Fix #9995: Adjust viewport zoom level for HiDPI displays

On HiDPI screens the zoom level is increased for detailed rendering. This causes hard-coded zoom levels to be off by this adjustment. To fix these default zoom levels, we scale the zoom level based on `_gui_zoom` to get the scaled zoom level.

src/industry_gui.cpp

@@ -837,7 +837,7 @@ public:
 
 		this->InitNested(window_number);
 		NWidgetViewport *nvp = this->GetWidget<NWidgetViewport>(WID_IV_VIEWPORT);
-		nvp->InitializeViewport(this, Industry::Get(window_number)->location.GetCenterTile(), ZOOM_LVL_INDUSTRY);
+		nvp->InitializeViewport(this, Industry::Get(window_number)->location.GetCenterTile(), ScaleZoomGUI(ZOOM_LVL_INDUSTRY));
 
 		this->InvalidateData();
 	}

src/main_gui.cpp

@@ -222,7 +222,7 @@ struct MainWindow : Window
 		ResizeWindow(this, _screen.width, _screen.height);
 
 		NWidgetViewport *nvp = this->GetWidget<NWidgetViewport>(WID_M_VIEWPORT);
-		nvp->InitializeViewport(this, TileXY(32, 32), ZOOM_LVL_VIEWPORT);
+		nvp->InitializeViewport(this, TileXY(32, 32), ScaleZoomGUI(ZOOM_LVL_VIEWPORT));
 
 		this->viewport->overlay = new LinkGraphOverlay(this, WID_M_VIEWPORT, 0, 0, 3);
 		this->refresh.SetInterval(LINKGRAPH_DELAY);

src/news_gui.cpp

@@ -310,7 +310,7 @@ struct NewsWindow : Window {
 		/* Initialize viewport if it exists. */
 		NWidgetViewport *nvp = this->GetWidget<NWidgetViewport>(WID_N_VIEWPORT);
 		if (nvp != nullptr) {
-			nvp->InitializeViewport(this, ni->reftype1 == NR_VEHICLE ? 0x80000000 | ni->ref1 : (uint32)GetReferenceTile(ni->reftype1, ni->ref1), ZOOM_LVL_NEWS);
+			nvp->InitializeViewport(this, ni->reftype1 == NR_VEHICLE ? 0x80000000 | ni->ref1 : (uint32)GetReferenceTile(ni->reftype1, ni->ref1),ScaleZoomGUI(ZOOM_LVL_NEWS));
 			if (this->ni->flags & NF_NO_TRANSPARENT) nvp->disp_flags |= ND_NO_TRANSPARENCY;
 			if ((this->ni->flags & NF_INCOLOUR) == 0) {
 				nvp->disp_flags |= ND_SHADE_GREY;

src/town_gui.cpp

@@ -40,6 +40,7 @@
 #include "table/strings.h"
 
 #include "safeguards.h"
+#include "zoom_func.h"
 
 TownKdtree _town_local_authority_kdtree(&Kdtree_TownXYFunc);
 
@@ -331,7 +332,7 @@ public:
 
 		this->flags |= WF_DISABLE_VP_SCROLL;
 		NWidgetViewport *nvp = this->GetWidget<NWidgetViewport>(WID_TV_VIEWPORT);
-		nvp->InitializeViewport(this, this->town->xy, ZOOM_LVL_NEWS);
+		nvp->InitializeViewport(this, this->town->xy, ScaleZoomGUI(ZOOM_LVL_TOWN));
 
 		/* disable renaming town in network games if you are not the server */
 		this->SetWidgetDisabledState(WID_TV_CHANGE_NAME, _networking && !_network_server);

src/vehicle_gui.cpp

@@ -2736,7 +2736,7 @@ public:
 		}
 		this->FinishInitNested(window_number);
 		this->owner = v->owner;
-		this->GetWidget<NWidgetViewport>(WID_VV_VIEWPORT)->InitializeViewport(this, this->window_number | (1 << 31), _vehicle_view_zoom_levels[v->type]);
+		this->GetWidget<NWidgetViewport>(WID_VV_VIEWPORT)->InitializeViewport(this, this->window_number | (1 << 31), ScaleZoomGUI(_vehicle_view_zoom_levels[v->type]));
 
 		this->GetWidget<NWidgetCore>(WID_VV_START_STOP)->tool_tip       = STR_VEHICLE_VIEW_TRAIN_STATUS_START_STOP_TOOLTIP + v->type;
 		this->GetWidget<NWidgetCore>(WID_VV_RENAME)->tool_tip           = STR_VEHICLE_DETAILS_TRAIN_RENAME + v->type;

src/viewport_gui.cpp

@@ -57,8 +57,8 @@ public:
 		this->InitNested(window_number);
 
