破碎的绘图形状

Question

在尝试实现绘画时，我决定从形状开始 我的初始化：

 def __init__(self, parent=None): 
    self.modified = False
    self.rectangle = False
    self.ellipse = False
    self.begin = QPoint()
    self.end = QPoint()
    self.myPenWidth = 1
    self.myFigureColor = Qt.black
    self.image = QImage()

我有一个事件，其中有绘制形状的功能

def mousePressEvent(self, event):
    if (event.button() == Qt.LeftButton) and self.rectangle:
        self.draw_rectandle(event)
    if (event.button() == Qt.LeftButton) and self.ellipse:
        self.draw_ellipse(event)

这里我们使用位于绘制图形的函数： 我会在下面发布它们

def mouseMoveEvent(self, event):
    if (event.buttons() & Qt.LeftButton) and self.rectangle:
        self.end = event.pos()
        self.update()
    if (event.buttons() & Qt.LeftButton) and self.ellipse:
        self.end = event.pos()
        self.update()

和

def mouseReleaseEvent(self, event):
    if (event.buttons() & Qt.LeftButton) and self.rectangle:
        self.begin = event.pos()
        self.end = event.pos()
    if (event.buttons() & Qt.LeftButton) and self.ellipse:
        self.begin = event.pos()
        self.end = event.pos()

还有另一个函数paintEvent：

def paintEvent(self, event):
    painter = QPainter(self)
    dirtyRect = event.rect()
    painter.drawImage(dirtyRect, self.image, dirtyRect)
    if self.rectangle == True:
        painter.setPen(QPen(self.myFigureColor, self.myPenWidth,
                            Qt.SolidLine, Qt.RoundCap, Qt.RoundJoin))
        painter.drawRect(QRect(self.begin, self.end))
    if self.ellipse == True:
        painter.setPen(QPen(self.myFigureColor, self.myPenWidth,
                            Qt.SolidLine, Qt.RoundCap, Qt.RoundJoin))
        painter.drawEllipse(QRect(self.begin, self.end))

人物本身的功能：

def draw_rectandle(self, event):
    painter = QPainter(self.image)
    painter.setPen(QPen(self.myFigureColor, self.myPenWidth,
                        Qt.SolidLine, Qt.RoundCap, Qt.RoundJoin))
    painter.drawRect(QRect(self.begin, self.end))
    self.begin = event.pos()
    self.end = event.pos()
    self.modified = True
    self.update()

def draw_ellipse(self, event):
    painter = QPainter(self.image)
    painter.setPen(QPen(self.myFigureColor, self.myPenWidth,
                        Qt.SolidLine, Qt.RoundCap, Qt.RoundJoin))
    painter.drawEllipse(QRect(self.begin, self.end))
    self.begin = event.pos()
    self.end = event.pos()
    self.modified = True
    self.update()

还有“伪绑定”

def rectangleOn(self):
    self.ellipse = False
    self.rectangle = True

def ellipseOn(self):
    self.rectangle = False
    self.ellipse = True

它们用于在按下形状按钮时更改功能标志。 如果您需要，按钮本身看起来像：

动作：

    self.rectangle = QAction(QIcon('Image/rectangle.png'), 'Rectangle', self)
    self.rectangle.triggered.connect(self.scribbleArea.rectangleOn)

    self.ellipse = QAction(QIcon('Image/Ellipse.png'), 'Ellipse', self)
    self.ellipse.triggered.connect(self.scribbleArea.ellipseOn)

带按钮的工具栏：

    toolbar = self.addToolBar('Tools')
    toolbar.addAction(self.rectangle)
    toolbar.addAction(self.ellipse)

我认为不需要改变颜色和大小的函数。因此，虽然我不会发布。

现在我会告诉你问题出在哪里。

在paintEvent 中，我有一个显示形状的绘图。也就是说，我们拉边缘，看看形状是如何变化的。但是从那里它不会保存在任何地方。

并且在 mousePressEvent 中已经绘制了矩形本身而没有这个拖动动画

看起来一切都很好，但是这里有一个错误

如您所见，矩形的绘制是通过 mousePressEvent 进行的。这意味着只有在我开始绘制下一个矩形时才会出现矩形。这已经是一个错误。但！如果我画了几个矩形并开始画一个椭圆，最后一个矩形就变成了一个椭圆。

还有我的其他形状。

如果我开始画一条线，然后切换到一个椭圆，在另一个地方开始画椭圆，我画的线会立即变成一个很窄的椭圆。

因此，我需要以某种方式从 mousePressEvent 中拉出这个函数，以便绘制所需的形状，并在工具之间进行这种切换。

如果您需要更多详细信息，请写 с:

附：如果有问题，我为我的英语道歉с:

