Route app frame decisions through app core

src/app_core/app_frame.h

@@ -0,0 +1,56 @@
+#pragma once
+
+namespace pp::app {
+
+struct AppInitialSurfacePlan {
+    float width = 960.0F;
+    float height = 540.0F;
+};
+
+struct AppFrameUpdatePlan {
+    bool update_frame = false;
+    bool update_layouts = false;
+    bool refresh_canvas_toolbar = false;
+};
+
+struct AppFrameDrawPlan {
+    bool draw_canvas_stroke = false;
+    bool draw_vr_ui = false;
+    bool draw_main_ui = true;
+    bool reset_redraw = true;
+};
+
+[[nodiscard]] constexpr AppInitialSurfacePlan plan_app_initial_surface() noexcept
+{
+    return AppInitialSurfacePlan {
+        .width = 1920.0F / 2.0F,
+        .height = 1080.0F / 2.0F,
+    };
+}
+
+[[nodiscard]] constexpr AppFrameUpdatePlan plan_app_frame_update(bool redraw, bool animate) noexcept
+{
+    const bool update_frame = redraw || animate;
+    return AppFrameUpdatePlan {
+        .update_frame = update_frame,
+        .update_layouts = update_frame,
+        .refresh_canvas_toolbar = update_frame,
+    };
+}
+
+[[nodiscard]] constexpr AppFrameDrawPlan plan_app_frame_draw(
+    bool has_canvas_node,
+    bool has_canvas_document,
+    bool vr_active,
+    bool ui_visible,
+    bool vr_only) noexcept
+{
+    return AppFrameDrawPlan {
+        .draw_canvas_stroke = has_canvas_node && has_canvas_document,
+        .draw_vr_ui = vr_active && ui_visible,
+        .draw_main_ui = !vr_only,
+        .reset_redraw = true,
+    };
+}
+
+} // namespace pp::app