前言
酷狗、网抑云和 QQ 音乐都有桌面歌词功能，这篇博客也将使用 pyqt 实现桌面歌词功能，效果如下图所示：
代码实现
桌面歌词部件 LyricWidget 在 paintEvent 中绘制歌词。我们可以直接使用 QPainter.drawText 来绘制文本，但是通过这种方式无法对歌词进行描边。所以这里更换为 QPainterPath 来实现，使用 QPainterPath.addText 将歌词添加到绘制路径中，接着使用 Qainter.strokePath 进行描边，Qainter.fillPath 绘制歌词，这里的绘制顺序不能调换。
对于歌词的高亮部分需要特殊处理，假设当前高亮部分的宽度为 w，我们需要对先前绘制歌词的 QPainterPath 进行裁剪，只留下宽度为 w 的部分，此处通过 QPainterPath.intersected 计算与宽度为 w 的矩形路径的交集来实现裁剪。
对于高亮部分的动画，我们既可以使用传统的 QTimer，也可以使用封装地更加彻底的 QPropertyAnimation 来实现（本文使用后者）。这里需要进行动画展示的是高亮部分，也就是说我们只需改变“高亮宽度”这个属性即可。PyQt 为我们提供了 pyqtProperty，类似于 python 自带的 property，使用 pyqtProperty 可以给部件注册一个属性，该属性可以搭配动画来食用。
除了高亮动画外，我们还在 LyricWidget 中注册了滚动动画，用于处理歌词长度大于视口宽度的情况。
# coding:utf-8
from PyQt5.QtCore import QPointF, QPropertyAnimation, Qt, pyqtProperty
from PyQt5.QtGui import (QColor, QFont, QFontMetrics, QPainter, QPainterPath,
QPen)
from PyQt5.QtWidgets import QWidget
config = {
"lyric.font-color": [255, 255, 255],
"lyric.highlight-color": [0, 153, 188],
"lyric.font-size": 50,
"lyric.stroke-size": 5,
"lyric.stroke-color": [0, 0, 0],
"lyric.font-family": "Microsoft YaHei",
"lyric.alignment": "Center"
}
class LyricWidget(QWidget):
""" Lyric widget """
def __init__(self, parent=None):
super().__init__(parent=parent)
self.setAttribute(Qt.WA_TranslucentBackground)
self.lyric = []
self.duration = 0
self.__originMaskWidth = 0
self.__translationMaskWidth = 0
self.__originTextX = 0
self.__translationTextX = 0
self.originMaskWidthAni = QPropertyAnimation(
self, b'originMaskWidth', self)
self.translationMaskWidthAni = QPropertyAnimation(
self, b'translationMaskWidth', self)
self.originTextXAni = QPropertyAnimation(
self, b'originTextX', self)
self.translationTextXAni = QPropertyAnimation(
self, b'translationTextX', self)
def paintEvent(self, e):
if not self.lyric:
return
painter = QPainter(self)
painter.setRenderHints(
QPainter.Antialiasing | QPainter.TextAntialiasing)
# draw original lyric
self.__drawLyric(
painter,
self.originTextX,
config["lyric.font-size"],
self.originMaskWidth,
self.originFont,
self.lyric[0]
)
if not self.hasTranslation():
return
# draw translation lyric
self.__drawLyric(
painter,
self.translationTextX,
25 config["lyric.font-size"]*5/3,
self.translationMaskWidth,
self.translationFont,
self.lyric[1]
)
def __drawLyric(self, painter: QPainter, x, y, width, font: QFont, text: str):
""" draw lyric """
painter.setFont(font)
# draw background text
path = QPainterPath()
path.addText(QPointF(x, y), font, text)
painter.strokePath(path, QPen(
QColor(*config["lyric.stroke-color"]), config["lyric.stroke-size"]))
painter.fillPath(path, QColor(*config['lyric.font-color']))
# draw foreground text
painter.fillPath(
self.__getMaskedLyricPath(path, width),
QColor(*config['lyric.highlight-color'])
)
def __getMaskedLyricPath(self, path: QPainterPath, width: float):
""" get the masked lyric path """
subPath = QPainterPath()
rect = path.boundingRect()
rect.setWidth(width)
subPath.addRect(rect)
return path.intersected(subPath)
def setLyric(self, lyric: list, duration: int, update=False):
""" set lyric
Parameters
----------
lyric: list
list contains original lyric and translation lyric
duration: int
lyric duration in milliseconds
update: bool
update immediately or not
"""
self.lyric = lyric or [""]
self.duration = max(duration, 1)
self.__originMaskWidth = 0
self.__translationMaskWidth = 0
# stop running animations
for ani in self.findChildren(QPropertyAnimation):
if ani.state() == ani.Running:
ani.stop()
# start scroll animation if text is too long
fontMetrics = QFontMetrics(self.originFont)
w = fontMetrics.width(lyric[0])
if w > self.width():
