爲什麼path.subtracted（path2）正在鏈接我的路徑？我怎樣才能脫鉤？

我正在使用pyqt5編寫一個簡單的Paint應用程序。我的目標是：爲什麼path.subtracted（path2）正在鏈接我的路徑？我怎樣才能脫鉤？

。根據鼠標事件自由繪製。完成！

。根據鼠標事件自由擦除。它沒有按預期工作！

我有一個QGraphicsView，QGraphicsScene，我添加QGraphicsItems，特別是QGraphicsPathItem。我的橡皮擦具有矩形形狀，我想要的是在移動橡皮擦的同時擦除部分圖形。

在MouseMoveEvent上，我檢查橡皮擦的形狀是否與我的繪圖路徑相交，如果是這樣，我只是從我的繪圖路徑中減去它。然後發生尷尬的行爲，它關閉我的繪圖路徑。

figure_1，顯示我的繪圖（QGraphicsPathItem）。圖2顯示了當我的橡皮擦（QGraphicsRectItem）與我的圖形相交時發生的情況。

Drawing freely lines working fine. Figure_1

Erasing drawing. Figure_2

我們可以看到，它繪製一條線連接我的第一點和結束點，收我的道路。我不想要它。我只想抹去我的繪圖路徑。

from PyQt5.QtCore import QRectF, Qt 
from PyQt5.QtGui import QPainterPath, QPen 
from PyQt5.QtWidgets import QApplication, QGraphicsScene, \ 
    QGraphicsView, QPushButton, QWidget, \ 
    QVBoxLayout, QGraphicsItem, QGraphicsPathItem, QGraphicsRectItem 

class Window(QWidget): 
    scene = None 

    def __init__(self): 
     QWidget.__init__(self) 
     self.view = View(self) 
     self.button = QPushButton('Clear View', self) 
     self.button.clicked.connect(self.handleClearView) 
     layout = QVBoxLayout(self) 
     layout.addWidget(self.view) 
     layout.addWidget(self.button) 

    def handleClearView(self): 
     self.view.scene.clear() 


class View(QGraphicsView): 
    def __init__(self, parent): 

     self.scribing = False 
     self.erasing = False 
     QGraphicsView.__init__(self, parent) 
     self.scene = QGraphicsScene() 
     self.setScene(self.scene) 

     self.free_draw_item = None 
     self.eraser_item = None 

    def resizeEvent(self, QResizeEvent): 
     self.setSceneRect(QRectF(self.viewport().rect())) 

    def mousePressEvent(self, event): 

     if event.buttons() == Qt.LeftButton: 
      self.scribing = True 
      pp = QPainterPath(event.pos()) 

      self.free_draw_item = QGraphicsPathItem(pp) 
      self.free_draw_item.setPen(QPen(Qt.green)) 
      self.free_draw_item.setFlags(QGraphicsItem.ItemIsSelectable) 

      self.free_draw_item.setPath(pp) 
      self.scene.addItem(self.free_draw_item) 

     if event.buttons() == Qt.RightButton: 
      self.erasing = True 
      self.eraser_item = QGraphicsRectItem(event.pos().x() - 5, 
               event.pos().y() - 5, 10, 10) 
      self.eraser_item.setPen(QPen(Qt.red)) 
      self.eraser_item.setBrush(Qt.transparent) 
      self.scene.addItem(self.eraser_item) 

    def mouseMoveEvent(self, event): 

     if (event.buttons() & Qt.LeftButton) and self.scribing: 
      if self.free_draw_item: 
       path = self.free_draw_item.path() 
       path.lineTo(event.pos()) 
       self.free_draw_item.setPath(path) 

     if event.buttons() & Qt.RightButton and self.erasing: 

      self.eraser_item.setRect(event.pos().x() - 5, event.pos().y() - 5, 
            10, 10) 

      for item in self.scene.collidingItems(self.eraser_item): 
       if isinstance(item, QGraphicsPathItem): 

        if item.path().intersected(self.eraser_item.shape()): 
         new = item.path().subtracted(self.eraser_item.shape()) 
         item.setPath(new) 
         #item.setBrush(Qt.red) 

    def mouseReleaseEvent(self, event): 
     self.scribing = False 
     self.erasing = False 

     if self.eraser_item != None: 
      self.scene.removeItem(self.eraser_item) 
     # if self.free_draw_item != None: 
     #  self.free_draw_item.setSelected(True) 


if __name__ == '__main__': 
    import sys 

    app = QApplication(sys.argv) 
    window = Window() 
    window.resize(640, 480) 
    window.show() 
    sys.exit(app.exec_())

這是我的代碼。

鼠標左鍵在場景中繪製綠色路徑。

鼠標右鍵擦除我的圖紙。

來源

2016-09-19 Jeremias Serafim

沒有什麼開箱即用的。您必須將路徑保留爲子路徑，並在修改子路徑時重新創建它。 – dtech

我有幾次和幾次相同的問題。

經過一些頭痛和一千個關於這個具體問題的不成功的研究，我已經回答了。

忘記只有一個路徑
而不關閉通道把它變成一個封閉的多邊形
看成是有許多路徑和現在的工作圍繞
你把所有子項，可以「你不能減用你的橡皮
使用您贊成減碰撞時刪除」他們
有3未對齊點每個路徑（至少在分計劃有一個多邊形）多路徑
集團作爲QGraphicsItemGroup（）如果你想操作作爲單個項目
由幾整個路徑（3分路）查看我的例子

