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 BodnarWebsite: zetcode.com Last edited: August 2017"""from PyQt5.QtWidgets import QMainWindow, QFrame, QDesktopWidget, QApplicationfrom PyQt5.QtCore import Qt, QBasicTimer, pyqtSignalfrom PyQt5.QtGui import QPainter, QColor import sys, randomclass 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 = 7class 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 resultif __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 = 10BoardHeight = 22Speed = 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 = 0self.curY = 0self.numLinesRemoved = 0self.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：