PyQt4 自定义窗体

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Mutse Young 12月 19, 2012

本文主要讲解如何使用 PyQt4 实现一个自定义的不规则窗体。

custom widget

源码

代码如下：

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#!/usr/bin/python
# -*- coding: utf-8 -*-
#

from PyQt4.QtGui import *
from PyQt4.QtCore import *
import sys

class Widget(QWidget):
	def __init__(self, parent = None):
		super(Widget, self).__init__(parent)

		self.setWindowFlags(Qt.ToolTip)
		self.setAttribute(Qt.WA_TranslucentBackground)
		self.setMouseTracking(True)

		self.startPos = QPoint(0,0)
		self.dragPosition = QPoint(0, 0)

		self.resize(QApplication.desktop().size())

		quit = QAction(self.tr(""), self)
		quit.setShortcut(self.tr("Ctrl+Q"))
		self.connect(quit, SIGNAL("triggered()"), qApp.quit)
		self.addAction(quit)
		self.setContextMenuPolicy(Qt.ActionsContextMenu)

	def paintEvent(self, event):
		painter = QPainter(self)
		painter.setPen(QColor(255,0,0))
		painter.setBrush(QColor(255,0,0))
		self.drawPainter(painter, QColor(255, 0, 0))

	def mousePressEvent(self, event):
		if event.button() == Qt.LeftButton:
			self.dragPosition = event.globalPos() - self.frameGeometry().topLeft()

		event.accept()

	def mouseMoveEvent(self, event):
		if event.buttons() & Qt.LeftButton:
			self.startPos += (event.pos() - self.dragPosition)
			self.dragPosition = event.pos()
			self.move(event.globalPos() - self.dragPosition)

		if self.size().width() < QApplication.desktop().width():
			self.resize(self.size() + QSize(1, 1))
		else:
			self.resize(self.size() - QSize(1, 1))

		event.accept()

	def resizeEvent(self, event):
		bmp = QBitmap(self.size())
		bmp.fill(QColor(255,255,255))

		painter = QPainter(bmp)
		painter.setPen(QColor(0,0,0))
		painter.setBrush(QColor(0,0,0))
		self.drawPainter(painter, QColor(0, 0, 0))

		self.setMask(bmp)

	def drawPainter(self, painter, color):
		path = QPainterPath()
		path.addEllipse(self.startPos.x(), self.startPos.y(), 100, 100)
		painter.fillPath(path, color)
		painter.end()

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

	sys.exit(app.exec_())

解析

定义窗体

首先定义一个 Widget，并继承 QWidget，在构造函数 __init__ 中调用基类 QWidget 的构造函数 super(Widget, self).__init__(parent)。

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class Widget(QWidget):
	def __init__(self, parent = None):
		super(Widget, self).__init__(parent)

并设置窗体属性：

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# 设置窗体置顶显示
self.setWindowFlags(Qt.ToolTip)

# 设置窗体背景透明
self.setAttribute(Qt.WA_TranslucentBackground)
self.setMouseTracking(True)

# 初始化成员变量
self.startPos = QPoint(0,0)
self.dragPosition = QPoint(0, 0)

# 设置窗体大小
self.resize(QApplication.desktop().size())

创建右键菜单

创建右键菜单，并连接相应的槽。

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# 创建quit菜单项
quit = QAction(self.tr(""), self)
quit.setShortcut(self.tr("Ctrl+Q"))

# 连接qApp.quit槽函数
self.connect(quit, SIGNAL("triggered()"), qApp.quit)

# 将菜单项添加至窗体上
self.addAction(quit)

# 设置上下文菜单
self.setContextMenuPolicy(Qt.ActionsContextMenu)

paintEvent 函数

创建一个不规则的窗体，需要重写 QWidget 类的 paintEvent 函数：

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def paintEvent(self, event):
	painter = QPainter(self)
	painter.setPen(QColor(255,0,0)) # 设置画笔颜色
	painter.setBrush(QColor(255,0,0)) # 设置画刷颜色
	self.drawPainter(painter, QColor(255, 0, 0)) # 不规则窗体绘制

mousePressEvent 函数

由于隐藏了不规则窗体的边框，想拖动它，还需实现 mousePressEvent 和 mouseMoveEvent 函数：

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def mousePressEvent(self, event):
	if event.button() == Qt.LeftButton:
		self.dragPosition = event.globalPos() - self.frameGeometry().topLeft()

	event.accept()

mouseMoveEvent 函数

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def mouseMoveEvent(self, event):
	if event.buttons() & Qt.LeftButton:
		self.startPos += (event.pos() - self.dragPosition)
		self.dragPosition = event.pos()
		self.move(event.globalPos() - self.dragPosition)

	# 用来解决窗体无法拖动的现象
	if self.size().width() < QApplication.desktop().width():
		self.resize(self.size() + QSize(1, 1))
	else:
		self.resize(self.size() - QSize(1, 1))

	event.accept()

窗体掩膜

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def resizeEvent(self, event):
	bmp = QBitmap(self.size())
	bmp.fill(QColor(255,255,255))

	painter = QPainter(bmp)
	painter.setPen(QColor(0,0,0))
	painter.setBrush(QColor(0,0,0))
	self.drawPainter(painter, QColor(0, 0, 0))

	self.setMask(bmp) # 设置窗体掩膜

绘制不规则窗体

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def drawPainter(self, painter, color):
	path = QPainterPath()
	# 绘制圆形窗体
	path.addEllipse(self.startPos.x(), self.startPos.y(), 100, 100)
	painter.fillPath(path, color)
	painter.end() # 解决运行时的段错误

若无 painter.end() 一行代码，运行时将产生段错误：

QPaintDevice: Cannot destroy paint device that is being painted
QPaintDevice: Cannot destroy paint device that is being painted
段错误

注： 用鼠标拖动圆形窗体时，窗体移动较缓慢，下次再分析其原因。

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