【PyQt实例6】渐变效果

#-*- coding:utf-8 -*-
import sys
import math

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

QTextCodec.setCodecForTr(QTextCodec.codecForName("utf-8"))

class StockDialog(QWidget):
    def __init__(self, parent=None):
        super(StockDialog, self).__init__(parent)
        self.setWindowTitle(self.tr("渐变效果"))
        
        self.startColor = Qt.green
        self.endColor = Qt.blue
        self.style = QGradient.LinearGradient
        self.spread = QGradient.PadSpread
        
        mainSplitter = QSplitter(Qt.Horizontal)
        mainSplitter.setOpaqueResize(True)
                  
        frame = QFrame(mainSplitter)
        mainLayout = QGridLayout(frame)
        mainLayout.setMargin(10)
        mainLayout.setSpacing(6)       
                                                    
        stack1 = QStackedWidget()
        stack1.setFrameStyle(QFrame.Panel|QFrame.Raised)
        
        mainSplitter1 = QSplitter(Qt.Horizontal)
        mainSplitter1.setOpaqueResize(True)
        
        self.area = PaintArea(self)
        
        stack1.addWidget(self.area)        
        frame1 = QFrame(mainSplitter1)
        mainLayout1 = QVBoxLayout(frame1)
        mainLayout1.setMargin(10)
        mainLayout1.setSpacing(6)
        mainLayout1.addWidget(stack1)  
    
        self.startPushButton = QPushButton(self.tr("start"))
        self.startPushButton.setAutoFillBackground(True)
        self.startPushButton.setPalette(QPalette(Qt.green))
        
        self.endPushButton = QPushButton(self.tr("end"))
        self.endPushButton.setAutoFillBackground(True)
        self.endPushButton.setPalette(QPalette(Qt.blue))
        
        self.connect(self.startPushButton,SIGNAL("clicked()"),self.slotStartColor)
        self.connect(self.endPushButton,SIGNAL("clicked()"),self.slotEndColor)
        
        self.grdientComboBox = QComboBox()
        self.grdientComboBox.addItem(self.tr("Linear Gradient"),QGradient.LinearGradient)
        self.grdientComboBox.addItem(self.tr("Radial Gradient"),QGradient.RadialGradient)
        self.grdientComboBox.addItem(self.tr("Conical Gradient"),QGradient.ConicalGradient)
        self.connect(self.grdientComboBox,SIGNAL("activated(int)"),self.slotSetStyle)
        
        self.spreadComboBox = QComboBox()
        self.spreadComboBox.addItem(self.tr("PadSpread"),QGradient.PadSpread)
        self.spreadComboBox.addItem(self.tr("RepeatSpread"),QGradient.RepeatSpread)
        self.spreadComboBox.addItem(self.tr("ReflctSpread"),QGradient.ReflectSpread)
        self.connect(self.spreadComboBox,SIGNAL("activated(int)"),self.slotSetSpread)
        
        mainLayout.addWidget(self.startPushButton,1,0)
        mainLayout.addWidget(self.endPushButton,1,1)
        mainLayout.addWidget(self.grdientComboBox,1,2)
        mainLayout.addWidget(self.spreadComboBox,1,3)
        
        layout = QGridLayout(self)
        layout.addWidget(mainSplitter1,0,0)
        layout.addWidget(mainSplitter,1,0)
        self.setLayout(layout)
        
    def slotStartColor(self):
        self.startColor = QColorDialog.getColor(Qt.green)
        self.startPushButton.setPalette(QPalette(self.startColor))
        self.area.setPen(QPen(self.startColor))
        
    def slotEndColor(self):
        self.endColor = QColorDialog.getColor(Qt.blue)
        self.endPushButton.setPalette(QPalette(self.endColor))
        self.area.setPen(QPen(self.endColor))
    
    def slotSetStyle(self,value):
        self.style = self.grdientComboBox.itemData(value,Qt.UserRole).toInt()[0]
    
    def slotSetSpread(self,value):
        self.spread = self.spreadComboBox.itemData(value,Qt.UserRole).toInt()[0]
         
        
                
class PaintArea(QWidget):
    def __init__(self,StockDialog):
        super(PaintArea,self).__init__()
        self.setPalette(QPalette(Qt.white))
        self.setAutoFillBackground(True)
        self.setMinimumSize(400,400)
        self.startPoint = QPointF(0,0)
        self.endPoint = QPointF(400,400)
        self.pen = QPen()
        self.sd = StockDialog
    
    def setPen(self,p):
        self.pen = p
        self.update()    
    
    def mousePressEvent(self,e):
        self.startPoint = QPointF(e.pos())
        
    def mouseReleaseEvent(self,e):
        self.endPoint = QPointF(e.pos())
        self.update()
    
    def paintEvent(self,QPaintEvent):
        p = QPainter(self)
        r = self.rect()
        p.setPen(self.pen)
        if(self.sd.style == QGradient.LinearGradient):
            linearGradient = QLinearGradient(self.startPoint,self.endPoint)
            linearGradient.setColorAt(0.0,self.sd.startColor)
            linearGradient.setColorAt(1.0,self.sd.endColor)
            linearGradient.setSpread(self.sd.spread)
            p.setBrush(linearGradient)
        elif(self.sd.style == QGradient.RadialGradient):
            rr = math.sqrt(math.pow(self.endPoint.x() - self.startPoint.x(),2) + math.pow(self.endPoint.y() - self.startPoint.y(),2))
            radialGradient = QRadialGradient(self.startPoint,rr,self.startPoint)
            radialGradient.setColorAt(0.0,self.sd.startColor)
            radialGradient.setColorAt(1.0,self.sd.endColor)
            radialGradient.setSpread(self.sd.spread)
            p.setBrush(radialGradient)
        elif(self.sd.style == QGradient.ConicalGradient):
            angle = math.atan2(self.endPoint.y() - self.startPoint.y(),self.endPoint.x() - self.startPoint.x())
            conicalGradient = QConicalGradient(self.startPoint,-(180 * angle)/math.pi)
            conicalGradient.setColorAt(0.0,self.sd.startColor)
            conicalGradient.setColorAt(1.0,self.sd.endColor)
            p.setBrush(conicalGradient)          
        p.drawRect(r)
        
if __name__=='__main__':
    
    app = QApplication(sys.argv)
    form = StockDialog()
    form.show()
    app.exec_()