PyQt QGraphicsView矩形外的暗区

Question

我需要为QgraphicsView创建一个可调整的选择矩形，下面是我目前拥有的：

我子类化了QGraphicsRecitem对象，添加了句柄和鼠标操作，运行得很好！我的代码受此启发： Resize a QGraphicsItem with the mouse

工作电流代码示例：

from PyQt5.QtCore import *
from PyQt5.QtGui import *
from PyQt5.QtWidgets import *


class GraphicsRectItem(QGraphicsRectItem):

    handleTopLeft = 1
    handleTopMiddle = 2
    handleTopRight = 3
    handleMiddleLeft = 4
    handleMiddleRight = 5
    handleBottomLeft = 6
    handleBottomMiddle = 7
    handleBottomRight = 8
    handleSpace = -4.0
    handleSize = 20

    handleCursors = {
        handleTopLeft: Qt.SizeFDiagCursor,
        handleTopMiddle: Qt.SizeVerCursor,
        handleTopRight: Qt.SizeBDiagCursor,
        handleMiddleLeft: Qt.SizeHorCursor,
        handleMiddleRight: Qt.SizeHorCursor,
        handleBottomLeft: Qt.SizeBDiagCursor,
        handleBottomMiddle: Qt.SizeVerCursor,
        handleBottomRight: Qt.SizeFDiagCursor,
    }

    def __init__(self, *args):
        """
        Initialize the shape.
        """
        super().__init__(*args)
        self.handles = {}
        self.handleSelected = None
        self.mousePressPos = None
        self.mousePressRect = None
        self.setAcceptHoverEvents(True)
        self.setFlag(QGraphicsItem.ItemIsMovable, True)
        self.setFlag(QGraphicsItem.ItemIsSelectable, True)
        self.setFlag(QGraphicsItem.ItemSendsGeometryChanges, True)
        self.setFlag(QGraphicsItem.ItemIsFocusable, False)


        self.updateHandlesPos()

    def handleAt(self, point):
        """
        Returns the resize handle below the given point.
        """
        for k, v, in self.handles.items():
            if v.contains(point):
                return k
        return None

    def hoverMoveEvent(self, moveEvent):
        """
        Executed when the mouse moves over the shape (NOT PRESSED).
        """
        if self.isSelected():
            handle = self.handleAt(moveEvent.pos())
            cursor = Qt.ArrowCursor if handle is None else self.handleCursors[handle]
            self.setCursor(cursor)
        super().hoverMoveEvent(moveEvent)

    def hoverLeaveEvent(self, moveEvent):
        """
        Executed when the mouse leaves the shape (NOT PRESSED).
        """
        self.setCursor(Qt.ArrowCursor)
        super().hoverLeaveEvent(moveEvent)

    def mousePressEvent(self, mouseEvent):
        """
        Executed when the mouse is pressed on the item.
        """

        self.handleSelected = self.handleAt(mouseEvent.pos())
        if self.handleSelected:
            self.mousePressPos = mouseEvent.pos()
            self.mousePressRect = self.boundingRect()
        super().mousePressEvent(mouseEvent)

    def mouseMoveEvent(self, mouseEvent):
        """
        Executed when the mouse is being moved over the item while being pressed.
        """
        if self.handleSelected is not None:
            self.interactiveResize(mouseEvent.pos())
        else:
            super().mouseMoveEvent(mouseEvent)

    def mouseReleaseEvent(self, mouseEvent):
        """
        Executed when the mouse is released from the item.
        """
        super().mouseReleaseEvent(mouseEvent)
        self.handleSelected = None
        self.mousePressPos = None
        self.mousePressRect = None
        self.update()

    def boundingRect(self):
        """
        Returns the bounding rect of the shape (including the resize handles).
        """
        o = self.handleSize + self.handleSpace
        return self.rect().adjusted(-o, -o, o, o)

    def updateHandlesPos(self):
        """
        Update current resize handles according to the shape size and position.
        """
        s = self.handleSize
        b = self.boundingRect()
        self.handles[self.handleTopLeft] = QRectF(b.left(), b.top(), s, s)
        self.handles[self.handleTopMiddle] = QRectF(b.center().x() - s / 2, b.top(), s, s)
        self.handles[self.handleTopRight] = QRectF(b.right() - s, b.top(), s, s)
        self.handles[self.handleMiddleLeft] = QRectF(b.left(), b.center().y() - s / 2, s, s)
        self.handles[self.handleMiddleRight] = QRectF(b.right() - s, b.center().y() - s / 2, s, s)
        self.handles[self.handleBottomLeft] = QRectF(b.left(), b.bottom() - s, s, s)
        self.handles[self.handleBottomMiddle] = QRectF(b.center().x() - s / 2, b.bottom() - s, s, s)
        self.handles[self.handleBottomRight] = QRectF(b.right() - s, b.bottom() - s, s, s)

