蛇年當然貪吃蛇 PyQt版貪吃蛇引子

本文轉載自查看原文 2013-02-18 17:00 3081 python/ pyqt/ Python

蛇年到，貪吃蛇還是要出馬下的，不准備寫完整的程序，就讓蛇跑起來，尾巴的長起來吧，蛇頭有點動畫得了。

先講講一些原理，蛇的腦袋使用鍵盤控制，因此重寫他的keyPressEvent是勢在必行的；

蛇身能夠增長，運動，原來我計划是蛇身的每一塊的坐標都會移動，可看見一個老哥說每次只要把尾巴移動的蛇腦袋那里，蛇腦袋再往前跑跑，蛇就動了，想想也是。蛇身是一塊塊組成的，很對的塊形成一個組，變成蛇的身子，每次蛇要長長，只要在這個組里增加新的塊即可。

因為使用了大量的圖形，因此使用PyQt里面的帶Graphics的那一堆類，重寫QGraphicsItem的類或者子類，完成特定的功能，作為基本的元素；使用QGraphicsScene增加元素；QGraphicsView顯示。

想使用動畫Animation，看了看里面需要QObject來初始化，而QGraphicsItem居然不是繼承自QObject的。因此我選擇了QGraphicsObject作為基類來完善需求，他繼承自QGraphicsItem和QObject，可以使用動畫的東西。

