Add support for single-image tile sets (not yet tested).

2 files changed, 151 insertions, 63 deletions

diff --git a/include/isogfx/asset.h b/include/isogfx/asset.h
index 9aeb55d..6050500 100644
--- a/include/isogfx/asset.h
+++ b/include/isogfx/asset.h
@@ -25,8 +25,15 @@ typedef struct Ts_Tile {
   uint32_t pixels; // Byte offset into the Ts_TileSet's 'pixels'.
 } Ts_Tile;
 
+// Tileset.
+//
+// Tile dimensions may be larger than the baseline tile dimensions of the
+// tileset if the tileset contains supertiles. Regardless, tile dimensions are
+// always a multiple of baseline dimensions along each axis.
 typedef struct Ts_TileSet {
   uint16_t num_tiles;
+  uint16_t tile_width;  // Baseline tile width.
+  uint16_t tile_height; // Baseline tile height.
   uint16_t _pad;
   Ts_Tile  tiles[1]; // Count: num_tiles.
   Pixel    pixels[]; // Count: sum_i(tile[i].width * tile[i].height).
@@ -64,8 +71,8 @@ typedef struct Tm_Map {
 ///
 /// Pixels are 8-bit indices into the sprite sheet's colour palette.
 typedef struct Ss_Row {
-  uint16_t num_cols;  /// Number of columns in this row.
-  uint8_t  pixels[1]; /// Count: num_cols * sprite_width * sprite_height.
+  uint16_t num_cols;  // Number of columns in this row.
+  uint8_t  pixels[1]; // Count: num_cols * sprite_width * sprite_height.
 } Ss_Row;
 
 typedef struct Ss_Palette {
@@ -77,11 +84,11 @@ typedef struct Ss_Palette {
 ///
 /// Sprite width and height are assumed constant throughout the sprite sheet.
 typedef struct Ss_SpriteSheet {
-  uint16_t   sprite_width;  /// Sprite width in pixels.
-  uint16_t   sprite_height; /// Sprite height in pixels.
+  uint16_t   sprite_width;  // Sprite width in pixels.
+  uint16_t   sprite_height; // Sprite height in pixels.
   uint16_t   num_rows;
-  Ss_Palette palette; /// Variable size.
-  Ss_Row     rows[1]; /// Count: num_rows. Variable offset.
+  Ss_Palette palette; // Variable size.
+  Ss_Row     rows[1]; // Count: num_rows. Variable offset.
 } Ss_SpriteSheet;
 
 // -----------------------------------------------------------------------------
diff --git a/tools/mkasset.py b/tools/mkasset.py
index ae27ead..9b9dc76 100644
--- a/tools/mkasset.py
+++ b/tools/mkasset.py
@@ -13,6 +13,7 @@
 import argparse
 import ctypes
 import sys
+from typing import Generator
 from xml.etree import ElementTree
 
 from PIL import Image
@@ -26,7 +27,7 @@ def drop_extension(filepath):
     return filepath[:filepath.rfind('.')]
 
 
-def to_char_array(string, length):
+def to_char_array(string, length) -> bytes:
     """Convert a string to a fixed-length ASCII char array.
 
     The length of str must be at most length-1 so that the resulting string can
@@ -38,58 +39,134 @@ def to_char_array(string, length):
     return chars + nulls
 
 
+def load_image(path) -> bytes:
+    """Load an image as an array of RGBA bytes."""
+    with Image.open(path) as im:
+        return im.convert('RGBA').tobytes()
+
+
+def carve_image(rgba_bytes, tile_width, tile_height, columns) -> Generator[bytearray]:
+    """Carve out individual tiles from a single-image tile set."""
+    # Image dimensions in pixels.
+    image_width = columns * tile_width
+    image_height = len(rgba_bytes) // image_width // 4
+
+    tiles_x = image_width // tile_width
+    tiles_y = image_height // tile_height
+
+    tile_bytes = bytearray(tile_width * tile_height * 4)
+    for i in range(tiles_y):
+        image_y0 = i * tile_height  # y-origin of tile inside image
+        for j in range(tiles_x):
+            image_x0 = j * tile_width  # x-origin of tile inside image
+            for y in range(tile_height):
+                image_y = image_y0 + y  # y of current pixel inside image
+                for x in range(tile_width):
+                    image_x = image_x0 + x  # x of current pixel inside image
+                    tile_bytes[(y * tile_width + x) * 4] = (
+                        rgba_bytes)[(image_y * image_width + image_x) * 4]
+            yield tile_bytes.copy()
+
+
 def convert_tsx(input_filepath, output_filepath):
     """Converts a Tiled .tsx tileset file to a .TS tile set file."""
     xml = ElementTree.parse(input_filepath)
-    root = xml.getroot()
+    tileset = xml.getroot()
+    assert (tileset.tag == "tileset")
 
