Updating part of a surface in python, or transparent surfaces
I have an application written in python that's basically an etch-a-sketch, you move pixels around with WASD and arrow keys and it leaves a trail. However, I want to add a counter for the amount of pixels on the screen. How do I have the counter update without updating the entire surface and pwning the pixel drawings?
Alternatively, can I make a surface that's completely transparent except for the text so you can see the drawing surface underneath?
Asked by: Carlos636 | Posted: 30-11-2021
To solve this problem, you want to have a separate surface for your Etch-a-Sketch pixels, so that they do not get clobbered when you go to refresh the screen. Unfortunately, with Rigo's scheme, the font will continue to render on top of itself, which will get messy for more than two pixel count changes.
So, here's some sample rendering code:
# Fill background screen.fill((0xcc, 0xcc, 0xcc)) # Blit Etch-a-Sketch surface (with the drawing) # etch_surf should be the same size as the screen screen.blit(etch_surf, (0, 0)) # Render the pixel count arial = pygame.font.SysFont('Arial', 20) counter_surf = arial.render(str(pixel_count), True, (0, 0, 0)) screen.blit(counter_surf, (16, 16)) # Refresh entire screen pygame.display.update()
Now, admittedly, updating the entire screen is rather inefficient. For this, you have two options: only refresh the screen when the drawing changes or track the location of drawing changes and refresh individual locations (see the update documentation). If you choose the second option, you will have to refresh the text and where it was previously; I would recommend having a Sprite manage this.Answered by: Sydney975 | Posted: 01-01-2022
What you need is pygame.font module
#define a font surface spamSurface = pygame.font.SysFont('Arial', 20) #then, in your infinite cycle... eggsPixels = spamSurface.render(str(pixelsOnScreen), True, (255, 255, 255)) hamDisplay.blit(eggsPixels, (10, 10))
spamSurface is a new font surface,
eggsPixels is the value that
spamSurface will render (display/show) and
hamDisplay is your main surface display.
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