Answer 1

我无法重现，因为您将代码显示为碎片，我建议您始终显示统一的代码，以便我们可以轻松地执行我们想要帮助的那些。

正如您所注意到的，如果您希望它们保留在图像中，则必须保存图像中的数据，并在小部件中直接绘制它们的临时数据。我的解决方案的逻辑是从mousePressEvent 直到直接在小部件中绘制mouseReleaseEvent 之前的瞬间，然后保存在图像中，为此我创建了一个名为AbstractScribbleArea 的类来实现该通用逻辑，如果如果你想为其他形状实现逻辑，你应该只覆盖draw() 方法。

from PyQt5 import QtCore, QtGui, QtWidgets


class AbstractScribbleArea(QtWidgets.QWidget):
    def __init__(self, parent=None):
        super(AbstractScribbleArea, self).__init__(parent)
        self._start = QtCore.QPoint()
        self._end = QtCore.QPoint()
        self._pixmap = QtGui.QPixmap() 
        self._shape = ""

        self._color = QtGui.QColor("black")
        self._pen_width = 1

        self._pen = QtGui.QPen(self._color, self._pen_width, 
            QtCore.Qt.SolidLine, QtCore.Qt.RoundCap, QtCore.Qt.RoundJoin)

    def mousePressEvent(self, event):
        if event.buttons() & QtCore.Qt.LeftButton:
            self._start = event.pos()
            self._end = event.pos()
            self.update()
        super(AbstractScribbleArea, self).mousePressEvent(event)

    def mouseMoveEvent(self, event):
        if event.buttons() & QtCore.Qt.LeftButton:
            self._end = event.pos()
            self.update()
        super(AbstractScribbleArea, self).mouseMoveEvent(event)

    def mouseReleaseEvent(self, event):
        # draw on image
        painter = QtGui.QPainter(self._pixmap)
        painter.setPen(self._pen)
        self.draw(painter, self._start, self._end, True)

        self._start = QtCore.QPoint()
        self._end = QtCore.QPoint()
        self.update()
        super(AbstractScribbleArea, self).mouseReleaseEvent(event)

    def paintEvent(self, event):
        painter = QtGui.QPainter(self)
        painter.drawPixmap(self.rect(), self._pixmap, self.rect())
        painter.setPen(self._pen)
        self.draw(painter, self._start, self._end, False)

    def resizeEvent(self, event):
        w = self.width() if self.width() > self._pixmap.width() else self._pixmap.width()
        h = self.height() if self.height() > self._pixmap.height() else self._pixmap.height()

        s = QtCore.QSize(w, h)
        if s != self._pixmap.size():
            pixmap = QtGui.QPixmap(self._pixmap)
            self._pixmap = QtGui.QPixmap(s)
            painter = QtGui.QPainter(self._pixmap)
            painter.fillRect(QtCore.QRect(0, 0, w, h), QtCore.Qt.white)
            painter.drawPixmap(pixmap.rect(), pixmap)
        super(AbstractScribbleArea, self).resizeEvent(event)

    def draw(self, painter, start, end, is_released):
        raise NotImplementedError

    def sizeHint(self):
        return QtCore.QSize(640, 480)

    def set_pen_width(self, width):
        self._pen.setWidth(width)

    def set_pen_color(self, color):
        self._pen.setColor(QtGui.QColor(color))

    def set_shape(self, shape):
        self._shape =shape

    def shape(self):
        return self._shape


class ScribbleArea(AbstractScribbleArea):
    def draw(self, painter, start, end, is_released):
        if start.isNull() or end.isNull():
            return
        if self.shape() == "rectangle":
            self.draw_rectangle(painter, start, end)
        elif self.shape() == "ellipse":
            self.draw_ellipse(painter, start, end)

    def draw_rectangle(self, painter, start, end):
        rect = QtCore.QRect(start, end)
        painter.drawRect(rect)

    def draw_ellipse(self, painter, start, end):
        rect = QtCore.QRect(start, end)
        painter.drawEllipse(rect)

    @QtCore.pyqtSlot()
    def rectangleOn(self):
        self.set_shape("rectangle")

    @QtCore.pyqtSlot()
    def ellipseOn(self):
        self.set_shape("ellipse")


class MainWindow(QtWidgets.QMainWindow):
    def __init__(self, parent=None):
        super(MainWindow, self).__init__(parent)
        self.scribbleArea = ScribbleArea()
        self.scribbleArea.set_pen_width(10)
        self.scribbleArea.set_pen_color("red")
        self.setCentralWidget(self.scribbleArea)
        self.rectangle = QtWidgets.QAction(QtGui.QIcon('Image/rectangle.png'), 'Rectangle', self)
        self.rectangle.triggered.connect(self.scribbleArea.rectangleOn)
        self.ellipse = QtWidgets.QAction(QtGui.QIcon('Image/Ellipse.png'), 'Ellipse', self)
        self.ellipse.triggered.connect(self.scribbleArea.ellipseOn)
        toolbar = self.addToolBar('Tools')
        toolbar.addAction(self.rectangle)
        toolbar.addAction(self.ellipse)


if __name__ == '__main__':
    import sys

    app = QtWidgets.QApplication(sys.argv)
    w = MainWindow()
    w.show()
    sys.exit(app.exec_())