下面是完整的代碼，先貼上：

View Code

  1 import sys
  2 import random
  3 from Queue import deque
  4 from PyQt4.QtCore import (QObject,QRectF,QRect,QPointF,
  5                           QTimer,SIGNAL,Qt,pyqtProperty,
  6                           QPropertyAnimation,QEasingCurve )
  7 from PyQt4.QtGui import (QMainWindow,QGraphicsScene,QGraphicsView,
  8                          QGraphicsPixmapItem,QGraphicsItem,
  9                          QFont,QPainter,QPixmap,
 10                          QPainter,QGraphicsItemGroup,
 11                          QApplication,QGraphicsObject)
 12 import qrc_resources
 13 
 14 class Segment(QGraphicsObject):
 15     width = 50
 16     def __init__(self,pos,parent=None):
 17         super(Segment,self).__init__(parent)
 18         self.setPixmap(QPixmap(":/img/book.jpg"))
 19         self.setFlags(QGraphicsItem.ItemIsSelectable|
 20                       QGraphicsItem.ItemIsMovable)
 21         self.setPos(pos)
 22 #    def setPos(self,pos):
 23 #        super(Segment,self).setPos(pos)
 24     def pixmap(self):
 25         return self.pix
 26     def setPixmap(self,pix):
 27         self.pix = pix
 28     def paint(self,painter,option,widget):
 29         painter.drawPixmap(QRect(0,0,self.width,self.width),
 30                            self.pixmap())        
 31     def boundingRect (self):
 32         return QRectF(0,0,self.width,self.width)
 33 class Head(Segment):
 34     speed = Segment.width    
 35     UP = 0
 36     DOWN = 1
 37     LEFT = 2
 38     RIGHT = 3
 39     TimeGap = 500
 40     CURVE_TYPES = [(n, c) for n, c in QEasingCurve.__dict__.items()
 41                 if isinstance(c, QEasingCurve.Type) and c != QEasingCurve.Custom]
 42     def _set_pos(self,pos):
 43         self.setPos(pos)
 44     def _get_pos(self):
 45         return self.pos()
 46     
 47     position = pyqtProperty(QPointF,fset = _set_pos,
 48                                      fget = _get_pos)
 49     def __init__(self,pos,parent=None):
 50         super(Head,self).__init__(pos,parent)
 51         self.setPixmap(QPixmap(":/img/person.jpg"))
 52         self.setFlags(QGraphicsItem.ItemIsSelectable|
 53                       QGraphicsItem.ItemIsMovable|
 54                       QGraphicsItem.ItemIsFocusable)
 55         self.curveType = QEasingCurve.OutBounce
 56         self.setPos(pos)
 57         self.setFocus(Qt.OtherFocusReason)
 58         self.direction = self.RIGHT
 59         self.timer = QTimer()
 60         self.timer.start(self.TimeGap)
 61         QObject.connect(self.timer, SIGNAL("timeout()"),
 62                      self.move)
 63     def move(self):
 64         pos = self.pos()
 65         # add animation,i dont know why must do this
 66         # else it wont be move
 67         if self.direction == self.LEFT:
 68             position = pos + QPointF(-self.speed,0)
 69         elif self.direction == self.RIGHT:
 70             position = pos + QPointF(self.speed,0)
 71         elif self.direction == self.UP:
 72             position = pos + QPointF(0,-self.speed)
 73         elif self.direction == self.DOWN:
 74             position = pos + QPointF(0,self.speed)
 75         
 76         pre = pos = position
 77         
 78         rect = QRectF(self.boundingRect())
 79         if self.direction == self.LEFT:
 80             self.setPos(pos+QPointF(-self.speed,0))
 81         elif self.direction == self.RIGHT:
 82             self.setPos(pos+QPointF(self.speed,0))
 83         elif self.direction == self.UP:
 84             self.setPos(pos+QPointF(0,-self.speed))
 85         elif self.direction == self.DOWN:
 86             self.setPos(pos+QPointF(0,self.speed))
 87         current = self.pos()
 88         self.animationChanged(pre, current)
 89 
 90     def animationChanged(self,pre,current):    
 91         self.anim= QPropertyAnimation(self,'position')
 92         self.anim.setStartValue(pre)
 93         self.anim.setEndValue(current)
 94         
 95         self.anim.setEasingCurve(self.curveType)
 96         self.anim.setDirection(self.TimeGap-200)
 97         self.anim.start()
 98     def keyPressEvent (self,event):
 99         key = event.key()
100         if key == Qt.Key_Left:
101             self.direction = self.LEFT
102             return
103         if key == Qt.Key_Right:
104             self.direction = self.RIGHT
105             return
106         if key == Qt.Key_Up:
107             self.direction = self.UP
108             return
109         if key == Qt.Key_Down:
110             self.direction = self.DOWN
111             return
112 class SegmentGroup(QObject):
113     def __init__(self,scene,parent = None):
114         super(SegmentGroup,self).__init__(parent)
115         self.scene = scene
116         self.items = deque()
117         
118     def addSegment(self,segment):
119         self.scene.addItem(segment)
120         self.items.append(segment)
121         
122     def move(self,headPos):
123         if not self.items:return 
124         tail = self.items.pop()
125         tail.setPos(headPos)
126         self.items.appendleft(tail)
127     
128     def tail(self):
129         if not self.items:return
130         return self.items[-1]
131 
132 class SnackScene(QGraphicsScene):
133     def __init__(self,parent=None):
134         super(SnackScene,self).__init__(parent)
135         self.setSceneRect(0,0,400,300)
136         self.segmentGroup = SegmentGroup(self)
137         self.segmentGroup.addSegment(Segment(QPointF(0,0)))
138         
139         self.head = Head(QPointF(Segment.width,0))
140         self.addItem(self.head)
141         
142         self.setFocusItem(self.head)
143         self.timer = QTimer()
144         self.timer.start(Head.TimeGap)
145         
146         self.connect(self.timer, SIGNAL("timeout()"),
147                      self.segmentMove)
148     def segmentMove(self):
149         self.segmentGroup.move(self.head.pos())
150     def mousePressEvent (self, event):
151         if event.button() == Qt.LeftButton:
152             tail = self.segmentGroup.tail()
153             self.segmentGroup.addSegment(
154                                          Segment(tail.pos())
155                                          )
156         elif event.button() == Qt.RightButton:
157             curveType = random.choice(Head.CURVE_TYPES)
158             self.head.curveType = QEasingCurve(curveType[1])
159 
160 class Form(QMainWindow):
161     def __init__(self,parent=None):
162         super(Form,self).__init__(parent)
163         self.fileMenu = self.menuBar().addMenu("&File")
164         self.statusBar().showMessage("Ready", 5000)
165         self.scene = SnackScene()
166         
167         self.view = QGraphicsView(self.scene)
168         self.view.setRenderHint(QPainter.SmoothPixmapTransform)
169         self.view.setDragMode(QGraphicsView.RubberBandDrag)
170         self.setCentralWidget(self.view)
171     
172 app = QApplication(sys.argv)
173 
174 form = Form()
175 form.show()
176 app.exec_()

資源文件：

View Code

1 <RCC>
2     <qresource prefix="/">
3         <file>img/book.jpg</file>
4         <file>img/person.jpg</file>
5         <file>img/cat.jpg</file>
6     </qresource>
7 </RCC>

