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本章我们要制作一个俄罗斯方块游戏。
Tetris
译注：称呼：方块是由四个小方格组成的
俄罗斯方块游戏是世界上最流行的游戏之一。是由一名叫 Alexey Pajitnov 的俄罗斯程序员在 1985 年制作的，从那时起，这个游戏就风靡了各个游戏平台。
俄罗斯方块归类为下落块迷宫游戏。游戏有 7 个基本形状：S、Z、T、L、反向 L、直线、方块，每个形状都由 4 个方块组成，方块最终都会落到屏幕底部。所以玩家通过控制形状的左右位置和旋转，让每个形状都以合适的位置落下，如果有一行全部被方块填充，这行就会消失，并且得分。游戏结束的条件是有形状接触到了屏幕顶部。
方块展示：
PyQt5 是专门为创建图形界面产生的，里面一些专门为制作游戏而开发的组件，所以 PyQt5 是能制作小游戏的。
制作电脑游戏也是提高自己编程能力的一种很好的方式。
开发
没有图片，所以就自己用绘画画出来几个图形。每个游戏里都有数学模型的，这个也是。
开工之前：
用 QtCore.QBasicTimer()创建一个游戏循环
模型是一直下落的
模型的运动是以小块为基础单位的，不是按像素
从数学意义上来说，模型就是就是一串数字而已
代码由四个类组成：Tetris, Board, Tetrominoe 和 Shape。Tetris 类创建游戏，Board 是游戏主要逻辑。Tetrominoe 包含了所有的砖块，Shape 是所有砖块的代码。
#!/usr/bin/python3
# -*- coding: utf-8 -*-
“””
ZetCode PyQt5 tutorial
This is a Tetris game clone.
Author: Jan Bodnar
Website: zetcode.com
Last edited: August 2017
“””
from PyQt5.QtWidgets import QMainWindow, QFrame, QDesktopWidget, QApplication
from PyQt5.QtCore import Qt, QBasicTimer, pyqtSignal
from PyQt5.QtGui import QPainter, QColor
import sys, random
class Tetris(QMainWindow):
def __init__(self):
super().__init__()
self.initUI()
def initUI(self):
”’initiates application UI”’
self.tboard = Board(self)
self.setCentralWidget(self.tboard)
self.statusbar = self.statusBar()
self.tboard.msg2Statusbar[str].connect(self.statusbar.showMessage)
self.tboard.start()
self.resize(180, 380)
self.center()
self.setWindowTitle(‘Tetris’)
self.show()
def center(self):
”’centers the window on the screen”’
screen = QDesktopWidget().screenGeometry()
size = self.geometry()
self.move((screen.width()-size.width())/2,
(screen.height()-size.height())/2)
class Board(QFrame):
msg2Statusbar = pyqtSignal(str)
BoardWidth = 10
BoardHeight = 22
Speed = 300
def __init__(self, parent):
super().__init__(parent)
self.initBoard()
def initBoard(self):
”’initiates board”’
self.timer = QBasicTimer()
self.isWaitingAfterLine = False
self.curX = 0
self.curY = 0
self.numLinesRemoved = 0
self.board = []
self.setFocusPolicy(Qt.StrongFocus)
self.isStarted = False
self.isPaused = False
self.clearBoard()
def shapeAt(self, x, y):
”’determines shape at the board position”’
return self.board[(y * Board.BoardWidth) + x]
def setShapeAt(self, x, y, shape):
”’sets a shape at the board”’
self.board[(y * Board.BoardWidth) + x] = shape
def squareWidth(self):
”’returns the width of one square”’
return self.contentsRect().width() // Board.BoardWidth
def squareHeight(self):
”’returns the height of one square”’
return self.contentsRect().height() // Board.BoardHeight
def start(self):
”’starts game”’
if self.isPaused:
return
self.isStarted = True
self.isWaitingAfterLine = False
self.numLinesRemoved = 0
self.clearBoard()
self.msg2Statusbar.emit(str(self.numLinesRemoved))
self.newPiece()
self.timer.start(Board.Speed, self)
def pause(self):
”’pauses game”’
if not self.isStarted:
return
self.isPaused = not self.isPaused
if self.isPaused:
self.timer.stop()
self.msg2Statusbar.emit(“paused”)
else:
self.timer.start(Board.Speed, self)
self.msg2Statusbar.emit(str(self.numLinesRemoved))
