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PyQt4 中的俄羅斯方塊
創建一個電腦游戲是很具挑戰性的。遲早程序員想創建一個電腦游戲。事實上，很多人對編程感興趣，是因為它們玩了游戲，然后想創建自己的游戲。創建一個游戲會提升你的編程技能。
俄羅斯方塊
俄羅斯方塊從創建開始就成為很流行的游戲之一。游戲最開始是由俄羅斯程序員 Alexey Pajitnov 設計和編寫的。從那時開始幾乎在所有的計算機平臺運行。甚至我的手機就有一個修改版的俄羅斯方塊。
這個游戲是落下方塊。我們可以有七種不同的形狀，稱為 tetromino 。S形狀，Z形狀，T形狀，L形狀，行，鏡像L形狀，方塊形狀。而這些形狀又由四個方塊構成。這些形狀會掉到板上。這個游戲的目標是移動和旋轉這些形狀，所以可以把他們填滿。如果我們填滿了一行，這行就被銷毀然后我們得分。游戲在方塊填到頂部就結束了。
PyQt4 是可以用于創建應用的。也有很多其它庫可以用于游戲。盡管如此，PyQt4 仍可以創建游戲。
下面的例子是一個改版的俄羅斯方塊，在 PyQt4 安裝的目錄下。
開發
我們不準備使用圖片，而是使用 PyQt4 的 API 。在每個計算機游戲背后，都有一個數學模型。俄羅斯方塊也是。
一些想法。
- 使用 QtCore.QBasicTimer 創建游戲的一輪
- 這些方塊是往下掉的
- 這些形狀一格格移動
- 游戲盤數學上是簡單的列表
#!/usr/bin/python
# tetris.py
import sys
import random
from PyQt4 import QtCore, QtGui
class Tetris(QtGui.QMainWindow):
def __init__(self):
#QtGui.QMainWindow.__init__(self)
super(Tetris, self).__init__()
self.setGeometry(300, 300, 180, 380)
self.setWindowTitle('Tetris')
self.tetrisboard = Board(self)
self.setCentralWidget(self.tetrisboard)
self.statusbar = self.statusBar()
self.connect(self.tetrisboard, QtCore.SIGNAL("messageToStatusbar(QString)"),
self.statusbar, QtCore.SLOT("showMessage(QString)"))
self.tetrisboard.start()
self.center()
def center(self):
screen = QtGui.QDesktopWidget().screenGeometry()
size = self.geometry()
self.move((screen.width()-size.width())/2,
(screen.height()-size.height())/2)
class Board(QtGui.QFrame):
BoardWidth = 10
BoardHeight = 22
Speed = 300
def __init__(self, parent):
#QtGui.QFrame.__init__(self, parent)
super(Board, self).__init__(parent)
self.timer = QtCore.QBasicTimer()
self.isWaitingAfterLine = False
self.curPiece = Shape()
self.nextPiece = Shape()
self.curX = 0
self.curY = 0
self.numLinesRemoved = 0
self.board = []
self.setFocusPolicy(QtCore.Qt.StrongFocus)
self.isStarted = False
self.isPaused = False
self.clearBoard()
self.nextPiece.setRandomShape()
def shapeAt(self, x, y):
return self.board[(y * Board.BoardWidth) + x]
def setShapeAt(self, x, y, shape):
self.board[(y * Board.BoardWidth) + x] = shape
def squareWidth(self):
return self.contentsRect().width() / Board.BoardWidth
def squareHeight(self):
return self.contentsRect().height() / Board.BoardHeight
def start(self):
if self.isPaused:
return
self.isStarted = True
self.isWaitingAfterLine = False
self.numLinesRemoved = 0
self.clearBoard()
self.emit(QtCore.SIGNAL("messageToStatusbar(QString)"),
str(self.numLinesRemoved))
self.newPiece()
self.timer.start(Board.Speed, self)
def pause(self):
if not self.isStarted:
return
self.isPaused = not self.isPaused
if self.isPaused:
self.timer.stop()
self.emit(QtCore.SIGNAL("messageToStatusbar(QString)"), "paused")
else:
self.timer.start(Board.Speed, self)
self.emit(QtCore.SIGNAL("messageToStatusbar(QString)"),
str(self.numLinesRemoved))
self.update()
def paintEvent(self, event):
painter = QtGui.QPainter(self)
rect = self.contentsRect()
boardTop = rect.bottom() - Board.BoardHeight * self.squareHeight()
for i in range(Board.BoardHeight):
for j in range(Board.BoardWidth):
shape = self.shapeAt(j, Board.BoardHeight - i - 1)
if shape != Tetrominoes.NoShape:
self.drawSquare(painter,
rect.left() + j * self.squareWidth(),
boardTop + i * self.squareHeight(), shape)
