Redraw connecting link graph overlay links when moving station sign

Add test console command

src/console_cmds.cpp

@@ -2282,6 +2282,26 @@ DEF_CONSOLE_CMD(ConViewportMarkDirty)
 	return true;
 }
 
+
+DEF_CONSOLE_CMD(ConViewportMarkStationOverlayDirty)
+{
+	if (argc != 2) {
+		IConsoleHelp("Debug: Mark main viewport link graph overlay station links.  Usage: 'viewport_mark_dirty_st_overlay <station-id>'");
+		return true;
+	}
+
+	if (_game_mode != GM_NORMAL && _game_mode != GM_EDITOR) {
+		return true;
+	}
+
+	const Station *st = Station::GetIfValid(atoi(argv[1]));
+	if (st == nullptr) return true;
+	MarkAllViewportOverlayStationLinksDirty(st);
+
+	return true;
+}
+
+
 DEF_CONSOLE_CMD(ConDoDisaster)
 {
 	if (argc == 0) {
@@ -2679,6 +2699,7 @@ void IConsoleStdLibRegister()
 	IConsoleCmdRegister("show_industry_window", ConShowIndustryWindow, nullptr, true);
 	IConsoleCmdRegister("viewport_debug", ConViewportDebug, nullptr, true);
 	IConsoleCmdRegister("viewport_mark_dirty", ConViewportMarkDirty, nullptr, true);
+	IConsoleCmdRegister("viewport_mark_dirty_st_overlay", ConViewportMarkStationOverlayDirty, nullptr, true);
 
 	/* NewGRF development stuff */
 	IConsoleCmdRegister("reload_newgrfs",  ConNewGRFReload, ConHookNewGRFDeveloperTool);

src/linkgraph/linkgraph_gui.cpp

@@ -16,6 +16,7 @@
 #include "../viewport_func.h"
 #include "../smallmap_gui.h"
 #include "../zoom_func.h"
+#include "../landscape.h"
 #include "../core/geometry_func.hpp"
 #include "../widgets/link_graph_legend_widget.h"
 
@@ -81,6 +82,29 @@ bool LinkGraphOverlay::CacheStillValid() const
 	}
 }
 
+void LinkGraphOverlay::MarkStationViewportLinksDirty(const Station *st)
+{
+	if (this->window->viewport) {
+		Viewport *vp = this->window->viewport;
+		const Point pt = RemapCoords2(TileX(st->xy) * TILE_SIZE, TileY(st->xy) * TILE_SIZE);
+		const int padding = ScaleByZoom(3 * this->scale, vp->zoom);
+		MarkViewportDirty(vp, pt.x - padding, pt.y - padding, pt.x + padding, pt.y - padding);
+
+		const int block_radius = ScaleByZoom(10, vp->zoom);
+		for (LinkList::iterator i(this->cached_links.begin()); i != this->cached_links.end(); ++i) {
+			if (i->from_id == st->index) {
+				const Station *stb = Station::GetIfValid(i->to_id);
+				if (stb == nullptr) continue;
+				MarkViewportLineDirty(vp, pt, RemapCoords2(TileX(stb->xy) * TILE_SIZE, TileY(stb->xy) * TILE_SIZE), block_radius);
+			} else if (i->to_id == st->index) {
+			const Station *sta = Station::GetIfValid(i->from_id);
+			if (sta == nullptr) continue;
+				MarkViewportLineDirty(vp, RemapCoords2(TileX(sta->xy) * TILE_SIZE, TileY(sta->xy) * TILE_SIZE), pt, block_radius);
+			}
+		}
+	}
+}
+
 /**
  * Rebuild the cache and recalculate which links and stations to be shown.
  */

src/linkgraph/linkgraph_gui.h

@@ -69,6 +69,7 @@ public:
 
 	void RebuildCache(bool incremental = false);
 	bool CacheStillValid() const;
+	void MarkStationViewportLinksDirty(const Station *st);
 	void Draw(const DrawPixelInfo *dpi);
 	void SetCargoMask(CargoTypes cargo_mask);
 	void SetCompanyMask(uint32 company_mask);

src/station_cmd.cpp

@@ -433,11 +433,15 @@ void Station::MoveSign(TileIndex new_xy)
 {
 	if (this->xy == new_xy) return;
 
+	MarkAllViewportOverlayStationLinksDirty(this);
+
 	_station_kdtree.Remove(this->index);
 
 	this->BaseStation::MoveSign(new_xy);
 
 	_station_kdtree.Insert(this->index);
+
+	MarkAllViewportOverlayStationLinksDirty(this);
 }
 