開始講解：

蛇的身體：

 1 class Segment(QGraphicsObject):
 2     width = 50
 3     def __init__(self,pos,parent=None):
 4         super(Segment,self).__init__(parent)
 5         self.setPixmap(QPixmap(":/img/book.jpg"))
 6         self.setFlags(QGraphicsItem.ItemIsSelectable|
 7                       QGraphicsItem.ItemIsMovable)
 8         self.setPos(pos)
 9 #    def setPos(self,pos):
10 #        super(Segment,self).setPos(pos)
11     def pixmap(self):
12         return self.pix
13     def setPixmap(self,pix):
14         self.pix = pix
15     def paint(self,painter,option,widget):
16         painter.drawPixmap(QRect(0,0,self.width,self.width),
17                            self.pixmap())        
18     def boundingRect (self):
19         return QRectF(0,0,self.width,self.width)

boundingRect是指明這個對象所占的矩形空間大小，因為有的時候你可以用鼠標選擇圖片，那么到底哪個區域呢，就是這個區域。

為了讓蛇身蛇頭的大小一致，設置了一個width作為蛇身的靜態成員變量，並且在paint方法中重繪了圖片，這樣，不管圖片多么大，畫出來都會變成指定的大小，保證了蛇身蛇頭相同的大小。

蛇頭

 1 class Head(Segment):
 2     speed = Segment.width    
 3     UP = 0
 4     DOWN = 1
 5     LEFT = 2
 6     RIGHT = 3
 7     TimeGap = 500
 8     CURVE_TYPES = [(n, c) for n, c in QEasingCurve.__dict__.items()
 9                 if isinstance(c, QEasingCurve.Type) and c != QEasingCurve.Custom]
10     def _set_pos(self,pos):
11         self.setPos(pos)
12     def _get_pos(self):
13         return self.pos()
14     
15     position = pyqtProperty(QPointF,fset = _set_pos,
16                                      fget = _get_pos)
17     def __init__(self,pos,parent=None):
18         super(Head,self).__init__(pos,parent)
19         self.setPixmap(QPixmap(":/img/person.jpg"))
20         self.setFlags(QGraphicsItem.ItemIsSelectable|
21                       QGraphicsItem.ItemIsMovable|
22                       QGraphicsItem.ItemIsFocusable)
23         self.curveType = QEasingCurve.OutBounce
24         self.setPos(pos)
25         self.setFocus(Qt.OtherFocusReason)
26         self.direction = self.RIGHT
27         self.timer = QTimer()
28         self.timer.start(self.TimeGap)
29         QObject.connect(self.timer, SIGNAL("timeout()"),
30                      self.move)
31     def move(self):
32         pos = self.pos()
33         # add animation,i dont know why must do this
34         # else it wont be move
35         if self.direction == self.LEFT:
36             position = pos + QPointF(-self.speed,0)
37         elif self.direction == self.RIGHT:
38             position = pos + QPointF(self.speed,0)
39         elif self.direction == self.UP:
40             position = pos + QPointF(0,-self.speed)
41         elif self.direction == self.DOWN:
42             position = pos + QPointF(0,self.speed)
43         
44         pre = pos = position
45         
46         rect = QRectF(self.boundingRect())
47         if self.direction == self.LEFT:
48             self.setPos(pos+QPointF(-self.speed,0))
49         elif self.direction == self.RIGHT:
50             self.setPos(pos+QPointF(self.speed,0))
51         elif self.direction == self.UP:
52             self.setPos(pos+QPointF(0,-self.speed))
53         elif self.direction == self.DOWN:
54             self.setPos(pos+QPointF(0,self.speed))
55         current = self.pos()
56         self.animationChanged(pre, current)
57 
58     def animationChanged(self,pre,current):    
59         self.anim= QPropertyAnimation(self,'position')
60         self.anim.setStartValue(pre)
61         self.anim.setEndValue(current)
62         
63         self.anim.setEasingCurve(self.curveType)
64         self.anim.setDirection(self.TimeGap-200)
65         self.anim.start()
66     def keyPressEvent (self,event):
67         key = event.key()
68         if key == Qt.Key_Left:
69             self.direction = self.LEFT
70             return
71         if key == Qt.Key_Right:
72             self.direction = self.RIGHT
73             return
74         if key == Qt.Key_Up:
75             self.direction = self.UP
76             return
77         if key == Qt.Key_Down:
78             self.direction = self.DOWN
79             return