x = self.width() - w
self.__setAnimation(self.originTextXAni, 0, x)
else:
self.__originTextX = self.__getLyricX(w)
self.originTextXAni.setEndValue(None)
# start foreground color animation
self.__setAnimation(self.originMaskWidthAni, 0, w)
if self.hasTranslation():
fontMetrics = QFontMetrics(self.translationFont)
w = fontMetrics.width(lyric[1])
if w > self.width():
x = self.width() - w
self.__setAnimation(self.translationTextXAni, 0, x)
else:
self.__translationTextX = self.__getLyricX(w)
self.translationTextXAni.setEndValue(None)
self.__setAnimation(self.translationMaskWidthAni, 0, w)
if update:
self.update()
def __getLyricX(self, w: float):
""" get the x coordinate of lyric """
alignment = config["lyric.alignment"]
if alignment == "Right":
return self.width() - w
elif alignment == "Left":
return 0
return self.width()/2 - w/2
def getOriginMaskWidth(self):
return self.__originMaskWidth
def getTranslationMaskWidth(self):
return self.__translationMaskWidth
def getOriginTextX(self):
return self.__originTextX
def getTranslationTextX(self):
return self.__translationTextX
def setOriginMaskWidth(self, pos: int):
self.__originMaskWidth = pos
self.update()
def setTranslationMaskWidth(self, pos: int):
self.__translationMaskWidth = pos
self.update()
def setOriginTextX(self, pos: int):
self.__originTextX = pos
self.update()
def setTranslationTextX(self, pos):
self.__translationTextX = pos
self.update()
def __setAnimation(self, ani: QPropertyAnimation, start, end):
if ani.state() == ani.Running:
ani.stop()
ani.setStartValue(start)
ani.setEndValue(end)
ani.setDuration(self.duration)
def setPlay(self, isPlay: bool):
""" set the play status of lyric """
for ani in self.findChildren(QPropertyAnimation):
if isPlay and ani.state() != ani.Running and ani.endValue() is not None:
ani.start()
elif not isPlay and ani.state() == ani.Running:
ani.pause()
def hasTranslation(self):
return len(self.lyric) == 2
def minimumHeight(self) -> int:
size = config["lyric.font-size"]
h = size/1.5 60 if self.hasTranslation() else 40
return int(size h)
@property
def originFont(self):
font = QFont(config["lyric.font-family"])
font.setPixelSize(config["lyric.font-size"])
return font
@property
def translationFont(self):
font = QFont(config["lyric.font-family"])
font.setPixelSize(config["lyric.font-size"]//1.5)
return font
originMaskWidth = pyqtProperty(
float, getOriginMaskWidth, setOriginMaskWidth)
translationMaskWidth = pyqtProperty(
float, getTranslationMaskWidth, setTranslationMaskWidth)
originTextX = pyqtProperty(float, getOriginTextX, setOriginTextX)
translationTextX = pyqtProperty(
float, getTranslationTextX, setTranslationTextX)上述代码对外提供了两个接口 setLyric(lyric, duration, update) 和 setPlay(isPlay)，用于更新歌词和控制歌词动画的开始与暂停。下面是一个最小使用示例，里面使用 Qt.SubWindow 标志使得桌面歌词可以在主界面最小化后仍然显示在桌面上，同时不会多出一个应用图标（Windows 是这样，Linux 不一定）：
class Demo(QWidget):
def __init__(self):
super().__init__(parent=None)
# 创建桌面歌词
self.desktopLyric = QWidget()
self.lyricWidget = LyricWidget(self.desktopLyric)
self.desktopLyric.setAttribute(Qt.WA_TranslucentBackground)
self.desktopLyric.setWindowFlags(
Qt.FramelessWindowHint | Qt.SubWindow | Qt.WindowStaysOnTopHint)
self.desktopLyric.resize(800, 300)
self.lyricWidget.resize(800, 300)
# 必须有这一行才能显示桌面歌词界面
self.desktopLyric.show()
# 设置歌词
self.lyricWidget.setLyric(["Test desktop lyric style", "测试桌面歌词样式"], 3000)
self.lyricWidget.setPlay(True)
if __name__ == '__main__':
app = QApplication(sys.argv)
w = Demo()
w.show()
app.exec_()后记
至此关于桌面歌词的实现方案已经介绍完毕，完整的播放器界面代码可参见：https://github.com/zhiyiYo/Groove，以上
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