我正在使用 QPainter 和 QPolygon 类在图像上绘制多边形。我需要用户能够通过拖动多边形中的点来编辑该多边形。 QPolygon 和 QPainter 类没有任何信号，因此我无法通过它们触发事件。
我意识到，如果我继续使用这种方法，那么每次移动一个点时都必须渲染图像，这可能看起来非常糟糕并且根本不平滑。
有人知道我如何将这些点放在图像顶部而不是将它们绘制在图像中吗？
如果您正在使用QGraphicsView和QGraphicsScene，最好使用这些项目，不要使用QPainter，因为您的任务只是绘制而不处理其他类型的事件。在下面的示例中，我展示了一个自定义 QGraphicsPolygonItem 来绘制多边形，并在每个顶点中显示另一个项目，其任务是移动和修改多边形的点。在我的示例中，您可以加载图像，还要创建多边形，您必须按多边形菜单，然后通过单击添加它，以表明您不想添加更多元素，您必须按 ESC，然后您可以通过拖动来移动每个顶点，或从项目的中心拖动多边形来移动。最后，如果您想要放大和缩小，请按 Ctrl++ 和 Ctrl+-。
from enum import Enum
from functools import partial
from PyQt5 import QtWidgets, QtGui, QtCore
class GripItem(QtWidgets.QGraphicsPathItem):
circle = QtGui.QPainterPath()
circle.addEllipse(QtCore.QRectF(-10, -10, 20, 20))
square = QtGui.QPainterPath()
square.addRect(QtCore.QRectF(-15, -15, 30, 30))
def __init__(self, annotation_item, index):
super(GripItem, self).__init__()
self.m_annotation_item = annotation_item
self.m_index = index
self.setPath(GripItem.circle)
self.setBrush(QtGui.QColor("green"))
self.setPen(QtGui.QPen(QtGui.QColor("green"), 2))
self.setFlag(QtWidgets.QGraphicsItem.ItemIsSelectable, True)
self.setFlag(QtWidgets.QGraphicsItem.ItemIsMovable, True)
self.setFlag(QtWidgets.QGraphicsItem.ItemSendsGeometryChanges, True)
self.setAcceptHoverEvents(True)
self.setZValue(11)
self.setCursor(QtGui.QCursor(QtCore.Qt.PointingHandCursor))
def hoverEnterEvent(self, event):
self.setPath(GripItem.square)
self.setBrush(QtGui.QColor("red"))
super(GripItem, self).hoverEnterEvent(event)
def hoverLeaveEvent(self, event):
self.setPath(GripItem.circle)
self.setBrush(QtGui.QColor("green"))
super(GripItem, self).hoverLeaveEvent(event)
def mouseReleaseEvent(self, event):
self.setSelected(False)
super(GripItem, self).mouseReleaseEvent(event)
def itemChange(self, change, value):
if change == QtWidgets.QGraphicsItem.ItemPositionChange and self.isEnabled():
self.m_annotation_item.movePoint(self.m_index, value)
return super(GripItem, self).itemChange(change, value)
class PolygonAnnotation(QtWidgets.QGraphicsPolygonItem):
def __init__(self, parent=None):
super(PolygonAnnotation, self).__init__(parent)
self.m_points = []
self.setZValue(10)
self.setPen(QtGui.QPen(QtGui.QColor("green"), 2))
self.setAcceptHoverEvents(True)
self.setFlag(QtWidgets.QGraphicsItem.ItemIsSelectable, True)
self.setFlag(QtWidgets.QGraphicsItem.ItemIsMovable, True)
self.setFlag(QtWidgets.QGraphicsItem.ItemSendsGeometryChanges, True)
self.setCursor(QtGui.QCursor(QtCore.Qt.PointingHandCursor))
self.m_items = []
def number_of_points(self):
return len(self.m_items)
def addPoint(self, p):
self.m_points.append(p)
self.setPolygon(QtGui.QPolygonF(self.m_points))
item = GripItem(self, len(self.m_points) - 1)
self.scene().addItem(item)
self.m_items.append(item)
item.setPos(p)
def removeLastPoint(self):
if self.m_points:
self.m_points.pop()
self.setPolygon(QtGui.QPolygonF(self.m_points))
it = self.m_items.pop()
self.scene().removeItem(it)
del it
def movePoint(self, i, p):
if 0 <= i < len(self.m_points):
self.m_points[i] = self.mapFromScene(p)
self.setPolygon(QtGui.QPolygonF(self.m_points))
def move_item(self, index, pos):
if 0 <= index < len(self.m_items):
item = self.m_items[index]
item.setEnabled(False)
item.setPos(pos)
item.setEnabled(True)
def itemChange(self, change, value):
if change == QtWidgets.QGraphicsItem.ItemPositionHasChanged:
for i, point in enumerate(self.m_points):
self.move_item(i, self.mapToScene(point))
return super(PolygonAnnotation, self).itemChange(change, value)
def hoverEnterEvent(self, event):
self.setBrush(QtGui.QColor(255, 0, 0, 100))
super(PolygonAnnotation, self).hoverEnterEvent(event)
def hoverLeaveEvent(self, event):
self.setBrush(QtGui.QBrush(QtCore.Qt.NoBrush))
super(PolygonAnnotation, self).hoverLeaveEvent(event)
class Instructions(Enum):
No_Instruction = 0
Polygon_Instruction = 1
class AnnotationScene(QtWidgets.QGraphicsScene):
def __init__(self, parent=None):
super(AnnotationScene, self).__init__(parent)
self.image_item = QtWidgets.QGraphicsPixmapItem()
self.image_item.setCursor(QtGui.QCursor(QtCore.Qt.CrossCursor))
self.addItem(self.image_item)
self.current_instruction = Instructions.No_Instruction
def load_image(self, filename):
self.image_item.setPixmap(QtGui.QPixmap(filename))
self.setSceneRect(self.image_item.boundingRect())
def setCurrentInstruction(self, instruction):
self.current_instruction = instruction
self.polygon_item = PolygonAnnotation()