設置了四個方向，並且重寫了keyPressEvent方法，鍵盤按下的時候，改變self.direction的方向。

CURVE_TYPES是動畫的所有可能取值，有40多種，可查閱QEasingCurve的文檔。

蛇頭的運動，是在move方法中實現的，如果不添加動畫的話，第一段if else語句並不需要加，程序運行正常，可添加動畫后，不知道為什么，每次運行到這里，pos的值與上一次運行move的值相同，不得已加了一段if else使得程序能正常運行。

animationChanged方法實現了蛇頭的動畫，self.anim.setEasingCurve(self.curveType)設置動畫效果，為了讓動畫效果可以轉變，因此保留了一個self.curveType變量。另外在構造時self.anim= QPropertyAnimation(self,'position'),第一個參數需要是QObject對象，而第二個參數需要時Qt的屬性，因此在上面我生命了一個position屬性，代碼如下:

1     def _set_pos(self,pos):
2         self.setPos(pos)
3     def _get_pos(self):
4         return self.pos()
5     
6     position = pyqtProperty(QPointF,fset = _set_pos,
7                                      fget = _get_pos)

構造方法的定時器讓蛇身連續移動，這個在我之前的博客中有介紹，不在啰嗦。

蛇身Group

 1 class SegmentGroup(QObject):
 2     def __init__(self,scene,parent = None):
 3         super(SegmentGroup,self).__init__(parent)
 4         self.scene = scene
 5         self.items = deque()
 6         
 7     def addSegment(self,segment):
 8         self.scene.addItem(segment)
 9         self.items.append(segment)
10         
11     def move(self,headPos):
12         if not self.items:return 
13         tail = self.items.pop()
14         tail.setPos(headPos)
15         self.items.appendleft(tail)
16     
17     def tail(self):
18         if not self.items:return
19         return self.items[-1]

這是為了方便管理，將蛇頭和整段身體分離而做的一個容器，因為主要實在第一節蛇身和蛇尾之間進行插入刪除操作，所以使用python的deque()來實現這個容器，並且這個容器直接將蛇身添加到scene中去。代碼木有神馬特別需要說明的。

Scene

 1 class SnackScene(QGraphicsScene):
 2     def __init__(self,parent=None):
 3         super(SnackScene,self).__init__(parent)
 4         self.setSceneRect(0,0,400,300)
 5         self.segmentGroup = SegmentGroup(self)
 6         self.segmentGroup.addSegment(Segment(QPointF(0,0)))
 7         
 8         self.head = Head(QPointF(Segment.width,0))
 9         self.addItem(self.head)
10         
11         self.setFocusItem(self.head)
12         self.timer = QTimer()
13         self.timer.start(Head.TimeGap)
14         
15         self.connect(self.timer, SIGNAL("timeout()"),
16                      self.segmentMove)
17     def segmentMove(self):
18         self.segmentGroup.move(self.head.pos())
19     def mousePressEvent (self, event):
20         if event.button() == Qt.LeftButton:
21             tail = self.segmentGroup.tail()
22             self.segmentGroup.addSegment(
23                                          Segment(tail.pos())
24                                          )
25         elif event.button() == Qt.RightButton:
26             curveType = random.choice(Head.CURVE_TYPES)
27             self.head.curveType = QEasingCurve(curveType[1])

在這個類中添加數據，蛇頭，蛇身管理器，設置了簡單的增長蛇身的事件——按下鼠標左鍵；而按下右鍵則是更改蛇頭的動畫效果。將蛇身的移動與蛇頭的移動對應起來，用一個與蛇頭定時器時間相同的定時器來實現。

最后的form則是使用mainwindow在實現的應用程序。

 1 class Form(QMainWindow):
 2     def __init__(self,parent=None):
 3         super(Form,self).__init__(parent)
 4         self.fileMenu = self.menuBar().addMenu("&File")
 5         self.statusBar().showMessage("Ready", 5000)
 6         self.scene = SnackScene()
 7         
 8         self.view = QGraphicsView(self.scene)
 9         self.view.setRenderHint(QPainter.SmoothPixmapTransform)
10         self.view.setDragMode(QGraphicsView.RubberBandDrag)
11         self.setCentralWidget(self.view)

后記：做這個依然是為了熟練qt，本來是想用圖形界面做設計模式的，但是有些模式想不好寫神馬好，就像裝飾者模式，用神馬例子捏？

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