Pygame不会将图像拖到画布上

Question

I've made an icon for a gui in a little project I'm working on, and pygame doesn't display it. What am I doing wrong?

import pygame
black = (0,0,0)
toolscanvas = pygame.Surface((700,120))

pygame.init()
gameDisplay = pygame.display.set_mode((0,0),pygame.FULLSCREEN)
gameDisplay.fill(black)
gameDisplay.convert()
clock = pygame.time.Clock()


class GuiHouse:
    def __init__(self):
        self.x = 0
        self.y = 20
        self.canvas = pygame.Surface((300,300))
        self.canvas.set_alpha(128)
        self.iconed = pygame.image.load("house_icon.png").convert_alpha()
        self.iconed = pygame.transform.scale(self.iconed, (60, 60))
    def display(self):
        global toolscanvas
        toolscanvas.fill((0,0,0))
        self.canvas.blit(self.iconed, (0, 0))
        toolscanvas.blit(self.canvas, (self.x, self.y))
        gameDisplay.blit(toolscanvas,(0,0))


guihouse = GuiHouse()
while True:
    for event in pygame.event.get():
        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_ESCAPE:
                pygame.quit()
                quit()
    guihouse.display()
    pygame.display.update()
    clock.tick(120)

Real code is a lot longer, let me know if it doesn't work. Here's what the icon should look like

Answer 1

There are two small errors

1. You forgot to draw toolscanvas on main pygame display ( gameDisplay.blit(toolscanvas, (0, 0)) )
2. An image is read with alfa channel and has only black pixels. So you are drawing a black picture on a black background. At example solution I have added filling image canvas with white color, so now the image is visible, but not pretty. But I hope you will find better solution :)

Example solution:

black = (0, 0, 0)
white = (255, 255, 255)
toolscanvas = pygame.Surface((700, 120))

pygame.init()
gameDisplay = pygame.display.set_mode((0, 0), pygame.FULLSCREEN)
gameDisplay.fill(black)
gameDisplay.convert()
clock = pygame.time.Clock()


class GuiHouse:
    def __init__(self):
        self.x = 0
        self.y = 20
        self.canvas = pygame.Surface((300, 300))
        self.canvas.set_alpha(128)
        self.canvas.fill(white)
        self.iconed = pygame.image.load("house_icon.png").convert_alpha()
        self.iconed = pygame.transform.scale(self.iconed, (60, 60))

    def display(self):
        global toolscanvas
        toolscanvas.fill((0, 0, 0))
        self.canvas.blit(self.iconed, (0, 0))
        toolscanvas.blit(self.canvas, (self.x, self.y))
        gameDisplay.blit(toolscanvas, (0, 0))

guihouse = GuiHouse()
while True:
    guihouse.display()
    pygame.display.update()
    clock.tick(120)