#!/usr/bin/env python # # The MIT License (MIT) # # Copyright (c) <2022-Present> # # Permission is hereby granted, free of charge, to any person obtaining a copy # of this software and associated documentation files (the 'Software'), to deal # in the Software without restriction, including without limitation the rights # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell # copies of the Software, and to permit persons to whom the Software is # furnished to do so, subject to the following conditions: # # The above copyright notice and this permission notice shall be included in # all copies or substantial portions of the Software. # # THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN # THE SOFTWARE. ''' dial ==== Example showing how to override the `paintEvent` and `eventFilter` for a `QDial`, creating a visually consistent, stylish `QDial` that supports highlighting the handle on the active or hovered dial. ''' import math import shared import sys parser = shared.create_parser() parser.add_argument( '--no-align', help='''allow larger widgets without forcing alignment.''', action='store_true' ) args, unknown = shared.parse_args(parser) QtCore, QtGui, QtWidgets = shared.import_qt(args) compat = shared.get_compat_definitions(args) colors = shared.get_colors(args, compat) def radius(dial): '''Get the radius of the dial.''' return min(dial.rect.width(), dial.rect.height()) // 2 def groove_rect(dial): '''Calculate the bounding rectangle for the dial groove.''' x0 = dial.rect.width() / 2 y0 = dial.rect.height() / 2 pos = dial.rect.topLeft() return pos.x() + x0, pos.y() + y0 def circle_percent(dial): '''Calculate the percentage of the dial.''' distance = dial.maximum - dial.minimum offset = dial.sliderPosition - dial.minimum return offset / distance def circle_position(dial, groove_rect, position, r): '''Calculate the (x, y) coordinates based on the position on a circle.''' # Get our center and the percent we've gone alone the dial. center = groove_rect.center() x0 = center.x() y0 = center.y() distance = dial.maximum - dial.minimum offset = position - dial.minimum percent = offset / distance # The position of points on a circle follows. The start angle is # at the left (0°), and we start from the bottom. The formula # to get the position on a circle is: # (x0 + r cos theta, y0 + r sin theta) # # However, our y point is inverted (goes from the top), so we modify it to: # (x0 + r cos theta, y0 - r sin theta) initial = 60 total_angle = 300 if dial.dialWrapping: initial = 90 total_angle = 360 angle = total_angle * percent theta = (angle - initial) * math.pi / 180 return x0 - r * math.cos(theta), y0 - r * math.sin(theta) def handle_position(dial, groove_rect, r): '''Calculate the position of the handle.''' return circle_position(dial, groove_rect, dial.sliderPosition, r) def default_pen(color, width): '''Create a pen with the default styles.''' return QtGui.QPen(color, width) def round_pen(color, width): '''Create a pen with round join styles.''' return QtGui.QPen( color, width, compat.SolidLine, compat.RoundCap, compat.RoundJoin, ) def event_pos(event): '''Determine the event position.''' if args.pyqt6: return event.position() return event.posF() class Dial(QtWidgets.QDial): '''QDial with a custom paint event.''' def __init__(self, widget=None): super().__init__(widget) if args.stylesheet == 'native': return self.installEventFilter(self) # Set some configuration settings, since we'll need them later. # No reason to recalculate them every time. self.font_size = self.font().pointSizeF() self.bd_width = 0.09 * self.font_size self.groove_width = 5 self.handle_radius = self.groove_width + 3 self.notch_start = self.groove_width + 2 self.notch_end = self.notch_start + 2 self.notch_width = 2 self.groove_bd_color = colors.GrooveBorder self.groove_bg_color = colors.GrooveBackground self.handle_bg_color = colors.HandleBackground self.handle_bd_color = colors.HandleBorder self.notch_color = colors.Notch self.selected_color = colors.Selected # Store some state changes. self.groove = (0, 0) self.handle = (0, 0) self.is_hovered = False def paintEvent(self, event): '''Override the paint event to ensure the ticks are painted.''' if args.stylesheet == 'native': return super().paintEvent(event) painter = QtWidgets.QStylePainter(self) options = QtWidgets.QStyleOptionSlider() self.initStyleOption(options) # Get our item colors. Override the color when selected/active. handle_bd_color = self.handle_bd_color mask = compat.State_HasFocus | compat.State_Selected # WindowActive if options.state & mask or self.is_hovered: handle_bd_color = self.selected_color # Get the groove settings: this defines the bounding rect # and the start and stop angles for the