self.update()
def paintEvent(self, event):
”’paints all shapes of the game”’
painter = 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 != Tetrominoe.NoShape:
self.drawSquare(painter,
rect.left() + j * self.squareWidth(),
boardTop + i * self.squareHeight(), shape)
if self.curPiece.shape() != Tetrominoe.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):
”’processes key press events”’
if not self.isStarted or self.curPiece.shape() == Tetrominoe.NoShape:
super(Board, self).keyPressEvent(event)
return
key = event.key()
if key == Qt.Key_P:
self.pause()
return
if self.isPaused:
return
elif key == Qt.Key_Left:
self.tryMove(self.curPiece, self.curX – 1, self.curY)
elif key == Qt.Key_Right:
self.tryMove(self.curPiece, self.curX + 1, self.curY)
elif key == Qt.Key_Down:
self.tryMove(self.curPiece.rotateRight(), self.curX, self.curY)
elif key == Qt.Key_Up:
self.tryMove(self.curPiece.rotateLeft(), self.curX, self.curY)
elif key == Qt.Key_Space:
self.dropDown()
elif key == Qt.Key_D:
self.oneLineDown()
else:
super(Board, self).keyPressEvent(event)
def timerEvent(self, event):
”’handles timer event”’
if event.timerId() == self.timer.timerId():
if self.isWaitingAfterLine:
self.isWaitingAfterLine = False
self.newPiece()
else:
self.oneLineDown()
else:
super(Board, self).timerEvent(event)
def clearBoard(self):
”’clears shapes from the board”’
for i in range(Board.BoardHeight * Board.BoardWidth):
self.board.append(Tetrominoe.NoShape)
def dropDown(self):
”’drops down a shape”’
newY = self.curY
while newY > 0:
if not self.tryMove(self.curPiece, self.curX, newY – 1):
break
newY -= 1
self.pieceDropped()
def oneLineDown(self):
”’goes one line down with a shape”’
if not self.tryMove(self.curPiece, self.curX, self.curY – 1):
self.pieceDropped()
def pieceDropped(self):
”’after dropping shape, remove full lines and create new shape”’
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):
”’removes all full lines from the board”’
numFullLines = 0
rowsToRemove = []
for i in range(Board.BoardHeight):
n = 0
for j in range(Board.BoardWidth):
if not self.shapeAt(j, i) == Tetrominoe.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.msg2Statusbar.emit(str(self.numLinesRemoved))
self.isWaitingAfterLine = True
self.curPiece.setShape(Tetrominoe.NoShape)
self.update()
def newPiece(self):
”’creates a new shape”’
self.curPiece = Shape()
self.curPiece.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(Tetrominoe.NoShape)
self.timer.stop()
self.isStarted = False
self.msg2Statusbar.emit(“Game over”)
def tryMove(self, newPiece, newX, newY):
”’tries to move a shape”’
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) != Tetrominoe.NoShape:
return False
self.curPiece = newPiece
self.curX = newX
self.curY = newY
self.update()
return True
def drawSquare(self, painter, x, y, shape):
”’draws a square of a shape”’
colorTable = [0x000000, 0xCC6666, 0x66CC66, 0x6666CC,
0xCCCC66, 0xCC66CC, 0x66CCCC, 0xDAAA00]
color = QColor(colorTable[shape])
painter.fillRect(x + 1, y + 1, self.squareWidth() – 2,