 		NWidgetViewport *nvp = this->GetWidget<NWidgetViewport>(WID_EV_VIEWPORT);
-		nvp->InitializeViewport(this, 0, ZOOM_LVL_VIEWPORT);
-		if (_settings_client.gui.zoom_min == ZOOM_LVL_VIEWPORT) this->DisableWidget(WID_EV_ZOOM_IN);
+		nvp->InitializeViewport(this, 0, ScaleZoomGUI(ZOOM_LVL_VIEWPORT));
+		if (_settings_client.gui.zoom_min == viewport->zoom) this->DisableWidget(WID_EV_ZOOM_IN);
 
 		Point pt;
 		if (tile == INVALID_TILE) {

src/waypoint_gui.cpp

@@ -27,6 +27,7 @@
 #include "table/strings.h"
 
 #include "safeguards.h"
+#include "zoom_func.h"
 
 /** GUI for accessing waypoints and buoys. */
 struct WaypointWindow : Window {
@@ -70,7 +71,7 @@ public:
 		this->flags |= WF_DISABLE_VP_SCROLL;
 
 		NWidgetViewport *nvp = this->GetWidget<NWidgetViewport>(WID_W_VIEWPORT);
-		nvp->InitializeViewport(this, this->GetCenterTile(), ZOOM_LVL_VIEWPORT);
+		nvp->InitializeViewport(this, this->GetCenterTile(), ScaleZoomGUI(ZOOM_LVL_VIEWPORT));
 
 		this->OnInvalidateData(0);
 	}

src/zoom_func.h

@@ -79,6 +79,26 @@ static inline int UnScaleGUI(int value)
 	return UnScaleByZoom(value, ZOOM_LVL_GUI);
 }
 
+/**
+ * Scale zoom level relative to GUI zoom.
+ * @param value zoom level to scale
+ * @return scaled zoom level
+ */
+static inline ZoomLevel ScaleZoomGUI(ZoomLevel value)
+{
+	return std::clamp(ZoomLevel(value + (ZOOM_LVL_GUI - ZOOM_LVL_OUT_4X)), ZOOM_LVL_MIN, ZOOM_LVL_MAX);
+}
+
+/**
+ * UnScale zoom level relative to GUI zoom.
+ * @param value zoom level to scale
+ * @return un-scaled zoom level
+ */
+static inline ZoomLevel UnScaleZoomGUI(ZoomLevel value)
+{
+	return std::clamp(ZoomLevel(value - (ZOOM_LVL_GUI - ZOOM_LVL_OUT_4X)), ZOOM_LVL_MIN, ZOOM_LVL_MAX);
+}
+
 /**
  * Scale traditional pixel dimensions to GUI zoom level.
  * @param value Pixel amount at #ZOOM_LVL_BASE (traditional "normal" interface size).

src/zoom_type.h

@@ -35,7 +35,7 @@ enum ZoomLevel : byte {
 	ZOOM_LVL_VIEWPORT = ZOOM_LVL_OUT_4X, ///< Default zoom level for viewports.
 	ZOOM_LVL_NEWS     = ZOOM_LVL_OUT_4X, ///< Default zoom level for the news messages.
 	ZOOM_LVL_INDUSTRY = ZOOM_LVL_OUT_8X, ///< Default zoom level for the industry view.
-	ZOOM_LVL_TOWN     = ZOOM_LVL_OUT_8X, ///< Default zoom level for the town view.
+	ZOOM_LVL_TOWN     = ZOOM_LVL_OUT_4X, ///< Default zoom level for the town view.
 	ZOOM_LVL_AIRCRAFT = ZOOM_LVL_OUT_4X, ///< Default zoom level for the aircraft view.
 	ZOOM_LVL_SHIP     = ZOOM_LVL_OUT_4X, ///< Default zoom level for the ship view.
 	ZOOM_LVL_TRAIN    = ZOOM_LVL_OUT_4X, ///< Default zoom level for the train view.