from PyQt5.QtCore import QPoint 
from PyQt5.QtCore import QRectF, Qt 
from PyQt5.QtGui import QBrush 
from PyQt5.QtGui import QPainter 
from PyQt5.QtGui import QPainterPath, QPen 
from PyQt5.QtWidgets import QApplication, QGraphicsScene, \ 
    QGraphicsView, QPushButton, QWidget, \ 
    QVBoxLayout, QGraphicsItem, QGraphicsPathItem, QGraphicsRectItem 
from PyQt5.QtWidgets import QGraphicsItemGroup 

from core.IQGraphicsPathItem import InteractQGraphicsPathItem 


class Window(QWidget): 
    scene = None 



    def __init__(self): 
     QWidget.__init__(self) 
     self.view = View(self) 
     self.button = QPushButton('Clear View', self) 
     self.button.clicked.connect(self.handleClearView) 
     layout = QVBoxLayout(self) 
     layout.addWidget(self.view) 
     layout.addWidget(self.button) 

    def handleClearView(self): 
     self.view.scene.clear() 


class View(QGraphicsView): 

    dic = {} 
    num_item = 0 
    _from_x_ = None 
    _from_y_ = None 
    pp = None 

    pen = None 

    group = None 

    def __init__(self, parent): 

     self.scribing = False 
     self.erasing = False 
     QGraphicsView.__init__(self, parent) 
     self.scene = QGraphicsScene() 
     self.setScene(self.scene) 
     self.setRenderHint(QPainter.Antialiasing) 
     self.free_draw_item = QGraphicsPathItem() 
     # self.free_draw_item.setPen(QPen(Qt.green)) 
     # self.free_draw_item.setFlags(QGraphicsItem.ItemIsSelectable) 
     self.eraser_item = None 
     self.pen = QPen(Qt.green,8) 
     self.pen.setBrush(QBrush(Qt.green)) 
     self.pen.setWidth(1) 

     self.group = QGraphicsItemGroup() 

    def resizeEvent(self, QResizeEvent): 
     self.setSceneRect(QRectF(self.viewport().rect())) 

    def mousePressEvent(self, event): 

     if event.buttons() == Qt.LeftButton: 
      self._from_x_ = event.pos().x() 
      self._from_y_ = event.pos().y() 

      self.scribing = True 

      self.group = QGraphicsItemGroup() 
      self.group.setFlags(QGraphicsItem.ItemIsSelectable) 
      self.scene.addItem(self.group) 

      self.pp = QPainterPath(event.pos()) 

      self.free_draw_item = QGraphicsPathItem(self.pp) 
      self.free_draw_item.setPen(self.pen) 
      # self.free_draw_item.setFlags(QGraphicsItem.ItemIsSelectable) 

      self.free_draw_item.setPath(self.pp) 
      self.scene.addItem(self.free_draw_item) 
      self.group.addToGroup(self.free_draw_item) 


     if event.buttons() == Qt.RightButton: 
      self.erasing = True 
      self.eraser_item = QGraphicsRectItem(event.pos().x() - 5, 
               event.pos().y() - 5, 10, 10) 
      self.eraser_item.setPen(QPen(Qt.red)) 
      self.eraser_item.setBrush(Qt.white) 
      self.scene.addItem(self.eraser_item) 

    def mouseMoveEvent(self, event): 

     x_adjust = 1 
     y_adjust = 1 

     # if event.pos().x() >= self._from_x_: 
     #  x_adjust = 1 
     # else: 
     #  x_adjust = -1 
     # if event.pos().y() >= self._from_y_: 
     #  y_adjust = 1 
     # else: 
     #  y_adjust = -1 



     if (event.buttons() & Qt.LeftButton) and self.scribing: 
      if self.free_draw_item: 

       # path = self.free_draw_item.path() 
       # path.lineTo(event.pos()) 
       # self.free_draw_item.setPath(path) 

       self.pp2 = QPainterPath(QPoint(self._from_x_, self._from_y_)) 
       self.pp2.lineTo(event.pos().x(), event.pos().y()) 
       self.pp2.lineTo(event.pos().x()+x_adjust, event.pos().y()+y_adjust) 
       self.pp2.lineTo(self._from_x_ + x_adjust, self._from_y_ + y_adjust) 
       self.free_draw_item.setPen(QPen(Qt.green, 8)) 
       self.free_draw_item.path = QGraphicsPathItem() 
       self.free_draw_item.path.setPath(self.pp2) 
       self.scene.addItem(self.free_draw_item.path) 
       self.group.addToGroup(self.free_draw_item) 

       self._from_x_ = event.pos().x() 
       self._from_y_ = event.pos().y() 

     if event.buttons() & Qt.RightButton and self.erasing: 

      self.eraser_item.setRect(event.pos().x() - 5, event.pos().y() - 5, 
            10, 10) 

      for item in self.scene.collidingItems(self.eraser_item): 

       new = item.path() - self.eraser_item.shape() 
       item.setPath(new) 
       print('collided') 



    def mouseReleaseEvent(self, event): 
     self.scribing = False 
     self.erasing = False 

     self.group.setSelected(True) 
     print(self.scene.items()) 

     if self.eraser_item != None: 
      self.scene.removeItem(self.eraser_item) 

     # if self.free_draw_item != None: 
     #  self.free_draw_item.setSelected(True) 


if __name__ == '__main__': 
    import sys 

    app = QApplication(sys.argv) 
    window = Window() 
    window.resize(640, 480) 
    window.show() 
    sys.exit(app.exec_())

如果您想要個性化您自己的筆我建議您覆蓋自己的QGraphicsPathItem（）。

我認爲它會工作得很好。

來源

2016-09-27 18:29:40 yurisnm

爲什麼path.subtracted（path2）正在鏈接我的路徑？我怎樣才能脫鉤？

回答

相關問題