if data.state == FlickData.Steady:
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if eventType == QtCore.QEvent.MouseButtonPress:
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if event.buttons() == self.button:
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self._set_press_pos_and_offset(event, data)
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data.state = FlickData.Pressed
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return True
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elif data.state == FlickData.Pressed:
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if eventType == QtCore.QEvent.MouseButtonRelease:
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# User didn't actually scroll but clicked in
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# the widget. Let the original press and release
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# event be evaluated on the Widget
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data.state = FlickData.Steady
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event1 = QtGui.QMouseEvent(QtCore.QEvent.MouseButtonPress,
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data.pressPos,
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QtCore.Qt.LeftButton,
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QtCore.Qt.LeftButton,
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QtCore.Qt.NoModifier)
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# Copy the current event
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event2 = QtGui.QMouseEvent(QtCore.QEvent.MouseButtonRelease,
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event.pos(),
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event.button(),
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event.buttons(),
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event.modifiers())
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data.ignored.append(event1)
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data.ignored.append(event2)
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QtWidgets.QApplication.postEvent(obj, event1)
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QtWidgets.QApplication.postEvent(obj, event2)
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return True
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elif eventType == QtCore.QEvent.MouseMove:
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data.state = FlickData.ManualScroll
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data.dragPos = QtGui.QCursor.pos()
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if not self.ticker.isActive():
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self.ticker.start(self.tick_time, self)
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return True
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elif data.state == FlickData.ManualScroll:
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if eventType == QtCore.QEvent.MouseMove:
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pos = event.pos()
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delta = pos - data.pressPos
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data.travelled += delta.manhattanLength()
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setScrollOffset(data.widget, data.offset - delta)
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return True
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elif eventType == QtCore.QEvent.MouseButtonRelease:
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if data.travelled <= self.travel_threshold:
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# If the user travelled less than the threshold
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# don't go into autoscroll mode but assume the user
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# intended to click instead
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return self._propagate_click(obj, event, data)
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data.state = FlickData.AutoScroll
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return True
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elif data.state == FlickData.AutoScroll:
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if eventType == QtCore.QEvent.MouseButtonPress:
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# Allow pressing when auto scroll is already slower than
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# the click in autoscroll threshold
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velocity = data.speed.manhattanLength()
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if velocity <= self.click_in_autoscroll_threshold:
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self._set_press_pos_and_offset(event, data)
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data.state = FlickData.Pressed
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else:
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data.state = FlickData.Stop
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data.speed = QtCore.QPoint(0, 0)
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return True
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elif eventType == QtCore.QEvent.MouseButtonRelease:
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data.state = FlickData.Steady
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data.speed = QtCore.QPoint(0, 0)
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return True
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elif data.state == FlickData.Stop:
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if eventType == QtCore.QEvent.MouseButtonRelease:
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data.state = FlickData.Steady
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# If the user had a very limited scroll smaller than the
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# threshold consider it a regular press and release.
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if data.travelled < self.travel_threshold:
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return self._propagate_click(obj, event, data)
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return True
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elif eventType == QtCore.QEvent.MouseMove:
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# Reset the press position and offset to allow us to "continue"
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# the scroll from the new point the user clicked and then held
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# down to continue scrolling after AutoScroll.
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self._set_press_pos_and_offset(event, data)
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data.state = FlickData.ManualScroll
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data.dragPos = QtGui.QCursor.pos()
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if not self.ticker.isActive():
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self.ticker.start(self.tick_time, self)
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return True
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return False
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def _set_press_pos_and_offset(self, event, data):
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"""Store current event position on Press"""
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data.state = FlickData.Pressed
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data.pressPos = copy.copy(event.pos())
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data.offset = scrollOffset(data.widget)
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data.travelled = 0
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def _propagate_click(self, obj, event, data):
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"""Propagate from Pressed state with MouseButtonRelease event.
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Use only on button release in certain states to propagate a click,
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for example when the user dragged only a slight distance under the
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travel threshold.
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"""
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data.state = FlickData.Pressed
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data.pressPos = copy.copy(event.pos())
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data.offset = scrollOffset(data.widget)
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data.travelled = 0
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self.eventFilter(obj, event)
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return True
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def timerEvent(self, event):
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count = 0
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for data in self.flickData.values():
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if data.state == FlickData.ManualScroll:
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count += 1
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cursorPos = QtGui.QCursor.pos()
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data.speed = cursorPos - data.dragPos
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data.dragPos = cursorPos
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elif data.state == FlickData.AutoScroll:
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count += 1
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data.speed = deaccelerate(data.speed,
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a=self.drag,
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maxVal=self.max_speed)
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p = scrollOffset(data.widget)
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new_p = p - data.speed
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setScrollOffset(data.widget, new_p)
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if scrollOffset(data.widget) == p:
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# If this scroll resulted in no change on the widget
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# we reached the end of the list and set the speed to
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# zero.
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data.speed = QtCore.QPoint(0, 0)
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if data.speed == QtCore.QPoint(0, 0):
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data.state = FlickData.Steady
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if count == 0:
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self.ticker.stop()
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super(FlickCharm, self).timerEvent(event)
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def scrollOffset(widget):
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x = widget.horizontalScrollBar().value()
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y = widget.verticalScrollBar().value()
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return QtCore.QPoint(x, y)
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def setScrollOffset(widget, p):
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widget.horizontalScrollBar().setValue(p.x())
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widget.verticalScrollBar().setValue(p.y())
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def deaccelerate(speed, a=1, maxVal=64):
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x = max(min(speed.x(), maxVal), -maxVal)
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y = max(min(speed.y(), maxVal), -maxVal)
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if x > 0:
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x = max(0, x - a)
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elif x < 0:
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x = min(0, x + a)
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if y > 0:
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y = max(0, y - a)
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elif y < 0:
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y = min(0, y + a)
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return QtCore.QPoint(x, y)
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def removeAll(list, val):
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found = False
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ret = []
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for element in list:
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if element == val:
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found = True
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else:
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ret.append(element)
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return found, ret
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