本文通過Python3+PyQt5實現(xiàn)《python Qt Gui 快速編程》這本書的page Designer應用程序，采用QGraphicsView，QGraphicsScene，QGraphicsItem，這個程序包含有多個文本，圖片和框的頁面。有些圖形類在PyQt5已過時，所以本代碼改動幅度比較大。主要的類或方法的改變如下：

QMatrix==>QTransform
setMatrix==>setTransform
rotate ==> setRotation

本例中，由于event.delta()已過時，還重寫了wheelEvent方法：

def wheelEvent(self, event):  #factor = 1.41 ** (-event.delta() / 240.0)   #factor = 1.41 ** (-abs(event.startX()-event.y()) / 240.0)  factor = event.angleDelta().y()/120.0  if event.angleDelta().y()/120.0 > 0:   factor=2  else:   factor=0.5  self.scale(factor, factor)

為了保持代碼可讀行，增加了一個類：

class GraphicsPixmapItem(QGraphicsPixmapItem):  #add by yangrongdong def __init__(self,pixmap):  super(QGraphicsPixmapItem, self).__init__(pixmap)

本例中還有包含菜單的按鈕：

 if text == "&Align":  menu = QMenu(self)  for text, arg in (     ("Align &Left", Qt.AlignLeft),     ("Align &Right", Qt.AlignRight),     ("Align &Top", Qt.AlignTop),     ("Align &Bottom", Qt.AlignBottom)):     wrapper = functools.partial(self.setAlignment, arg)     self.wrapped.append(wrapper)     menu.addAction(text, wrapper)    button.setMenu(menu)

本例中還針對QStyleOptionGraphicsItem.levelOfDetail已過時,改寫如下：

option.levelOfDetailFromTransform(self.transform())

