Add texture display bounds for non-uniform sprite content, closes #235

Textures can now specify display_size and display_origin to crop sprite
rendering to a sub-region within each atlas cell. This supports texture
atlases where content doesn't fill the entire cell (e.g., 16x24 sprites
centered in 32x32 cells).

API: Texture("sprites.png", 32, 32, display_size=(16, 24), display_origin=(8, 4))
Properties: display_width, display_height, display_offset_x, display_offset_y

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/unit/texture_display_bounds_test.py

@@ -0,0 +1,60 @@
+"""Test texture display bounds for non-uniform sprite content (#235).
+
+Verifies that Texture accepts display_size and display_origin parameters
+to crop sprite rendering to a sub-region within each atlas cell.
+"""
+import mcrfpy
+import sys
+
+def test_default_display_bounds():
+    """Without display bounds, display dims equal sprite dims."""
+    tex = mcrfpy.Texture("assets/kenney_tinydungeon.png", 16, 16)
+    assert tex.display_width == 16, f"Expected 16, got {tex.display_width}"
+    assert tex.display_height == 16, f"Expected 16, got {tex.display_height}"
+    assert tex.display_offset_x == 0, f"Expected 0, got {tex.display_offset_x}"
+    assert tex.display_offset_y == 0, f"Expected 0, got {tex.display_offset_y}"
+    print("  PASS: default display bounds")
+
+def test_custom_display_size():
+    """display_size crops sprite content within cells."""
+    tex = mcrfpy.Texture("assets/kenney_tinydungeon.png", 16, 16,
+                         display_size=(12, 14))
+    assert tex.display_width == 12, f"Expected 12, got {tex.display_width}"
+    assert tex.display_height == 14, f"Expected 14, got {tex.display_height}"
+    assert tex.sprite_width == 16, f"sprite_width should be unchanged: {tex.sprite_width}"
+    assert tex.sprite_height == 16, f"sprite_height should be unchanged: {tex.sprite_height}"
+    print("  PASS: custom display size")
+
+def test_custom_display_origin():
+    """display_origin offsets content within cells."""
+    tex = mcrfpy.Texture("assets/kenney_tinydungeon.png", 16, 16,
+                         display_size=(12, 14), display_origin=(2, 1))
+    assert tex.display_offset_x == 2, f"Expected 2, got {tex.display_offset_x}"
+    assert tex.display_offset_y == 1, f"Expected 1, got {tex.display_offset_y}"
+    print("  PASS: custom display origin")
+
+def test_display_bounds_sprite_creation():
+    """Sprites created from bounded textures should work in UI elements."""
+    tex = mcrfpy.Texture("assets/kenney_tinydungeon.png", 16, 16,
+                         display_size=(12, 14), display_origin=(2, 1))
+    sprite = mcrfpy.Sprite(pos=(10, 10), texture=tex, sprite_index=0)
+    assert sprite is not None, "Sprite creation with display bounds failed"
+    print("  PASS: sprite creation with display bounds")
+
+def test_display_bounds_in_grid():
+    """Entities using bounded textures should render in grids."""
+    tex = mcrfpy.Texture("assets/kenney_tinydungeon.png", 16, 16,
+                         display_size=(12, 14), display_origin=(2, 1))
+    grid = mcrfpy.Grid(grid_size=(10, 10), texture=tex)
+    entity = mcrfpy.Entity(grid_pos=(3, 3), texture=tex, sprite_index=5, grid=grid)
+    assert entity is not None, "Entity creation with display bounds failed"
+    print("  PASS: entity with display bounds in grid")
+
+print("Testing #235: Texture display bounds...")
+test_default_display_bounds()
+test_custom_display_size()
+test_custom_display_origin()
+test_display_bounds_sprite_creation()
+test_display_bounds_in_grid()
+print("All #235 tests passed.")
+sys.exit(0)