翻译自原文:Tetris in PyQt5

翻译时间 2020 年 8 月 20 日

在本章中,我们将创建一个俄罗斯方块的游戏模仿。

俄罗斯方块

俄罗斯方块 游戏是有史以来最受欢迎的电脑游戏之一。最初的游戏是由俄罗斯程序员阿列克谢·帕吉特诺夫在1985年设计和编程的。自那时起,俄罗斯方块 几乎在每个计算机平台上都有各种变化。

俄罗斯方块被称为下降块益智游戏。在这个游戏中,我们有七种不同的形状称为四角形:一个S形,一个Z形,一个T形,一个L形,一个线形,一个镜像L形状,和一个方形。这些形状中每个形状都用四个正方形组成。形状从木板上掉下来了。俄罗斯方块游戏的对象是移动和旋转形状,以便它们尽可能适合。如果我们设法形成一个行,行被摧毁,我们得分。我们玩俄罗斯方块游戏, 直到我们顶部溢出。

image-20200820214701778

图: 特特罗米诺

PyQt5 是一个旨在创建应用程序的工具包。还有其他库旨在创建计算机游戏。然而,PyQt5 和其他应用程序工具包可用于创建简单的游戏。

创建电脑游戏是提高编程技能的好办法。

开发

我们没有用于 俄罗斯方块游戏的图像,我们使用 PyQt5 编程工具包中提供的绘图 API 绘制四元图。每个电脑游戏的背后都有一个数学模型。所以在俄罗斯方块。

游戏背后的一些想法:

  • 我们使用 QtCore.QBasicTimer创建游戏周期。
  • 画出四分位。
  • 形状按方形移动(而不是按像素)。
  • 从数学上讲,棋盘是一个简单的数字列表。

代码由四个类组成:TetrisBoardTetrominoeShape

  • Tetris类设置游戏。
  • Board类是编写游戏逻辑的地方。
  • Tetrominoe类包含所有四分段的名称
  • Shape类包含四分段的代码。

tetris.py

import random
import sys

from PyQt5.QtCore import Qt, QBasicTimer, pyqtSignal
from PyQt5.QtGui import QPainter, QColor
from PyQt5.QtWidgets import QMainWindow, QFrame, QDesktopWidget, QApplication


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(int((screen.width() - size.width()) / 2),
                  int((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


def main():

    app = QApplication([])
    tetris = Tetris()
    sys.exit(app.exec_())


if __name__ == '__main__':
    main()

游戏是简化一点,以便更容易理解。游戏启动后立即启动。我们可以按p键暂停游戏。按Space 键会立即将四分位放置到底部。游戏以恒定的速度进行,没有实现加速。分数是我们已删除的行数。

self.tboard = Board(self)
self.setCentralWidget(self.tboard)

将创建类的实例并设置为应用程序的中心Board部件。

self.statusbar = self.statusBar()
self.tboard.msg2Statusbar[str].connect(self.statusbar.showMessage)

我们创建一个状态栏,在其中显示消息。我们将显示三个可能的消息:已删除的行数、暂停的消息或游戏通过消息。是在板类中实现的自定义信号msg2StatusbarshowMessage是一种内置方法,在状态栏上显示消息。

self.tboard.start()

此行启动游戏。

class Board(QFrame):

    msg2Statusbar = pyqtSignal(str)
...

使用 pyqtSignal创建自定义信号。msg2Statusbar是当我们要将消息或分数写入状态栏时发出的信号。

BoardWidth = 10
BoardHeight = 22
Speed = 300

这些是Board的类变量。BoardWidthBoardHeight定义块中板的大小。Speed定义游戏的速度。每个300ms一个新的游戏周期将开始。

...
self.curX = 0
self.curY = 0
self.numLinesRemoved = 0
self.board = []
...

