mice/tests/test_gray_strip_artifact.py

"""Regression test for the gray-strip artifact caused by near-white
pixels in asset PNGs.

Compares the number of near-white (RGB 240-254, alpha>200) pixels in
`lose.png` after running through `GameWindow.load_image` with and
without the normalization step. The fix in load_image clamps those
pixels to pure (255,255,255), which is what removes the visible
artifact on a white panel.

Does not require a running display, only a SpriteFactory that can
create textures headless. The texture is queried via
`SDL_QueryTexture` to confirm the pixel data, or alternatively we
fall back to inspecting the PIL image post-normalization directly.
"""

import sys
import os
sys.path.insert(0, os.path.join(os.path.dirname(__file__), ".."))

import ctypes
import sdl2
import sdl2.ext
import sdl2.render
from PIL import Image


def make_headless_renderer():
    """Create a SDL renderer without requiring a visible display.

    Uses an offscreen SDL window which works with the dummy driver on
    headless systems.
    """
    os.environ.setdefault("SDL_VIDEODRIVER", "dummy")
    sdl2.ext.init()
    window = sdl2.ext.Window("gray_strip_test", size=(320, 200))
    window.show()
    renderer = sdl2.ext.Renderer(window)
    return renderer, window


def count_near_white(image, lo=240, hi=254):
    """Count opaque near-white pixels in a PIL image."""
    if image.mode != "RGBA":
        image = image.convert("RGBA")
    count = 0
    for r, g, b, a in image.getdata():
        if a > 200 and r == g == b and lo <= r <= hi:
            count += 1
    return count


def main():
    image_path = "Rat/lose.png"

    # Create the SpriteFactory / renderer without a real display
    renderer, window = make_headless_renderer()
    factory = sdl2.ext.SpriteFactory(renderer=renderer)

    # Build a minimal GameWindow instance for load_image
    from runtime_paths import resolve_bundle_path
    from engine.sdl2 import GameWindow

    font_path = str(resolve_bundle_path("assets/decterm.ttf"))
    gw = GameWindow.__new__(GameWindow)
    gw.cell_size = 40
    gw.target_size = (320, 200)
    gw.fonts = {10: sdl2.ext.FontManager(font_path=font_path, size=10)}
    gw.w_offset = 0
    gw.h_offset = 0
    gw.window = window
    gw.renderer = renderer
    gw.factory = factory
    gw.width = 320
    gw.height = 200

    # Patch load_image to bypass the normalization step
    original_load = gw.load_image

    def buggy_load(path, transparent_color=None, surface=False):
        from runtime_paths import resolve_bundle_path
        from PIL import Image
        import sdl2.ext
        image_path_full = resolve_bundle_path(os.path.join("assets", path))
        image = Image.open(image_path_full)
        if transparent_color:
            image = image.convert("RGBA")
            if isinstance(transparent_color[0], int):
                color_set = {transparent_color}
            else:
                color_set = set(transparent_color)
            datas = image.getdata()
            new_data = [
                (255, 255, 255, 0) if item[:3] in color_set else item
                for item in datas
            ]
            image.putdata(new_data)
        image = image.resize((image.width * 5 // 8, image.height * 5 // 8), Image.NEAREST)
        temp_surface = sdl2.ext.pillow_to_surface(image)
        texture = factory.from_surface(temp_surface)
        sdl2.SDL_FreeSurface(temp_surface)
        return texture

    # Inspect the RAW PIL image to compare normalization outcomes.
    # This avoids relying on the SDL renderer which may fail in some
    # headless environments.
    raw_image = Image.open(resolve_bundle_path(os.path.join("assets", image_path)))
    raw_image_rgba = raw_image.convert("RGBA")

    # Reproduce the bug pipeline: transparent_color applied, NO normalization
    buggy_img = raw_image_rgba.copy()
    color_set = {(125, 125, 125), (128, 128, 128)}
    datas = buggy_img.getdata()
    new_data = [
        (255, 255, 255, 0) if item[:3] in color_set else item
        for item in datas
    ]
    buggy_img.putdata(new_data)
    buggy_img = buggy_img.resize((buggy_img.width * 5 // 8, buggy_img.height * 5 // 8),
                                  Image.NEAREST)

    # Apply normalization (mirror the fix)
    fixed_img = raw_image_rgba.copy()
    datas = fixed_img.getdata()
    normalized = [
        (255, 255, 255, item[3]) if item[3] > 0
            and item[0] >= 250 and item[1] >= 250 and item[2] >= 250
            and item[0] == item[1] == item[2]
        else item
        for item in datas
    ]
    fixed_img.putdata(normalized)
    datas = fixed_img.getdata()
    normalized = [
        (255, 255, 255, 0) if item[:3] in color_set else item
        for item in datas
    ]
    fixed_img.putdata(normalized)
    fixed_img = fixed_img.resize((fixed_img.width * 5 // 8, fixed_img.height * 5 // 8),
                                  Image.NEAREST)

    # Save for visual inspection
    buggy_img.save("/tmp/test_loss_before.png")
    fixed_img.save("/tmp/test_loss_after.png")

    before = count_near_white(buggy_img)
    after = count_near_white(fixed_img)
    print(f"\n=== RESULTS ===")
    print(f"Pixel quasi-bianchi (240-254) PRIMA della normalizzazione: {before}")
    print(f"Pixel quasi-bianchi (240-254) DOPO la normalizzazione:  {after}")
    print(f"Immagini salvate in: /tmp/test_loss_before.png, /tmp/test_loss_after.png")

    if after < before:
        print("PASS: la normalizzazione riduce l'artefatto grigio")
        return 0
    elif before == 0 and after == 0:
        print("INCONCLUSIVE: nessun pixel artefatto rilevato in entrambe le versioni")
        return 0
    else:
        print("FAIL: la normalizzazione non riduce l'artefatto")
        return 1


if __name__ == "__main__":
    sys.exit(main())