 /** Update the virtual coords needed to draw the station sign for all stations. */

src/viewport.cpp

@@ -259,7 +259,6 @@ struct ViewportDrawer {
 	Point foundation_offset[FOUNDATION_PART_END];    ///< Pixel offset for ground sprites on the foundations.
 };
 
-static void MarkViewportDirty(Viewport * const vp, int left, int top, int right, int bottom);
 static void MarkRouteStepDirty(RouteStepsMap::const_iterator cit);
 static void MarkRouteStepDirty(const TileIndex tile, uint order_nr);
 
@@ -3375,7 +3374,7 @@ void UpdateActiveScrollingViewport(Window *w)
  * @param bottom Bottom edge of area to repaint
  * @ingroup dirty
  */
-static void MarkViewportDirty(Viewport * const vp, int left, int top, int right, int bottom)
+void MarkViewportDirty(Viewport * const vp, int left, int top, int right, int bottom)
 {
 	/* Rounding wrt. zoom-out level */
 	right  += (1 << vp->zoom) - 1;
@@ -3479,6 +3478,22 @@ void MarkAllViewportMapsDirty(int left, int top, int right, int bottom)
 	}
 }
 
+/**
+ * Mark all viewport overlays for a specific station dirty (in need of repaint).
+ * @param st     Station
+ * @ingroup dirty
+ */
+void MarkAllViewportOverlayStationLinksDirty(const Station *st)
+{
+	Window *w;
+	FOR_ALL_WINDOWS_FROM_BACK(w) {
+		Viewport *vp = w->viewport;
+		if (vp != nullptr && vp->overlay != nullptr) {
+			vp->overlay->MarkStationViewportLinksDirty(st);
+		}
+	}
+}
+
 void ConstrainAllViewportsZoom()
 {
 	Window *w;
@@ -3522,6 +3537,40 @@ void MarkTileGroundDirtyByTile(TileIndex tile, const ZoomLevel mark_dirty_if_zoo
 	MarkAllViewportsDirty(top.x - TILE_PIXELS * ZOOM_LVL_BASE, top.y - TILE_HEIGHT * ZOOM_LVL_BASE, top.x + TILE_PIXELS * ZOOM_LVL_BASE, bot.y);
 }
 
+void MarkViewportLineDirty(Viewport * const vp, const Point from_pt, const Point to_pt, const int block_radius)
+{
+	int x1 = from_pt.x / block_radius;
+	int y1 = from_pt.y / block_radius;
+	const int x2 = to_pt.x / block_radius;
+	const int y2 = to_pt.y / block_radius;
+
+	/* http://en.wikipedia.org/wiki/Bresenham%27s_line_algorithm#Simplification */
+	const int dx = abs(x2 - x1);
+	const int dy = abs(y2 - y1);
+	const int sx = (x1 < x2) ? 1 : -1;
+	const int sy = (y1 < y2) ? 1 : -1;
+	int err = dx - dy;
+	for (;;) {
+		MarkViewportDirty(
+				vp,
+				(x1 - 2) * block_radius,
+				(y1 - 2) * block_radius,
+				(x1 + 2) * block_radius,
+				(y1 + 2) * block_radius
+		);
+		if (x1 == x2 && y1 == y2) break;
+		const int e2 = 2 * err;
+		if (e2 > -dy) {
+			err -= dy;
+			x1 += sx;
+		}
+		if (e2 < dx) {
+			err += dx;
+			y1 += sy;
+		}
+	}
+}
+
 void MarkTileLineDirty(const TileIndex from_tile, const TileIndex to_tile)
 {
 	assert(from_tile != INVALID_TILE);

src/viewport_func.h

@@ -33,9 +33,12 @@ Point GetTileBelowCursor();
 void UpdateViewportPosition(Window *w);
 void UpdateViewportSizeZoom(Viewport *vp);
 
+void MarkViewportDirty(Viewport * const vp, int left, int top, int right, int bottom);
 void MarkAllViewportsDirty(int left, int top, int right, int bottom, const ZoomLevel mark_dirty_if_zoomlevel_is_below = ZOOM_LVL_END);
 void MarkAllViewportMapsDirty(int left, int top, int right, int bottom);
+void MarkAllViewportOverlayStationLinksDirty(const Station *st);
 void MarkAllRouteStepsDirty(const Vehicle *veh);
+void MarkViewportLineDirty(Viewport * const vp, const Point from_pt, const Point to_pt, const int block_radius);
 void MarkTileLineDirty(const TileIndex from_tile, const TileIndex to_tile);
 void MarkAllRoutePathsDirty(const Vehicle *veh);
 void CheckMarkDirtyFocusedRoutePaths(const Vehicle *veh);