-    tile_count = int(root.attrib["tilecount"])
-    max_tile_width = int(root.attrib["tilewidth"])
-    max_tile_height = int(root.attrib["tileheight"])
+    # Header.
+    tileset_tile_count = int(tileset.attrib["tilecount"])
+    tileset_tile_width = int(tileset.attrib["tilewidth"])
+    tileset_tile_height = int(tileset.attrib["tileheight"])
 
-    print(f"Tile count: {tile_count}")
-    print(f"Max width:  {max_tile_width}")
-    print(f"Max height: {max_tile_height}")
+    print(f"Tile count:  {tileset_tile_count}")
+    print(f"Tile width:  {tileset_tile_width}")
+    print(f"Tile height: {tileset_tile_height}")
 
     pixels = []  # List of byte arrays
     pixels_offset = 0
 
+    def output_tile(output, tile_width, tile_height, tile_image_bytes):
+        # Expecting RGBA pixels.
+        assert (len(tile_image_bytes) == (tile_width * tile_height * 4))
+
+        nonlocal pixels_offset
+        tile_pixels_offset = pixels_offset
+        pixels.append(tile_image_bytes)
+        pixels_offset += len(tile_image_bytes)
+
+        output.write(ctypes.c_uint16(tile_width))
+        output.write(ctypes.c_uint16(tile_height))
+        output.write(ctypes.c_uint32(tile_pixels_offset))
+
     with open(output_filepath, 'bw') as output:
         # Write the header.
-        output.write(ctypes.c_uint16(tile_count))
-        # output.write(ctypes.c_uint16(max_tile_width))
-        # output.write(ctypes.c_uint16(max_tile_height))
+        output.write(ctypes.c_uint16(tileset_tile_count))
+        output.write(ctypes.c_uint16(tileset_tile_width))
+        output.write(ctypes.c_uint16(tileset_tile_height))
         output.write(ctypes.c_uint16(0))  # Pad.
 
+        # A tileset made up of multiple images contains various 'tile' children,
+        # each with their own 'image':
+        #
+        #   <tile id="0">
+        #     <image width="32" height="32" source="separated images/tile_000.png"/>
+        #   </tile>
+        #   <tile id="1">
+        #     <image width="32" height="32" source="separated images/tile_001.png"/>
+        #   </tile>
+        #
+        # A tileset made up of a single image contains a single 'image' child:
+        #
+        #   <image source="tileset.png" width="416" height="368"/>
         num_tile = 0
-        for tile in root:
-            # Skip the "grid" and other non-tile elements.
-            if not tile.tag == "tile":
-                continue
-
-            # Assuming tiles are numbered 0..N.
-            tile_id = int(tile.attrib["id"])
-            assert (tile_id == num_tile)
-            num_tile += 1
-
-            image = tile[0]
-            tile_width = int(image.attrib["width"])
-            tile_height = int(image.attrib["height"])
-            tile_path = image.attrib["source"]
-
-            assert (tile_width > 0)
-            assert (tile_height > 0)
-
-            tile_pixels_offset = pixels_offset
-            with Image.open(tile_path) as im:
-                bytes = im.convert('RGBA').tobytes()
-                pixels.append(bytes)
-                pixels_offset += len(bytes)
-
-            # Write the tile.
-            output.write(ctypes.c_uint16(tile_width))
-            output.write(ctypes.c_uint16(tile_height))
-            output.write(ctypes.c_uint32(tile_pixels_offset))
+        for child in tileset:
+            if child.tag == "image":
+                # This is a single-image tileset.
+                image = child
+                image_path = image.attrib["source"]
+                image_bytes = load_image(image_path)
+
+                # We expect the 'columns' attribute to be >0 for a single-image
+                # tile set.
+                columns = int(tileset.attrib["columns"])
+                assert (columns > 0)
+
+                # Tile dimensions are those given by the tileset's baseline width and height.
+                tile_width = tileset_tile_width
+                tile_height = tileset_tile_height
+
+                # Cut each of the WxH tiles, and store them in the output in "tile order".
+                for tile_bytes in carve_image(image_bytes, tile_width, tile_height, columns):
+                    output_tile(output, tile_width, tile_height, tile_bytes)
+
+                # Make sure not to process 'tile' elements, which may exist in
+                # a single-image tileset to define probabilities, for example.
+                break
+
+            elif child.tag == "tile":
+                # This is a tile image in a tileset made of a collection of images.
+                tile = child
+
+                # We assume that tiles are numbered 0..N-1. Assert this.
+                tile_id = int(tile.attrib["id"])
+                assert (tile_id == num_tile)
+                num_tile += 1
+
+                image = tile[0]
+                tile_width = int(image.attrib["width"])
+                tile_height = int(image.attrib["height"])
+                image_path = image.attrib["source"]
+
+                # Tile dimensions must be a multiple of the tileset's baseline
+                # tile width and height.
+                assert (tile_width > 0)
+                assert (tile_height > 0)
+                assert ((tile_width % tileset_tile_width) == 0)
+                assert ((tile_height % tileset_tile_height) == 0)
+
+                image_bytes = load_image(image_path)
+                output_tile(output, tile_width, tile_height, image_bytes)
 
