step 3: add widget shell and renderer foundation

tests/test_step3_widget_renderer.py

@@ -0,0 +1,78 @@
+# pyright: reportGeneralTypeIssues=false
+
+from collections.abc import Generator
+
+import dearpygui.dearpygui as dpg
+import pytest
+
+import dpg_gauges as dpgg
+from dpg_gauges.state import clear_registry, get_gauge_state
+
+
+@pytest.fixture
+def dpg_context() -> Generator[None]:
+    clear_registry()
+    dpgg.configure()
+    dpg.create_context()
+    try:
+        yield
+    finally:
+        clear_registry()
+        dpg.destroy_context()
+
+
+def test_dpg_gauge_shell_registers_before_yield(dpg_context: None) -> None:
+    with (
+        dpg.window(label="Smoke"),
+        dpgg.digital_gauge(tag="speed", label="Speed", value=42, width=180, height=80) as config,
+    ):
+        state = get_gauge_state("speed")
+        assert config.tag == "speed"
+        assert state.renderer is not None
+        assert dpg.does_item_exist(state.container_tag)
+        assert state.drawlist_tag is not None
+        assert dpg.does_item_exist(state.drawlist_tag)
+
+
+def test_runtime_update_redraws_attached_gauge(dpg_context: None) -> None:
+    with dpg.window(label="Smoke"):
+        dpgg.digital_gauge(tag="rpm", label="RPM", value=1000, max_value=8000, width=200, height=90)
+
+    dpgg.set_value("rpm", 2500)
+
+    state = get_gauge_state("rpm")
+    debug = dpgg.get_gauge_debug_state("rpm")
+    assert state.displayed_value == 2500
+    assert state.dirty == 0
+    assert debug["renderer"]["drawlist_tag"] == "rpm__drawlist"
+    assert "rpm__value" in debug["renderer"]["layers"]["dynamic"]
+
+
+def test_hidden_gauge_preserves_configured_size(dpg_context: None) -> None:
+    with dpg.window(label="Hidden"):
+        dpgg.digital_gauge(tag="hidden", value=1, width=160, height=70, show=False)
+
+    state = get_gauge_state("hidden")
+    assert state.measured_width == 160
+    assert state.measured_height == 70
+    assert state.last_nonzero_width == 160
+    assert state.last_nonzero_height == 70
+
+    dpgg.set_show("hidden", True)
+    assert dpg.does_item_exist(state.container_tag)
+    assert state.config.show is True
+
+
+def test_panel_and_grid_are_lightweight_containers(dpg_context: None) -> None:
+    with (
+        dpg.window(label="Dashboard"),
+        dpgg.gauge_panel(tag="engine", label="Engine", width=300, height=180) as panel,
+        dpgg.gauge_grid(tag="engine_grid", columns=2) as grid,
+    ):
+        assert panel == "engine"
+        assert grid == "engine_grid"
+        dpgg.digital_gauge(tag="temp", label="Temp", value=90, width=120, height=60)
+
+    assert dpg.does_item_exist("engine")
+    assert dpg.does_item_exist("engine_grid")
+    assert get_gauge_state("temp").renderer is not None