Article pygame drag the implementation of the method

The effect is as follows:

Take the volume adjustment as an example, first draw a horizontal line and a solid circle, the specific position and size can be specified by yourself:

# filled circle abscissa positionVPOS = 300# Draw a horizontal straight line, the parameters are (surface, color, start_pos, end_pos, width)pygame.draw.line(self.screen, self.BLUE, (150, 900), (450, 900), 5)# Draw a solid circle as a button, the parameters are (surface, color, center, radius, width)volume_button = pygame.draw.circle(self.screen, self.GREEN, (VPOS, 900), 10, width=0)

In order to make the drag feel better, we can drag the position of the circle as long as the button is pressed until it is lifted.To this end, we set the variable value volume_state. When the value is 0, the filled circle will not change position with the mouse; when the value is 1, it will change with the mouse.Under normal conditions, the value is 0. When the mouse is pressed on the solid circle, we set the value to 1, and the value changes back to 0 until the mouse is lifted.

# default is not adjustablevolume_state = 0# pygame loopwhile running:# When it is detected that the mouse is pressed at the button, the button position and volume can be adjustedif pygame.mouse.get_pressed()[0]:if volume_button.collidepoint(pos):volume_state = 1# When it is detected that the mouse is lifted, the adjustment is stopped, and it cannot be changed after the next mouse pressfor event in pygame.event.get():if event.type == pygame.MOUSEBUTTONUP and volume_state:volume_state = 0# Get the current position of the mousepos = pygame.mouse.get_pos()# The specific process of adjusting the volumeif volume_state:# The position of the circle is the same as the position of the horizontal coordinate of the mouseVPOS = pos[0]# Limit the position of the button center to the horizontal lineif VPOS > 450:VPOS = 450elif VPOS < 150:VPOS = 150# Actual volume valuevolume = (VPOS - 150) / 300.0