if self.curPiece.shape() != Tetrominoes.NoShape:
for i in range(4):
x = self.curX + self.curPiece.x(i)
y = self.curY - self.curPiece.y(i)
self.drawSquare(painter, rect.left() + x * self.squareWidth(),
boardTop + (Board.BoardHeight - y - 1) * self.squareHeight(),
self.curPiece.shape())
def keyPressEvent(self, event):
if not self.isStarted or self.curPiece.shape() == Tetrominoes.NoShape:
QtGui.QWidget.keyPressEvent(self, event)
return
key = event.key()
if key == QtCore.Qt.Key_P:
self.pause()
return
if self.isPaused:
return
elif key == QtCore.Qt.Key_Left:
self.tryMove(self.curPiece, self.curX - 1, self.curY)
elif key == QtCore.Qt.Key_Right:
self.tryMove(self.curPiece, self.curX + 1, self.curY)
elif key == QtCore.Qt.Key_Down:
self.tryMove(self.curPiece.rotatedRight(), self.curX, self.curY)
elif key == QtCore.Qt.Key_Up:
self.tryMove(self.curPiece.rotatedLeft(), self.curX, self.curY)
elif key == QtCore.Qt.Key_Space:
self.dropDown()
elif key == QtCore.Qt.Key_D:
self.oneLineDown()
else:
QtGui.QWidget.keyPressEvent(self, event)
def timerEvent(self, event):
if event.timerId() == self.timer.timerId():
if self.isWaitingAfterLine:
self.isWaitingAfterLine = False
self.newPiece()
else:
self.oneLineDown()
else:
QtGui.QFrame.timerEvent(self, event)
def clearBoard(self):
for i in range(Board.BoardHeight * Board.BoardWidth):
self.board.append(Tetrominoes.NoShape)
def dropDown(self):
newY = self.curY
while newY > 0:
if not self.tryMove(self.curPiece, self.curX, newY - 1):
break
newY -= 1
self.pieceDropped()
def oneLineDown(self):
if not self.tryMove(self.curPiece, self.curX, self.curY - 1):
self.pieceDropped()
def pieceDropped(self):
for i in range(4):
x = self.curX + self.curPiece.x(i)
y = self.curY - self.curPiece.y(i)
self.setShapeAt(x, y, self.curPiece.shape())
self.removeFullLines()
if not self.isWaitingAfterLine:
self.newPiece()
def removeFullLines(self):
numFullLines = 0
rowsToRemove = []
for i in range(Board.BoardHeight):
n = 0
for j in range(Board.BoardWidth):
if not self.shapeAt(j, i) == Tetrominoes.NoShape:
n = n + 1
if n == 10:
rowsToRemove.append(i)
rowsToRemove.reverse()
for m in rowsToRemove:
for k in range(m, Board.BoardHeight):
for l in range(Board.BoardWidth):
self.setShapeAt(l, k, self.shapeAt(l, k + 1))
numFullLines = numFullLines + len(rowsToRemove)
if numFullLines > 0:
self.numLinesRemoved = self.numLinesRemoved + numFullLines
self.emit(QtCore.SIGNAL("messageToStatusbar(QString)"),
str(self.numLinesRemoved))
self.isWaitingAfterLine = True
self.curPiece.setShape(Tetrominoes.NoShape)
self.update()
def newPiece(self):
self.curPiece = self.nextPiece
self.nextPiece.setRandomShape()
self.curX = Board.BoardWidth / 2 + 1
self.curY = Board.BoardHeight - 1 + self.curPiece.minY()
if not self.tryMove(self.curPiece, self.curX, self.curY):
self.curPiece.setShape(Tetrominoes.NoShape)
self.timer.stop()
self.isStarted = False
self.emit(QtCore.SIGNAL("messageToStatusbar(QString)"), "Game over")
def tryMove(self, newPiece, newX, newY):
for i in range(4):
x = newX + newPiece.x(i)
y = newY - newPiece.y(i)
if x < 0 or x >= Board.BoardWidth or y < 0 or y >= Board.BoardHeight:
return False