    def interactiveResize(self, mousePos):
        """
        Perform shape interactive resize.
        """
        offset = self.handleSize + self.handleSpace
        boundingRect = self.boundingRect()
        rect = self.rect()
        diff = QPointF(0, 0)

        self.prepareGeometryChange()

        if self.handleSelected == self.handleTopLeft:

            fromX = self.mousePressRect.left()
            fromY = self.mousePressRect.top()
            toX = fromX + mousePos.x() - self.mousePressPos.x()
            toY = fromY + mousePos.y() - self.mousePressPos.y()
            diff.setX(toX - fromX)
            diff.setY(toY - fromY)
            boundingRect.setLeft(toX)
            boundingRect.setTop(toY)
            rect.setLeft(boundingRect.left() + offset)
            rect.setTop(boundingRect.top() + offset)
            self.setRect(rect)

        elif self.handleSelected == self.handleTopMiddle:

            fromY = self.mousePressRect.top()
            toY = fromY + mousePos.y() - self.mousePressPos.y()
            diff.setY(toY - fromY)
            boundingRect.setTop(toY)
            rect.setTop(boundingRect.top() + offset)
            self.setRect(rect)

        elif self.handleSelected == self.handleTopRight:

            fromX = self.mousePressRect.right()
            fromY = self.mousePressRect.top()
            toX = fromX + mousePos.x() - self.mousePressPos.x()
            toY = fromY + mousePos.y() - self.mousePressPos.y()
            diff.setX(toX - fromX)
            diff.setY(toY - fromY)
            boundingRect.setRight(toX)
            boundingRect.setTop(toY)
            rect.setRight(boundingRect.right() - offset)
            rect.setTop(boundingRect.top() + offset)
            self.setRect(rect)

        elif self.handleSelected == self.handleMiddleLeft:

            fromX = self.mousePressRect.left()
            toX = fromX + mousePos.x() - self.mousePressPos.x()
            diff.setX(toX - fromX)
            boundingRect.setLeft(toX)
            rect.setLeft(boundingRect.left() + offset)
            self.setRect(rect)

        elif self.handleSelected == self.handleMiddleRight:
            # print("MR")
            fromX = self.mousePressRect.right()
            toX = fromX + mousePos.x() - self.mousePressPos.x()
            diff.setX(toX - fromX)
            boundingRect.setRight(toX)
            rect.setRight(boundingRect.right() - offset)
            self.setRect(rect)

        elif self.handleSelected == self.handleBottomLeft:

            fromX = self.mousePressRect.left()
            fromY = self.mousePressRect.bottom()
            toX = fromX + mousePos.x() - self.mousePressPos.x()
            toY = fromY + mousePos.y() - self.mousePressPos.y()
            diff.setX(toX - fromX)
            diff.setY(toY - fromY)
            boundingRect.setLeft(toX)
            boundingRect.setBottom(toY)
            rect.setLeft(boundingRect.left() + offset)
            rect.setBottom(boundingRect.bottom() - offset)
            self.setRect(rect)

        elif self.handleSelected == self.handleBottomMiddle:

            fromY = self.mousePressRect.bottom()
            toY = fromY + mousePos.y() - self.mousePressPos.y()
            diff.setY(toY - fromY)
            boundingRect.setBottom(toY)
            rect.setBottom(boundingRect.bottom() - offset)
            self.setRect(rect)

        elif self.handleSelected == self.handleBottomRight:

            fromX = self.mousePressRect.right()
            fromY = self.mousePressRect.bottom()
            toX = fromX + mousePos.x() - self.mousePressPos.x()
            toY = fromY + mousePos.y() - self.mousePressPos.y()
            diff.setX(toX - fromX)
            diff.setY(toY - fromY)
            boundingRect.setRight(toX)
            boundingRect.setBottom(toY)
            rect.setRight(boundingRect.right() - offset)
            rect.setBottom(boundingRect.bottom() - offset)
            self.setRect(rect)

        self.updateHandlesPos()

    def shape(self):
        """
        Returns the shape of this item as a QPainterPath in local coordinates.
        """
        path = QPainterPath()
        path.addRect(self.rect())
        if self.isSelected():
            for shape in self.handles.values():
                path.addEllipse(shape)
        return path

    def paint(self, painter, option, widget=None):
        """
        Paint the node in the graphic view.
        """
        painter.setBrush(QBrush(QColor(255, 0, 0, 0)))
        painter.setPen(QPen(QColor(127, 127, 127), 2.0, Qt.DashLine))
        painter.drawRect(self.rect())

        painter.setRenderHint(QPainter.Antialiasing)
        painter.setBrush(QBrush(QColor(81, 168, 220, 200)))
        painter.setPen(QPen(QColor(0, 0, 0, 255), 1.0, Qt.SolidLine, Qt.RoundCap, Qt.RoundJoin))
        for handle, rect in self.handles.items():
            if self.handleSelected is None or handle == self.handleSelected:
                painter.drawRect(rect)


if __name__ == '__main__':
    import sys
    from PyQt5.QtWidgets import QApplication

    app = QApplication(sys.argv)
    view = QGraphicsView()
    scene = QGraphicsScene()
    scene.setSceneRect(0, 0, 1000, 1000)
    view.setScene(scene)
    box = GraphicsRectItem(100, 100, 200, 200)
    scene.addItem(box)
    view.show()
    sys.exit(app.exec_())