下面為完整的代碼：

#!/usr/bin/env python3import functoolsimport randomimport sysfrom PyQt5.QtCore import (QByteArray, QDataStream, QFile, QFileInfo,       QIODevice, QPoint, QPointF, QRectF, Qt)from PyQt5.QtWidgets import (QApplication, QDialog,        QDialogButtonBox, QFileDialog, QFontComboBox,        QGraphicsItem, QGraphicsPixmapItem,        QGraphicsScene, QGraphicsTextItem, QGraphicsView, QGridLayout,        QHBoxLayout, QLabel, QMenu, QMessageBox,QPushButton, QSpinBox,        QStyle, QTextEdit, QVBoxLayout)from PyQt5.QtGui import QFont,QCursor,QFontMetrics,QTransform,QPainter,QPen,QPixmapfrom PyQt5.QtPrintSupport import QPrinter,QPrintDialogMAC = Truetry: from PyQt5.QtGui import qt_mac_set_native_menubarexcept ImportError: MAC = False#PageSize = (595, 842) # A4 in pointsPageSize = (612, 792) # US Letter in pointsPointSize = 10MagicNumber = 0x70616765FileVersion = 1Dirty = Falseclass TextItemDlg(QDialog): def __init__(self, item=None, position=None, scene=None, parent=None):  super(QDialog, self).__init__(parent)  self.item = item  self.position = position  self.scene = scene  self.editor = QTextEdit()  self.editor.setAcceptRichText(False)  self.editor.setTabChangesFocus(True)  editorLabel = QLabel("&Text:")  editorLabel.setBuddy(self.editor)  self.fontComboBox = QFontComboBox()  self.fontComboBox.setCurrentFont(QFont("Times", PointSize))  fontLabel = QLabel("&Font:")  fontLabel.setBuddy(self.fontComboBox)  self.fontSpinBox = QSpinBox()  self.fontSpinBox.setAlignment(Qt.AlignRight|Qt.AlignVCenter)  self.fontSpinBox.setRange(6, 280)  self.fontSpinBox.setValue(PointSize)  fontSizeLabel = QLabel("&Size:")  fontSizeLabel.setBuddy(self.fontSpinBox)  self.buttonBox = QDialogButtonBox(QDialogButtonBox.Ok|           QDialogButtonBox.Cancel)  self.buttonBox.button(QDialogButtonBox.Ok).setEnabled(False)  if self.item is not None:   self.editor.setPlainText(self.item.toPlainText())   self.fontComboBox.setCurrentFont(self.item.font())   self.fontSpinBox.setValue(self.item.font().pointSize())  layout = QGridLayout()  layout.addWidget(editorLabel, 0, 0)  layout.addWidget(self.editor, 1, 0, 1, 6)  layout.addWidget(fontLabel, 2, 0)  layout.addWidget(self.fontComboBox, 2, 1, 1, 2)  layout.addWidget(fontSizeLabel, 2, 3)  layout.addWidget(self.fontSpinBox, 2, 4, 1, 2)  layout.addWidget(self.buttonBox, 3, 0, 1, 6)  self.setLayout(layout)  self.fontComboBox.currentFontChanged.connect(self.updateUi)  self.fontSpinBox.valueChanged.connect(self.updateUi)  self.editor.textChanged.connect(self.updateUi)  self.buttonBox.accepted.connect(self.accept)  self.buttonBox.rejected.connect(self.reject)  self.setWindowTitle("Page Designer - {0} Text Item".format(    "Add" if self.item is None else "Edit"))  self.updateUi() def updateUi(self):  font = self.fontComboBox.currentFont()  font.setPointSize(self.fontSpinBox.value())  self.editor.document().setDefaultFont(font)  self.buttonBox.button(QDialogButtonBox.Ok).setEnabled(    bool(self.editor.toPlainText())) def accept(self):  if self.item is None:   self.item = TextItem("", self.position, self.scene)  font = self.fontComboBox.currentFont()  font.setPointSize(self.fontSpinBox.value())  self.item.setFont(font)  self.item.setPlainText(self.editor.toPlainText())   self.item.update()  global Dirty  Dirty = True  QDialog.accept(self)class TextItem(QGraphicsTextItem): def __init__(self, text, position, scene,     font=QFont("Times", PointSize), matrix=QTransform()):  super(TextItem, self).__init__(text)  self.setFlags(QGraphicsItem.ItemIsSelectable|      QGraphicsItem.ItemIsMovable)  self.setFont(font)  self.setPos(position)  self.setTransform(matrix)  scene.clearSelection()  scene.addItem(self)  self.setSelected(True)  global Dirty  Dirty = True def parentWidget(self):  return self.scene().views()[0] def itemChange(self, change, variant):  if change != QGraphicsItem.ItemSelectedChange:   global Dirty   Dirty = True  return QGraphicsTextItem.itemChange(self, change, variant) def mouseDoubleClickEvent(self, event):  dialog = TextItemDlg(self, self.parentWidget())  dialog.exec_()class GraphicsPixmapItem(QGraphicsPixmapItem):  #add by yangrongdong def __init__(self,pixmap):  super(QGraphicsPixmapItem, self).