initBoard方法中,我们初始化了一些重要的变量。 self.board变量是 0 到 7 的数字列表。它代表各种形状的位置和棋盘上形状保留的位置。

def shapeAt(self, x, y):
    """determines shape at the board position"""

    return self.board[(y * Board.BoardWidth) + x]

shapeAt方法确定给定块中的形状类型。

def squareWidth(self):
    """returns the width of one square"""

    return self.contentsRect().width() // Board.BoardWidth

电路板可以动态调整大小。因此,块的大小可能会更改。squareWidth计算单个正方形的宽度(以像素为单位)并返回它。Board.BoardWidth是块中的板的大小。

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方法暂停游戏。它停止计时器并在状态栏上显示一条消息。

def paintEvent(self, event):
    """paints all shapes of the game"""

    painter = QPainter(self)
    rect = self.contentsRect()
...

绘画发生在方法paintEvent中。QPainter负责 PyQt5 中所有低级绘画。

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)

游戏的绘画分为两个步骤。在第一步中,我们绘制所有形状,或已掉到板底部的形状的保留。列表变量中记住所有方块。使用shapeAt 方法访问self.board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())

下一步是绘制正在坠落的实际作品。

elif key == Qt.Key_Right:
    self.tryMove(self.curPiece, self.curX + 1, self.curY)

keyPressEvent方法中,我们检查按下的键。如果我们按右箭头键,我们尝试将该件向右移动。我们说尝试,因为片可能不能移动。

elif key == Qt.Key_Up:
    self.tryMove(self.curPiece.rotateLeft(), self.curX, self.curY)

箭头键Up将向左旋转掉落的零件。

elif key == Qt.Key_Space:
    self.dropDown()

Space键会立即将掉落的一块掉落到底部。

elif key == Qt.Key_D:
    self.oneLineDown()

按d键,件子会向下一块。它可以用来使一块的掉落有点。

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)

在计时器事件中,我们要么在上一个片掉到底部后创建一个新片,要么向下移动一个下降的一块。

def clearBoard(self):
    """clears shapes from the board"""

    for i in range(Board.BoardHeight * Board.BoardWidth):
        self.board.append(Tetrominoe.NoShape)

clearBoard方法通过设置板的每个块Tetrominoe.NoShape来清除板。

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)
 ...

如果该件触底,我们调用 removeFullLines方法。我们找出所有完整的行,并删除他们。我们通过将当前整行上方的所有线向下移动来移动以将其删除。请注意,我们反转要删除的行的顺序。否则,它无法正常工作。在我们的案例中,我们使用天真的重力。这意味着碎片可能漂浮在空隙上方。

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")

newPiece方法随机创建一个新的四分法。如果该作品不能进入其初始位置,游戏将结束。

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

tryMove方法中,我们尝试移动我们的形状。如果形状位于板的边缘或与其他部分相邻,我们返回 False。否则,我们将当前下降件放在一个新的位置。

class Tetrominoe(object):

    NoShape = 0
    ZShape = 1
    SShape = 2
    LineShape = 3
    TShape = 4
    SquareShape = 5
    LShape = 6
    MirroredLShape = 7

Tetrominoe类保存所有可能形状的名称。我们也有一个空白空间NoShape

Shape类保存有关四分位的信息。

class Shape(object):

    coordsTable = (
        ((0, 0),     (0, 0),     (0, 0),     (0, 0)),
        ((0, -1),    (0, 0),     (-1, 0),    (-1, 1)),
        ...
    )
...

元组coordsTable保存我们四分位的所有可能的坐标值。这是一个模板,所有片段都从该模板中显示其坐标值。

self.coords = [[0,0] for i in range(4)]

创建时,我们创建一个空坐标列表。列表将保存四分块的坐标。

Coordinates图:坐标

上图将有助于更好地理解坐标值。例如,元对 (0, -1), (0, 0), (-1, 0), (-1, -1) 表示 Z 形状。该图说明了形状。

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

rotateLeft方法将一块向左旋转。广场不必旋转。这就是为什么我们只返回对当前对象的引用。将创建一个新作品,其坐标设置为旋转件的坐标。

image-20200820220337438

图: 特瑞斯

这是 Pyqt5 中的特瑞斯游戏。