为了使所选区域更可见，我想让矩形外的区域更暗，下面是一个快速的photoshop预览：

有什么办法吗？我试着在顶部添加一个半透明的矩形，它可以工作，但是否可以使用我选择的矩形项作为“遮罩”？在

谢谢。在

Answer 1

在这个答案中，我没有使用您示例的代码，但我已经将this project从C++转换为Python，因为它具有添加大小调整器而不修改自定义代码的优点，唯一的要求是该项必须具有一个方法^{{cd1>}和^{cd2>}方法，允许我们调整某些功能的大小。

正如我看到要使用的项选择^{cd3>}的内部部分时，我将创建具有内部间隙的^{{cd4>}类，如下所示：

import sys

from PyQt5.QtCore import Qt, QRectF
from PyQt5.QtGui import QBrush, QColor, QPen, QPixmap, QPainterPath, QPainter
from PyQt5.QtWidgets import QGraphicsRectItem, QGraphicsItem, QGraphicsPathItem, QApplication, QGraphicsView, QGraphicsScene


class HandleItem(QGraphicsRectItem):
    def __init__(self, position_flags, parent):
        QGraphicsRectItem.__init__(self, -10, -10, 20, 20, parent)
        self._positionFlags = position_flags

        self.setBrush(QBrush(QColor(81, 168, 220, 200)))
        self.setPen(QPen(QColor(0, 0, 0, 255), 1.0, Qt.SolidLine, Qt.RoundCap, Qt.RoundJoin))
        self.setFlag(self.ItemIsMovable)
        self.setFlag(self.ItemSendsGeometryChanges)

    def positionflags(self):
        return self._positionFlags

    def itemChange(self, change, value):
        retVal = value
        if change == self.ItemPositionChange:
            retVal = self.restrictPosition(value)
        elif change == self.ItemPositionHasChanged:
            pos = value
            if self.positionflags() == SizeGripItem.TopLeft:
                self.parentItem().setTopLeft(pos)
            elif self.positionflags() == SizeGripItem.Top:
                self.parentItem().setTop(pos.y())
            elif self.positionflags() == SizeGripItem.TopRight:
                self.parentItem().setTopRight(pos)
            elif self.positionflags() == SizeGripItem.Right:
                self.parentItem().setRight(pos.x())
            elif self.positionflags() == SizeGripItem.BottomRight:
                self.parentItem().setBottomRight(pos)
            elif self.positionflags() == SizeGripItem.Bottom:
                self.parentItem().setBottom(pos.y())
            elif self.positionflags() == SizeGripItem.BottomLeft:
                self.parentItem().setBottomLeft(pos)
            elif self.positionflags() == SizeGripItem.Left:
                self.parentItem().setLeft(pos.x())
        return retVal

    def restrictPosition(self, newPos):
        retVal = self.pos()

        if self.positionflags() & SizeGripItem.Top or self.positionflags() & SizeGripItem.Bottom:
            retVal.setY(newPos.y())

        if self.positionflags() & SizeGripItem.Left or self.positionflags() & SizeGripItem.Right:
            retVal.setX(newPos.x())

        if self.positionflags() & SizeGripItem.Top and retVal.y() > self.parentItem()._rect.bottom():
            retVal.setY(self.parentItem()._rect.bottom())

        elif self.positionflags() & SizeGripItem.Bottom and retVal.y() < self.parentItem()._rect.top():
            retVal.setY(self.parentItem()._rect.top())

        if self.positionflags() & SizeGripItem.Left and retVal.x() > self.parentItem()._rect.right():
            retVal.setX(self.parentItem()._rect.right())

        elif self.positionflags() & SizeGripItem.Right and retVal.x() < self.parentItem()._rect.left():
            retVal.setX(self.parentItem()._rect.left())

        return retVal


class SizeGripItem(QGraphicsItem):
    Top = 0x01
    Bottom = 0x1 << 1
    Left = 0x1 << 2
    Right = 0x1 << 3
    TopLeft = Top | Left
    BottomLeft = Bottom | Left
    TopRight = Top | Right
    BottomRight = Bottom | Right

