pygame绘制/选择圆

Question

I am working on a project and I need to crete a Node Graph.

This is what I did so far(a screen and a function to draw circle numerotaded at the mouse click possition) and now i am stuck.

How can i select a circle after creating to move it around?

import pygame
WHITE =     (255, 255, 255)
BLUE =      (  0,   0, 255)
GREEN =     (  0, 255,   0)
RED =       (255,   0,   0)
TEXTCOLOR = (  0,   0,  0)
(width, height) = (800, 600)
BASICFONTSIZE = 10
count = 0

running = True


def getPos():
    pos = pygame.mouse.get_pos()
    return (pos)

def drawCircle():
    global count
    pos = getPos()
    radius = 20
    pygame.draw.circle(screen, BLUE, pos, radius,7)
    textSurf = BASICFONT.render(str(count), True, TEXTCOLOR)
    textRect = textSurf.get_rect()
    textRect.center = int(pos[0]),int(pos[1])
    screen.blit(textSurf, textRect)
    count += 1

def main():
    global running, screen, BASICFONT

    pygame.init()
    BASICFONT = pygame.font.Font('freesansbold.ttf', BASICFONTSIZE)
    screen = pygame.display.set_mode((width, height))
    pygame.display.set_caption("TUFF")
    screen.fill(WHITE)
    pygame.display.update()

    while running:
        ev = pygame.event.get()

        for event in ev:

            if event.type == pygame.MOUSEBUTTONUP:
                drawCircle()
                pygame.display.update()

            if event.type == pygame.QUIT:
                running = False


if __name__ == '__main__':
    main()

Answer 1

from random import randrange, choice
import pygame
import sys
from pygame.locals import *

snode = int(input("How manny nodes do you need? = "))
FR = 30
SIZE = 640, 480
BGCOLOR = (255,255,255)
NODECOLOR = (255,0,170)
NODESIZE = 25,25
GRIDSPACING = 50
MAXTRIES = 1000
STARTINGNODES = snode
TEXTCOLOR = (0,255,0)
BASICFONTSIZE = 20


class Graph(object):
    def __init__(self):
        self.nodes = set()
        # record positions of each node so that we can check for overlaps
        self.positions = dict()

    def add(self, node):
        global count
        count = 0
        added = False
        # add node at random location
        while not added:
            x, y = (randrange(0, SIZE[0], GRIDSPACING),
                        randrange(0, SIZE[1], GRIDSPACING))
            if not (x,y) in self.positions:
                added = True
                self.nodes.add(node)
                node.setpos((x,y), self)
            count += 1
            if count >= MAXTRIES:
                raise ValueError("Could not alocate space for node representation")


    def update(self):
        SCREEN.fill(BGCOLOR)
        for node in self.nodes:
            pygame.draw.rect(SCREEN, node.color, node.rect, 5)
            textSurf = BASICFONT.render(str(node.id), True, TEXTCOLOR)
            textRect = textSurf.get_rect()
            textRect.center = int(node.rect[0] + 13),int(node.rect[1] + 13)
            SCREEN.blit(textSurf, textRect)
            for neighbor in node.neighbors:
                pygame.draw.line(SCREEN, NODECOLOR,node.rect.center, neighbor.rect.center)


class Node(object):
    # incremented with each
    # each node has a unique ID that
    creation_counter = 0
    def __init__(self):
        self.id = self.__class__.creation_counter
        self.__class__.creation_counter += 1
        self.rect = None
        self.color = NODECOLOR
        self.neighbors = set()

    def setpos(self, pos, graph = None):
        if self.rect and graph:
            # remove self from previous position in the graph:
            graph.positions.pop(self.rect.topleft, None)
        self.rect = pygame.Rect(pos[0], pos[1],NODESIZE[0], NODESIZE[1])
        if graph:
            graph.positions[pos] = self

    def  __hash__(self):
        return self.id


def create_graph():
    # create new graph:
    graph = Graph()
    nodes = []
    for i in range(STARTINGNODES):
        node = Node()
        graph.add(node)
    return graph

def init():
    global SCREEN
    pygame.init()
    SCREEN = pygame.display.set_mode(SIZE)

def quit():
    pygame.quit()

def main():

    global BASICFONT, screen

    graph = create_graph()
    selected = None
    try:
        init()
        BASICFONT = pygame.font.Font('freesansbold.ttf', BASICFONTSIZE)
        while True:
            graph.update()
            pygame.event.pump()
            # Exit "ESC" key is pressed
            if pygame.key.get_pressed()[pygame.K_ESCAPE]:
                break
            for event in pygame.event.get():
                if event.type == pygame.MOUSEBUTTONDOWN:
                    x, y = event.pos
                    # round down x,y to multiples of NODESIZE
                    x -= x % NODESIZE[0]
                    y -= y % NODESIZE[1]
                    pygame.draw.rect(SCREEN, (0,0,255), (x,y) + NODESIZE)
                    if (x,y) in graph.positions:
                        node = graph.positions[x,y]
                        if selected:
                            print selected.id, node.id
                            if selected is node:
                                selected = None
                                node.color = NODECOLOR
                            elif selected not in node.neighbors:
                                selected.neighbors.add(node)
                                node.neighbors.add(selected)
                            else:
                                selected.neighbors.remove(node)
                                node.neighbors.remove(selected)
                        else:
                            node.color = (0,0,0)
                            selected = node
                    elif selected:
                        selected.setpos((x,y), graph)
                elif event.type == pygame.MOUSEMOTION and event.buttons[0] and selected:
                    x, y = event.pos
                    # round down x,y to multiples of NODESIZE
                    x -= x % NODESIZE[0]
                    y -= y % NODESIZE[1]
                    selected.setpos((x,y), graph)

            pygame.display.flip()
            pygame.time.delay(FR)
    finally:
        quit()


if __name__ == "__main__":
    main()