__init__(pixmap)class BoxItem(QGraphicsItem): def __init__(self, position, scene, style=Qt.SolidLine,     rect=None, matrix=QTransform()):  super(BoxItem, self).__init__()  self.setFlags(QGraphicsItem.ItemIsSelectable|      QGraphicsItem.ItemIsMovable|      QGraphicsItem.ItemIsFocusable)  if rect is None:   rect = QRectF(-10 * PointSize, -PointSize, 20 * PointSize,       2 * PointSize)  self.rect = rect  self.style = style  self.setPos(position)  self.setTransform(matrix)  scene.clearSelection()  scene.addItem(self)  self.setSelected(True)  self.setFocus()  global Dirty  Dirty = True def parentWidget(self):  return self.scene().views()[0] def boundingRect(self):  return self.rect.adjusted(-2, -2, 2, 2) def paint(self, painter, option, widget):  pen = QPen(self.style)  pen.setColor(Qt.black)  pen.setWidth(1)  if option.state & QStyle.State_Selected:   pen.setColor(Qt.blue)  painter.setPen(pen)  painter.drawRect(self.rect) def itemChange(self, change, variant):  if change != QGraphicsItem.ItemSelectedChange:   global Dirty   Dirty = True  return QGraphicsItem.itemChange(self, change, variant) def contextMenuEvent(self, event):  wrapped = []  menu = QMenu(self.parentWidget())  for text, param in (    ("&Solid", Qt.SolidLine),    ("&Dashed", Qt.DashLine),    ("D&otted", Qt.DotLine),    ("D&ashDotted", Qt.DashDotLine),    ("DashDo&tDotted", Qt.DashDotDotLine)):   wrapper = functools.partial(self.setStyle, param)   wrapped.append(wrapper)   menu.addAction(text, wrapper)  menu.exec_(event.screenPos()) def setStyle(self, style):  self.style = style  self.update()  global Dirty  Dirty = True def keyPressEvent(self, event):  factor = PointSize / 4  changed = False  if event.modifiers() & Qt.ShiftModifier:   if event.key() == Qt.Key_Left:    self.rect.setRight(self.rect.right() - factor)    changed = True   elif event.key() == Qt.Key_Right:    self.rect.setRight(self.rect.right() + factor)    changed = True   elif event.key() == Qt.Key_Up:    self.rect.setBottom(self.rect.bottom() - factor)    changed = True   elif event.key() == Qt.Key_Down:    self.rect.setBottom(self.rect.bottom() + factor)    changed = True  if changed:   self.update()   global Dirty   Dirty = True  else:   QGraphicsItem.keyPressEvent(self, event)class GraphicsView(QGraphicsView): def __init__(self, parent=None):  super(GraphicsView, self).__init__(parent)  self.setDragMode(QGraphicsView.RubberBandDrag)  self.setRenderHint(QPainter.Antialiasing)  self.setRenderHint(QPainter.TextAntialiasing) def wheelEvent(self, event):  #factor = 1.41 ** (-event.delta() / 240.0)   factor = event.angleDelta().y()/120.0  if event.angleDelta().y()/120.0 > 0:   factor=2  else:   factor=0.5  self.scale(factor, factor)class MainForm(QDialog): def __init__(self, parent=None):  super(MainForm, self).__init__(parent)  self.filename = ""  self.copiedItem = QByteArray()  self.pasteOffset = 5  self.prevPoint = QPoint()  self.addOffset = 5  self.borders = []  self.printer = QPrinter(QPrinter.HighResolution)  self.printer.setPageSize(QPrinter.Letter)  self.view = GraphicsView()  self.scene = QGraphicsScene(self)  self.scene.setSceneRect(0, 0, PageSize[0], PageSize[1])  self.addBorders()  self.view.setScene(self.scene)  self.wrapped = [] # Needed to keep wrappers alive  buttonLayout = QVBoxLayout()  for text, slot in (    ("Add &Text", self.addText),    ("Add &Box", self.addBox),    ("Add Pi&xmap", self.addPixmap),    ("&Align", None),    ("&Copy", self.copy),    ("C&ut", self.cut),    ("&Paste", self.paste),    ("&Delete...", self.delete),    ("&Rotate", self.rotate),    ("Pri&nt...", self.print_),    ("&Open...", self.open),    ("&Save", self.save),    ("&Quit", self.accept)):   button = QPushButton(text)   if not MAC:    button.setFocusPolicy(Qt.NoFocus)   if slot is not None:    button.clicked.connect(slot)   if text == "&Align":    menu = QMenu(self)    for text, arg in (      ("Align &Left", Qt.AlignLeft),      ("Align &Right", Qt.AlignRight),      ("Align &Top", Qt.AlignTop),      ("Align &Bottom", Qt.AlignBottom)):     wrapper = functools.partial(self.setAlignment, arg)     self.wrapped.append(wrapper)     menu.addAction(text, wrapper)    button.setMenu(menu)   