python - 如何擦除/删除 QGraphicPathItem 的特定部分?
问题描述
我正在将 QgraphicsPathItem 添加到场景中,并希望删除 Qgraphicspathitem 的特定部分。我在这里使用 QgraphicsrectItem 作为 Eraser。这两个项目都在碰撞,但 QgraphicsPathItem 没有被擦除。它在场景中保持不变。我减去两条路径并将其添加到 QGraphicspathItem
class GraphicsSceneClass(QGraphicsScene):
def __init__(self):
super().__init__()
self.setItemIndexMethod(QGraphicsScene.NoIndex)
self.setBackgroundBrush(QBrush(Qt.black))
self.setSceneRect(0,0,1000,1000)
self.horizontal=QHBoxLayout()
self.widget=QWidget()
self.drawrect=False
self.gridOn = 0
self.selectionMode = 1
self.targetForLine = QRect()
self.drawEnd = True
self.resizemode=0
self.eraser_item = None
self.erasing=False
self.rect=QGraphicsRectItem()
def mousePressEvent(self,event):
try:
sampleTransform = QTransform()
self.objectAtMouse = self.itemAt(event.scenePos(), sampleTransform)
if self.selectionMode == 2:
if self.drawEnd == True:
self.drawEnd = False
elif self.drawEnd == False:
self.drawEnd = True
self.drawLineObj = None
if self.drawEnd == False:
self.lineInsertPoint = self.TargPosForLine(event.scenePos(), "ForLine")
tempPainterPath = QPainterPath()
self.drawLineObj = QGraphicsPathItem()
self.drawLineObj.setPos(self.lineInsertPoint.x(), self.lineInsertPoint.y())
self.drawLineObj.setPen(QPen(Qt.NoPen))
self.drawLineObj.setBrush(QBrush(QColor(Qt.gray)))
self.drawLineObj.setPath(tempPainterPath)
self.addItem(self.drawLineObj)
self.drawLineObj.setFlag(QGraphicsItem.ItemIsSelectable)
if event.buttons() == Qt.RightButton and self.resizemode == 1:
self.erasing = True
self.rect.setRect(event.scenePos().x()-5, event.scenePos().y()-5, 10, 10)
print(event.pos().x(),event.pos().y())
self.addItem(self.rect)
self.rect.setPen(QColor(Qt.red))
except Exception as e:
print("Error in mousepress",e)
def mouseMoveEvent(self,event):
try:
if self.selectionMode == 2 and self.drawEnd == False and self.erasing == False:
f1 = QPainterPath()
gridPos = self.TargPosForLine(event.scenePos(), "ForLine")
f1.moveTo(0, 0)
f1.lineTo(0, 6)
f1.lineTo((gridPos.x() - self.lineInsertPoint.x()), 6)
f1.lineTo((gridPos.x() - self.lineInsertPoint.x()), 0)
f1.closeSubpath()
self.drawLineObj.setPath(f1)
self.drawLineObj.setPos(self.lineInsertPoint.x(), self.lineInsertPoint.y() + 5)
self.drawLineObj.setBrush(QBrush(QColor(Qt.gray)))
pen = QPen(QColor(Qt.gray))
pen.setWidth(0)
self.drawLineObj.setPen(pen)
self.drawLineObj._property = []
self.drawLineObj._angle = 0
if self.selectionMode == 2 and self.drawEnd == True:
self.targetForLine = self.TargPosForLine(event.scenePos(), "ForRect")
self.update()
if event.buttons() & Qt.RightButton and self.erasing:
print(event.scenePos().x(),event.scenePos().y())
self.rect.setRect(event.scenePos().x() - 5, event.scenePos().y() - 5,
10, 10)
for item in self.collidingItems(self.rect):
new = item.path()-(self.rect.shape())
item.setPath(new)
print('collided')
else:
self.targetForLine = QRect()
except Exception as e:
print("Error in mousemove",e)
def mouseReleaseEvent(self, event):
if self.drawrect==True or self.tLext==2 or self.tRext==2 or self.BLext==2 or self.BRext==2:
self.drawrect=False
self.tLext=0
self.tRext=0
self.BLext=0
self.BRext=0
QApplication.changeOverrideCursor(Qt.ArrowCursor)
QApplication.setOverrideCursor(Qt.ArrowCursor)
mainWindow.pointer.setChecked(False)
if self.rect != None:
self.removeItem(self.rect)
def TargPosForLine(self, position, mode):
try:
clicked_column = int((position.y() // 16)) * 16
clicked_row = int((position.x() // 16)) * 16
if clicked_column < 0:
clicked_column = 0
if clicked_row < 0:
clicked_row = 0
if (mode == "ForRect"):
return QRect(clicked_row, clicked_column, 16, 16)
elif (mode == "ForLine"):
return QPointF(clicked_row, clicked_column)
except Exception as e:
print("Error in TargPosForLine", e)
class MainWindow(QMainWindow):
def __init__(self):
super().__init__()
self.scene = GraphicsSceneClass()
self.view=QGraphicsView(self.scene)
self.view.setMouseTracking(True)
self.view.setAcceptDrops(True)
self.view.setRenderHint(QPainter.HighQualityAntialiasing)
self.linePointerButton = QToolButton()
self.linePointerButton.setCheckable(True)
self.linePointerButton.setText("Drawline")
self.linePointerButton.setToolTip("Draw Track")
self.linePointerButton.clicked.connect(self.setPointerMode)
self.resizebutton = QToolButton()
self.resizebutton.setText("Resize")
self.resizebutton.setCheckable(True)
self.resizebutton.clicked.connect(self.resizepath)
self.widg=QWidget()
self.horizontal=QHBoxLayout()
self.horizontal.addWidget(self.view)
self.widg.setLayout(self.horizontal)
self.setCentralWidget(self.widg)
self.tool=self.addToolBar("Tool")
self.tool.addWidget(self.linePointerButton)
self.tool.addWidget(self.resizebutton)
def keyPressEvent(self, event):
try:
key = event.key()
if key == Qt.Key_Escape:
but = self.linePointerButton
self.scene.selectionMode = 1
but.setChecked(True)
except Exception:
print("Keypress is not working")
def setPointerMode(self):
try:
self.scene.selectionMode =2
except Exception:
print("Not able to change the selectionmode")
def resizepath(self):
self.scene.resizemode=1
self.scene.selectionMode = 1
self.linePointerButton.setChecked(False)
if __name__=="__main__":
import sys
app=QApplication(sys.argv)
mainWindow = MainWindow()
mainWindow.show()
sys.exit(app.exec_())
解决方案
路径和item
形状self.rect
从不共享相同的坐标系。因此,当您想从线条中移除橡皮擦时rect
,您必须使用通用坐标系(例如,您的场景):
for item in self.collidingItems(self.rect):
new = item.mapToScene(item.path())-self.rect.mapToScene(self.rect.shape()) # translate the paths to the scene coords system
item.setPath(item.mapFromScene(new)) # translate the path from the scene coords system
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