if self.shapeAt(x, y) != Tetrominoes.NoShape:
return False
self.curPiece = newPiece
self.curX = newX
self.curY = newY
self.update()
return True
def drawSquare(self, painter, x, y, shape):
colorTable = [0x000000, 0xCC6666, 0x66CC66, 0x6666CC,
0xCCCC66, 0xCC66CC, 0x66CCCC, 0xDAAA00]
color = QtGui.QColor(colorTable[shape])
painter.fillRect(x + 1, y + 1, self.squareWidth() - 2,
self.squareHeight() - 2, color)
painter.setPen(color.light())
painter.drawLine(x, y + self.squareHeight() - 1, x, y)
painter.drawLine(x, y, x + self.squareWidth() - 1, y)
painter.setPen(color.dark())
painter.drawLine(x + 1, y + self.squareHeight() - 1,
x + self.squareWidth() - 1, y + self.squareHeight() - 1)
painter.drawLine(x + self.squareWidth() - 1,
y + self.squareHeight() - 1, x + self.squareWidth() - 1, y + 1)
class Tetrominoes(object):
NoShape = 0
ZShape = 1
SShape = 2
LineShape = 3
TShape = 4
SquareShape = 5
LShape = 6
MirroredLShape = 7
class Shape(object):
coordsTable = (
((0, 0), (0, 0), (0, 0), (0, 0)),
((0, -1), (0, 0), (-1, 0), (-1, 1)),
((0, -1), (0, 0), (1, 0), (1, 1)),
((0, -1), (0, 0), (0, 1), (0, 2)),
((-1, 0), (0, 0), (1, 0), (0, 1)),
((0, 0), (1, 0), (0, 1), (1, 1)),
((-1, -1), (0, -1), (0, 0), (0, 1)),
((1, -1), (0, -1), (0, 0), (0, 1))
)
def __init__(self):
self.coords = [[0,0] for i in range(4)]
self.pieceShape = Tetrominoes.NoShape
self.setShape(Tetrominoes.NoShape)
def shape(self):
return self.pieceShape
def setShape(self, shape):
table = Shape.coordsTable[shape]
for i in range(4):
for j in range(2):
self.coords[i][j] = table[i][j]
self.pieceShape = shape
def setRandomShape(self):
self.setShape(random.randint(1, 7))
def x(self, index):
return self.coords[index][0]
def y(self, index):
return self.coords[index][1]
def setX(self, index, x):
self.coords[index][0] = x
def setY(self, index, y):
self.coords[index][1] = y
def minX(self):
m = self.coords[0][0]
for i in range(4):
m = min(m, self.coords[i][0])
return m
def maxX(self):
m = self.coords[0][0]
for i in range(4):
m = max(m, self.coords[i][0])
return m
def minY(self):
m = self.coords[0][1]
for i in range(4):
m = min(m, self.coords[i][1])
return m
def maxY(self):
m = self.coords[0][1]
for i in range(4):
m = max(m, self.coords[i][1])
return m
def rotatedLeft(self):
if self.pieceShape == Tetrominoes.SquareShape:
return self
result = Shape()
result.pieceShape = self.pieceShape
for i in range(4):
result.setX(i, self.y(i))
result.setY(i, -self.x(i))
return result
def rotatedRight(self):
if self.pieceShape == Tetrominoes.SquareShape:
return self
result = Shape()
result.pieceShape = self.pieceShape
for i in range(4):
result.setX(i, -self.y(i))
result.setY(i, self.x(i))
return result
app = QtGui.QApplication(sys.argv)
tetris = Tetris()
tetris.show()
sys.exit(app.exec_())
我稍微簡化了此游戲，所以理解起來比較容易。游戲在載入后就立即開始了。我們可以按 'p' 來暫停游戲。而空格可以讓形狀立即掉到底部。游戲以恒速進行，并沒有實現加速。分數是我們移掉的行數。
self.statusbar = self.statusBar()
self.connect(self.tetrisboard, QtCore.SIGNAL("messageToStatusbar(QString)"),
self.statusbar, QtCore.SLOT("showMessage(QString)"))
我們創建了狀態欄，用于顯示消息。我們將顯示三種可能的消息。移除的行數，暫停消息，結束消息。
...
self.curX = 0
self.curY = 0
self.numLinesRemoved = 0
self.board = []
...