if text == "Pri&nt...":    buttonLayout.addStretch(5)   if text == "&Quit":    buttonLayout.addStretch(1)   buttonLayout.addWidget(button)  buttonLayout.addStretch()  layout = QHBoxLayout()  layout.addWidget(self.view, 1)  layout.addLayout(buttonLayout)  self.setLayout(layout)  fm = QFontMetrics(self.font())  self.resize(self.scene.width() + fm.width(" Delete... ") + 50,     self.scene.height() + 50)  self.setWindowTitle("Page Designer") def addBorders(self):  self.borders = []  rect = QRectF(0, 0, PageSize[0], PageSize[1])  self.borders.append(self.scene.addRect(rect, Qt.yellow))  margin = 5.25 * PointSize  self.borders.append(self.scene.addRect(    rect.adjusted(margin, margin, -margin, -margin),    Qt.yellow)) def removeBorders(self):  while self.borders:   item = self.borders.pop()   self.scene.removeItem(item)   del item def reject(self):  self.accept() def accept(self):  self.offerSave()  QDialog.accept(self) def offerSave(self):  if (Dirty and QMessageBox.question(self,       "Page Designer - Unsaved Changes",       "Save unsaved changes?",       QMessageBox.Yes|QMessageBox.No) ==    QMessageBox.Yes):   self.save() def position(self):  point = self.mapFromGlobal(QCursor.pos())  if not self.view.geometry().contains(point):   coord = random.randint(36, 144)   point = QPoint(coord, coord)  else:   if point == self.prevPoint:    point += QPoint(self.addOffset, self.addOffset)    self.addOffset += 5   else:    self.addOffset = 5    self.prevPoint = point  return self.view.mapToScene(point) def addText(self):  dialog = TextItemDlg(position=self.position(),        scene=self.scene, parent=self)  dialog.exec_() def addBox(self):  BoxItem(self.position(), self.scene) def addPixmap(self):  path = (QFileInfo(self.filename).path()   if self.filename else ".")  fname,filetype = QFileDialog.getOpenFileName(self,    "Page Designer - Add Pixmap", path,    "Pixmap Files (*.bmp *.jpg *.png *.xpm)")  if not fname:   return  self.createPixmapItem(QPixmap(fname), self.position()) def createPixmapItem(self, pixmap, position, matrix=QTransform()):  item = GraphicsPixmapItem(pixmap)  item.setFlags(QGraphicsItem.ItemIsSelectable|      QGraphicsItem.ItemIsMovable)  item.setPos(position)  item.setTransform(matrix)  self.scene.clearSelection()  self.scene.addItem(item)  item.setSelected(True)  global Dirty  Dirty = True  return item def selectedItem(self):  items = self.scene.selectedItems()  if len(items) == 1:   return items[0]  return None def copy(self):  item = self.selectedItem()  if item is None:   return  self.copiedItem.clear()  self.pasteOffset = 5  stream = QDataStream(self.copiedItem, QIODevice.WriteOnly)  self.writeItemToStream(stream, item) def cut(self):  item = self.selectedItem()  if item is None:   return  self.copy()  self.scene.removeItem(item)  del item def paste(self):  if self.copiedItem.isEmpty():   return  stream = QDataStream(self.copiedItem, QIODevice.ReadOnly)  self.readItemFromStream(stream, self.pasteOffset)  self.pasteOffset += 5 def setAlignment(self, alignment):  # Items are returned in arbitrary order  items = self.scene.selectedItems()  if len(items) <= 1:   return  # Gather coordinate data  leftXs, rightXs, topYs, bottomYs = [], [], [], []  for item in items:   rect = item.sceneBoundingRect()   leftXs.append(rect.x())   rightXs.append(rect.x() + rect.width())   topYs.append(rect.y())   bottomYs.append(rect.y() + rect.height())  # Perform alignment  if alignment == Qt.AlignLeft:   xAlignment = min(leftXs)   for i, item in enumerate(items):    item.moveBy(xAlignment - leftXs[i], 0)  elif alignment == Qt.AlignRight:   xAlignment = max(rightXs)   for i, item in enumerate(items):    item.moveBy(xAlignment - rightXs[i], 0)  elif alignment == Qt.AlignTop:   yAlignment = min(topYs)   for i, item in enumerate(items):    item.moveBy(0, yAlignment - topYs[i])  elif alignment == Qt.AlignBottom:   yAlignment = max(bottomYs)   for i, item in enumerate(items):    item.moveBy(0, yAlignment - bottomYs[i])  global Dirty  Dirty = True def rotate(self):  for item in self.scene.selectedItems():   item.setRotation(item.rotation()+30) def delete(self):  items = self.scene.selectedItems()  if (len(items) and