python3+PyQt5图形项的自定义和交互 python3实现page Designer应用程序

本文通过Python3+PyQt5实现《python Qt Gui 快速编程》这本书的page Designer应用程序，采用QGraphicsView，QGraphicsScene，QGraphicsItem，这个程序包含有多个文本，图片和框的页面。有些图形类在PyQt5已过时，所以本代码改动幅度比较大。主要的类或方法的改变如下：

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

本例中，由于event.delta()已过时，还重写了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)

为了保持代码可读行，增加了一个类：

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

本例中还有包含菜单的按钮：

 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)

本例中还针对QStyleOptionGraphicsItem.levelOfDetail已过时,改写如下：

option.levelOfDetailFromTransform(self.transform())

下面为完整的代码：

#!/usr/bin/env python3

import functools
import random
import sys
from 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,QPixmap
from PyQt5.QtPrintSupport import QPrinter,QPrintDialog

MAC = True
try:
 from PyQt5.QtGui import qt_mac_set_native_menubar
except ImportError:
 MAC = False

#PageSize = (595, 842) # A4 in points
PageSize = (612, 792) # US Letter in points
PointSize = 10

MagicNumber = 0x70616765
FileVersion = 1

Dirty = False

class 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 yangrongdong

app = 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_()

运行结果

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