initial commit; cv 0.0.3

Api/CanvasPanel.hpp

@@ -0,0 +1,32 @@
+#pragma once
+
+#include "PanelWidget.hpp"
+#include "CanvasPanelSlot.hpp"
+
+namespace PalUIExtension::Api
+{
+    // UCanvasPanel adds exactly one function of its own. Everything else
+    // it offers comes from UPanelWidget and UWidget, which is now inherited
+    // rather than re-declared.
+    class CanvasPanel : public PanelWidget
+    {
+    public:
+        static auto ClassPath() -> const TCHAR* { return STR("/Script/UMG.CanvasPanel"); }
+        static auto DebugTag()  -> const TCHAR* { return STR("Canvas"); }
+
+        CanvasPanel() = default;
+        explicit CanvasPanel(UObject* Obj)
+            : PanelWidget(Obj, ClassOf<CanvasPanel>(), DebugTag()) {}
+
+        // Returns an invalid CanvasPanelSlot if the call failed or the
+        // engine handed back null. Check it before using it -- the wrapper
+        // will refuse to dispatch and log, but silently doing nothing is
+        // not what you want out of a layout call.
+        auto AddChildToCanvas(UObject* Content) -> CanvasPanelSlot
+        {
+            struct P { UObject* Content; UObject* ReturnValue; } p{ Content, nullptr };
+            auto Result = CallForReturn(STR("AddChildToCanvas"), p, &P::ReturnValue);
+            return (Result && *Result) ? CanvasPanelSlot{ *Result } : CanvasPanelSlot{};
+        }
+    };
+}