如何添加涟漪效果？答案

【问题标题】：How to add ripple effect?如何添加涟漪效果？
【发布时间】：2021-02-25 07:59:42
【问题描述】：

如何在 PyQt5 中实现这样的涟漪效果？

【问题讨论】：

【解决方案1】：

这是一种使用 QTimer 并重新实现 paintEvent 以在 timeout 上绘制半径增加的椭圆的方法。

import sys
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *
from PyQt5.QtGui import *

class Button(QPushButton):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.r = 0
        self.timer = QTimer(interval=25, timeout=self.set_radius)
        self.clicked.connect(self.timer.start)

    def set_radius(self):
        if self.r < self.width() / 2:
            self.r += self.width() / 20
        else:
            self.timer.stop()
            self.r = 0
        self.update()

    def paintEvent(self, event):
        super().paintEvent(event)
        if self.r:
            qp = QPainter(self)
            qp.setBrush(QColor(255, 255, 255, 127))
            qp.setPen(Qt.NoPen)
            qp.drawEllipse(self.rect().center(), self.r, self.r)
        

if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = QWidget()
    layout = QVBoxLayout(window)
    layout.addWidget(Button('Start'))
    window.setStyleSheet('''
    QPushButton {
        color: #fff;
        background-color: #09e;
        padding: 20px;
        font-size: 24pt;
        border: none;
    }
    QPushButton:pressed {
        color: #ddd;
    }''')
    window.show()
    sys.exit(app.exec_())

【讨论】：

【解决方案2】：

如果你想实现任何动画，那么你必须使用继承自 QAbstractAnimation 的类来平滑地实现属性的变化。

在以下示例中，我使用 QVariantAnimation：

import sys

from PyQt5.QtCore import Qt, QVariantAnimation
from PyQt5.QtGui import QColor, QPainter
from PyQt5.QtWidgets import QApplication, QPushButton, QVBoxLayout, QWidget


class Button(QPushButton):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        self._radius = 0

        self._animation = QVariantAnimation(startValue=0.0)
        self._animation.valueChanged.connect(self._handle_valueChanged)
        self._animation.finished.connect(self._handle_finished)
        self._animation.setDuration(300)
        self.pressed.connect(self._start_animation)

    def _start_animation(self):
        self._animation.setEndValue(self.width() / 2.0)
        self._animation.start()

    def _handle_valueChanged(self, value):
        self._radius = value
        self.update()

    def _handle_finished(self):
        self._radius = 0
        self.update()

    def paintEvent(self, event):
        super().paintEvent(event)
        if self._radius:
            qp = QPainter(self)
            qp.setBrush(QColor(255, 255, 255, 127))
            qp.setPen(Qt.NoPen)
            qp.drawEllipse(self.rect().center(), self._radius, self._radius)


if __name__ == "__main__":
    app = QApplication(sys.argv)
    window = QWidget()
    layout = QVBoxLayout(window)
    layout.addWidget(Button("Start"))
    window.setStyleSheet(
        """
    QPushButton {
        color: #fff;
        background-color: #09e;
        padding: 20px;
        font-size: 24pt;
        border: none;
    }
    QPushButton:pressed {
        color: #ddd;
    }"""
    )
    window.show()
    sys.exit(app.exec_())

【讨论】：

【解决方案3】：

试试这个:)

import sys
from PyQt5.QtWidgets import *
from PyQt5.QtCore import *
from PyQt5.QtGui import *

class Button(QPushButton):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        self.r = 0
        self.timer = QTimer(interval=70, timeout=self.set_radius)
        self.countr = 0
    def set_radius(self):
        self.countr += 1
        if self.r < self.width() / 2:
            self.r += self.width() /10
        else:
            self.timer.stop()
            self.r = 0
            self.countr = 0
        self.update()
    def mousePressEvent(self,event):
        super().mousePressEvent(event)
        self.x,self.y = event.x(),event.y()
        self.timer.start()
    def paintEvent(self, event):
        super().paintEvent(event)
        if self.r:
            self.qp = QPainter(self)
            self.qp.setBrush(QColor(255, 255, 255, 127))
            self.qp.setRenderHint(QPainter.Antialiasing)
            # delete this lines if don't like light effect
            #///
            if self.countr == 4: 
                self.qp.setOpacity(0.8)
                
            else:
                self.qp.setOpacity(0.3)
                self.qp.setPen(QPen(QColor(Qt.transparent), 0))
            #\\\    
            #self.qp.setOpacity(0.3)
            #self.qp.setPen(QPen(QColor(Qt.transparent), 0))
            self.qp.drawEllipse(QPoint(self.x,self.y), self.r, self.r)
            self.qp.end()

if __name__ == '__main__':
    app = QApplication(sys.argv)
    window = QWidget()
    layout = QVBoxLayout(window)
    layout.addWidget(Button('Start'))
    window.setStyleSheet('''
    QPushButton {
        color: #fff;
        background-color: #09e;
        padding: 20px;
        font-size: 24pt;
        border: none;
    }
    QPushButton:pressed {
        color: #ddd;
    }''')
    window.show()
    sys.exit(app.exec_())

【讨论】：