pyqt5实现俄罗斯方块游戏

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：

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