         # Write the pixel data.
         for bytes in pixels:
@@ -273,6 +350,8 @@ def convert_sprite_sheet(input_file_paths, sprite_width, sprite_height,
         # getpalette() also returns a flattened list, which is why we must *4.
         num_colours = len(im.getcolors())
         colours = im.getpalette(rawmode="RGBA")[:4 * num_colours]
+        # TODO: This palette list does not seem really necessary.
+        #  Define palette = bytearray(im.getpalette(...))
         palette = []
         for i in range(0, 4 * num_colours, 4):
             palette.append((colours[i], colours[i + 1], colours[i + 2],
@@ -310,36 +389,38 @@ def convert_sprite_sheet(input_file_paths, sprite_width, sprite_height,
 
 
 def main():
-    # TODO: Use subparser for each type of input file.
+    # TODO: Use a subparser for each type of input file for clarity of arguments.
     parser = argparse.ArgumentParser()
-    parser.add_argument("input",
-                        nargs="+",
-                        help="Input file (.tsx, .tmx) or path regex (sprite sheets)")
-    parser.add_argument("-W", "--width", type=int, help="Sprite width in pixels")
-    parser.add_argument("-H", "--height", type=int, help="Sprite height in pixels")
-    parser.add_argument("-o", "--out", help="Output file (sprite sheets)")
+    subparsers = parser.add_subparsers(dest="command")
+    # Tile sets.
+    tileset_parser = subparsers.add_parser("tileset")
+    tileset_parser.add_argument("input", help="Input file (.tsx)")
+    # Tile maps.
+    tilemap_parser = subparsers.add_parser("tilemap")
+    tilemap_parser.add_argument("input", help="Input file (.tmx)")
+    # Sprite sheet.
+    sprite_parser = subparsers.add_parser("sprite")
+    sprite_parser.add_argument("input", nargs="+", help="Input files")
+    sprite_parser.add_argument("-W", "--width", type=int, required=True, help="Sprite width in pixels")
+    sprite_parser.add_argument("-H", "--height", type=int, required=True, help="Sprite height in pixels")
+    sprite_parser.add_argument("-o", "--out", help="Output file")
     args = parser.parse_args()
 
-    # TODO: Add support for TSX files made from a single image. Currently, only collections are supported.
-    if ".tsx" in args.input[0]:
-        args.input = args.input[0]  # TODO: Remove this.
+    if args.command == "tileset":
+        print(f"Processing: {args.input}")
         output_filepath_no_ext = drop_extension(args.input)
         output_filepath = output_filepath_no_ext + ".ts"
         convert_tsx(args.input, output_filepath)
-    elif ".tmx" in args.input[0]:
-        args.input = args.input[0]  # TODO: Remove this.
+    elif args.command == "tilemap":
+        print(f"Processing: {args.input}")
         output_filepath_no_ext = drop_extension(args.input)
         output_filepath = output_filepath_no_ext + ".tm"
         convert_tmx(args.input, output_filepath)
-    else:
-        # Sprite sheets.
-        if not args.width or not args.height:
-            print("Sprite width and height must be given")
-            return 1
+    elif args.command == "sprite":
+        print(f"Processing: {args.input}")
         output_filepath = args.out if args.out else "out.ss"
         convert_sprite_sheet(args.input, args.width, args.height,
                              output_filepath)
-
     return 0