groove. We also # make the radius 20% smaller, so it fits nicely within # the bounding rect. groove_width = self.groove_width * painter.pen().widthF() r = radius(options) - 2 * groove_width gx, gy = groove_rect(options) self.groove = (gx, gy) rect = QtCore.QRectF(gx - r, gy - r, 2 * r, 2 * r) # The arc should be everything besides ~30° at the bottom. # Units are measured in 1/16th of a degree. start_angle = 240 * 16 span_angle = -300 * 16 if options.dialWrapping: # Have a wrapping dial: have the full circle. start_angle = 270 * 16 span_angle = -360 * 16 # Get the handle settings. hx, hy = handle_position(options, rect, r) self.handle = (hx, hy) # First, we draw the border for the slider. # This is simple, since we just add `0.09em` to the actual groove # width and draw it first. groove_bd_width = groove_width + self.bd_width painter.setPen(round_pen(self.groove_bd_color, groove_bd_width)) painter.drawArc(rect, start_angle, span_angle) # Draw the groove for the slider. We want to stroke the groove so # it's quite large, and then we can create a border, etc. for it. groove_percent = circle_percent(options) groove_stop = int(groove_percent * span_angle) painter.setPen(round_pen(self.groove_bg_color, groove_width)) painter.drawArc(rect, start_angle, span_angle) painter.setPen(round_pen(self.selected_color, groove_width)) painter.drawArc(rect, start_angle, groove_stop) # Now, we need to draw the notches. We need to draw these before # the handle, since the handle needs to be above the notches. notch_step = self.notchSize() * self.singleStep() painter.setPen(default_pen(self.notch_color, self.notch_width)) notch_start = r + self.notch_start notch_end = r + self.notch_end if self.notchesVisible() and notch_step != 0: distance = options.maximum - options.minimum position = 0 # Need an inclusive range: by default dial range is 0-99, but # range(0, 100) is 0-99, and we need 0-100. Specially draw # the first and the last items. positions = list(range(0, distance, notch_step)) + [options.maximum] for position in positions: nx0, ny0 = circle_position(options, rect, position, notch_start) nx1, ny1 = circle_position(options, rect, position, notch_end) painter.drawLine(int(nx0), int(ny0), int(nx1), int(ny1)) # Now, we need to draw the handle. First, we need to get the position # of the slider, based on the position and angle it's at. painter.setPen(default_pen(handle_bd_color, self.bd_width)) painter.setBrush(QtGui.QBrush(self.handle_bg_color)) handle_pos = QtCore.QPointF(hx, hy) painter.drawEllipse(handle_pos, self.handle_radius, self.handle_radius) def eventFilter(self, obj, event): '''Override the color when we have a hover event.''' # If the window isn't active, ignore the hover event. if not self.window().isActiveWindow(): self.is_hovered = False return super().eventFilter(obj, event) # Determine if we have a hover event, and if the handle # is hovered or no longer hovered, change the hover state # and trigger a paint event. We need to trigger an immediate # paint event, since otherwise we might have a delay in UI change. # # We use a very mild hack: we merely calculate the bounding rect # for the handle, and determine if the mouse is contained in there, # rather than calculate if it's actually in the circle. This won't # matter except if the dial is scaled by a large amount. if event.type() == compat.HoverEnter or event.type() == compat.HoverMove: x0 = self.handle[0] - self.handle_radius y0 = self.handle[1] - self.handle_radius size = 2 * self.handle_radius rect = QtCore.QRectF(x0, y0, size, size) self.is_hovered = rect.contains(event_pos(event)) self.repaint() elif event.type() == compat.HoverLeave: self.is_hovered = False self.repaint() return super().eventFilter(obj, event) class Ui: '''Main class for the user interface.''' def setup(self, MainWindow): MainWindow.setObjectName('MainWindow') MainWindow.resize(1068, 824) self.centralwidget = QtWidgets.QWidget(MainWindow) self.centralwidget.setObjectName('centralwidget') self.layout = QtWidgets.QVBoxLayout(self.centralwidget) self.layout.setObjectName('layout') if not args.no_align: self.layout.setAlignment(compat.AlignHCenter) MainWindow.setCentralWidget(self.centralwidget) self.dial1 = Dial(self.centralwidget) self.layout.addWidget(self.dial1) self.dial2 = Dial(self.centralwidget) self.dial2.setNotchesVisible(True) self.layout.addWidget(self.dial2) self.dial3 = Dial(self.centralwidget) self.dial3.setWrapping(True) self.layout.addWidget(self.dial3) def main(): 'Application entry point' app, window = shared.setup_app(args, unknown, compat) # setup ui ui = Ui() ui.setup(window) window.setWindowTitle('QDial') return shared.exec_app(args, app, window, compat) if __name__ == '__main__': sys.exit(main())