self.squareHeight() – 2, color)
painter.setPen(color.lighter())
painter.drawLine(x, y + self.squareHeight() – 1, x, y)
painter.drawLine(x, y, x + self.squareWidth() – 1, y)
painter.setPen(color.darker())
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 Tetrominoe(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 = Tetrominoe.NoShape
self.setShape(Tetrominoe.NoShape)
def shape(self):
”’returns shape”’
return self.pieceShape
def setShape(self, shape):
”’sets a 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):
”’chooses a random shape”’
self.setShape(random.randint(1, 7))
def x(self, index):
”’returns x coordinate”’
return self.coords[index][0]
def y(self, index):
”’returns y coordinate”’
return self.coords[index][1]
def setX(self, index, x):
”’sets x coordinate”’
self.coords[index][0] = x
def setY(self, index, y):
”’sets y coordinate”’
self.coords[index][1] = y
def minX(self):
”’returns min x value”’
m = self.coords[0][0]
for i in range(4):
m = min(m, self.coords[i][0])
return m
def maxX(self):
”’returns max x value”’
m = self.coords[0][0]
for i in range(4):
m = max(m, self.coords[i][0])
return m
def minY(self):
”’returns min y value”’
m = self.coords[0][1]
for i in range(4):
m = min(m, self.coords[i][1])
return m
def maxY(self):
”’returns max y value”’
m = self.coords[0][1]
for i in range(4):
m = max(m, self.coords[i][1])
return m
def rotateLeft(self):
”’rotates shape to the left”’
if self.pieceShape == Tetrominoe.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 rotateRight(self):
”’rotates shape to the right”’
if self.pieceShape == Tetrominoe.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
if __name__ == ‘__main__’:
app = QApplication([])
tetris = Tetris()
sys.exit(app.exec_())
游戏很简单，所以也就很好理解。程序加载之后游戏也就直接开始了，可以用 P 键暂停游戏，空格键让方块直接落到最下面。游戏的速度是固定的，并没有实现加速的功能。分数就是游戏中消除的行数。
self.tboard = Board(self)
self.setCentralWidget(self.tboard)
创建了一个 Board 类的实例，并设置为应用的中心组件。
self.statusbar = self.statusBar()
self.tboard.msg2Statusbar[str].connect(self.statusbar.showMessage)
创建一个 statusbar 来显示三种信息：消除的行数，游戏暂停状态或者游戏结束状态。msg2Statusbar 是一个自定义的信号，用在（和）Board 类（交互），showMessage()方法是一个内建的，用来在 statusbar 上显示信息的方法。
self.tboard.start()
初始化游戏：
class Board(QFrame):
msg2Statusbar = pyqtSignal(str)
…
创建了一个自定义信号 msg2Statusbar，当我们想往 statusbar 里显示信息的时候，发出这个信号就行了。
BoardWidth = 10
BoardHeight = 22
Speed = 300
这些是 Board 类的变量。BoardWidth 和 BoardHeight 分别是 board 的宽度和高度。Speed 是游戏的速度，每 300ms 出现一个新的方块。
…
self.curX = 0
self.curY = 0
self.numLinesRemoved = 0
self.board = []
…
在 initBoard()里初始化了一些重要的变量。self.board 定义了方块的形状和位置，取值范围是 0 -7。
def shapeAt(self, x, y):
return self.board[(y * Board.BoardWidth) + x]
shapeAt()决定了 board 里方块的的种类。
def squareWidth(self):
return self.contentsRect().width() // Board.BoardWidth
board 的大小可以动态的改变。所以方格的大小也应该随之变化。squareWidth()计算并返回每个块应该占用多少像素 – 也即 Board.BoardWidth。
def pause(self):
”’pauses game”’
if not self.isStarted:
return
self.isPaused = not self.isPaused
if self.isPaused:
self.timer.stop()
self.msg2Statusbar.emit(“paused”)
else:
self.timer.start(Board.Speed, self)