    handleCursors = {
        TopLeft: Qt.SizeFDiagCursor,
        Top: Qt.SizeVerCursor,
        TopRight: Qt.SizeBDiagCursor,
        Left: Qt.SizeHorCursor,
        Right: Qt.SizeHorCursor,
        BottomLeft: Qt.SizeBDiagCursor,
        Bottom: Qt.SizeVerCursor,
        BottomRight: Qt.SizeFDiagCursor,
    }

    def __init__(self, parent):
        QGraphicsItem.__init__(self, parent)
        self._handleItems = []

        self._rect = QRectF(0, 0, 0, 0)
        if self.parentItem():
            self._rect = self.parentItem().rect()

        for flag in (self.TopLeft, self.Top, self.TopRight, self.Right,
                     self.BottomRight, self.Bottom, self.BottomLeft, self.Left):
            handle = HandleItem(flag, self)
            handle.setCursor(self.handleCursors[flag])
            self._handleItems.append(handle)

        self.updateHandleItemPositions()

    def boundingRect(self):
        if self.parentItem():
            return self._rect
        else:
            return QRectF(0, 0, 0, 0)

    def paint(self, painter, option, widget):
        painter.setRenderHint(QPainter.Antialiasing)
        painter.setPen(QPen(QColor(127, 127, 127), 2.0, Qt.DashLine))
        painter.drawRect(self._rect)

    def doResize(self):
        self.parentItem().setRect(self._rect)
        self.updateHandleItemPositions()

    def updateHandleItemPositions(self):
        for item in self._handleItems:
            item.setFlag(QGraphicsItem.ItemSendsGeometryChanges, False)

            if item.positionflags() == self.TopLeft:
                item.setPos(self._rect.topLeft())
            elif item.positionflags() == self.Top:
                item.setPos(self._rect.left() + self._rect.width() / 2 - 1,
                            self._rect.top())
            elif item.positionflags() == self.TopRight:
                item.setPos(self._rect.topRight())
            elif item.positionflags() == self.Right:
                item.setPos(self._rect.right(),
                            self._rect.top() + self._rect.height() / 2 - 1)
            elif item.positionflags() == self.BottomRight:
                item.setPos(self._rect.bottomRight())
            elif item.positionflags() == self.Bottom:
                item.setPos(self._rect.left() + self._rect.width() / 2 - 1,
                            self._rect.bottom())
            elif item.positionflags() == self.BottomLeft:
                item.setPos(self._rect.bottomLeft())
            elif item.positionflags() == self.Left:
                item.setPos(self._rect.left(),
                            self._rect.top() + self._rect.height() / 2 - 1)
            item.setFlag(QGraphicsItem.ItemSendsGeometryChanges, True)

    def setTop(self, v):
        self._rect.setTop(v)
        self.doResize()

    def setRight(self, v):
        self._rect.setRight(v)
        self.doResize()

    def setBottom(self, v):
        self._rect.setBottom(v)
        self.doResize()

    def setLeft(self, v):
        self._rect.setLeft(v)
        self.doResize()

    def setTopLeft(self, v):
        self._rect.setTopLeft(v)
        self.doResize()

    def setTopRight(self, v):
        self._rect.setTopRight(v)
        self.doResize()

    def setBottomRight(self, v):
        self._rect.setBottomRight(v)
        self.doResize()

    def setBottomLeft(self, v):
        self._rect.setBottomLeft(v)
        self.doResize()

class CropItem(QGraphicsPathItem):
    def __init__(self, parent):
        QGraphicsPathItem.__init__(self, parent)
        self.extern_rect = parent.boundingRect()
        self.intern_rect = QRectF(0, 0, self.extern_rect.width()/2, self.extern_rect.height()/2)
        self.intern_rect.moveCenter(self.extern_rect.center())
        self.setBrush(QColor(10, 100, 100, 100))
        self.setPen(QPen(Qt.NoPen))
        SizeGripItem(self)
        self.create_path()

    def create_path(self):
        self._path = QPainterPath()
        self._path.addRect(self.extern_rect)
        self._path.moveTo(self.intern_rect.topLeft())
        self._path.addRect(self.intern_rect)
        self.setPath(self._path)


    def rect(self):
        return self.intern_rect

    def setRect(self, rect):
        self._intern = rect
        self.create_path()


if __name__ == '__main__':
    app = QApplication(sys.argv)
    view = QGraphicsView()
    scene = QGraphicsScene()
    view.setScene(scene)
    pixmapItem = scene.addPixmap(QPixmap("Lenna.png"))
    cropItem = CropItem(pixmapItem)
    view.fitInView(scene.sceneRect(), Qt.KeepAspectRatio)

    view.show()
    view.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
    view.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
    view.setFixedSize(view.size())
    sys.exit(app.exec_())