Add font loader

pytools/.gitignore

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+venv/

pytools/BUILD

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+load("@pytools_deps//:requirements.bzl", "requirement")
+
+py_binary(
+    name = "font",
+    srcs = ["font.py"],
+    deps = [
+        requirement("pillow"),
+    ],
+    visibility = ["//visibility:public"],
+)

pytools/font.py

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+from typing import Tuple
+from PIL import Image
+import sys
+
+
+def main(font_name, n_glyphs, fname_png, fname_c):
+    glyphs = load_glyphs(fname_png)
+    assert(len(glyphs) == n_glyphs), f"must be exactly {n_glyphs} glyphs"
+
+    with open(fname_c, "wt") as output:
+        output.writelines([
+            "// generated code! be nice!\n",
+            "#include \"sys/sys.h\";\n",
+            f"sys_glyph {font_name}[{n_glyphs}] = {{{', '.join(str(g) for g in glyphs)}}};\n"
+        ])
+
+
+def load_glyphs(fname_png: str):
+    with Image.open(fname_png) as im:
+        width = im.width
+        height = im.height
+
+        assert width % 8 == 0, "width must be a multiple of 8"
+        assert height % 8 == 0, "height must be a multiple of 8"
+
+        data = list(im.convert("RGBA").getdata())
+        monochrome = [pixel_to_monochrome(p) for p in data]
+
+        glyphs = []
+        for gy in range(0, height, 8):
+            for gx in range(0, width, 8):
+                glyph = 0
+                for py in range(0, 8):
+                    for px in range(0, 8):
+                        x = gx + px
+                        y = gy + py
+                        if monochrome[y * width + x]:
+                            glyph |= 1 << (py * 8 + px)
+                glyphs.append(glyph)
+
+        return glyphs
+
+
+def pixel_to_monochrome(rgba: Tuple[int, int, int, int]):
+    if rgba[3] < 128: return False
+    if (rgba[0] + rgba[1] + rgba[2])/3 < 128: return False
+    return True
+
+
+if __name__ == "__main__":
+    assert len(sys.argv) == 5, \
+        "there must be four args (font name, n glyphs, src png, out c)"
+    main(sys.argv[1], int(sys.argv[2]), sys.argv[3], sys.argv[4])

pytools/requirements.txt

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+pillow==10.2.0