self.msg2Statusbar.emit(str(self.numLinesRemoved))
self.update()
pause()方法用来暂停游戏，停止计时并在 statusbar 上显示一条信息。
def paintEvent(self, event):
”’paints all shapes of the game”’
painter = QPainter(self)
rect = self.contentsRect()
…
渲染是在 paintEvent()方法里发生的 QPainter 负责 PyQt5 里所有低级绘画操作。
for i in range(Board.BoardHeight):
for j in range(Board.BoardWidth):
shape = self.shapeAt(j, Board.BoardHeight – i – 1)
if shape != Tetrominoe.NoShape:
self.drawSquare(painter,
rect.left() + j * self.squareWidth(),
boardTop + i * self.squareHeight(), shape)
渲染游戏分为两步。第一步是先画出所有已经落在最下面的的图，这些保存在 self.board 里。可以使用 shapeAt()查看这个这个变量。
if self.curPiece.shape() != Tetrominoe.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())
第二步是画出更在下落的方块。
elif key == Qt.Key_Right:
self.tryMove(self.curPiece, self.curX + 1, self.curY)
在 keyPressEvent()方法获得用户按下的按键。如果按下的是右方向键，就尝试把方块向右移动，说尝试是因为有可能到边界不能移动了。
elif key == Qt.Key_Up:
self.tryMove(self.curPiece.rotateLeft(), self.curX, self.curY)
上方向键是把方块向左旋转一下
elif key == Qt.Key_Space:
self.dropDown()
空格键会直接把方块放到底部
elif key == Qt.Key_D:
self.oneLineDown()
D 键是加速一次下落速度。
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) != Tetrominoe.NoShape:
return False
self.curPiece = newPiece
self.curX = newX
self.curY = newY
self.update()
return True
tryMove()是尝试移动方块的方法。如果方块已经到达 board 的边缘或者遇到了其他方块，就返回 False。否则就把方块下落到想要
def timerEvent(self, event):
if event.timerId() == self.timer.timerId():
if self.isWaitingAfterLine:
self.isWaitingAfterLine = False
self.newPiece()
else:
self.oneLineDown()
else:
super(Board, self).timerEvent(event)
在计时器事件里，要么是等一个方块下落完之后创建一个新的方块，要么是让一个方块直接落到底（move a falling piece one line down）。
def clearBoard(self):
for i in range(Board.BoardHeight * Board.BoardWidth):
self.board.append(Tetrominoe.NoShape)
clearBoard()方法通过 Tetrominoe.NoShape 清空 broad。
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) == Tetrominoe.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)
…
如果方块碰到了底部，就调用 removeFullLines()方法，找到所有能消除的行消除它们。消除的具体动作就是把符合条件的行消除掉之后，再把它上面的行下降一行。注意移除满行的动作是倒着来的，因为我们是按照重力来表现游戏的，如果不这样就有可能出现有些方块浮在空中的现象。
def newPiece(self):
self.curPiece = Shape()
self.curPiece.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(Tetrominoe.NoShape)
self.timer.stop()
self.isStarted = False
self.msg2Statusbar.emit(“Game over”)
newPiece()方法是用来创建形状随机的方块。如果随机的方块不能正确的出现在预设的位置，游戏结束。
class Tetrominoe(object):
NoShape = 0
ZShape = 1
SShape = 2
LineShape = 3
TShape = 4
SquareShape = 5
LShape = 6
MirroredLShape = 7
Tetrominoe 类保存了所有方块的形状。我们还定义了一个 NoShape 的空形状。
Shape 类保存类方块内部的信息。
class Shape(object):
coordsTable = (
((0, 0), (0, 0), (0, 0), (0, 0)),
((0, -1), (0, 0), (-1, 0), (-1, 1)),
…
)
…
coordsTable 元组保存了所有的方块形状的组成。是一个构成方块的坐标模版。
self.coords = [[0,0] for i in range(4)]
上面创建了一个新的空坐标数组，这个数组将用来保存方块的坐标。
坐标系示意图：
上面的图片可以帮助我们更好的理解坐标值的意义。比如元组 (0, -1), (0, 0), (-1, 0), (-1, -1) 代表了一个 Z 形状的方块。这个图表就描绘了这个形状。
def rotateLeft(self):
if self.pieceShape == Tetrominoe.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
rotateLeft()方法向右旋转一个方块。正方形的方块就没必要旋转，就直接返回了。其他的是返回一个新的，能表示这个形状旋转了的坐标。
程序展示：
