PyQt5 图形项的定义和交互（一）

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 #幻数
FileVersion = 1
Dirty = False #是否有未保存的更改

class TextItemDlg(QDialog):#添加文本的对话框
    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): #文本图形项
    def __init__(self, text, position, scene,
                 font=QFont("Times", PointSize), matrix=QTransform()):
        super(TextItem, self).__init__(text)
        #设置图形项为 可选中、可移动
        self.setFlags(QGraphicsItem.ItemIsSelectable|QGraphicsItem.ItemIsMovable)
        self.setFont(font)
        self.setPos(position)
        self.setTransform(matrix)
        scene.clearSelection() #清除场景中的选择
        scene.addItem(self)#将自身添加到场景中
        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): #双击出现修改对话框
        dialog = TextItemDlg(self, self.parentWidget())
        dialog.exec_()
class GraphicsPixmapItem(QGraphicsPixmapItem):      #像素图图形项
    def __init__(self,pixmap):
        super(QGraphicsPixmapItem, self).__init__(pixmap)

class BoxItem(QGraphicsItem): #方框（普通图形项）
    def __init__(self, position, scene, style=Qt.SolidLine,
                 rect=None, matrix=QTransform()):
        super(BoxItem, self).__init__()
        #属性设为可选、可移动、可聚焦
        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): #添加右键菜单
        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): #键盘事件
        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):#图形视图类
    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()#图形视图类
        self.scene = QGraphicsScene(self)#场景
        self.scene.setSceneRect(0, 0, PageSize[0], PageSize[1])#场景坐标和长宽
        self.addBorders()#添加边框
        self.view.setScene(self.scene)#为视图指定场景
        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):#对齐
        # 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): #旋转
        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()#清除场景选择
            self.removeBorders()#打印前清除边框
            self.scene.render(painter)
            self.addBorders()#打印后恢复边框

    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 = "."
            #保存为自定义文件类型 .pgd
            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) #创建数据流
            stream.setVersion(QDataStream.Qt_5_7)
            stream.writeInt32(MagicNumber)
            stream.writeInt16(FileVersion)
            for item in self.scene.items(): #循环将图形项写进数据流
                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):
        #从数据流读取图形项
        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):
        #将项写进数据流的 实现
        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_()