1 #!/usr/bin/env python
   2 
   3 import sys
   4 from PyQt4.QtCore import *
   5 from PyQt4.QtGui import *
   6 
   7 class Window(QWidget):
   8 
   9     def __init__(self):
  10     
  11         QWidget.__init__(self)
  12         self.largest_rect = QRect(50, 50, 400, 400)
  13         
  14         self.clip_rect = QRect(50, 50, 400, 400)
  15         self.dragging = None
  16         self.drag_offset = QPoint()
  17         self.handle_offsets = (
  18             QPoint(8, 8), QPoint(-1, 8), QPoint(8, -1), QPoint(-1, -1)
  19             )
  20         
  21         self.path = QPainterPath()
  22         self.path.moveTo(100, 250)
  23         font = QFont()
  24         font.setPixelSize(80)
  25         self.path.addText(100, 300, font, "Clipping")
  26         
  27         self.polygon = QPolygon([QPoint(250, 100), QPoint(400, 250),
  28                                  QPoint(250, 400), QPoint(100, 250),
  29                                  QPoint(250, 100)])
  30     
  31     def paintEvent(self, event):
  32     
  33         painter = QPainter()
  34         painter.begin(self)
  35         painter.fillRect(event.rect(), QBrush(Qt.white))
  36         painter.setRenderHint(QPainter.Antialiasing)
  37         painter.setPen(QPen(QBrush(Qt.red), 1, Qt.DashLine))
  38         painter.drawRect(self.largest_rect)
  39         painter.setPen(QPen(Qt.black))
  40         painter.drawRect(self.clip_rect)
  41         for i in range(4):
  42             painter.drawRect(self.corner(i))
  43         
  44         painter.setClipRect(self.clip_rect)
  45         painter.drawPolyline(self.polygon)
  46         painter.setBrush(QBrush(Qt.blue))
  47         painter.drawPath(self.path)
  48         painter.end()
  49     
  50     def corner(self, number):
  51     
  52         if number == 0:
  53             return QRect(self.clip_rect.topLeft() - self.handle_offsets[0], QSize(8, 8))
  54         elif number == 1:
  55             return QRect(self.clip_rect.topRight() - self.handle_offsets[1], QSize(8, 8))
  56         elif number == 2:
  57             return QRect(self.clip_rect.bottomLeft() - self.handle_offsets[2], QSize(8, 8))
  58         elif number == 3:
  59             return QRect(self.clip_rect.bottomRight() - self.handle_offsets[3], QSize(8, 8))
  60     
  61     def mousePressEvent(self, event):
  62     
  63         for i in range(4):
  64             rect = self.corner(i)
  65             if rect.contains(event.pos()):
  66                 self.dragging = i
  67                 self.drag_offset = rect.topLeft() - event.pos()
  68                 break
  69         else:
  70             self.dragging = None
  71     
  72     def mouseMoveEvent(self, event):
  73     
  74         if self.dragging is None:
  75             return
  76         
  77         left = self.largest_rect.left()
  78         right = self.largest_rect.right()
  79         top = self.largest_rect.top()
  80         bottom = self.largest_rect.bottom()
  81         
  82         point = event.pos() + self.drag_offset + self.handle_offsets[self.dragging]
  83         point.setX(max(left, min(point.x(), right)))
  84         point.setY(max(top, min(point.y(), bottom)))
  85         
  86         if self.dragging == 0:
  87             self.clip_rect.setTopLeft(point)
  88         elif self.dragging == 1:
  89             self.clip_rect.setTopRight(point)
  90         elif self.dragging == 2:
  91             self.clip_rect.setBottomLeft(point)
  92         elif self.dragging == 3:
  93             self.clip_rect.setBottomRight(point)
  94         
  95         self.update()
  96     
  97     def mouseReleaseEvent(self, event):
  98     
  99         self.dragging = None
 100     
 101     def sizeHint(self):
 102         return QSize(500, 500)
 103 
 104 
 105 if __name__ == "__main__":
 106 
 107     app = QApplication(sys.argv)
 108     window = Window()
 109     window.show()
 110     sys.exit(app.exec_())