place the selection panel beside what it describes

src/ui/ControlsPanel.h

@@ -7,6 +7,7 @@
 #include <QWidget>
 
 #include "ControlAction.h"
+#include "FloatingPanel.h"
 
 class GameWorldView;
 class QLabel;
@@ -29,7 +30,7 @@ class QVBoxLayout;
 // while the game is paused, so there is no tick to hang it on either. The rebuild is
 // skipped unless the resolved content actually differs, which is a vector of enums to
 // compare.
-class ControlsPanel : public QWidget
+class ControlsPanel : public QWidget, public FloatingPanel
 {
     Q_OBJECT
 
@@ -42,10 +43,11 @@ public:
     // Places the panel in the bottom-left corner of the game world view. It shares the
     // bottom edge with the build button bar rather than clearing its strip, the bar
     // being centered and sized to its buttons and so usually leaving the left free; it
-    // rises above the bar only when the two would otherwise overlap. `buildBarRect` is
-    // the bar's current geometry in the same coordinates, or a null rect when there is
-    // none to avoid (REQ-UI-CONTROLS-PANEL, REQ-UI-BUILD-BAR).
-    void anchorTo(const QRect& worldRect, const QRect& buildBarRect);
+    // rises above the bar only when the two would otherwise overlap
+    // (REQ-UI-CONTROLS-PANEL, REQ-UI-BUILD-BAR). The bar is the only thing placed before
+    // it, so it is the only rect it ever has to rise above.
+    void placeIn(const QRect& viewRect,
+                 const std::vector<QRect>& occupiedRects) override;
 
 protected:
     // Clicking the heading collapses and expands the panel (REQ-UI-CONTROLS-PANEL).
@@ -59,8 +61,8 @@ private:
     // The heading's "<name> * <detail>" text for the context, detail omitted when the
     // context has none.
     QString getHeadingText(const ControlContext& context) const;
-    // Re-fits the panel to its content within the anchored band.
-    void refit();
+    // Asks for the placement pass to be re-run, the panel's own size having changed.
+    void invalidateLayout();
 
     const GameWorldView* m_view;
 
@@ -82,9 +84,4 @@ private:
     // Survives context changes and simulation restarts; presentation only, never a
     // command (REQ-UI-CONTROLS-PANEL).
     bool m_collapsed = false;
-
-    // The world view the panel sits in, and the build button bar it steps around, both
-    // in the coordinates of its parent. Null until the owner has anchored it.
-    QRect m_worldRect;
-    QRect m_buildBarRect;
 };