(svn r21018) -Doc: Add Doxygen comments to some function.

src/main_gui.cpp

@@ -128,8 +128,13 @@ void ShowNetworkGiveMoneyWindow(CompanyID company)
 #endif /* ENABLE_NETWORK */
 
 
-/* Zooms a viewport in a window in or out
- * No button handling or what so ever */
+/**
+ * Zooms a viewport in a window in or out.
+ * @param how Zooming direction.
+ * @param w   Window owning the viewport.
+ * @return Returns \c true if zooming step could be done, \c false if further zooming is not possible.
+ * @note No button handling or what so ever is done.
+ */
 bool DoZoomInOutWindow(ZoomStateChange how, Window *w)
 {
 	ViewPort *vp;

src/viewport.cpp

@@ -1886,11 +1886,21 @@ bool ScrollWindowTo(int x, int y, int z, Window *w, bool instant)
 	return true;
 }
 
+/**
+ * Scrolls the viewport of the main window to a given location.
+ * @param tile    Desired tile to center on.
+ * @param instant Jump to the location instead of slowly moving to it.
+ * @return Destination of the viewport was changed (to activate other actions when the viewport is already at the desired position).
+ */
 bool ScrollMainWindowToTile(TileIndex tile, bool instant)
 {
 	return ScrollMainWindowTo(TileX(tile) * TILE_SIZE + TILE_SIZE / 2, TileY(tile) * TILE_SIZE + TILE_SIZE / 2, -1, instant);
 }
 
+/**
+ * Set a tile to display a red error square.
+ * @param tile Tile that should show the red error square.
+ */
 void SetRedErrorSquare(TileIndex tile)
 {
 	TileIndex old;

src/viewport_type.h

@@ -51,10 +51,14 @@ struct ViewportSign {
 	void MarkDirty() const;
 };
 
+/**
+ * Directions of zooming.
+ * @see DoZoomInOutWindow
+ */
 enum ZoomStateChange {
-	ZOOM_IN   = 0,
-	ZOOM_OUT  = 1,
-	ZOOM_NONE = 2, // hack, used to update the button status
+	ZOOM_IN   = 0, ///< Zoom in (get more detailed view).
+	ZOOM_OUT  = 1, ///< Zoom out (get helicopter view).
+	ZOOM_NONE = 2, ///< Hack, used to update the button status.
 };
 
 /**