Blur Picker Effect Example

The blur picker effect example demonstrates how to apply graphical effects on items in the view.

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main.py

# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
from __future__ import annotations

"""PySide6 port of the widgets/effects/blurpicker example from Qt v6.x"""

import sys
from PySide6.QtWidgets import QApplication
from blurpicker import BlurPicker


if __name__ == "__main__":
    app = QApplication(sys.argv)

    blur_picker = BlurPicker()
    blur_picker.setWindowTitle("Application Picker")

    blur_picker.setFixedSize(400, 300)
    blur_picker.show()

    sys.exit(app.exec())

blurpicker.py

# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
from __future__ import annotations


from pathlib import Path
from PySide6.QtCore import (
    QEasingCurve,
    QPointF,
    Qt,
    QAbstractAnimation,
    QPropertyAnimation,
    Property,
)
from PySide6.QtGui import QPainter, QTransform, QPixmap
from PySide6.QtWidgets import QGraphicsView, QFrame, QGraphicsScene, QGraphicsPixmapItem
from math import pi, sin, cos
from blureffect import BlurEffect


class BlurPicker(QGraphicsView):
    def __init__(self, parent=None):
        super().__init__(parent)
        self._index = 0
        self._animation = QPropertyAnimation(self, b"index")
        self._path = Path(__file__).resolve().parent

        self._background = QPixmap(self._path / "images" / "background.jpg")
        self.setBackgroundBrush(self._background)
        self.setScene(QGraphicsScene(self))

        self._icons = []

        self.setup_scene()
        self.index = 0

        self._animation.setDuration(400)
        self._animation.setEasingCurve(QEasingCurve.InOutSine)

        self.setRenderHint(QPainter.RenderHint.Antialiasing, True)
        self.setFrameStyle(QFrame.NoFrame)

    @Property(float)
    def index(self) -> float:
        return self._index

    @index.setter
    def index(self, index: float):
        self._index = index

        base_line = 0.0
        iconAngle = 2 * pi / len(self._icons)

        for i, icon in enumerate(self._icons):
            a = (i + self._index) * iconAngle
            xs = 170 * sin(a)
            ys = 100 * cos(a)
            pos = QPointF(xs, ys)
            pos = QTransform().rotate(-20).map(pos)
            pos -= QPointF(40, 40)
            icon.setPos(pos)
            base_line = max(base_line, ys)

            icon.graphicsEffect().set_base_line(base_line)

        self.scene().update()

    def setup_scene(self):
        self.scene().setSceneRect(-200, -120, 400, 240)

        names = ["accessories-calculator.png", "accessories-text-editor.png",
                 "help-browser.png", "internet-group-chat.png",
                 "internet-mail.png", "internet-web-browser.png", "office-calendar.png",
                 "system-users.png"]

        for name in names:
            pixmap = QPixmap(self._path / "images" / name)
            icon: QGraphicsPixmapItem = self.scene().addPixmap(pixmap)
            icon.setZValue(1)
            icon.setGraphicsEffect(BlurEffect(icon))
            self._icons.append(icon)

        bg: QGraphicsPixmapItem = self.scene().addPixmap(self._background)
        bg.setZValue(0)
        bg.setPos(-200, -150)

    def keyPressEvent(self, event):
        delta = 0
        if event.key() == Qt.Key_Left:
            delta = -1
        elif event.key() == Qt.Key_Right:
            delta = 1

        if self._animation.state() == QAbstractAnimation.Stopped and delta:
            self._animation.setEndValue(self._index + delta)
            self._animation.start()
            event.accept()

    def mousePressEvent(self, event):
        right = event.position().x() > (self.width() / 2)
        delta = 1 if right else -1

        if self._animation.state() == QAbstractAnimation.Stopped:
            self._animation.setEndValue(self._index + delta)
            self._animation.start()
            event.accept()

blureffect.py

# Copyright (C) 2022 The Qt Company Ltd.
# SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
from __future__ import annotations


from PySide6.QtCore import QRect
from PySide6.QtGui import QPainter
from PySide6.QtWidgets import QGraphicsBlurEffect


class BlurEffect(QGraphicsBlurEffect):
    def __init__(self, item):
        super().__init__()
        self._base_line = 200
        self._item = item

    def adjust_for_item(self):
        y = self._base_line - self._item.pos().y()

        # radius = qBound(qreal(0.0), y / 32, qreal(16.0)); which is equivalent to
        radius = max(0, min(y / 32, 16))

        self.setBlurRadius(radius)

    def set_base_line(self, base_line):
        self._base_line = base_line

    def boundingRect(self) -> QRect:
        self.adjust_for_item()
        return super().boundingRect()

    def draw(self, painter: QPainter):
        self.adjust_for_item()
        super().draw(painter)

images/README.txt

The background is taken from a public domain photo at:
http://www.photos8.com/view/computer_board2-800x600.html

All other icons are from the Tango Desktop project:
http://tango.freedesktop.org/Tango_Desktop_Project