QMessageBox.question(self,    "Page Designer - Delete",    "Delete {0} item{1}?".format(len(items),    "s" if len(items) != 1 else ""),    QMessageBox.Yes|QMessageBox.No) ==    QMessageBox.Yes):   while items:    item = items.pop()    self.scene.removeItem(item)    del item   global Dirty   Dirty = True def print_(self):  dialog = QPrintDialog(self.printer)  if dialog.exec_():   painter = QPainter(self.printer)   painter.setRenderHint(QPainter.Antialiasing)   painter.setRenderHint(QPainter.TextAntialiasing)   self.scene.clearSelection()   self.removeBorders()   self.scene.render(painter)   self.addBorders() def open(self):  self.offerSave()  path = (QFileInfo(self.filename).path()    if self.filename else ".")  fname,filetype = QFileDialog.getOpenFileName(self,    "Page Designer - Open", path,    "Page Designer Files (*.pgd)")  if not fname:   return  self.filename = fname  fh = None  try:   fh = QFile(self.filename)   if not fh.open(QIODevice.ReadOnly):    raise IOError(str(fh.errorString()))   items = self.scene.items()   while items:    item = items.pop()    self.scene.removeItem(item)    del item   self.addBorders()   stream = QDataStream(fh)   stream.setVersion(QDataStream.Qt_5_7)   magic = stream.readInt32()   if magic != MagicNumber:    raise IOError("not a valid .pgd file")   fileVersion = stream.readInt16()   if fileVersion != FileVersion:    raise IOError("unrecognised .pgd file version")   while not fh.atEnd():    self.readItemFromStream(stream)  except IOError as e:   QMessageBox.warning(self, "Page Designer -- Open Error",     "Failed to open {0}: {1}".format(self.filename, e))  finally:   if fh is not None:    fh.close()  global Dirty  Dirty = False def save(self):  if not self.filename:   path = "."   fname,filetype = QFileDialog.getSaveFileName(self,     "Page Designer - Save As", path,     "Page Designer Files (*.pgd)")   if not fname:    return   self.filename = fname  fh = None  try:   fh = QFile(self.filename)   if not fh.open(QIODevice.WriteOnly):    raise IOError(str(fh.errorString()))   self.scene.clearSelection()   stream = QDataStream(fh)   stream.setVersion(QDataStream.Qt_5_7)   stream.writeInt32(MagicNumber)   stream.writeInt16(FileVersion)   for item in self.scene.items():    self.writeItemToStream(stream, item)  except IOError as e:   QMessageBox.warning(self, "Page Designer -- Save Error",     "Failed to save {0}: {1}".format(self.filename, e))  finally:   if fh is not None:    fh.close()  global Dirty  Dirty = False def readItemFromStream(self, stream, offset=0):  type = ""  position = QPointF()  matrix = QTransform()  rotateangle=0#add by yangrongdong  type=stream.readQString()  stream >> position >> matrix  if offset:   position += QPointF(offset, offset)  if type == "Text":   text = ""   font = QFont()   text=stream.readQString()   stream >> font   rotateangle=stream.readFloat()   tx=TextItem(text, position, self.scene, font, matrix)   tx.setRotation(rotateangle)  elif type == "Box":   rect = QRectF()   stream >> rect   style = Qt.PenStyle(stream.readInt16())   rotateangle=stream.readFloat()   bx=BoxItem(position, self.scene, style, rect, matrix)   bx.setRotation(rotateangle)  elif type == "Pixmap":   pixmap = QPixmap()   stream >> pixmap   rotateangle=stream.readFloat()   px=self.createPixmapItem(pixmap, position, matrix)   px.setRotation(rotateangle) def writeItemToStream(self, stream, item):  if isinstance(item, TextItem):   stream.writeQString("Text")   stream<<item.pos()<< item.transform()    stream.writeQString(item.toPlainText())   stream<< item.font()   stream.writeFloat(item.rotation())#add by yangrongdong  elif isinstance(item, GraphicsPixmapItem):   stream.writeQString("Pixmap")   stream << item.pos() << item.transform() << item.pixmap()   stream.writeFloat(item.rotation())#add by yangrongdong  elif isinstance(item, BoxItem):   stream.writeQString("Box")   stream<< item.pos() << item.transform() << item.rect   stream.writeInt16(item.style)   stream.writeFloat(item.rotation())#add by yangrongdongapp = QApplication(sys.argv)form = MainForm()rect = QApplication.desktop().availableGeometry()form.resize(int(rect.width() * 0.6), int(rect.height() * 0.9))form.show()app.exec_()