add implementation

Author: mattlink

.gitignore

@@ -1 +1,2 @@
 venv
+.vscode

examples/hello-ncurses.py

@@ -0,0 +1,26 @@
+import pyxp
+image_layers = pyxp.load("hello.xp")
+layer = image_layers[0]
+pos = lambda x, y: x + y * layer.height
+
+from curses import wrapper
+import _curses
+import locale
+
+def main(stdscr):
+    locale.setlocale(locale.LC_ALL, '')
+    stdscr.clear()    
+    for i in range(layer.width):
+        for j in range(layer.height):
+            tile = layer.tiles[pos(i, j)]
+            try:
+                char = tile.ascii_code.decode("cp437")
+                char = char.replace(chr(0), "")
+                stdscr.addstr(i, j, char)
+            except _curses.error:
+                pass
+    
+    stdscr.refresh()
+    stdscr.getkey()
+
+wrapper(main)

examples/hello.xp

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+[build-system]
+requires = [
+    "setuptools>=42",
+    "wheel"
+]
+build-backend = "setuptools.build_meta"

pyproject.toml

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+[metadata]
+name = pyxp-mattlink
+version = 0.0.1
+author = Matt Link
+author_email = author@example.com
+description = A small REXPaint .xp file loader
+long_description = file: README.md
+long_description_content_type = text/markdown
+url = https://github.com/mattlink/pyxp
+project_urls =
+    Bug Tracker = https://github.com/mattlink/pyxp/issues
+classifiers =
+    Programming Language :: Python :: 3
+    License :: OSI Approved :: GPL
+    Operating System :: OS Independent
+
+[options]
+package_dir =
+    = src
+packages = find:
+python_requires = >=3.6
+
+[options.packages.find]
+where = src

setup.cfg

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+import gzip
+from typing import List
+from dataclasses import dataclass
+
+META_SIZE = 8
+META_OFFSETS = {
+    "version": (0,4),
+    "layers": (4,8),
+}
+
+# offsets relative to a given layer context (starting byte)
+LAYER_META_SIZE = 8
+LAYER_META_OFFSETS = {
+    "width": (0, 4),
+    "height": (4, 8),
+}
+
+# offests relative to given image contxt within layer
+TILE_SIZE = 10
+TILE_OFFSETS = {
+    "ascii": (0, 4),
+    "fg_r": (4, 5),
+    "fg_g": (5, 6),
+    "fg_b": (6, 7),
+    "bg_r": (7, 8),
+    "bg_g": (8, 9),
+    "bg_b": (9, 10),
+}
+
+def load_offset_raw(xp_data: bytes, offsets: dict, offset_key: str) -> str:
+    offset = offsets.get(offset_key)
+    assert offset, f"No offset found for {offset_key}"
+    return xp_data[offset[0]:offset[1]]
+
+def load_offset(xp_data: bytes, offsets: dict, offset_key: str) -> int:
+    offset = offsets.get(offset_key)
+    assert offset, f"No offset found for {offset_key}"
+    return int.from_bytes(
+        xp_data[offset[0]:offset[1]],
+        byteorder="little"
+    )
+
+
+@dataclass
+class Tile:
+    ascii_code: str
+    fg_r: str
+    fg_g: str
+    fg_b: str
+    bg_r: str
+    bg_g: str
+    bg_b: str
+
+
+@dataclass
+class ImageLayer:
+    width: int
+    height: int
+    tiles: List[Tile]
+
+
+def load(file_name: str) -> List[ImageLayer]:
+    images = []
+
+    xp_data = gzip.open(file_name).read()
+ 
+    version = load_offset(xp_data, META_OFFSETS, "version")
+    layers = load_offset(xp_data, META_OFFSETS, "layers")
+
+    # Reset offset context (we're done parsing metadata)
+    xp_data = xp_data[META_SIZE:] 
+
+    for layer in range(layers):
+        image_width = load_offset(xp_data, LAYER_META_OFFSETS, "width")
+        image_height = load_offset(xp_data, LAYER_META_OFFSETS, "height")
+
+        image = ImageLayer(image_width, image_height, [])
+
+        # Reset layer offset context
+        xp_data = xp_data[LAYER_META_SIZE:]
+
+        num_tiles = image_width * image_height
+        for tile in range(num_tiles):
+            
+            ascii_code = load_offset_raw(xp_data, TILE_OFFSETS, "ascii")
+            fg_r = load_offset(xp_data, TILE_OFFSETS, "fg_r")
+            fg_g = load_offset(xp_data, TILE_OFFSETS, "fg_g")
+            fg_b = load_offset(xp_data, TILE_OFFSETS, "fg_b")
+            bg_r = load_offset(xp_data, TILE_OFFSETS, "bg_r")
+            bg_g = load_offset(xp_data, TILE_OFFSETS, "bg_g")
+            bg_b = load_offset(xp_data, TILE_OFFSETS, "bg_b")
+
+            image.tiles.append(Tile(ascii_code, fg_r, fg_g, fg_b, bg_r, bg_g, bg_b))
+
+            # Reset tile offset context
+            xp_data = xp_data[TILE_SIZE:]
+
+        images.append(image)
+
+    return images