在游戲開始前，我們先初始化一些重要的變量。變量 self.board 是一組 0 到 7 的列表。它代表這些形狀的位置，以及剩余的形狀。
for j in range(Board.BoardWidth):
shape = self.shapeAt(j, Board.BoardHeight - i - 1)
if shape != Tetrominoes.NoShape:
self.drawSquare(painter,
rect.left() + j * self.squareWidth(),
boardTop + i * self.squareHeight(), shape)
游戲的繪制被分為兩部分。第一步，我們繪制所有的形狀，或剩余的形狀，這些是已經掉落的。所有的都記在 self.board 中。我們使用 shapeAt() 方法訪問它。
if self.curPiece.shape() != Tetrominoes.NoShape:
for i in range(4):
x = self.curX + self.curPiece.x(i)
y = self.curY - self.curPiece.y(i)
self.drawSquare(painter, rect.left() + x * self.squareWidth(),
boardTop + (Board.BoardHeight - y - 1) * self.squareHeight(),
self.curPiece.shape())
下一步我們繪制落下的部分。
elif key == QtCore.Qt.Key_Left:
self.tryMove(self.curPiece, self.curX - 1, self.curY)
elif key == QtCore.Qt.Key_Right:
self.tryMove(self.curPiece, self.curX + 1, self.curY)
在 keyPressEvent 中，我們檢查按鍵。如果我們按向右的鍵，那么那塊就會往右移。我們說 try，是因為可能不能移。
def tryMove(self, newPiece, newX, newY):
for i in range(4):
x = newX + newPiece.x(i)
y = newY - newPiece.y(i)
if x < 0 or x >= Board.BoardWidth or y < 0 or y >= Board.BoardHeight:
return False
if self.shapeAt(x, y) != Tetrominoes.NoShape:
return False
self.curPiece = newPiece
self.curX = newX
self.curY = newY
self.update()
return True
在這個方法中，我們嘗試移動形狀。如果到了畫板邊緣或是碰到其它，我們就返回 False 。否則，我們就放置到新的位置。
def timerEvent(self, event):
if event.timerId() == self.timer.timerId():
if self.isWaitingAfterLine:
self.isWaitingAfterLine = False
self.newPiece()
else:
self.oneLineDown()
else:
QtGui.QFrame.timerEvent(self, event)
在計時器事件中，我們或者是創建一個新的方塊，或是讓方塊下落。
def removeFullLines(self):
numFullLines = 0
rowsToRemove = []
for i in range(Board.BoardHeight):
n = 0
for j in range(Board.BoardWidth):
if not self.shageAt(j, i) == Tetrominoes.NoShape:
n = n + 1
if n == 10:
rowsToRemove.append(i)
rowsToRemove.reverse()
for m in rowsToRemove:
for k in range(m, Board.BoardHeight):
for l in range(Board.BoardWidth):
self.setShapeAt(l, k, self.shapeAt(l, k + 1))
...
如果那塊碰到底部，我們就調用 removeFullLines() 方法。首先，我們找到所有的行數。然后我們移除他們。我們要把滿了的行數移除。注意，我們把要移除的列表進行反轉。否則，它可能不能正確移除。我們沒有使用重力效應。這就意味著某些方塊會懸浮。
def newPiece(self):
self.curPiece = self.nextPiece
self.nextPiece.setRandomShape()
self.curX = Board.BoardWidth / 2 + 1
self.curY = Board.BoardHeight - 1 + self.curPiece.minY()
if not self.tryMove(self.curPiece, self.curX, self.curY):
self.curPiece.setShape(Tetrominoes.NoShape)
self.timer.stop()
self.isStarted = False
self.emit(QtCore.SIGNAL("messageToStatusbar(QString)"), "Game Over")
newPiece() 方法隨機創建一個方塊。如果這個方塊不能動了，游戲就結束了。
Shape 類保存了每個方塊的形狀。
self.coords = [[0,0] for i in range(4)]
在創建時，我們創建了一個空的坐標列表。這個列表保存每個方塊的坐標。比如，這些元組 (0,-1),(0,0),(-1,0),(-1,-1) 代表旋轉的 S 形狀。下面的圖表指示了這個形狀。
當我們繪制方塊時，我們就把它畫在 self.curX 和 self.curY 上。然后我們把四個方塊畫起來。
這是一個用 PyQt4 寫的俄羅斯方塊。
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