self.addItem(self.polygon_item)
def mousePressEvent(self, event):
if self.current_instruction == Instructions.Polygon_Instruction:
self.polygon_item.removeLastPoint()
self.polygon_item.addPoint(event.scenePos())
# movable element
self.polygon_item.addPoint(event.scenePos())
super(AnnotationScene, self).mousePressEvent(event)
def mouseMoveEvent(self, event):
if self.current_instruction == Instructions.Polygon_Instruction:
self.polygon_item.movePoint(self.polygon_item.number_of_points()-1, event.scenePos())
super(AnnotationScene, self).mouseMoveEvent(event)
class AnnotationView(QtWidgets.QGraphicsView):
factor = 2.0
def __init__(self, parent=None):
super(AnnotationView, self).__init__(parent)
self.setRenderHints(QtGui.QPainter.Antialiasing | QtGui.QPainter.SmoothPixmapTransform)
self.setMouseTracking(True)
QtWidgets.QShortcut(QtGui.QKeySequence.ZoomIn, self, activated=self.zoomIn)
QtWidgets.QShortcut(QtGui.QKeySequence.ZoomOut, self, activated=self.zoomOut)
@QtCore.pyqtSlot()
def zoomIn(self):
self.zoom(AnnotationView.factor)
@QtCore.pyqtSlot()
def zoomOut(self):
self.zoom(1 / AnnotationView.factor)
def zoom(self, f):
self.scale(f, f)
if self.scene() is not None:
self.centerOn(self.scene().image_item)
class AnnotationWindow(QtWidgets.QMainWindow):
def __init__(self, parent=None):
super(AnnotationWindow, self).__init__(parent)
self.m_view = AnnotationView()
self.m_scene = AnnotationScene(self)
self.m_view.setScene(self.m_scene)
self.setCentralWidget(self.m_view)
self.create_menus()
QtWidgets.QShortcut(QtCore.Qt.Key_Escape, self, activated=partial(self.m_scene.setCurrentInstruction, Instructions.No_Instruction))
def create_menus(self):
menu_file = self.menuBar().addMenu("File")
load_image_action = menu_file.addAction("&Load Image")
load_image_action.triggered.connect(self.load_image)
menu_instructions = self.menuBar().addMenu("Intructions")
polygon_action = menu_instructions.addAction("Polygon")
polygon_action.triggered.connect(partial(self.m_scene.setCurrentInstruction, Instructions.Polygon_Instruction))
@QtCore.pyqtSlot()
def load_image(self):
filename, _ = QtWidgets.QFileDialog.getOpenFileName(self,
"Open Image",
QtCore.QStandardPaths.writableLocation(QtCore.QStandardPaths.PicturesLocation), #QtCore.QDir.currentPath(),
"Image Files (*.png *.jpg *.bmp)")
if filename:
self.m_scene.load_image(filename)
self.m_view.fitInView(self.m_scene.image_item, QtCore.Qt.KeepAspectRatio)
self.m_view.centerOn(self.m_scene.image_item)
if __name__ == '__main__':
import sys
app = QtWidgets.QApplication(sys.argv)
w = AnnotationWindow()
w.resize(640, 480)
w.show()
sys.exit(app.exec_())
@eyllanesc 的答案中有一个小问题，当你用 ESC 键完成绘制多边形时，多边形会错过最后一个 GripItem。
要改进，只需用下面的代码替换类 AnnotationScene 即可。修改的行标记为#new
class AnnotationScene(QtWidgets.QGraphicsScene):
def __init__(self, parent=None):
super(AnnotationScene, self).__init__(parent)
self.image_item = QtWidgets.QGraphicsPixmapItem()
self.image_item.setCursor(QtGui.QCursor(QtCore.Qt.CursorShape.CrossCursor))
self.addItem(self.image_item)
self.current_instruction = Instructions.No_Instruction
self.last_mouse_location = [0, 0] # new
def load_image(self, filename):
self.image_item.setPixmap(QtGui.QPixmap(filename))
self.setSceneRect(self.image_item.boundingRect())
def setCurrentInstruction(self, instruction):
self.current_instruction = instruction
if instruction == Instructions.Polygon_Instruction:
self.polygon_item = PolygonAnnotation()
self.addItem(self.polygon_item)
def mousePressEvent(self, event):
if self.current_instruction == Instructions.Polygon_Instruction:
self.polygon_item.removeLastPoint()
self.polygon_item.addPoint(event.scenePos())
# movable element
self.polygon_item.addPoint(event.scenePos())
super(AnnotationScene, self).mousePressEvent(event)
def keyReleaseEvent(self, event) -> None: # new
if event.key() == QtCore.Qt.Key.Key_Escape and self.current_instruction == Instructions.No_Instruction:
pt = QPointF(self.last_mouse_location[0], self.last_mouse_location[1])
self.polygon_item.removeLastPoint()
self.polygon_item.addPoint(pt)
super(AnnotationScene, self).keyReleaseEvent(event)
def mouseMoveEvent(self, event):
if self.current_instruction == Instructions.Polygon_Instruction:
self.polygon_item.movePoint(self.polygon_item.number_of_points()-1, event.scenePos())
super(AnnotationScene, self).mouseMoveEvent(event)
self.last_mouse_location = [event.scenePos().x(), event.scenePos().y()] # new